.Mascular system

.Mascular system
types
muscles
charactersitics
function of muscle
classification of muscles
sarcoplasmic organelles
structure of msucles
how to name muscle
neck muscle
intrinsic back muscle
extrinsic back muscles
anterior compartment of thih muscle
hamstring group muscles
IM injection common sites
muscular tension

1. Muscular System

2. Objectives At the end of this session, the students will be able to: Define the following terms as Endomysium, Fascia, epimysium perimysium, tendons Describe the location and function of major muscles of: Neck, face, back, arms, legs

3. Introduction to muscles The muscular system consists of about 600 skeletal muscles excluding cardiac and smooth muscles. Myology is the study of muscles. A skeletal muscle is composed of both muscular tissue and connective tissue.

4. Functions of Muscles Movement Stability Communication—facial expression, body language Control of body openings and passages Heat production (thermogenesis)

5. Properties of Muscular Tissue Four properties that enable it to function. 1. Electrical excitability 2. Contractility 3. Extensibility 4. Elasticity

6. Classification of Muscles Striation based Action based Situation based

7. Features of Muscles Features Skeletal Cardiac Smooth Shape Cylindrical , unbranched Branched Spindle, unbranched Length 1—4 cm 80—100  50—200  Nucleus More than one one one Striations present present absent Myofibrils present present Absent Sarcomere present present absent Troponin present present Absent Depolarization Upon stimulation Spontaneous Spontaneous Tetanus Possible Not possible Not Possible RMP Stable Stable Unstable Ca ++ binds with Troponin Troponin Calmodulin Nerve supply Somatic Autonomic Autonomic Control Neurogenic Myogenic Neurogenic and Myogenic

8. Sarcoplasmic Organelles 1. Nuclei 2. Myofibrils 3. Golgi apparatus 4. Mitochondria 5. Sarcoplasmic reticulum 6. Ribosomes 7. Glycogen droplets 8. Occasional lipid droplets.

9. Microscopic Structure of a Myofibril Myofibrils are fine parallel filaments in sarcoplasm . Run through the entire length of the muscle fiber . Each myofibril consists of a number of two alternating bands which are also called the sections, segments or disks. These bands are formed by muscle proteins. The two bands are: 1. Light band or ‘I’ band (isotropic to polarized light) 2. Dark band or ‘A’ band (Anisotropic to polarized light)

10. Microscopic Structure of a Myofibril Cont... ‘I’ band is divided by ‘Z’ line or ‘Z’ disk The ‘Z’ line is formed by a protein disk, which does not permit the passage of light. The portion of myofibril between two ‘Z’ lines is called sarcomere . Sarcomere is structural and functional unit of a skeletal muscle. It is also called the basic contractile unit of the muscle. Sarcomere consists of many threadlike structures called myofilaments . Myofilaments are of two types: 1. Actin filaments 2. Myosin filaments.

11. Sarcomere Myocyte

12. Troponin Troponin is formed by three subunits: 1. Troponin I, which is attached to F-actin 2. Troponin T, which is attached to tropomyosin 3. Troponin C, which is attached to calcium ions.

13. Key Terms Endomysium: An areolar connective tissue membrane that surrounds a single skeletal muscle cell (muscle fiber). Fascicle (fasc= bundle+ icle= little): The muscle fibers that are grouped in a bundle . It is also called fasciculus. Perimysium: A connective tissue sheath which separates one fascicle from neighboring ones. Epimysium: A connective tissue sheet that surrounds a muscle as a whole. It is the outermost layer. Fascia: A connective tissue sheet that wraps around groups of muscles. Aponeurosis : a white fibrous sheet of tissue by which certain muscles are attached to bones. It is actually tendon which is thin and flat but tough.

14. How to Name Muscles Name Meaning Example Location Pectoralis (of the chest) Brachii (of the arm) Pectoralis major Biceps brachii Size Maximus Minimus Longus Brevis Latissimus Longissimus Magnus Major Minor Vastus Largest Smallest Long Short Widest Longest Larger Larger Smaller Huge Gluteus maximus Gluteus minimus Adductor longus Abductor brevis Latissimus dorsi Longissimus capitis Adductor magnus Pectoralis major Pectoralis minor Vastus lateralis

15. How to Name Muscles Name Meaning Example 3. Shape Deltoid Serratus Orbicularis Pectinate Platys Gracilis Triangular Sawtoothed Circular Comb like Flat Slender Deltoid Serratus anterior (thoracic) Orbicularis oculi Pectineus (femoral muscle ) Platysma (neck muscle) Gracilis 4 . Number of origins Biceps Triceps Quadriceps Two origins Three origins Four origins Biceps brachii Triceps brachii Quadriceps femoris

16. How to Name Muscles Name Meaning Example 5. Origin and insertion Sternocleidomastoid Originating on the sternum and clavicle and inserting on the mastoid process of the temporal bone Sternocleidomastoid 6 . Direction Rectus Transverse Oblique Parallel to midline Perpendicular to midline Diagonal to midline Rectus abdominis Transverse abdominis External oblique (of abdomen)

17. How to Name Muscles Name Meaning Example 7. Action Flexor Extensor Abductor Adductor Levator Depressor Supinator Pronator Decreases a joint angle Increases a joint angle Moves a bone away from midline Moves a bone closer to midline Elevates a body part Depresses Supinates Pronates Flexor carpi radialis External carpi ulnaris Levator palpebrae Depressor anguli oris Supinator teres Pronator teres

18. Names of selected muscles Face Muscles Orbicularis Occuli Closes eyelid and compresses lacrimal glands Levator palpebrae (opens eye & raises upper lid Masseter (chewing) Orbicularis oris (closes & protrudes lips) Buccinator (compresses cheeks, blowing, suction) Zygomaticus minor and major Draws corners of mouth laterally and upward as in smiling and laughing Platysma Depresses mandible, opens and widens mouth Neck Muscles Sternocleidomastoid Flexes neck and draws head down Scalenes Flex neck laterally and elevate ribs 1 &2 in inspiration Trapezius Abducts and extends neck Splenius capitis Rotate head and extend neck Digastric Opens mouth by lowering mandible Raises hyoid bone Sternohyoid Depresses hyoid bone after swallowing Thyrohyoid Raises larynx

19. Neck Muscles

20. Back Muscles Muscles in the back are classified as extrinsic and intrinsic. Extrinsic muscles consist of superficial and intermediate group of muscles. Superficial muscles are involved with the movements of upper limbs while the intermediate muscles are associated with the thoracic wall. Extrinsic muscles are innervated by the anterior rami of spinal nerves. Intrinsic muscles lying deep in the back are innervated by posterior rami of spinal nerves.

21. Extrinsic Back Muscles Superficial Group Trapezius Superior fibers elevate scapula; middle fibers retract it; inferior fibers depress it. Levator scapulae Elevates scapula Rhomboid minor & major Retracts(adducts) and elevates scapula Latissimus dorsi (swimming) Extends, adducts, and medially rotates humerus Intermediate Group (Respiratory muscles) Serratus posterior superior Elevates ribs II to V Serratus posterior inferior Depresses ribs IX to XII

22. Intrinsic Back Muscles Splenius Capitis Together—draw head backward, extending neck Individually—draw and rotate head to one side Splenius Cervicis Together—extend neck Individually—draw and rotate head to one side Erector spinae (erecting back) Illiocostalis cervicis extend and laterally flex vertebral column Illiocostalis thoracis and lumborum Rotate ribs during forceful inspiration

23. Arm Muscles Deltoid (abduct humerus ) Teres major (adduct and medially rotate humerus ) Teres minor (abduct and laterally rotate humerus ) Biceps brachii (flexes elbow) Brachialis (flexes elbow) Triceps brachii (extends elbow) Pronator ( teres , quadratus ) pronates forearm Supinator ( teres , quadratus ) supinates forearm Flexor carpi radialis Flexes wrist Palmaris longus Flexes wrist Flexor carpi ulnaris Flexes wrist Extensor carpi radialis Extensor carpi ulnaris Flexor pollicis ( longus , brevis ) Flexes thumb Extensor pollicis ( longus , brevis ) Extends thumb Flexor digitorum ( superfi , profun ) Flexes fingers II—V Extensor digitorum

24. Anterior Compartment Thigh Muscles Psoas major Flexes thigh at hip joint Iliacus Flexes thigh at hip joint Vastus Extends the leg at knee joint Rectus femoris Extends leg at knee and flexes the thigh at hip Sartorius Flexes thigh at hip and leg at knee

25. Hamstring Group Muscles Biceps femoris Flexes knee, extends hip, laterally rotates leg Semitendinous Flexes knee, extends hip, medially rotates tibia Semimembranous Flexes knee, extends hip, medially rotates tibia

26. IM injection common sites Deltoid muscle of the arm. The deltoid muscle is the site most typically used for vaccines. ... Vastus lateralis muscle of the thigh. ... On the front of the thigh Ventrogluteal muscle of the hip. At the outer upper thigh... Dorsogluteal at the upper outer quadrant of buttock