Muscular System PDF

Muscular system Dr. Udeshika Yapa Bandara B Sc. Human Biology (USJP), PhD (UOC)1 Learning outcomes: Students should be able to identify – Muscles of the face – Muscles of the neck – Muscles of the trunk – Muscles of the back – Muscles of the abdominal...

Muscular system Dr. Udeshika Yapa Bandara B Sc. Human Biology (USJP), PhD (UOC)1 Learning outcomes: Students should be able to identify – Muscles of the face – Muscles of the neck – Muscles of the trunk – Muscles of the back – Muscles of the abdominal wall – Muscles of the thorax – Muscles of the pelvic floor – Muscles of the shoulder & upper limb – Muscles of the hip & lower limb 2  Muscles of the face Many muscles involve to, - change facial expression - move the lower jaw during chewing and speaking Present as pairs 3  Muscles of the face that produce facial expressions Occipitofrontalis Orbicularis oris Levator palpebrae superioris Buccinator Orbicularis oculi 4 Muscles of the face and neck 5  Occipitofrontalis ( unpaired) - Anterior part Origin - Epicranial Aponeurosis Insertion - Skin superior to supraorbital margin Action - Draws scalp anteriorly - Raises eyebrows - wrinkles skin of forehead horizontally as in look of surprise - Posterior part Origin - Occipital bone Insertion - Aponeurosis of occipitofrontalis Action - Draws scalp posteriorly Nerve - facial nerve 6  Levator palpebrae superioris Origin - posterior part of the orbital cavity Insertion - upper eye lid Action - elevate upper eye lids (open eyes) Nerve - Oculomotor nerve 7  Orbicularis oculi Origin - medial wall of orbit Insertion - circular path around orbit Action - close the eye Nerve - Facial nerve 8  Orbicularis oris (unpaired) Muscles in the lips that encircles the mouth. Origin – Maxilla and mandible Insertion - skin at corner of mouth Action - closes the lips - shapes lips during speech & whistling Nerve – Facial nerve 9  Buccinator Flat muscle of the cheek Origin - Alveolar processes of maxilla & mandible Insertion - Orbicularis oris Action - Presses cheeks against teeth and lips as in whistling - assist in mastication Nerve – Facial nerve 10  Muscles of the neck Sternocleidomastoid Trapezius 11  Sternocleidomastoid Origin – sternum & clavicle Insertion – mastoid process of the temporal bone Action - assists in turning the head from side to side - accessory muscle in respiration Nerve - Accessory nerve 12  Trapezius Large triangular muscle covers the shoulder & back of the neck Origin- ✓ Superior trapezius: medial third of superior nuchal line; external occipital protuberance, nuchal ligament ✓ Middle trapezius: spinous processes of the vertebrae T1-T4 ✓ Inferior trapezius: spinous processes of the vertebrae T5-T12 Insertion ✓ Superior trapezius: lateral third of the clavicle ✓ Middle trapezius: acromion ✓ Inferior trapezius: spine of the scapula 13  Action - pulls the head backwards - squares the shoulders - controls the movement of the scapula when the shoulder joint is in use Nerve - Accessory nerve & cervical spinal nerves C3- C5 14  Muscles of the trunk These muscles, – stabilize the association between the appendicular and axial skeletons – allow movement of the shoulders and upper arms Divided into - muscles of the back - muscles of the abdominal wall - muscles of the thorax 16  Muscles of the back Form the posterior abdominal wall Six pairs of large muscles in the back - trapezius - latissimus dorsi - teres major - quadratus lumborum - sacrospinalis 17  21 the main muscles of the back Latissimus dorsi Origin – posterior part of the iliac crest & spinous processes of the lumbar & lower thoracic vertebrae Insertion – bicipital groove of the humerus Action – abducts, medially rotates, extends the arm Nerve - Thoracodorsal nerve 19 Teres major Origin – inferior angle of the scapula Insertion – humerus below the shoulder joint Action – extends, abducts & medially rotates the arm Nerve - Lower subscapular nerve 20  Quadratus lumborum Origin – iliac crest Insertion – inferior border of the12th rib Action – together the two muscles fix the lower rib during respiration - cause extension of the vertebral column (bending backwards) Nerve -Thoracic spinal nerve T12 and lumbar spinal nerves L1–L3 or L1–L4 21 Sacrospinalis (erector spinae ) Lying between the spinous & transverse process of the vertebrae Origin – sacrum Insertion – occipital bone Action – extension of the vertebral column (bending backwards) Nerve - Spinal nerves 22  Muscles of the abdominal wall Functions – Form the strong muscular anterior wall of the abdominal cavity – Compress the abdominal organs – Flex the vertebral column in the lumbar region Linea alba – A strong midline tendinous cord & divided anterior abdomen longitudinally 23 24 1. Anterior abdominal wall Rectus abdominis External oblique Internal oblique Transversus abdominis 2. Posterior abdominal wall Psoas major Quadratus lumborum 25 26 Rectus abdominis Most superficial muscle Separated midline by the linea alba Origin - transverse part of the pubic bone Insertion - lower ribs & xiphoid process of the sternum. Action - flexes vertebral column - compresses abdomen to aid in defecation, urination, & childbirth Nerve - Thoracic spinal nerves T7 – T12 27 External oblique Origin - lower 8th ribs Insertion - iliac crest & linea alba Action -Acting together (bilaterally), compress abdomen and flex vertebral column ; - Acting singly (unilaterally), laterally flex vertebral column Nerve - Thoracic spinal nerves T7 – T12 28 Internal oblique Lie deep with to the external oblique Origin - iliac crest, inguinal ligament & lumbar fascia Insertion - Cartilage of ribs 7–10 & linea alba Action - same as external oblique Nerve - Thoracic spinal nerves T8 – T12 29 Transversus abdominis Deepest muscle of the abdominal wall Origin - iliac crest & lumbar vertebrae Insertion - xipoid process, linea alba & pubis Action - Compresses abdomen Nerve - Thoracic spinal nerves (T8 – T12) 30  Muscles of the thorax Anterior thoracic muscles – Pectoralis minor – Serratus anterior – Intercostal muscles - Internal intercostal muscle - External intercostal muscle – Diaphragm 31 Pectoralis minor Smaller triangular muscle lying deep to the pectoralis major Origin - margins of the third to fifth ribs adjacent to the costochondral junction. Insertion - coracoid process of the scapula Action - abducts scapula & rotates it downwards Nerve - Medial pectoral nerve 32 Serratus anterior Origin - 1st to 8/9th rib Insertion - anterior surface of the medial border of the scapula Action - abducts scapula & rotates it upwards Nerve - Long thoracic nerve 33 Internal intercostal muscles Origin - superior border of the ribs below Insertion - inferior border of the rib above Action - depress rib cage, aid in forced expiration Nerve - Thoracic spinal nerves ( T2 – T12) 34 External intercostal muscles Origin - inferior border of the rib above Insertion - superior border of the rib below Action - contraction elevate rib cage, aids in inhalation - relaxation depress the rib result in exhalation Nerve - Thoracic spinal nerves T2 – T12 35 Diaphragm Dome shaped muscular structure Most important muscle in breathing Separate the thoracic & abdominal cavities Formed partly by muscle & partly by flattened tendon called central tendon Origin - xiphoid process of the sternum, costal cartilage Insertion - central tendon Action - helps to inhalation & exhalation Nerve - Phrenic nerve 36 37  Muscles of the shoulder & upper limb Helps to – stabilize the association between the appendicular and axial skeleton – stabilize and allow movement of the shoulders and upper arms 38 Axial muscles that move the humerus – Pectoralis major – Latissimus dorsi Scapular muscles that move the humerus – Deltoid – Subscapularis – Supraspinatus – Infraspinatus 39 40 Deltoid Origin - Clavicle, acromion process & spine of scapula Insertion - deltoid tuberosity of the humerus Action - forms the fleshy & rounded contour of the shoulder - movement of the arm - flexion, abduction and laterally rotates the shoulder joint Nerve - Axillary nerve 42 Pectoralis major Large fan shaped muscle Forms anterior part of the axilla Origin - middle third of the clavicle & sternum Insertion - lip of the intertubercular groove of the humerus Action - draws the arm forwards & towards the body Nerve - Medial and lateral pectoral nerves 43 Biceps brachii lies on the anterior aspect of the upper arm Origin- short head - coracoid process the scapula - long head- rim of the glenoid cavity of scapula Insertion - radial tuberosity of radius Action - stabilize & flex the shoulder joint - assist the flexion & supination at elbow joint Nerve - Musculocutaneous nerve 44 Triceps Lies on the posterior aspect of the humerus Origin- one head from the scapula & two heads from the posterior surface of the humerus Insertion- common tendon to the olecranon process of the ulna Action- stabilize the shoulder joint - assists in abduction of the arm & extends the elbow joint Nerve- Radial nerve 45  Muscles of the pelvic floor Muscles are - Levator ani - coccygeus Supports the organs of the pelvis & maintains continence Resists raised intra pelvic pressure during micturition, defecation 46 Levator ani Pair of broad, flat muscles largest and most important muscle of the pelvic floor Origin - inner surface of the side of the lesser pelvis Insertion - inner surface of coccyx Action - aids in defecation - supports the pelvic organs Nerve -sacral spinal nerves ( S2- S4) 47 Coccygeus Paired triangular sheet of muscle tendinous fibers situated behind the levator ani. Origin - medial surface of the ischium Insertion - sacrum & coccyx Action - supports pelvic viscera - supports coccyx & pulls it forward Nerve - Sacral spinal nerves S4 – S5 48  Muscles of the hip and lower limb Biggest muscles of the body can find here Main function - weight bearing - shock absorber 49 Main muscles of the right lower limb 52 Quadriceps femoris Group of four muscle lying on the front & sides of the thigh - rectus femoris - vastus lateralis - vastus medialis - vastus intermedius (lies deep) 51 52 Gluteal muscles Consist gluteus maximus, medius & minimus Form the fleshy part of the buttock Origin - ilium & sacrum Insertion - femur Action - extension, abduction & medial rotation at the hip joint Nerve - inferior & superior gluteal nerve 53 54 Hamstrings Lie on the posterior aspect of the thigh They are biceps femoris, semimembranosus & semitendinosus muscles Origin - ischium Insertion - upper end of the tibia Action - flex the knee joint Nerve - tibial nerve 55 Soleus Major muscles of the calf of the leg Origin - heads & upper parts of the fibula & the tibia Insertion - calcanean ( Achilles ) tendon Action - plantar flexion at the ankle - helps to stabilize the joint when standing Nerve - tibial nerve 56 Intramuscular injection( IM) Penetrates the skin & subcutaneous tissue IM is used when prompt action is desired Have a faster speed of delivery than oral medications but slower than intravenous Common sites of injection include, - Gluteus medius ( ventrogluteal ) - Vastus lateralis muscle - Rectus femoris - Deltoid muscle 57  Diseases of muscle Myasthenia gravis Autoimmune disease The immune system inappropriately produces antibodies that bind & block the acetylcholine receptors of the neuromuscular junction Causes progressive & extensive muscle weakness Extrinsic & eyelid muscles affected first, causing ptosis (drooping of the eye lid) or diplopia ( double vision ) Affecting for chewing, swallowing & speech 58 Muscular Dystrophy A group of inherited muscle-destroying diseases that cause progressive degeneration of skeletal muscle fibers. 59