UNIT- 14 THE MUSCULAR SYSTEM.ANATOMY ptx

FOR THE GENERAL NURSING STUDENTS PPT ACCODRING TO SYLLBUS WISE ANATOMY AND PHYSIOLOGY INEASY WAY

1. What is the Muscular System? The muscular system is an organ system, involved majorly in the movement of the body. There are about 700 muscles that are connected to the bones of the skeletal system, which roughly half make up the human’s body weight. Every muscle is a different organ made of skeletal muscle tissue, blood vessels, nerves, and tendons. Muscle tissues are found in the heart, blood vessels, and digestive system.

2. There are three types of muscle tissues in our body

3. a. Visceral muscles Visceral muscles are found inside the organs like stomach, intestine and blood vessels. Visceral muscles makes organs contract to move substances through the organs , because visceral muscles is controlled by the unconscious part of the brain ,it is known as involuntary muscles The term smooth muscle

4. b.Cardiac muscles This muscle is present only in Heart and responsible for supplying blood all over the body. It is also an involuntary muscle since it cannot be controlled. When brain signals adapt the rate of contraction, cardiac muscle stimulates by itself to contract. The natural pace of the heart is made up of cardiac muscle tissue and stimulates other cardiac muscle cells to shrink. The cardiac muscle cells are straight which reveals that they seem to have dark and light stripes when seen under a microscope. The protein fibers arrangement within the cells is responsible for these dark and light stripes.

5. c. Skeletal muscles Skeletal muscles is only voluntary muscles tissues in the human body it is controlled consciously. Every physical action that a person consciously performs( eg : speaking ,walking and writing )requires skeletal muscles. The functions of skeletal muscles is to contract to move part of the body close to the bone that the muscles is attached to it .

6. Structure of muscles This muscle is attached to the bones by an elastic tissue or collagen fibres called tendons. These tendons are comprised of connective tissues. The skeletal muscles consist of a bundle of muscle fibres naming fascicule. These fascicules are cylindrical in shape. These muscle fibres are surrounded by blood vessels and a number of layers of other tissues enclosing it. Each muscle fibre is a line by plasma membrane naming sarcolemma reticulum. It encloses a cytoplasm called sarcoplasm which has the endoplasmic reticulum. The muscle fibres consist of myofibrils which have two important proteins naming actin and myosin in it. The fascicule is enclosed by perimysium and the endomysium is the connective tissue that encloses the muscle fibres.

7. The muscular tissues are bundled together and surrounded by a tough connective tissue similar to cartilage known as epimysium. The bundle of nerve cells that run in long fibers called fascicles are surrounded by the epimysium. The fascicles are surrounded by a protective layer known as perimysium. It allows the flow of nerves and blood to the individual fibers. Another protective layer, the endomysium surrounds the fibers. These layers and muscles help in the contraction of different parts of the muscles.  The different bundles slide past one another as they contract. The epimysium connects to the tendons attached to the periosteum connective tissue that surrounds the bones. This helps in the movement of the skeleton when the muscles contract. The epimysium connects to other connective tissues to produce force on the organs and control everything from circulation to food processing.

8. Properties of muscular tissue Contractibility – It is the ability of muscle cells to shorten forcefully. Extensibility – A muscle has the ability to be stretched. Elasticity – The muscles have the ability to recoil back to its original length after being stretched. Excitability – The muscle tissue responds to a stimulus delivered from a motor neuron or hormone.

9. Functions of muscles Locomotion (body movement) Maintenance of posture Respiration- diaphragm and intercostal contraction Communication –verbal and facial Constriction of organs and vessels – peristalsis of intestine tract. Vasoconstriction of blood vessels and other structure like pupils. Heart beat Production of body heat ( thermogenesis )

10. Muscles of the face and neck 1.Occipitofrontalis This consists of a posterior muscular part over the occipital bone, an anterior part over the frontal bone ,and an extensive flat tendon that stretches over the dome of the skull and joins the two muscular part. It raises the eyebrows.

11. 2.Levator palpebrae superioris This muscle extends from the posterior part of the orbital cavity to the upper eyelid. It raises the eyelid. 3.Orbicularis oculi This muscle surrounds the eye, eyelid and orbital cavity. It closes the eye and when strongly contracted ‘screws up’ the eyes.

12. 4.Buccinator This flat muscle of the cheek draws the cheeks in towards the teeth in chewing and in forcible expulsion of air from the mouth. 5.Orbicularis oris This muscle surrounds the mouth and blends with the muscles of the cheeks. It closes the lips and, when strongly contracted, shapes the mouth for whistling.

13. 7.Masseter This is a broad muscle, extending from the zygomatic arch to the angle of the jaw. In chewing it draws the mandible up to the maxilla, closing the jaw, and exerts considerable pressure on the food. 8.Temporalis This muscle covers the squamous part of the temporal bone. It passes behind the zygomatic arch to be inserted into the coronoid process of the mandible. It closes the mouth and assists with chewing. 9.Pterygoid This muscle extends from the sphenoid bone to the mandible. It closes the mouth and pulls the lower jaw forward.

14. Muscles of the neck 1. Sternocleidomastoid This muscle arises from the manubrium of the sternum and the clavicle and extends upwards to the mastoid process of the temporal bone. It assists in turning the head from side to side. When the muscle on one side contracts it draws the head towards the shoulder. When both contract at the same time they flex the cervical vertebrae or draw the sternum and clavicles upwards when the head is maintained in a fixed position, e.g. in forced respiration .

15. 2.Trapezius This muscle covers the shoulder and the back of the neck. The upper attachment is to the occipital protuberance, the medial attachment is to the transverse processes of the cervical and thoracic vertebrae and the lateral attachment is to the clavicle and to the spinous and acromion processes of the scapula. It pulls the head backwards, squares the shoulders and controls the movements of the scapula when the shoulder joint is in use.

16. Muscles of the trunk These muscles stabilize the association between the appendicular and axial skeletons at the pectoral girdle, and stabilize and allow movement of the shoulders and upper arms.

17. Muscles of the back There are six pairs of large muscles in the back, in addition to those forming the posterior abdominal wall. The arrangement of these muscles is the same on each side of the vertebral column. They are: • trapezius • latissimus dorsi • teres major • psoas • quadratus lumborum • sacrospinalis.

18.  a lumbar vertebra and its associated muscles. 1.Latissimus dorsi This arises from the posterior part of the iliac crest and the spinous processes of the lumbar and lower thoracic vertebrae. It passes upwards across the back then under the arm to be inserted into the bicipital groove of the humerus. It adducts, medially rotates and extends the arm. 2.Teres major This originates from the inferior angle of the scapula and is inserted into the humerus just below the shoulder joint. It extends, adducts and medially rotates the arm. Transverse section of the posterior abdominal wall:

19. 3.Quadratus lumborum This muscle originates from the iliac crest, then it passes upwards, parallel and close to the vertebral column and it is inserted into the 12th rib . Together the two muscles fix the lower rib during respiration and cause extension of the vertebral column (bending backwards). If one muscle contracts it causes lateral flexion of the lumbar region of the vertebral column. 4.Sacrospinalis This is a group of muscles lying between the spinous &transverse processes of the vertebrae .They originate from the sacrum and are finally inserted into the occipital bone. Their contraction causes extension of the vertebral column.

20. The muscles of the anterior abdominal wall . The anterior abdominal wall is divided longitudinally by a very strong midline tendinous cord, the  linea alba  (meaning ‘white cord’) which extends from the xiphoid process of the sternum to the symphysis pubis. The structure of the abdominal wall on each side of the linea alba is identical.

21. 1.Rectus abdominis This is the most superficial muscle. It is broad and flat, originating from the transverse part of the pubic bone then passing upwards to be inserted into the lower ribs and the xiphoid process of the sternum. Medially the two muscles are attached to the linea alba.

22. 2.External oblique This muscle extends from the lower ribs downwards and forward to be inserted into the iliac crest and, by an aponeurosis, to the linea alba. 3.Transversus abdominis This is the deepest muscle of the abdominal wall. The fibres arise from the iliac crest and the lumbar vertebrae and pass across the abdominal wall to be inserted into the linea alba by an aponeurosis. The fibres are at right angles to those of the rectus abdominis.

23. 4.Internal oblique This muscle lies deep to the external oblique. Its fibres arise from the iliac crest and by a broad band of fascia from the spinous processes of the lumbar vertebrae. The fibres pass upwards towards the midline to be inserted into the lower ribs and, by an aponeurosis, into the linea alba. The fibres are at right angles to those of the external oblique.

24. Functions The main function of these paired muscles is to form the strong muscular anterior wall of the abdominal cavity. When the muscles contract together they: compress the abdominal organs flex the vertebral column in the lumbar region Contraction of the muscles on one side only bends the trunk towards that side. Contraction of the oblique muscles on one side rotates the trunk

25. Muscles of the thorax 1.Intercostal muscles There are 11 pairs of intercostal muscles that occupy the spaces between the 12 pairs of ribs. They are arranged in two layers, the external and internal intercostal muscles. a. external intercostal muscles These extend downwards and forwards from the lower border of the rib above to the upper border of the rib below. They are involved in inspiration.

26. b. internal intercostals muscles These extend downwards and backwards from the lower border of the rib above to the upper border of the rib below, crossing the external intercostals muscle fibers at right angles. The internal intercostals are used when exhalation becomes active, as in exercise. The first rib is fixed. Therefore, when the external intercostal muscles contract they pull all the other ribs towards the first rib. Because of the shape and sizes of the ribs they move outwards when pulled upwards, enlarging the thoracic cavity. The intercostal muscles are stimulated to contract by the  intercostal nerves .

27. 2.Diaphragm muscle The diaphragm separates the thoracic cavity from the abdominal cavity . ORIGIN It originates on the L1-L5 vertebrae, the lower 6 costal cartilages, and the xiphoid process. INSERTION It inserts onto the central tendon of the diaphragm. In other words, it inserts on itself . A ctions of the diaphragm muscle The diaphragm does most of the work during breathing. As it contracts it flattens, pulls on the lungs, and creates a negative pressure to allow more room for air to fill the lung

28. Muscles of chest wall 1.Pectoralis Major The pectoralis major is the most superficial muscle in the pectoral region. It is large and fan shaped, and is composed of a sternal head and a clavicular head: Attachments :   The distal attachment of both heads is into the intertubercular sulcus of the  humerus . Clavicular head – originates from the anterior surface of the medial  clavicle . Sternocostal head – originates from the anterior surface of the  sternum , the superior six costal cartilages and the aponeurosis of the external oblique muscle. Function :   Adducts and medially rotates the upper limb, and draws the scapula anteroinferiorly. The clavicular head also acts individually to flex the upper limb.

29. 2.Pectoralis Minor The pectoralis minor lies underneath its larger counterpart muscle, pectoralis major. Both of these muscles form part of the anterior wall of the axilla region. Attachments:  Originates from the 3rd-5th ribs, and inserts into the coracoid process of the scapula. Function:  Stabilises the scapula by drawing it anteroinferiorly against the thoracic wall.

30. 3.Serratus Anterior The serratus anterior is located more laterally in the chest wall, and forms the medial border of the axilla region. Attachments:  The muscle consists of several strips, which originate from the lateral aspects of ribs 1-8. They attach to the rib surface of the medial border of the scapula. Function:  Rotates the scapula, allowing the arm to be raised over 90 degrees. It also holds the scapula against the ribcage.

31. 4.Subclavius The subclavius is small muscle, which is located directly underneath the clavicle, running horizontally. It affords some minor protection to the underlying neurovascular structures . Attachments : Originates from the junction of the 1st rib and its costal cartilage, inserting into the inferior surface of the middle third of the clavicle. Function : Anchors & depresses the clavicle.

32. Muscles of the pelvic floor The pelvic floor is divided into two identical halves that unite along the midline. Each half consists of fascia and muscle. The muscles are….. 1.Levator ani This is a pair of broad flat muscles, forming the anterior part of the pelvic floor. They originate from the inner surface of the true pelvis and unite in the midline. Together they form a sling that supports the pelvic organs.

33. 2.Coccygeus This is a paired triangular sheet of muscle and tendinous fibres situated behind the levator ani. They originate from the medial surface of the ischium and are inserted into the sacrum and coccyx. They complete the formation of the pelvic floor, which is perforated in the male by the urethra and anus, and in the female by the urethra, vagina and anus . Functions The pelvic floor supports the organs of the pelvis and maintains continence, i.e. it resists raised intrapelvic pressure during micturition and defecation

34. Muscles of the shoulder and upper limb These muscles stabilize the association between the appendicular and axial skeletons at the pectoral girdle, and stabilize and allow movement of the shoulders and upper arms.

35. 1.Deltoid muscles - These muscle fibres originate from the clavicle, acromion process and spine of scapula and radiate over the shoulder joint to be inserted into the deltoid tuberosity of the humerus. It forms the fleshy and rounded contour of the shoulder and the main function is movement of the arm. The anterior part causes flexion, the middle or main part abduction and the posterior part extends and laterally rotates the shoulder joint.

36. 2.Pectoralis major This lies on the anterior thoracic wall. The fibres originate from the middle third of the clavicle and from the sternum and are inserted into the lip of the intertubercular groove of the humerus. It draws the arm forward and towards the body, that flexes and adducts. 3.Coracobrachialis This lies on the upper medial aspect of the arm. It arises from the coracoid process of the scapula, stretches across in front of the shoulder joint and is inserted into the middle third of the humerus. It flexes the shoulder joint.

37. 4.Biceps This lies on the anterior aspect of the upper arm. At its proximal end it is divided into two parts (heads), each of which has its own tendon. The short head rises from the coracoids process of the scapula and passes in front of the shoulder joint to the arm. The long head originates from the rim of the glenoid cavity and its tendon passes through the joint cavity and the bicipital groove of the humerus to the arm. It is retained in the bicipital groove by a transverse humeral ligament that stretches across the groove. The distal tendon crosses the elbow joint and is inserted into the radial tuberosity. It helps to stabilise and flex the shoulder joint and at the elbow joint it assists with flexion and supination.

38. 5.Pronator quadratus This square-shaped muscle is the main muscle causing pronation of the hand & has attachments on the lower sections of both the radius & the ulna. 6.Pronator teres This lies obliquely across the upper third of the front of the forearm. It arises from the medial epicondyle of the humerus &the coronoid process of the ulna & passes obliquely across the forearm to be inserted into the lateral surface of the shaft of the radius. It rotates the radioulnar joints, changing the hand from the anatomical to the writing position, that is pronation.

39. 7.Triceps This lies on the posterior aspect of the humerus. It arises from three heads, one from the scapula two from the posterior surface of the humerus. The insertion is by a common tendon to the olecranon process of the ulna. It helps to stabilise the shoulder joint, assists in adduction of the arm & extends the elbow joint. 8.Brachioradialis The brachioradialis spans the elbow joint, originating on the distal end of the humerus&inserts on the lateral epicondyle of the radius. When it contracts, it flexes the elbow joint.

40. 9.Supinator This lies obliquely across the posterior & lateral aspects of the forearm. Its fibres arise from the lateral epicondyle of the humerus & the upper part of the ulna and are inserted into the lateral surface of the upper third of the radius. It rotates the radioulnar joints, often with help from the biceps, changing the hand from the writing to the anatomical position, supination. It lies deep to the muscles.

41. 10.Flexor carpi radialis This lies on the anterior surface of the forearm. It originates from the medial epicondyle of the humerus & is inserted into the second & third metacarpal bones. It flexes the wrist joint, & when acting with the extensor carpi radialis, abducts the joint. 11.Flexor carpi ulnaris This lies on the medial aspect of the forearm. It originates from the medial epicondyle of the humerus & the upper parts of the ulna & is inserted into the pisiform, the hamate & the fifth metacarpal bones. It flexes the wrist, & when acting with the extensor carpi ulnaris, adducts the joint

42. 12.Extensor carpi radialis longus and brevis These lie on the posterior aspect of the forearm. The fibres originate from the lateral epicondyle of the humerus & are inserted by a long tendon into the second & third metacarpal bones. They extend & abduct the wrist. 13.Extensor carpi ulnaris This lies on the posterior surface of the forearm. It originates from the lateral epicondyle of the humerus& is inserted into the fifth metacarpal bone. It extends & adducts the wrist.

43. 14.Palmaris longus This muscle resists shearing forces that might pull the skin &fascia of the palm away from the underlying structures& flexes the wrist. Its origin is on the medial epicondyle of the humerus,& it inserts on tendons on the palm of the hand. 15.Extensor digitorum This muscle originates on the lateral epicondyle of the humerus & spans both the elbow and wrist joints; in the wrist, it divides into four tendons, one for each finger. Action of this muscle can extend any of the joints across which it passes, the elbow, wrist or finger joints.

44. Muscles that control finger movements Large muscles in the forearm that extend to the hand give power to the hand and fingers, but not the delicacy of movement needed for fine and dextrous finger control. Smaller muscles, which originate on the carpal and metacarpal bones, control tiny and precise finger movements via tendinous attachments on the phalanges; muscle fibres do not extend into the fingers.

45. Muscles of the hip and lower limb The biggest muscles of the body are found here, since their function is largely in weight bearing. The lower parts of the body are designed to transmit the force of body weight in walking, running, etc., evenly throughout weight-bearing structures, and as shock absorbers. 1.Psoas This arises from the transverse processes and bodies of the lumbar vertebrae. It passes across the flat part of the ilium and behind the inguinal ligament to be inserted into the femur. Together with the iliacus it flexes the hip joint.

46. 2.Iliacus T his lies in the iliac fossa of the innominate bone. It originates from the iliac crest, passes over the iliac fossa and joins the tendon of the psoas muscle to be inserted into the lesser trochanter of the femur. The combined action of the iliacus and psoas flexes the hip joint.

47. 3. Quadriceps femoris--- This is a group of four muscles lying on the front and sides of the thigh. They are the  rectus femoris  and three  vasti : lateralis, medialis and intermedius . The rectus femoris originates from the ilium and the three vasti from the upper end of the femur. Together they pass over the front of the knee joint to be inserted into the tibia by the patellar tendon. Only the rectus femoris flexes the hip joint. Together, the group acts as a very strong extensor of the knee joint.

48. 4.Obturators The obturators, deep muscles of the buttock, have their origins in the rim of the obturator foramen of the pelvis and insert into the proximal femur. Their main function lies in lateral rotation at the hip joint. 5.Gluteals These consist of the  gluteus maximus ,  medius  &  minimus , which together form the fleshy part of the buttock. They originate from the ilium and sacrum and are inserted into the femur. They cause extension, abduction and medial rotation at the hip joint.

49. 6.Sartorius This is the longest muscle in the body and crosses both the hip & knee joints. It originates from the anterior superior iliac spine &passes obliquely across the hip joint, thigh and knee joint to be inserted into the medial surface of the upper part of the tibia. It is associated with flexion and abduction at the hip joint and flexion at the knee. 7.Adductor group This lies on the medial aspect of the thigh. They originate from the pubic bone and are inserted into the linea aspera of the femur. They adduct and medially rotate the thigh.

50. 8 .Hamstrings These lie on the posterior aspect of the thigh. They originate from the ischium & are inserted into the upper end of the tibia. They are the  bicepsfemoris ,  semimembranosus  and  semitendinosus muscles . They flex the knee joint. 9.Gastrocnemius This forms the bulk of the calf of the leg. It arises by two heads, one from each condyle of the femur& passes down behind the tibia to be inserted into the Achilles tendon. It crosses both knee & ankle joints, causing flexion at the knee & plantar flexion (rising onto the ball of the foot) at the ankle .

51. 10.Anterior tibialis This originates from the upper end of the tibia, lies on the anterior surface of the leg & is inserted into the middle cuneiform bone by a long tendon. It is associated with dorsiflexion of the foot . 11.Soleus This is one of the main muscles of the calf of the leg, lying immediately deep to the gastrocnemius. It originates from the head & upper parts of the fibula & the tibia. Its tendon joins that of the gastrocnemius so that they have a common insertion into the calcaneus by the achilles tendon. It causes plantar flexion at the ankle and helps to stabilise the joint when standing .