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Gross Anatomy

1. Gross Anatomy Class ANA 211

2. COURSE OUTLINE 1. Introduction To Anatomy Approaches to studying anatomy Anatomical Planes Anatomical Terms of Relationship and Comparison Kinesiology Joints and classification o f joints Movements o f joints Types o f muscles Attachment o f muscles

3. 2. Surface, Applied And Radiological Anatomy o f The Upper Limb and Lower Limb i . Upper Limb Bones o f upper limb Pectoral, scapular and deltoid regions Axilla and brachial plexus Arm and cubital f ossa forearm Hand Joints o f the upper limb Axilla and brachial plexus M ammary gland

4. ii. Lower Limb Bones o f lower limb Fascia, veins, lymphatics and cutaneous nerves o f lower limb Anterior and medial regions o f the thigh Gluteal and posterior thigh regions Popliteal f ossa and leg Foot Joints o f lower limb

5. INTRODUCTION TO HUMAN ANATOMY Human anatomy is a branch o f biology that deals with the study o f human body structure. Gross anatomy is a part o f anatomy that involves the study o f the body’s organs as seen with the naked eye during visual inspection and when the body is cut open f or examination. The three main approaches to studying anatomy are regional, systemic, and clinical (or applied), reflecting the body’s organization and the priorities and purposes for studying it

6. REGIONAL ANATOMY Regional anatomy (topographical anatomy) considers the organization of the human body as major parts or segments: a main body, consisting of the head, neck, and trunk (subdivided into thorax, abdomen, back, and pelvis/perineum), and paired upper limbs and lower limbs Regional anatomy also recognizes the body’s organization by layers: skin, subcutaneous tissue, and deep fascia covering the deeper structures of muscles, skeleton, and cavities , which contain viscera (internal organs)

7. Surface anatomy is an essential part of the study of regional anatomy. It provides knowledge of what lies under the skin and what structures are perceptible to touch (palpable) in the living body at rest and in action Physical examination is the clinical application of surface anatomy. Palpation is a clinical technique, used with observation and listening for examining the body Regional study of deep structures and abnormalities in a living person is now also possible by means of radiographic and sectional imaging and endoscopy. Radiographic and sectional imaging (radiographic anatomy)

8. SYSTEMIC ANATOMY Systemic anatomy is the study of the body’s organ systems that work together to carry out complex functions. The basic systems and the field of study or treatment of each are: The integumentary system (dermatology) consists of the skin (L. integumentum , a covering) and its appendages— hairs, nails, and sweat glands , The skeletal system (osteology) consists of bones and cartilage The articular system ( arthrology ) consists of joints and their associated ligaments The muscular system (myology) consists of skeletal muscles that act (contract) to move or position parts of the body The nervous system (neurology) consists of the central nervous system (brain and spinal cord) and the peripheral nervous system (nerves and ganglia, together with their motor and sensory endings)

9. The circulatory system (angiology) consists of the cardio vascular and lymphatic systems, which function in parallel to transport the body’s fluids The cardiovascular system (cardiology) consists of the heart and blood vessels that propel and conduct blood through the body, delivering oxygen, nutrients, and hormones to cells and removing their waste product The lymphatic system is a network of lymphatic vessels that withdraws excess tissue fluid (lymph) from the body’s interstitial (intercellular) fluid compartment, filters it through lymph nodes, and returns it to the bloodstream.

10. The alimentary or digestive system (gastroenterology) consists of the digestive tract from the mouth to the anus, with all its associated organs and glands The respiratory system (pulmonology) consists of the air passages and lungs that supply oxygen to the blood for cellular respiration and eliminate carbon dioxide from it. The urinary system (urology) consists of the kidneys, ureters, urinary bladder, and urethra, which filter blood and subsequently produce, transport, store, and intermittently excrete urine (liquid waste ).

11. The genital (reproductive) system (gynecology for females; andrology for males) consists of the gonads ( ovaries and testes) that produce oocytes (eggs) and sperms, the ducts that transport them, and the genitalia that enable their union The endocrine system (endocrinology) consists of specialized structures that secrete hormones

12. CLINICAL ANATOMY Clinical anatomy (applied anatomy) emphasizes aspects of bodily structure and function important in the practice of medicine, dentistry, and the allied health sciences. It incorporates the regional and systemic approaches to studying anatomy and stresses clinical application. Clinical anatomy often involves inverting or reversing the thought process typically followed when studying regional or systemic anatomy.

13. ANATOMICAL PLANES Anatomical descriptions are based on four imaginary planes (median, sagittal, frontal, and transverse ) The median plane (median sagittal plane), the vertical plane passing longitudinally through the body, divides the body into right and left halves Sagittal planes are vertical planes passing through the body parallel to the median plane . Frontal (coronal) planes are vertical planes passing through the body at right angles to the median plane, dividing the body into anterior (front) and posterior (back) parts. • Transverse planes are horizontal planes passing through the body at right angles to the median and frontal planes, dividing the body into superior (upper) and inferior (lower) parts

14. The main use of anatomical planes is to describe sections: • Longitudinal sections run lengthwise or parallel to the long axis of the body or of any of its parts, and the term applies regardless of the position of the body Transverse sections, or cross sections, are slices of the body or its parts that are cut at right angles to the longitudinal axis of the body or of any of its parts . Oblique sections are slices of the body or any of its parts that are not cut along the previously listed anatomical planes

15. Anatomical Terms o f Relationship and Comparison These terms describe the position o f structures or locations in the body. Superior or cranial- toward the head end o f the body; upper. Inferior or caudal – away from the head; lower. Anterior or ventral – front. Posterior or dorsal – back. Medial – towards the midline o f the body. Lateral – towards the side o f the body Proximal – toward or nearest the trunk or the point o f origin o f a part. Distal – away f rom or f arthest f rom the trunk or the point o f origin o f a part. Superficial – closer to the surface o f the body Deep – f urther from the surface o f the body

16. Anatomical Terms o f Movement (kinesiology) Kinesiology is the study o f movement. Flexion indicates bending or decreasing the angle between the bones or parts of the body Extension indicates straightening or increasing the angle between the bones or parts of the body Abduction means moving away from the median plane Adduction means moving towards the median plane Circumduction is a circular movement that involves sequential flexion , abduction, extension, and adduction (or in the opposite order) in such a way that the distal end of the part moves in a circle

17. Rotation involves turning or revolving a part of the body around its longitudinal axis, such as turning one’s head to face sideways Pronation rotates the radius medially so that the palm of the hand faces posteriorly and its dorsum faces anteriorly . Supination is the opposite rotational movement, rotating the radius laterally and uncrossing it from the ulna, returning the pronated forearm to the anatomical position

18. Classi f ication o f Joints Joints are unions or junctions between two or more bones or rigid parts of the skeleton Three classes of joints are described, based on the manner or type of material by which the articulating bones are united. 1 . The articulating bones of synovial joints are united by a joint (articular) capsule (composed of an outer fibrous layer lined by a serous synovial membrane) spanning and enclosing an articular cavity 2. The articulating bones of fibrous joints are united by fibrous tissue. The amount of movement occurring at a fibrous joint depends in most cases on the length of the fibers uniting the articulating bones . 3. The articulating structures of cartilaginous joints are united by hyaline cartilage or fibrocartilage .

19. Movement o f Joints The movement of joint is based on the type o f synovial joint at that part of the body. There are six types o f synovial joints. These are: Plane joints permit gliding or sliding movements in the plane of the articular surfaces. An example is the acromioclavicular joint between the acromion of the scapula and the clavicle Hinge joints permit flexion and extension only, movements that occur in one plane (sagittal) around a single axis that runs transversely. The elbow joint is a hinge joint Saddle joints permit abduction and adduction as well as flexion and extension, movements occurring around two axes at right angles to each other. The carpometacarpal joint at the base of the 1st digit (thumb) is a saddle joint.

20. Condyloid joints permit flexion and extension as well as abduction and adduction; The metacarpophalangeal joints (knuckle joints) are condyloid joint Ball and socket joints allow movement in multiple axes and planes: flexion and extension, abduction and adduction, medial and lateral rotation, and circumduction. The hip joint is a ball and socket joint Pivot joints permit rotation around a central axis

21. Types o f muscles The muscular system consists of all the muscles of the body. There are three muscle types : 1 . Skeletal striated muscle is voluntary somatic muscle that makes up the gross skeletal muscles that compose the muscular system, moving or stabilizing bones and other structures. 2 . Cardiac striated muscle is involuntary visceral muscle that forms most of the walls of the heart and adjacent parts of the great vessels, such as the aorta, and pumps blood. 3 . Smooth muscle ( unstriated muscle) is involuntary visceral muscle that forms part of the walls of most vessels and hollow organs (viscera), moving substances through them by coordinated sequential contractions (pulsations or peristaltic contractions).

22. Attachment o f muscle All skeletal muscles, commonly referred to simply as “muscles,” have fleshy , reddish, contractile portions (one or more heads or bellies) composed of skeletal striated muscle. Some muscles are fleshy throughout, but most also have white non-contractile portions (tendons), composed mainly of organized collagen bundles, that provide a means of attachment When referring to the length of a muscle, both the belly and the tendons are included. In other words, a muscle’s length is the distance between its attachments. Most skeletal muscles are attached directly or indirectly to bones, cartilages , ligaments, or fascias or to some combination of these structures. Some muscles are attached to organs (the eyeball , for example), skin (such as facial muscles), and mucous membranes (intrinsic tongue muscles).

23. Muscles may be described or classified according to their shape, for which a muscle may also be named: • Flat muscles have parallel fibers often with aponeurosis. The sartorius is a narrow flat muscle with parallel fibers • Pennate muscles are feather-like for example, extensor digitorum longus, rectus femoris , and deltoid. • Fusiform muscles are spindle shaped with a round, thick belly (or bellies) and tapered ends for example, biceps brachii . • Convergent muscles arise from a broad area and converge to form a single tendon for example, pectoralis major.

24. Quadrate muscles have four equal sides for example, the rectus abdominis. Circular or sphincteral muscles surround a body opening or orifice, constricting it when contracted for example, orbicularis oculi (closes the eyelids). Multiheaded or multibellied muscles have more than one head of attachment or more than one contractile belly, respectively. Biceps muscles have two heads of attachment (e.g., biceps brachii ), triceps muscles have three heads (e.g., triceps brachii ), and the digastric and gastrocnemius muscles have two bellies.

25. THE UPPER LIMB The upper limb is characterized by its mobility and ability to grasp, strike and conduct fine motor skills (manipulation). It is divided into shoulder, arm, forearm and hand. The shoulder: this is the proximal segment of the upper limb that overlaps parts of the trunk (thorax and back) and lower lateral neck. It includes the pectoral, scapular and deltoid regions of the upper limb and the lateral part (supraclavicular fossa) o f the lateral cervical region. It overlies half o f the pectoral girdle.

26. Arm: this is the first segment of the free upper limb and the longest segment of the limb. It extends between and connects the shoulder and the elbow and consists of anterior and posterior regions of the arm, centered around the humerus . Forearm: second longest segment of the limb. It extends between and connects the elbow and the wrist and includes anterior and posterior regions of the f orearm overlying the radius and ulna. Hand : part of the upper limb distal to the forearm that is formed around the carpus, metacarpus and phalanges. It is composed of the wrist, palm, dorsum of hand and digits and is richly supplied with sensory endings f or touch, pain and temperature .

27. Bones of the Upper Limb Clavicle (collar bone): this connects the upper limb to the trunk. The sha f t o f the clavicle has a double curve in a horizontal plane. Its medial two thirds is convex anterior , and its sternal end is enlarged and triangular where it articulates with the manubrium o f the sternum at the sternoclavicular (SC) joint . Its lateral third is flattened and concave anteriorly , and its acromial end is f lat where it articulates with the acromium o f the scapula at the a cromioclavicular (AC) joint. These curvatures gives the clavicle its elongated capital S shape.

28. The superior surface of the clavicle lying just deep to the skin and platysma muscle in the subcutaneous tissue is smooth while the inferior surface is rough because strong ligaments bind it to the first rib near its sternal end and suspend the scapula from its acromial end. The conoid tubercle , near the acromial end of the clavicle gives attachment to the conoid ligament , the medial part of the coracoclavicular ligament by which the remainder of the upper limb is passively suspended from the clavicle. Also , near the acromial end of the clavicle is the trapezoid line , to which the trapezoid ligament attaches; it is the lateral part of the coracoclavicular ligament.

29. The subclavian groove in the medial third of the clavicle is the site for the attachment of the subclavius muscle . More medially, is the impression for the costoclavicular ligament (costal tuberosity) which gives attachment to the ligament binding the first rib to the clavicle, limiting elevation of the shoulder.

30. Scapula The scapula is the triangular flat bone that lies on the posterolateral aspect of the thorax, overlying the 2nd and 7 th ribs the convex posterior surface of the scapula is unevenly divided by a thick projecting ridge of the bone, the spine o f the scapula, into a small supraspinous fossa and a much larger infraspinous fossa . The concave costal surface o f most o f the scapula f orms a large subscapular f ossa . The broad bony surfaces o f the three f ossae provides attachments f or f leshy muscles. The spine continues laterally as the f lat, expanded acromium which articulates with the acromial end o f the clavicle. The deltoid tubercle o f the scapular spine indicates the medial point of attachment o f the deltoid muscle. The spine and acromium serves as levers f or the attached muscles, particularly the trapezius .

31. Superiolaterally , the surface o f the scapula has a glenoid cavity, which receives and articulates with the head o f the humerus at the glenohumeral joint . The glenoid cavity is a shallow, concave, oval f ossa, directed anterolaterally and slightly superior. The break-like coracoid process is superior to the glenoid cavity and projects anterolaterally . T his process provides the in f erior attachment f or the passively supporting coracoclavicular ligament.

32. The scapula has medial , lateral , and superior borders and superior , lateral and inferior angles . When the scapular body is in the anatomical position, the thin medial border of the scapula runs parallel to and approximately 5cm lateral to the spinous processes of the thoracic vertebrae; hence it is often called the vertebral border . The superior border of the scapula is marked by the suprascapular notch , which is located where the superior border joins the base of the coracoid process

33. Humerus The humerus is the largest bone in the upper limb, articulates with the scapula at the glenohumeral joint and the radius and the ulna at the elbow joint. The proximal end o f the humerus has a head, surgical and anatomical necks and greater and lesser tubercles . The spherical head o f the humerus articulates with the glenoid cavity o f the scapula. The anatomical neck is f ormed by the groove circumscribing the head and separating it f rom the greater and lesser tubercles. It indicates the line o f attachment o f the glenohumeral joint capsule . The surgical neck o f the humerus , a common site o f f racture, is the narrow part distal to the head and tubercles.

34. The junction of the head and neck with the shaft of the humerus is indicated by the greater and lesser tubercles, which provide attachment and leverage to some scapulohumeral muscles . The greater tubercle is at the lateral margin of the humerus , whereas the lesser tubercle projects anteriorly from the bone. The intertubercular sulcus (bicipital groove) seperates the tubercles and provides protected passage for the slender tendon of the long head of the biceps muscle .

35. The sha f t o f the humerus has two prominent f eatures; the deltoid tuberosity laterally, for attachment o f the deltoid muscle and the oblique radial groove (groove or the radial, spiral groove) posteriorly. The in f erior end o f the humeral sha f t widens as the sharp medial and lateral supra- epicondylar (supracondylar ) ridges f orm and then end distally in the especially prominent medial epicondyle and the lateral epicondyle , providing f or muscle attachment f or the anterior ( f lexor) and posterior (extensor) muscle o f the f orearm.

36. The distal end of the humerus including the trochlea and capitulum , as well as the olecranon , coronoid and radial fossae makes up the condyle of the humerus . The condyle has two articular surfaces: a lateral capitulum for articulation with the head of the radius and a medial pulley-like trochlea for articulation with the proximal end (trochlear notch) of the ulna. Two fossae (hollows) occur back to back superior to the trochlea, making the condyle quite thin between the epicondyles.

37. Anteriorly, the coronoid fossa receives the coronoid process of the ulna during full flexion of the elbow. Posteriorly, the olecranon fossa accommodates the olecranon of the ulna during full extention of the elbow. Superior to the capitulum anteriorly, a shallower radial fossa accommodates the edge of the head of the radius when the forearm is fully flexed.

38. Bones o f the Forearm Ulna The ulna is the stabilizing bone of the forearm and is the medial and longer of the two forearm bones. It articulates with the humerus proximally and with the radius laterally. For articulation with the humerus , the ulna has two prominent projections: (1) the olecranon , which projects proximally from its posterior aspect (forming the point of the elbow), and serves as a short lever for extension of the elbow, and (2) the coronoid process , which projects anteriorly. The olecranon and coronoid processes form the walls of the trochlear notch The articulation between the ulna and humerus primarily allows only flexion and extension of the elbow joint Inferior to the coronoid process is the tuberosity of the ulna for attachment of the tendon of the brachialis muscle

39. On the lateral side of the coronoid process is a smooth, rounded concavity, the radial notch , which receives the broad periphery of the head of the radius. Inferior to the radial notch on the lateral surface of the ulnar shaft is a prominent ridge, the supinator crest . Between it and the distal part of the coronoid process is a concavity, the supinator fossa . The deep part of the supinator muscle attaches to the supinator crest and fossa. At the narrow distal end of the ulna is a small but abrupt enlargement, the ulnar styloid process . The ulna does not reach and therefore does not participate in the wrist (radiocarpal) joint

40. Radius The radius is the lateral and shorter of the two forearm bones. Its proximal end includes a short head, neck, and medially directed tuberosity, Proximally , the smooth superior aspect of the discoid head of the radius is concave for articulation with the capitulum of the humerus during flexion and extension of the elbow joint . The head also articulates peripherally with the radial notch of the ulna; thus the head is covered with articular cartilage

41. The oval radial tuberosity is distal to the medial part of the neck, and demarcates the proximal end (head and neck) of the radius from the shaft . The distal end of the radius is essentially four sided when sectioned transversely . Its medial aspect forms a concavity, the ulnar notch which accommodates the head of the ulna . Its lateral aspect becomes increasingly ridge-like, terminating distally in the radial styloid process ( The radial styloid process is larger than the ulnar styloid process, and extends farther distally). Projecting dorsally, the dorsal tubercle of the radius lies between otherwise shallow grooves for the passage of the tendons of forearm muscles.

42. Bones o f the Hand The wrist, or carpus , is composed of eight carpal bones, arranged in proximal and distal rows of four. These small bones give flexibility to the wrist. The carpus is markedly convex from side to side posteriorly, and concave anteriorly. Augmenting movement at the wrist joint, the two rows of carpal bones glide on each other; in addition, each bone glides on those adjacent to it.

43. From lateral to medial, the four carpal bones in the proximal row are the : Scaphoid: a boat-shaped bone that articulates proximally with the radius, and has a prominent scaphoid tubercle; it is the largest bone in the proximal row of carpals . Lunate : a moon-shaped bone between the scaphoid and the triquetral bones; it articulates proximally with the radius and is broader anteriorly than posteriorly. Triquetrum: a pyramidal bone on the medial side of the carpus; it articulates proximally with the articular disc of the distal radio-ulnar joint . Pisiform: a small, pea-shaped bone that lies on the palmar surface of the triquetrum.

44. From lateral to medial, the four carpal bones in the distal row are the: Trapezium: a four-sided bone on the lateral side of the carpus; it articulates with the 1st and 2nd metacarpals, scaphoid, and trapezoid bones. Trapezoid : a wedge-shaped bone that resembles the trapezium ; it articulates with the 2nd metacarpal, trapezium, capitate, and scaphoid bones. Capitate: a head-shaped bone with a rounded extremity, it is the largest bone in the carpus; it articulates primarily with the 3rd metacarpal distally, and with the trapezoid, scaphoid, lunate, and hamate. Hamate: a wedge-shaped bone on the medial side of the hand; it articulates with the 4th and 5th metacarpal, capitate, and triquetral bones; it has a distinctive hooked process, the hook of the hamate, that extends anteriorly.

45. The metacarpus forms the skeleton of the palm of the hand between the carpus and the phalanges . It is composed of five metacarpal bones (metacarpals). Each metacarpal consists of a base, shaft, and head. The proximal bases of the metacarpals articulate with the carpal bones, and the distal heads of the metacarpals articulate with the proximal phalanges , and form the knuckles of the hand. The 1st metacarpal (of the thumb) is the thickest and shortest of these bones. The 3rd metacarpal is distinguished by a styloid process on the lateral side of its base.

46. Each digit (finger) has three phalanges except for the first (the thumb), which has only two; however, the phalanges of the first digit are stouter than those in the other fingers. Each phalanx has a base proximally, a shaft (body), and a head distally. The proximal phalanges are the largest, the middle ones are intermediate in size, and the distal ones are the smallest. The shafts of the phalanges taper distally. The terminal phalanges are flattened and expanded at their distal ends, which underlie the nail beds

47. Joints of t he Upper Limb The sternoclavicular (SC) joint is a saddle type of synovial joint. The SC joint is the only articulation between the upper limb and the axial skeleton, and it can be readily palpated because the sternal end of the clavicle lies superior to the manubrium of the sternum

48. Articulation of Sternoclavicular Joint The sternal end of the clavicle articulates with the manubrium and the 1st costal cartilage (cartilage associated with the first rib). The articular surfaces are covered with fibrocartilage .

49. Joint Capsule of Sternoclavicular Joint The joint capsule of the SC joint extends to the borders of the articular surfaces. It is lined internally by a synovial membrane, which produces synovial fluid to reduce friction between the articulating structures.

50. Ligaments of Sternoclavicular Joint Anterior and posterior sternoclavicular ligaments reinforce the joint capsule anteriorly and posteriorly . The interclavicular ligament strengthens the capsule superiorly. It extends from the sternal end of one clavicle to the sternal end of the other clavicle. In between, it is also attached to the superior border of the manubrium. The costoclavicular ligament anchors the inferior surface of the sternal end of the clavicle to the 1st rib and its costal cartilage, limiting elevation of the pectoral girdle

51. Movements of Sternoclavicular Joint Elevation of the shoulders- shrugging the shoulders or abducting the arm over 90° Depression of the shoulders- drooping shoulders or extending the arm at the shoulder behind the body Protraction of the shoulders- moving the shoulder girdle anteriorly Retraction of the shoulders- moving the shoulder girdle posteriorly Rotation –when the arm is raised over the head, the clavicle rotates passively as the scapula

52. Blood and Nerve Supply of Sternoclavicular Joint The SC joint is supplied by the internal thoracic and suprascapular arteries Branches of the medial supraclavicular nerve and the nerve to the subclavius supply the SC joint

53. Acromioclavicular Joint The acromioclavicular joint (AC joint) is a plane type of synovial joint, between the clavicle and the acromiom of the scapula

54. Articulation of Acromioclavicular Joint The acromial end of the clavicle articulates with the acromion of the scapula. The articular surfaces, covered with fibrocartilage , are separated by an incomplete wedge-shaped articular disc.

55. Joint Capsule of Acromioclavicular Joint The joint capsule of the AC joint encloses the two articular surfaces. It consists of a loose layer of fibrous tissue, which is lined internally by a synovial membrane. The posterior aspect of the joint capsule is reinforced by fibers from the trapezius muscle

56. Ligaments of Acromioclavicular Joint The acromioclavicular ligament is a fibrous band extending from the acromion to the clavicle that strengthens the AC joint superiorly. The coracoclavicular ligament is a strong pair of bands that unite the coracoid process of the scapula to the clavicle, anchoring the clavicle to the coracoid process . The coracoclavicular ligament consists of two ligaments, the conoid and trapezoid ligaments , which are often separated by a bursa . The conoid ligament runs vertically from the coracoid process of the scapula to the conoid tubercle of the clavicle The trapezoid ligament runs from the coracoid process of the scapula to the trapezoid line of the clavicle

57. Movements of Acromioclavicular Joint The acromioclavicular joint allows a gliding movement in the superior/inferior and anteroposterior planes, along with a small amount of axial rotation. As no muscle acts directly on the joint, all movements are passive, and are initiated by movement at other joints.

58. Blood Supply and Nerve Supply of Acromioclavicular Joint The AC joint is supplied by the suprascapular and thoracoacromial arteries The lateral pectoral and axillary nerves supply the AC joint. I nnervation is also provided to the AC joint by the cutaneous lateral supraclavicular nerve

59. Glenohumeral Joint The glenohumeral (shoulder) joint is a ball-and-socket type of synovial joint that permits a wide range of movement; however, its mobility makes the joint relatively unstable.

60. Articulation of Glenohumeral Joint The large, round humeral head articulates with the relatively shallow glenoid cavity of the scapula, which is deepened slightly but effectively by the ring-like, fibrocartilaginous glenoid labrum . Both articular surfaces are covered with hyaline cartilage

61. Joint Capsule of Glenohumeral Joint The loose fibrous layer of the joint capsule surrounds the glenohumeral joint and is attached medially to the margin of the glenoid cavity and laterally to the anatomical neck of the humerus . The synovial membrane lines the inner surface of the capsule and produces synovial fluid to reduce friction between the articular surfaces.

62. Ligaments of Glenohumeral Joint Ligaments play an important role in stabilising the shoulder joint: Glenohumeral ligaments  (superior, middle and inferior) – extend from the humerus to the glenoid fossa, reinforcing the joint capsule. They act to stabilise the anterior aspect of the joint. Coracohumeral ligament  – extends from the base of the coracoid process to the greater tubercle of the humerus . It supports the superior part of the joint capsule. Transverse humeral ligament  – extends between the two tubercles of the humerus . It holds the tendon of the long head of the biceps in the intertubercular groove. Coracoacromial ligament  – extends between the acromion and coracoid process of the scapula, forming an arch-like structure over the shoulder joint ( coracoacromial arch). This resists superior displacement of the humeral head.

63. Bursae A  bursa  is a synovial fluid filled sac, which acts as a cushion between tendons and other joint structures. There are several bursae present in the shoulder joint: Subacromial   – located deep to the deltoid and acromion, and superficial to the supraspinatus tendon and joint capsule. It reduces friction beneath the deltoid, promoting free motion of the rotator cuff tendons. Subscapular  – located between the subscapularis tendon and the scapula. It reduces friction on the tendon during movement at the shoulder joint. There are other minor bursae present between the tendons of the muscles around the joint.

64. Movements and Muscles that Permit Movement of Glenohumeral Joint The shoulder joint is an extremely  mobile  joint, with a wide range of movement possible: Extension (upper limb backwards in sagittal plane)  – posterior deltoid, latissimus dorsi and teres major. Flexion (upper limb forwards in sagittal plane)  –  pectoralis major, anterior deltoid and coracobrachialis . Biceps brachii weakly assists in forward flexion. Abduction (upper limb away from midline in coronal plane): The first 0-15 degrees of abduction is produced by the supraspinatus. The middle fibres of the deltoid are responsible for the next 15-90 degrees. Past 90 degrees, the scapula needs to be rotated to achieve abduction – that is carried out by the trapezius and serratus anterior.

65. Adduction (upper limb towards midline in coronal plane)  –  pectoralis major, latissimus dorsi and teres major. Internal rotation (rotation towards the midline, so that the thumb is pointing medially)  –  subscapularis , pectoralis major, latissimus dorsi , teres major and anterior deltoid. External rotation (rotation away from the midline, so that the thumb is pointing laterally)  – infraspinatus and teres minor. Circumduction (moving the upper limb in a circle)  – produced by a combination of the movements described above.

66. Blood and Nerve Supply of Glenohumeral Joint The glenohumeral joint is supplied by the anterior and posterior circumflex humeral arteries and branches of the suprascapular artery The suprascapular , axillary, and lateral pectoral nerves supply the glenohumeral joint

67. Elbow Joint The elbow joint, a hinge type of synovial joint, it is the joint connecting the upper arm to the forearm

68. Articulation of Elbow Joint The elbow joint consists of two separate articulations: Trochlear notch of the  ulna  and the trochlea of the  humerus Head of the  radius  and the capitulum of the  humerus

69. Joint Capsule of Elbow Joint The fibrous layer of the joint capsule surrounds the elbow joint. It is attached to the humerus at the margins of the lateral and medial ends of the articular surfaces of the capitulum and trochlea. Anteriorly and posteriorly , it is carried superiorly, proximal to the coronoid and olecranon fossae. The synovial membrane lines the internal surface of the fibrous layer of the capsule and the intracapsular non articular parts of the humerus . It is also continuous inferiorly with the synovial membrane of the proximal radio-ulnar joint. The joint capsule is weak anteriorly and posteriorly but is strengthened on each side by collateral ligaments

70. Ligaments of Elbow Joint The joint capsule of the elbow is strengthened by ligaments medially and laterally. The  radial collateral  ligament is found on the lateral side of the joint, extending from the  lateral epicondyle , and blending with the annular ligament of the radius (a ligament from the proximal radioulnar joint). The  ulnar collateral  ligament originates from the  medial epicondyle , and attaches to the coronoid process and olecranon of the ulna.

71. Movements and Muscles that allow Movement at the Elbow Joint The orientation of the bones forming the elbow joint produces a hinge type synovial joint, which allows for extension and flexion of the forearm: Extension  – triceps brachii and anconeus Flexion  – brachialis, biceps brachii , brachioradialis Note – pronation and supination do not occur at the elbow – they are produced at the nearby  radioulnar joints .

72. Blood and Nerve Supply Of Elbow Joint The arteries supplying the elbow joint are derived from the anastomosis around the elbow joint which is formed by branches of the  brachial artery . The elbow joint is supplied by the musculocutaneous, radial, and ulnar nerves

73. Proximal Radio-Ulnar Joint The proximal (superior) radio-ulnar joint is a pivot type of synovial joint that allows movement of the head of the radius on the ulna

74. Articulation of Proximal Radio-ulnar Joint The head of the radius articulates with the radial notch of the ulna. The radial head is held in position by the anular ligament of the radius.

75. Joint Capsule of Proximal Radio-ulnar Joint The fibrous layer of the joint capsule encloses the joint and is continuous with that of the elbow joint. The synovial membrane lines the deep surface of the fibrous layer and non-articulating aspects of the bones. The synovial membrane is an inferior prolongation of the synovial membrane of the elbow joint

76. Ligaments of Proximal Radio-ulnar Joint The strong anular ligament, attached to the ulna anterior and posterior to its radial notch, surrounds the articulating bony surfaces and forms a collar that, with the radial notch, creates a ring that completely encircles the head of the radius. The deep surface of the anular ligament is lined with synovial membrane, which continues distally as a sacciform recess of the proximal radio-ulnar joint on the neck of the radius. This arrangement allows the radius to rotate within the anular ligament without binding, stretching, or tearing the synovial membrane

77. Movements of Proximal Radio-ulnar Joint Movement is produced by the head of the radius rotating within the annular ligament. There are two movements possible at this joint; pronation and supination. Pronation : Produced by the pronator quadratus and pronator teres . Supination :  Produced by the supinator and biceps brachii .

78. Blood and Nerve Supply of Proximal Radio-ulnar Joint The proximal radio-ulnar joint is supplied by the radial portion of the peri -articular arterial anastomosis of the elbow joint: Brachial artery branches Deep brachial artery branches Radial artery branches Ulna artery branches The proximal radio-ulnar joint is supplied mainly by the musculocutaneous, median, and radial nerves. Pronation is essentially a function of the median nerve, whereas supination is a function of the musculocutaneous and radial nerves.

79. Distal Radioulnar Joint The distal (inferior) radio-ulnar joint is a pivot type of synovial joint. It is the joint between the ulnar notch of the radius and the distal ulnar head

80. Articular surfaces Distal head of ulna, ulnar notch of radius

81. Ligaments of Distal Radio-ulnar Joint Anterior and posterior ligaments strengthen the fibrous layer of the joint capsule of the distal radio-ulnar joint.

82. MOVEMENTS OF DISTAL RADIO-ULNAR JOINT Pronation : Produced by the pronator quadratus and pronator teres Supination :  Produced by the supinator and biceps brachii

83. BLOOD SUPPLY: The anterior and posterior interosseous arteries supply the distal radio-ulnar joint INNERVATION: The anterior and posterior interosseous nerves supply the distal radio-ulnar joint

84. The Wrist ( Radiocarpal ) Joint The wrist (radiocarpal) joint is a condyloid type of synovial joint . It is an articulation between the radius and the carpal bones of the hand.

85. Articulating Surfaces The   wrist joint  is formed by an articulation between: Distal end of the radius and the articular disc above the Proximal row of the carpal bones (except the pisiform).

86. Joint Capsule The  joint capsule  of the wrist joint attaches to the radius, ulna and the proximal row of the carpal bones. It is lined internally by a  synovial membrane , which produces synovial fluid to reduce friction between the articulating structures.

87. Ligaments There are four main ligaments located at the wrist joint: Palmar radiocarpal   – located on the palmar (anterior) side of the joint. It passes from the radius to both rows of carpal bones. Its function, apart from increasing stability, is to ensure that the hand follows the forearm during supination. Dorsal radiocarpal  – Found on the dorsum (posterior) side of the hand. It passes from the radius to both rows of carpal bones. It contributes to the stability of the wrist, but also ensures that the hand follows the forearm during pronation. Ulnar collateral  – Runs from the ulnar styloid process to the triquetrum and pisiform. It acts to prevent excessive radial (lateral) deviation of the hand. Radial collateral  – Runs from the radial styloid process to the scaphoid and trapezium. It acts to prevent excessive ulnar (medial) deviation of the hand.

88. Movements All the movements of the wrist are performed by the muscles of the forearm. Flexion   –  Produced mainly by the flexor carpi ulnaris , flexor carpi radialis , with assistance from the flexor digitorum superficialis . Extension   –  Produced mainly by the extensor carpi radialis longus and brevis , and extensor carpi ulnaris , with assistance from the extensor digitorum . Adduction   –  Produced by the extensor carpi ulnaris and flexor carpi ulnaris Abduction   –  Produced by the abductor pollicis longus , flexor carpi radialis , extensor carpi radialis longus and brevis .

89. Blood Supply: The arteries supplying the wrist joint are branches of the dorsal and palmar carpal arches Innervation: Innervation to the wrist is delivered by branches of three nerves: Median nerve  – Anterior interosseous branch. Radial nerve  – Posterior interosseous branch. Ulnar nerve  – deep and dorsal branches.

90. The Intercarpal (IC) Joints The intercarpal (IC) joints, interconnecting the carpal bones, are plane synovial joints, which may be summarized as follows: Joints between the carpal bones of the proximal row. Joints between the carpal bones of the distal row The midcarpal joint, a complex joint between the proximal and distal rows of carpal bones . The pisotriquetral joint, formed from the articulation of the pisiform with the palmar surface of the triquetrum

91. Joint Capsule of Intercarpal Joints: The fibrous layer of the joint capsule surrounds the IC joints, which helps unite the carpals. The synovial membrane lines the fibrous layer and is attached to the margins of the articular surfaces of the carpals Ligaments of Intercarpal Joints: The carpals are united by anterior, posterior, and interosseous ligament

92. Movements of Intercarpal Joints The gliding movements possible between the carpals occur concomitantly with movements at the wrist joint, augmenting them and increasing the overall range of movement. Flexion and extension of the hand are actually initiated at the midcarpal joint, between the proximal and the distal rows of carpals. Most flexion and adduction occur mainly at the wrist joint, whereas extension and abduction occur primarily at the midcarpal joint. Movements at the other IC joints are small, with the proximal row being more mobile than the distal row

93. Blood Supply of Intercarpal Joints: The arteries supplying the IC joints are derived from the dorsal and palmar carpal arches Innervation of Intercarpal Joints: The IC joints are supplied by the anterior interosseous branch of the median nerve and the dorsal and deep branches of the ulnar nerve.

94. The Carpometacarpal (CMC) and Intermetacarpal (IM) Joints The carpometacarpal (CMC) and intermetacarpal (IM) joints are the plane type of synovial joint, except for the CMC joint of the thumb, which is a saddle joint

95. Articulations of Carpometacarpal and Intermetacarpal Joints The distal surfaces of the carpals of the distal row articulate with the carpal surfaces of the bases of the metacarpals at the CMC joints. The important CMC joint of the thumb is between the trapezium and the base of the 1st metacarpal; it has a separate articular cavity. Like the carpals, adjacent metacarpals articulate with each other IM joints occur between the radial and ulnar aspects of the bases of the metacarpals

96. Joint Capsule of Carpometacarpal and Intermetacarpal Joints The medial four CMC joints and three IM joints are enclosed by a common joint capsule on the palmar and dorsal surfaces. A common synovial membrane lines the internal surface of the fibrous layer of the joint capsule, surrounding a common articular cavity. The fibrous layer of the CMC joint of the thumb surrounds the joint and is attached to the margins of the articular surfaces. The synovial membrane lines the internal surface of the fibrous layer. The looseness of the capsule facilitates free movement of the joint of the thumb

97. Ligaments of Carpometacarpal and Intermetacarpal Joints The bones are united in the region of the joints by palmar and dorsal CMC and IM ligaments and by interosseous IM ligaments. In addition, the superficial and deep transverse metacarpal ligaments (the former part of the palmar aponeurosis), associated with the distal ends of the metacarpals, play a role in limiting movement at the CMC and IM joints as they limit separation of the metacarpal heads.

98. Movements of Carpometacarpal and Intermetacarpal Joints The CMC joint of the thumb permits angular movements in any plane ( flexion–extension , abduction–adduction, or circumduction) and a restricted amount of axial rotation. Most important, the movement essential to opposition of the thumb occurs here. Although the opponens pollicis is the prime mover, all of the hypothenar muscles contribute to opposition. Almost no movement occurs at the CMC joints of the 2nd and 3rd digits, that of the 4th digit is slightly mobile, and that of the 5th digit is moderately mobile, flexing and rotating slightly during a tight grasp.

99. Blood Supply of Carpometacarpal and Intermetacarpal Joints The CMC and IM joints are supplied by peri -articular arterial anastomoses of the wrist and hand (dorsal and palmar carpal arches, deep palmar arch, and metacarpal arteries)

100. Innervation of Carpometacarpal and Intermetacarpal Joints The CMC and IM joints are supplied by the anterior interosseous branch of the median nerve, posterior interosseous branch of the radial nerve, and dorsal and deep branches of the ulnar nerve

101. The Metacarpophalangeal Joints and The Interphalangeal joints The metacarpophalangeal joints are the condyloid type of synovial joint that permit movement in two planes: flexion – extension and adduction–abduction. The interphalangeal joints are the hinge type of synovial joint that permit flexion – extension only

102. Articulations of Metacarpophalangeal and Interphalangeal Joints The heads of the metacarpals articulate with the bases of the proximal phalanges in the MP joints, and the heads of the phalanges articulate with the bases of more distally located phalanges in the IP joints

103. Joint Capsules of Metacarpophalangeal and Interphalangeal Joints A joint capsule encloses each MC and IP joint with a synovial membrane lining a fibrous layer that is attached to the margins of each joint

104. Ligaments of Metacarpophalangeal and Interphalangeal Joints MC ligaments are: collateral metacarpophalangeal ligaments, reinforcing the medial and lateral aspects o the joint capsule; palmar ligament, reinforcing the anterior aspect; the deep transverse metacarpal ligaments. IP ligaments are: main and accessory collateral ligaments

105. Movements of Metacarpophalangeal and Interphalangeal Joints Flexion–extension , abduction–adduction, and circumduction of the 2nd–5th digits occur at the 2nd–5th MP joints. Movement at the MP joint of the thumb is limited to flexion – extension. Only flexion and extension occur at the IP joints

106. Blood Supply of Metacarpophalangeal and Interphalangeal Joints: Deep digital arteries that arise from the superficial palmar arches supply the MC and IP joints Innervation of Metacarpal and Interphalangeal Joints: Digital nerves arising from the ulnar and median nerves supply the MC and IP joint

107. Fascia o f the upper limb Fascia is a type o f connective tissue that surrounds muscles, organs and other structures in the body. It provides support and protection and helps to keep everything in its place. The upper limb has superficial and deep f ascia: (1 ) subcutaneous tissue ( superficial fascia) containing fat, and ( 2) deep fascia compartmentalizing and investing the muscles. If no structure (muscle, tendon, or bursa, for example) intervenes between the skin and bone, the deep fascia is usually attached to bone. There are six f asciae in the upper limb: the pectoral f ascia, the clavipectoral f ascia, the axillary f ascia, the deltoid f ascia, the brachial f ascia and the antebrachial f ascia.

108. AXILLA The axilla is the pyramidal space inferior to the glenohumeral joint and superior to the axillary fascia at the junction of the arm and thorax. The axilla provides a passageway , or “distribution center,” usually protected by the adducted upper limb, for the neurovascular structures that serve the upper limb. From this distribution center, neurovascular structures pass: Superiorly via the cervico -axillary canal to (or from) the root of the neck • Anteriorly via the clavipectoral triangle to the pectoral region. • Inferiorly and laterally into the limb itself. • Posteriorly via the quadrangular space to the scapular region. • Inferiorly and medially along the thoracic wall to the inferiorly placed axio -appendicular muscles (serratus anterior and latissimus dorsi ).

109. The axilla has an apex, a base, and four walls (three of which are muscular ): The apex of axilla is the cervico -axillary canal, the passageway between the neck and axilla, bounded by the 1st rib, clavicle, and superior edge of the scapula. The arteries, veins, lymphatics, and nerves traverse this superior opening of the axilla to pass to or from the arm The base of axilla is formed by the concave skin, subcutaneous tissue, and axillary (deep) fascia extending from the arm to the thoracic wall (approximately the 4th rib level), forming the axillary fossa (armpit). The base of the axilla and axillary fossa are bounded by the anterior and posterior axillary folds, the thoracic wall, and the medial aspect of the arm.

110. The anterior wall of axilla has two layers, formed by the pectoralis major and pectoralis minor and the pectoral and clavicopectoral fascia associated with them. The anterior axillary fold is the inferiormost part of the anterior wall that may be grasped between the fingers ; it is formed by the pectoralis major, as it bridges from thoracic wall to humerus , and the overlying integument The posterior wall of axilla is formed chiefly by the scapula and subscapularis on its anterior surface and inferiorly by the teres major and latissimus dorsi . The posterior axillary fold is the inferiormost part of the posterior wall that may be grasped. It extends farther inferiorly than the anterior wall and is formed by latissimus dorsi , teres major, and overlying integument

111. The medial wall of axilla is formed by the thoracic wall (1st–4th ribs and intercostal muscles) and the overlying serratus anterior. • The lateral wall of axilla is a narrow bony wall formed by the intertubercular sulcus in the humerus Proximally, the neurovascular structures of the axilla are ensheathed in a sleeve-like extension of the cervical fascia, the axillary sheath

112. Axillary Artery The axillary artery begins at the lateral border of the 1st rib as the continuation of the subclavian artery, and ends at the inferior border of the teres major. It passes posterior to the pectoralis minor into the arm, and becomes the brachial artery when it passes the inferior border of the teres major, at which point it usually has reached the humerus

113. For descriptive purposes, the axillary artery is divided into three parts by the pectoralis minor (the part number also indicates the number of its branches): 1 . The first part of the axillary artery is located between the lateral border of the 1st rib and the medial border of the pectoralis minor; it is enclosed in the axillary sheath and has one branch—the superior thoracic artery’ 2 . The second part of the axillary artery lies posterior to pectoralis minor and has two branches—the thoracoacromial and lateral thoracic arteries—which pass medial and lateral to the muscle, respectively. 3 . The third part of the axillary artery extends from the lateral border of pectoralis minor to the inferior border of teres major; it has three branches. The subscapular artery is the largest branch of the axillary artery. Opposite the origin of this artery, the anterior circumflex humeral and posterior circumflex humeral arteries arise, sometimes by means of a common trunk.

114. Branches of the axillary artery Superior thoracic artery : Superior thoracic artery is a very small branch which arises from the first part of the axillary artery (near the subclavius ). It runs downwards, forwards and medially, passes between the two pectoral muscles, and ends by supplying these muscles and the thoracic wall Thoracoacromial artery : is a branch from the second part of the axillary artery. It emerges at the upper border of the pectoralis minor, pierces the clavipectoral fascia, and soon divides into the following four terminal branches. a . The pectoral branch passes between the pectoral muscles, and supplies these muscles as well as the breast. b . The deltoid branch runs in the deltopectoral groove, along with the cephalic vein. c . The acromial branch crosses the coracoid process and ends by joining the anastomoses over the acromion. d . The clavicular branch runs superomedially deep to the pectoralis major, and supplies the sternoclavicular joint and subclavius

115. Lateral thoracic artery : is a branch of the second part of the axillary artery. It emerges at, and runs along, the lower border of the pectoralis minor in close relation with the anterior group of axillary lymph nodes. In females, the artery is large and gives off the lateral mammary branches to the breast . Anterior circumflex humeral artery : is a small branch arising from the third part of the axillary artery, at the lower border of the subscapularis. It passes laterally in front of the inter tubercular sulcus of the humerus , and anastomoses with the posterior circumflex humeral artery , to form an arterial circle round the surgical neck of the humerus . It gives off an ascending branch which runs in the intertubercular sulcus, and supplies the head of the humerus and shoulder joint.

116. Posterior circumflex humeral artery is much larger than the anterior artery. It arises from the third part of the axillary artery at the lower border of the subscapularis. It runs backwards, accompanied by the axillary nerve, passes through the quadrangular intermuscular space, and ends by anastomosing with the anterior circumflex humeral artery around the surgical neck of the humerus . It supplies the shoulder joint, the deltoid, and the muscles bounding the quadrangular space . It gives off a descending branch which anastomoses with the ascending branch of the profunda brachii artery .

117. Subscapular artery is the largest branch of the axillary artery , arising from its third part. It runs along the lower border of the subscapularis to terminate near the inferior angle of the scapula. It supplies the latissimus dorsi and the serratus anterior. It gives off a large branch, the circumflex scapular artery, which is larger than the continuation of the main artery. This branch passes through the triangular intermuscular space, winds round the lateral border of the scapula deep to the teres minor, and gives a branch to the subscapular fossa, and another branch to the infraspinous fossa, both of which take part in the anastomoses around the scapula

118. Axillary vein The axillary vein lies initially on the anteromedial side of the axillary artery, with its terminal part antero -inferior to the artery. This large vein is formed by the union of the brachial vein (the accompanying veins of the brachial artery) and the basilic vein at the inferior border of the teres major. The axillary vein has three parts, which correspond to the three parts of the axillary artery. Thus the initial, distal end is the third part, whereas the terminal, proximal end is the first part. The axillary vein ( first part) ends at the lateral border of the 1st rib, where it becomes the subclavian vein.

119. Axillary Lymph Nodes The axillary lymph nodes are scattered in the fibrofatty tissue of the axilla. They are divided into five groups. The nodes of the anterior (pectoral) group lie along the lateral thoracic vessels, i.e. along the lower border of the pectoralis minor. They receive lymph from the upper half of the anterior wall of the trunk, and from the major part of the breast The nodes of the posterior (scapular) group lie along the subscapular vessels, on the posterior fold of the axilla. They receive lymph from the posterior wall of the upper half of the trunk, and from the axillary tail of the breast

120. The nodes of the lateral group lie along the upper part of the humerus , medial to the axillary vein. They receive lymph from the upper limb. The nodes of the central group lie in the fat of the upper axilla. They receive lymph from the preceding groups and drain into the apical group. They receive some direct vessels from the floor of the axilla. The intercostobrachial nerve is closely related to them The nodes of the apical or infraclavicular group lie deep to the clavipectoral fascia, along the axillary vessels. They receive lymph from the central group, from the upper part of the breast, and from the thumb and its web. The lymphatics from the thumb accompany the cephalic vein

121. Brachial plexus The  brachial plexus  is a network of nerve fibres that supplies the skin and musculature of the upper limb. It begins in the root of the neck, passes through the  axilla , and runs through the entire upper extremity . The plexus is formed by the  anterior rami  (divisions) of cervical spinal nerves C5, C6, C7 and C8, and the first thoracic spinal nerve, T1 . The brachial plexus is divided into five parts; roots, trunks, divisions, cords and branches  (a good mnemonic for this is  R ead  T hat  D amn  C adaver  B ook) . There are no functional differences between these divisions – they are simply used to aid explanation of the brachial plexus

122. The roots The roots of the brachial plexus are formed by the  anterior rami  of spinal nerves C5-T1 (the posterior divisions innervate the skin and musculature of the intrinsic back muscles). After their formation, these nerves pass between the anterior and medial  scalene  muscles to enter the base of the neck.

123. Trunks At the base of the neck, the roots of the brachial plexus converge to form three  trunks . These structures are named by their relative anatomical location: Superior trunk  – a combination of C5 and C6 roots. Middle trunk  – continuation of C7. Inferior trunk  – combination of C8 and T1 roots. The trunks traverse laterally, crossing the  posterior triangle  of the neck

124. Divisions Each trunk divides into two branches within the posterior triangle of the neck. One division moves  anteriorly  (toward the front of the body) and the other  posteriorly  (towards the back of the body). Thus, they are known as the anterior and posterior divisions. We now have   three anterior and three posterior nerve fibres . These divisions leave the posterior triangle and pass into the  axilla . They  recombine  into the cords of the brachial plexus.

125. Cords Once the anterior and posterior divisions have entered the axilla, they combine together to form three cords, named by their position relative to the  axillary artery. The  lateral cord  is formed by: The anterior division of the superior trunk The anterior division of the middle trunk The  posterior cord  is formed by: The posterior division of the superior trunk The posterior division of the middle trunk The posterior division of the inferior trunk The  medial cord  is formed by : The anterior division of the inferior trunk. The cords give rise to the major branches of the brachial plexus.

126. Major branches In the axilla and the proximal aspect of the upper limb, the three cords give rise to five major branches. These nerves continue into the upper limb to provide innervation to the muscles and skin present. In this sect

127. Musculocutaneous Nerve Roots : C5, C6, C7. Motor Functions : Innervates the brachialis, biceps brachii and coracobrachialis muscles. Sensory Functions : Gives off the lateral cutaneous branch of the forearm, which innervates the lateral half of the anterior forearm, and a small lateral portion of the posterior forearm.

128. Axillary Nerve Roots : C5 and C6. Motor Functions : Innervates the teres minor and deltoid muscles. Sensory Functions : Gives off the superior lateral cutaneous nerve of arm, which innervates the inferior region of the deltoid (“regimental badge area”).

129. Median Nerve Roots : C6 – T1. (Also contains fibres from C5 in some individuals). Motor Functions : Innervates most of the flexor muscles in the forearm, the thenar muscles, and the two lateral lumbricals associated with the index and middle fingers. Sensory Functions : Gives off the palmar cutaneous branch, which innervates the lateral part of the palm, and the digital cutaneous branch, which innervates the lateral three and a half fingers on the anterior (palmar) surface of the hand

130. Radial Nerve Roots : C5 – T1. Motor Functions : Innervates the triceps brachii , and the muscles in the posterior compartment of the forearm (which are primarily, but not exclusively, extensors of the wrist and fingers). Sensory Functions : Innervates the posterior aspect of the arm and forearm, and the posterolateral aspect of the hand.

131. Ulnar Nerve Roots : C8 and T1. Motor Functions : Innervates the muscles of the hand (apart from the thenar muscles and two lateral lumbricals ), flexor carpi ulnaris and medial half of flexor digitorum profundus . Sensory Functions : Innervates the anterior and posterior surfaces of the medial one and half fingers, and associated palm area.

132. Minor branches Dorsal scapular nerve  Long thoracic nerve Suprascapular nerve  Nerve to subclavius Lateral pectoral nerve Medial pectoral nerve  Medial cutaneous nerve of arm Medial cutaneous nerve of forearm Superior subscapular nerve  Thoracodorsal nerve Inferior subscapular nerve

133. Vessels And Nerves of t he Upper Limb The arterial supply of the upper limb begins with the axillary artery, the second part of a single continuous artery changing its name three times. The first part is the subclavian artery which contributes to the supply of the scapular region but is considered an artery of the neck. The subclavian artery becomes an axillary artery upon crossing the first rib.

134. The axillary artery supplies the shoulder and pectoral regions and in turn becomes a brachial artery (artery of the arm) as it crosses the inferior border of the teres major. In the elbow region, the brachial artery terminates by dividing into two arteries of the forearm: the ulnar artery on the medial aspect and the radial artery on the lateral aspect. The ulnar and radial arteries terminate by communicating within the palm as superficial and deep palmar arches

135. Venous Drainage of t he Upper Limb: Super f icial Veins The main superficial veins of the upper limb, the cephalic and basilic veins, originate in the subcutaneous tissue on the dorsum of the hand from the dorsal venous network. The cephalic vein ascends in the subcutaneous tissue from the lateral aspect of the dorsal venous network, proceeding along the lateral border of the wrist and the anterolateral surface of the proximal forearm and arm; it is often visible through the skin . Anterior to the elbow, the cephalic vein communicates with the median cubital vein, which passes obliquely across the anterior aspect of the elbow in the cubital fossa (a depression in front of the elbow), and joins the basilic vein.

136. The basilic vein ascends in the subcutaneous tissue from the medial end of the dorsal venous network along the medial side of the forearm and the inferior part of the arm; it is often visible through the skin

137. Deep veins Deep veins lie internal to the deep fascia, and—in contrast to the superficial veins—usually occur as paired (continually interanastomosing ) accompanying veins that travel with, and bear the same name as, the major arteries of the limb

138. Cutaneous Innervation of The Upper Limb Most cutaneous nerves of the upper limb are derived from the brachial plexus The nerves to the shoulder, however, are derived from the cervical plexus

139. Cutaneous Nerve o f Upper Limb Cutaneous Nerve Contributing Spinal Nerves Source Course and Distribution Supraclavicular nerves C3, C4 Cervical plexus Pass anterior to clavicle, immediately deep to platysma, and supply skin over clavicle and superolateral aspect of pectoralis major Superior lateral cutaneous nerve o arm C5, C6 Terminal branch of axillary nerve Emerges from beneath posterior margin of deltoid and supplies skin over lower part of this muscle and on lateral side of midarm inferior lateral cutaneous nerve of arm C5, C6 Radial nerve (or posterior cutaneous nerve of arm) Perforates lateral head of triceps, passing close to cephalic vein to supply skin over inferolateral aspect of arm Posterior cutaneous nerve of arm C5–C8 Radial nerve (in axilla) Crosses posterior to and communicates with intercostobrachial nerve and supplies skin on posterior arm as far as olecranon Posterior cutaneous nerve of forearm C5–C8 Radial nerve (with inferior lateral cutaneous nerve of arm) Perforates lateral head of triceps, descends laterally in arm, then runs along and supplies posterior forearm to wrist.

140.   Cutaneous Nerve   Contributing Spinal Nerves   Source   Course and Distribution Lateral cutaneous nerve of forearm C6–C7 Musculocutaneous nerve (terminal branch) Emerges lateral to biceps tendon deep to cephalic vein, supplying skin of anterolateral forearm to wrist Medial cutaneous nerve of forearm C8, T1 Medial cord of brachial plexus (in axilla) Descends medial to brachial artery, pierces deep fascia with basilic vein in midarm, dividing into anterior and posterior branches that enter forearm and supply skin of anteromedial aspect to wrist Medial cutaneous nerve of arm C8–T2 Medial cord of brachial plexus (in axilla) Communicates with intercostobrachial nerve, continuing to supply skin of medial aspect of distal arm Intercostobrachial nerve T2 Second intercostal nerve (as its lateral cutaneous branch) Extends laterally, communicating with posterior and medial cutaneous nerves of arm, supplying skin of axilla and medial aspect of proximal arm

141. Motor Innervation o f Upper Limb Somatic motor (general somatic efferent) fibers traveling in the same mixed peripheral nerves that convey sensory fibers to the cutaneous nerves transmit impulses to the voluntary muscles of the upper limb. The unilateral embryological muscle mass (and derived muscle) receiving innervation from a single spinal cord segment or spinal nerve constitutes a myotome . Upper limb muscles usually receive motor fibers from several spinal cord segments or nerves. Thus most muscles are made up of more than one myotome , and multiple spinal cord segments are usually involved in producing the movement of the upper limb. The intrinsic muscles of the hand constitute a single myotome (T1).

142. Muscles of the Pectoral and Scapular Region Muscle Proximal attachment Distal attachment innervation Action Pectoralis major Clavicular head: anterior surface of medial half of clavicle Sternocostal head: anterior surface of sternum, superior six costal cartilages, aponeurosis of external oblique muscle Lateral lip of intertubercular sulcus of humerus Lateral and medial pectoral nerves; clavicular head (C5, C6), sternocostal head (C7, C8, T1) Adducts and medially rotates humerus ; draws scapula anteriorly and inferiorly Acting alone, clavicular head flexes humerus and sternocostal head extends it from the flexed position Pectoralis minor 3rd–5th ribs near their costal cartilages Medial border and superior surface of coracoid process of scapula Medial pectoral nerve (C8, T1) Stabilizes scapula by drawing it inferiorly and anteriorly against thoracic wall

143. Muscle Proximal attachment Distal attachment Innervation Action Subclavius Junction of 1st rib and its costal cartilage Inferior surface of middle third of clavicle Nerve to subclavius (C5, C6) Anchors and depresses clavicle Serratus anterior External surfaces of lateral parts of 1st–8th ribs Anterior surface of medial border of scapula Long thoracic nerve (C5, C6, C7) Protracts scapula and holds it against thoracic wall; rotates scapula

144. Muscle Proximal attachment Distal attachment Innervation Action Trapezius Medial third of superior nuchal line; external occipital protuberance; nuchal ligament ; spinous processes of C7–T12 vertebrae Lateral third of clavicle; acromion and spine of scapula Spinal accessory nerve (CN XI) (motor fi bers ) and C3, C4 spinal nerves (pain and proprioceptive fi bers ) Descending part elevates; ascending part depresses; and middle part (or all parts together) retracts scapula; descending and ascending parts act together to rotate glenoid cavity superiorly Latissimus dorsi Spinous processes of inferior 6 thoracic vertebrae, thoracolumbar fascia, iliac crest, and inferior 3 or 4 ribs Floor of intertubercular sulcus of humerus Thoracodorsal nerve (C6, C7, C8) Extends, adducts, and medially rotates humerus ; raises body toward arms during climbing

145. Muscle Proximal attachment Distal attachment Innervation Action Levator scapulae Posterior tubercles of transverse processes of C1–C4 vertebrae Medial border of scapula superior to root of scapular spine Dorsal scapular (C4, C5) and cervical (C3, C4) nerves Elevates scapula and rotates its glenoid cavity inferiorly by rotating scapula Rhomboid minor and major Minor: nuchal ligament; spinous processes of C7 and T1 vertebrae Major: spinous processes of T2–T5 vertebra Minor: smooth triangular area at medial end of scapular spine Major: medial border of scapula from level of spine to inferior angle Dorsal scapular nerve (C4, C5) Retract scapula and rotate its glenoid cavity inferiorly; fix scapula to thoracic wall

146. Muscle Proximal attachment Distal attachment Innervation Action Deltoid Lateral third of clavicle; acromion and spine of scapula Deltoid tuberosity of humerus Axillary nerve (C5, C6) Clavicular (anterior) part: fl exes and medially rotates arm Acromial (middle) part: abducts arm Spinal (posterior) part: extends and laterally rotates arm Supraspinatus Supraspinous fossa of scapula Superior facet of greater tubercle of humerus Suprascapular nerve (C4, C5, C6) Initiates and assists deltoid in abduction of arm and acts with rotator cuff muscles Infraspinatus Infraspinous fossa of scapula Middle facet of greater tubercle of humerus Suprascapular nerve (C5, C6) Laterally rotates arm; and acts with rotator cuff musclesb

147. Muscle Proximal attachment Distal attachment Innervation Action Teres minor Middle part of lateral border of scapula Inferior facet of greater tubercle of humerus Axillary nerve (C5, C6) Laterally rotates arm; and acts with rotator cuff muscles Teres major Posterior surface of inferior angle of scapula Medial lip of intertubercular sulcus of humerus Lower subscapular nerve (C5, C6) Adducts and medially rotates arm Subscapularis Subscapular fossa (most of anterior surface of scapula Lesser tubercle of humerus Upper and lower subscapular nerves (C5, C6) Medially rotates arm; as part of rotator cuff, helps hold head of humerus in glenoid cavity

148. Arteries of the Arm The brachial artery provides the main arterial supply to the arm and is the continuation of the axillary artery . It begins at the inferior border of the teres major, and ends in the cubital fossa opposite the neck of the radius where, under cover of the bicipital aponeurosis , it divides into the radial and ulnar arteries

149. Branches The profunda brachii artery (deep artery of the arm) is the largest branch of the brachial artery and has the most superior origin. The profunda brachii accompanies the radial nerve along the radial groove as it passes posteriorly around the shaft of the humerus . The profunda brachii terminates by dividing into middle and radial collateral arteries, which participate in the peri -articular arterial anastomoses around the elbow The main humeral nutrient artery arises from the brachial artery around the middle of the arm, and enters the nutrient canal on the anteromedial surface of the humerus . The artery runs distally in the canal toward the elbow. Other smaller humeral nutrient arteries also occur

150. The superior ulnar collateral artery arises from the medial aspect of the brachial artery near the middle of the arm, and accompanies the ulnar nerve posterior to the medial epicondyle of the humerus . Here it anastomoses with the posterior ulnar recurrent artery and the inferior ulnar collateral artery, participating in the peri -articular arterial anastomoses of the elbow The inferior ulnar collateral artery arises from the brachial artery approximately 5 cm proximal to the elbow crease. It then passes inferomedially anterior to the medial epicondyle of the humerus , and joins the peri -articular arterial anastomoses of the elbow region by anastomosing with the anterior ulnar recurrent artery

151. Veins of the Arm Two sets of veins of the arm, superficial and deep, anastomose freely with each other. The superficial veins are in the subcutaneous tissue, and the deep veins accompany the arteries. Both sets of veins have valves, but they are more numerous in the deep veins than in the superficial veins The two main superficial veins of the arm, the cephalic and basilic veins The brachial vein begins at the elbow by union of the accompanying veins of the ulnar and radial arteries, and ends by merging with the basilic vein to form the axillary vein. Not uncommonly, the deep veins join to form one brachial vein during part of their course

152. Nerves of the Arm Four main nerves pass through the arm: median, ulnar, musculocutaneous , and radial. The median and ulnar nerves supply no branches to the arm

153. The musculocutaneous nerve begins opposite the inferior border of the pectoralis minor, pierces the coracobrachialis , and continues distally between the biceps and the brachialis. After supplying all three muscles of the anterior compartment of the arm, the musculocutaneous nerve emerges lateral to the biceps as the lateral cutaneous nerve of the forearm. It becomes truly subcutaneous when it pierces the deep fascia proximal to the cubital fossa to course initially with the cephalic vein in the subcutaneous tissue. After crossing the anterior aspect of the elbow, it continues to supply the skin of the lateral aspect of the forearm

154. The radial nerve in the arm supplies all the muscles in the posterior compartment of the arm (and forearm). The radial nerve enters the arm posterior to the brachial artery, medial to the humerus , and anterior to the long head of the triceps, where it gives branches to the long and medial heads of the triceps. The radial nerve then descends inferolaterally with the profunda brachii artery and passes around the humeral shaft in the radial groove. The branch of the radial nerve to the lateral head of the triceps arises within the radial groove.

155. When it reaches the lateral border of the humerus , the radial nerve pierces the lateral intermuscular septum, and continues inferiorly in the anterior compartment of the arm between the brachialis and the brachioradialis to the level of the lateral epicondyle of the humerus . Anterior to the lateral epicondyle, the radial nerve divides into deep and superficial branches. • The deep branch of the radial nerve is entirely muscular and articular in its distribution. • The superficial branch of the radial nerve is entirely cutaneous in its distribution, supplying sensation to the dorsum of the hand and fingers.

156. The median nerve in the arm runs distally in the arm on the lateral side of the brachial artery until it reaches the middle of the arm, where it crosses to the medial side and contacts the brachialis. The median nerve then descends into the cubital fossa, where it lies deep to the bicipital aponeurosis and median cubital vein. The median nerve has no branches in the axilla or arm, but it does supply articular branches to the elbow joint

157. The ulnar nerve in the arm passes distally from the axilla anterior to the insertion of the teres major and to the long head of the triceps, on the medial side of the brachial artery. Around the middle of the arm, it pierces the medial intermuscular septum with the superior ulnar collateral artery and descends between the septum and the medial head of the triceps. The ulnar nerve passes posterior to the medial epicondyle and medial to the olecranon to enter the forearm. Posterior to the medial epicondyle, where the ulnar nerve is referred to in lay terms as the “funny bone.” The ulnar nerve is superficial , easily palpable, and vulnerable to injury. Like the median nerve, the ulnar nerve has no branches in the arm, but it also supplies articular branches to the elbow joint

158. Cubital Fossa The cubital fossa is seen superficially as a depression on the anterior aspect of the elbow. Deeply, it is a space filled with a variable amount of fat anterior to the most distal part of the humerus and the elbow joint. The three boundaries of the triangular cubital fossa are as follows: Superiorly , an imaginary line connecting the medial and lateral epicondyles . Medially , the mass of flexor muscles of the forearm arising from the common flexor attachment on the medial epicondyle; most specifically , the pronator teres . Laterally , the mass of extensor muscles of the forearm arising from the lateral epicondyle and supra- epicondylar ridge; most specifically , the brachioradialis . The floor of the cubital fossa is formed by the brachialis and supinator muscles of the arm and forearm, respectively. The roof of the cubital fossa is formed by the continuity of brachial and antebrachial (deep) fascia reinforced by the bicipital aponeurosis , subcutaneous tissue, and skin.

159. The contents of the cubital fossa are the: • Terminal part of the brachial artery and the commencement of its terminal branches, the radial and ulnar arteries. The brachial artery lies between the biceps tendon and the median nerve. • (Deep) accompanying veins of the arteries. • Biceps brachii tendon. • Median nerve. • Radial nerve, deep between the muscles forming lateral boundary of the fossa (the brachioradialis , in particular) and the brachialis, dividing into its superficial and deep branches. The muscles must be retracted to expose the nerve . Superficially , in the subcutaneous tissue overlying the cubital fossa are the median cubital vein, lying anterior to the brachial artery, and the medial and lateral cutaneous nerves of the forearm, related to the basilic and cephalic veins.

160. Muscles of the Forearm Muscle Proximal attachment Distal attachment Innervation Action Biceps brachii Short head: tip of coracoid process of scapula Long head: supraglenoid tubercle of scapula Tuberosity of radius and fascia of forearm via bicipital aponeurosis Musculocutaneous nerve (C5, C6, C7) Supinates forearm and, when it is supine. flexes forearm; short head resists dislocation of shoulder Coracobrachialis Tip of coracoid process of scapula Middle third of medial surface of humerus Musculocutaneous nerve (C5, C6, C7) Helps flex and adduct arm; resists dislocation of shoulder Brachialis Distal half of anterior surface of humerus Coronoid process and tuberosity ulna Musculocutaneous nerveb (C5, C6) and radial nerve (C5, C7) Flexes forearm in all positions

161. Muscle Proximal attachment Distal attachment Innervation Action Triceps brachii Long head: infraglenoid tubercle of scapula Lateral head: posterior surface of humerus , superior to radial groove Medial head: posterior surface of humerus , inferior to radial groove Proximal end of olecranon of ulna and fascia of forearm Radial nerve (C6, C7, C8) Chief extensor of forearm; long head resists dislocation of humerus ; especially important during adduction Anconeus Lateral epicondyle of humerus Lateral surface of olecranon and superior part of posterior surface of ulna Radial nerve (C7, C8, T1) Assists triceps in extending forearm; stabilizes elbow joint; may abduct ulna during pronation