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Sternocleidomastoid
- Two-headed muscle located deep to platysma on anterolateral surface of neck
- O-manubrium of sternum and medial portion of clavicle
- I-mastoid process of temporal bone and superior nuchal line of occiptial bone
- Action - Flexes and laterally rotates the head
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Erector Spinae
- Action - Prime move of back extension
- Three column: iliocostalis, logissimus, and spinalis muscles
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Rectus abdominis
- Medial muscle pair; extend from pubis to rib cage; ensheathed by aponeuroses of lateral muscles; segmented by three tendinous intersections
- O-pubic crest and symphysis
- I-xiphoid process and costal cartilages of ribs
- A-Flex and rotate lumbar region of vertebral column
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Pectoralis minor
- Flate, thin muscle directly beneath and obscured by pectoralis major
- O-anterior surfaces of ribes 3-5
- I-coracoid process of scapula
- A-With ribs fixed, draws scapula forward and downward
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Serratus anterior
- Fan-shaped muscle; lies deep to scapula, deep and inferior to pectoral muscles on later rib cage
- O-by series of muscle slips from ribs 1-8
- I-entire anterior surface of vertebral borders scapula
- A-Rotates scapula so that its inferior angle moves laterally and upward
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Subclavius
- Small cylindrical muscle extending from rib 1 to clavicle
- O-costal cartilage of rib 1
- I-groove on inferior surface of clavicle
- A-Help stablize and depress pectoral girdle
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Trapezius
- Most superficial muscle of posterior thorax; flat and triangular
- O-occipital bone, ligamentum nuchae, and spines of C7 and all thoracic vertebrae
- I-a continuos insertion along acromion and spine of scapula and lateral third of clavicle
- A-Stabilizes, raises, retracts, and rotates scapula
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Levator scapulae
- Located at back and side of neck, deep to trapezius; thick, traplike muscle
- O-transverse processes of C-1-C4
- I-medial border of the scapula, superior to the spine
- A-Elevates/adducts scapula
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Rhomboids
- Two rectangular muscles lying deep to trapezius and inferior to levator scapulae; rhomboid minor is the more superior muscle
- O-Spinous processes of C7 and T1 and spinjous processes of T2-T7
- I-medial border of scapula
- A-Stabilize scapula
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Pectoralis major
- Large, fan shaped muscle covering upper porrtion of chest
- O-Sternal end of clavicle, sternum, cartilage of ribs
- I-fibers converge to insert by a short tendon into greater tubercle of humerus
- A-Prime mover of arm flexion; rotates arm medially; adducts arm
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Deltoid
- Thick, multipennate muscl forming rounded shoulder muscle mass
- O-embraces inserstion of the trapezius; lateral third of clavicle; acromion and spine of scapula
- I-deltoid tuberosity of humerus
- A-Prime mover of arm abduction when all its fiber contract simultaneously
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Latissimus dorsi
- Broad, flat, triangular muscle of lower back (lumbar region)
- O-indirect attachment via thoracolumbar fascia into spines of lower six thoracic vertebrae, lumbar vertebrae, lower 3 to 4 ribs and iliac crest
- I-spirals around teres major in insert in floor of intertubercular sulcus of humerus
- A-Prime movers of arm extension; adduction and medial rotation at shoulder
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Teres major
- thick, rounded muscle; located inferior to teres minor;
- O-posterior surface of scapula at inferior angle
- I-crest of lesser tubercle on anterior humerus; insertion tendon fused with that of latissimus dorsi
- A-Extends, medially rotates, and adducts humerus
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Coracobrachialis
- Small, cylindrical muscle
- O-coracoid process of scapula
- I-medial surface of humerus shaft
- A-Flexion and adduction of the humerus
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Subscapularis
- Forms part of posterior wall of axilla
- O-subscapular fossa of scapula
- I-lesser tubercle of humerus
- A-Chief meidal rotator of humerus
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Supraspinatus
- Named for its location on posterior aspect of scapula
- O-supraspinous fossa of scapula
- I-superior part of greater tubercle of humerus
- A-initiates abduction
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Infraspinatus
- Partially coverd by deltoid and trapezius
- O-infraspinous fossa of scapula
- I-greater tubercle of humerus posterior to insertion of supraspinatus
- A-Rotates humerus laterally
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Teres minor
- small, elongated muscle; lies inferior to infraspinatus and may be inseparable from that muscle; a rotator cuff muscle
- O-lateral border of dorsal scapular surface
- I-greater tubercle of humerus inferior to infraspinatus insertion
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Triceps brachii
- Large fleshy muscle; the only muscle of posterior eompartment of arm
- O-long head; infraglenoid tubercle of scapula
- I-by common tendon into olecranon process of ulna
- A-Powerful forearm extensor
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Biceps brachii
- Two headed fusiform muscle; bellies unite as insertion point is approached
- O-short head; coracoid process; long head: supraglenoid tubercle and lip of glenoid cavity
- I-by common tendon into radial tuberosity
- A-Flexes elbow joint and supinates forearm
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Brachialis
- Strong muscle that is immediately deep to beceps brachii on distal humerus
- O-front of distal humerus
- I-coronoid process of ulna and capsule of elbow joint
- A-A major forearm flexor
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Pronator teres
- Two-headed muscle; seen in superficial view between proximal margins of brachioradialis and flexor carpi radialis
- O-medial epicondyle of humerus; coronoid process of ulna
- I-by common tendon into lateral radius, midshaft
- A-Pronates forearm
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Flexor carpi radialis
- Runs diagonally across forearm;
- O-medial epicondyle of humerus
- I-base of second and third metacarpals
- A-Powerful flexor of wrist
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Palmaris longus
- Small fleshy muscle with a long insertion tendon
- O-medial epicondyle of humerus
- I-fascia of palm (palmar aponeurosis)
- A-Tenses skin and fascia of palm during hand movements
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Flexor carpi ulnaris
- Most medial muscle of this group; two headed
- O-medial epicondyle of humerus; olecranon process an dposterior surface of ulna
- I-pisiform and hamate bones and base of fifth metacarpal
- A-Powerful flexor of wrist; also adducts hand
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flexor digitorum
- two head muscle; more deeply placed
- O-medial epicondlye of humerus, coronoid process of ulna
- I-by four tendons into middle phalanges of fingers 2-5
- A-Flexes wrist and middle phalanges of fingers 2-5
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