CHP10TheMuscularSystem

Partial tendons sleeve around proximal end of humerus

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Unformatted text preview: eres major, coracobrachialis, & 4 scapular deltoid teres coracobrachialis synergist muscles of the rotator cuff rotator ‘Shoulder’ Muscles (cont.) Deltoid= thick muscle ‘capping’ shoulder; flexes, extends, & thick abducts shoulder depending on which fibers contract abducts • Antagonized by pectoralis major & lat’s • Origin @ clavicle, scapular spine, acromion, inserts on deltoid Origin tuberosity tuberosity Teres major= assists in extension of shoulder • Origin @ inferior angle to lateral border of scapula, inserts on Origin medial aspect of upper humerus medial Coracobrachialis= assists in flexion & adduction assists Rotator Cuff Rotator Tendons of remaining 4 muscles form ‘rotator cuff’= partial Tendons sleeve around proximal end of humerus to stabilize head in glenoid cavity glenoid 4 muscles originate on scapular surfaces (fossae) & insert on muscles greater/lesser tubercles greater/lesser ‘SITS’- supraspinatus, infraspinaus, teres minor, subscapularis SITS’muscles Subscapularis= anterior (ventral side) Subscapularis Supraspinatus= dorsal side Infraspinatus= dorsal side Teres minor= origin @ lateral border Rotator cuff damaged by strenuous circumduction (pitching) Muscles of Forearm Muscles Muscles acting on forearm explained in table 10.12 Muscles acting (Tables 10.11, 10.13 for actions of shoulder & arm) (Tables Elbow/forearm has 4 motions: flex/extend & supine/prone Elbow/forearm motions: Main flexors= biceps brachii (elevates radius) & brachialis (ulna) • Biceps brachii= flexes elbow, abducts arm, supinates forearm, flexes holds humerus in g.cavity holds • Origins differ for long/short heads, so separate tendons arise from Origins scapula; single tendon inserts on radial tuberosity scapula; • Brachialis= flexes elbow; origin @ distal humerus & inserts on flexes coronoid process/capsule of elbow jnt jnt Muscles of Forearm Muscles Brachioradialis= elbow flex synergist; belly adjacent to radius • Origin @ lateral epicondyle of humerus, inserts on styloid Origin process of radius process Main extensors= triceps brachii (anconeus, synergist that synergist crosses back of elbow) crosses Triceps brachii- extends; long head adducts humerus • Origins of 3 heads differ, inserts as 1 tendon on olecranon Pronate by 2 anterior muscles= pronator teres & pronator Pronate pronator quadratus quadratus Supinate by posterior muscle= supinator (+ biceps) (+ Muscles of Wrist & Hand Muscles Table 10.14 (actions summarized in 10.15) Hand motions caused by extrinsic muscles of forearm & Hand extrinsic intrinsic muscles of hand intrinsic • Flex/extend, ab/adduct, opposition of thumb to fingers Tendons extend into wrist/hand, pass under a retinaculum Tendons retinaculum • Flexor retinaculum- (transverse carpal ligament) anterior • Extensor retinaculum- (dorsal carpal ligament) posterior Carpal tunnel= tight space btw carpals & flexor retinaculum • F...
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