Anatomy Lab Practical #3 Muscles

Pectoralis Major

Origin: sternal end of clavicle

Insertion: intertubercular sulcus

Shape: fan-shaped

Function: flex, adduct, and medially rotate arm

Deltoid

Origin: clavicle

Insertion: deltoid tuberosity

Shape: large muscle

Function: abduct the arm; arm rotation, flexion and extension

Trapezius

Origin: occipital bone

Insertion: acromion of spine

Shape: triangular-shaped

Function: elevate and adduct the scapula; extend the head

Latissimus dorsi

Origin: spinous process T7-T12

Insertion: intertubercular sulcus

Shape: broad and flat

Function: arm extension, adduct and medially rotates arm

Supraspinatus

Origin: supraspinous fossa

Insertion: greater tubercle of humerus

Shape: covered by trapezius

Function: stabilize the shoulder joint and abduct the arm

Infraspinatus

Origin: infraspinous fossa

Insertion: greater tubercle of humerus

Shape: covered by deltoid and trapezius

Function: stabilize the shoulder joint and laterally rotate the arm

Teres minor

Origin: lateral border of scapula

Insertion: greater tubercle of humerus

Shape: located between infraspinatus and teres major

Function: stabilize the shoulder joint and laterally rotate the arm

Subscapularis

Origin: subscapular fossa of the scapula

Insertion: lesser tubercle of the humerus

Shape: anterior surface of scapula (rotator cuff)

Function: stabilize the shoulder joint and medially rotate the arm

Triceps brachii

Origin: posterior shaft of the humerus

Insertion: olecranon

Shape: large muscle on posterior side of arm

Function: extend the forearm

Biceps brachii

Origin: coracoid process

Insertion: radial tuberosity of the radius

Shape: anterior side of humerus

Function: flex and supinate the forearm

Brachialis

Origin: distal portion humerus

Insertion: coronoid process of ulna

Shape: deep in the biceps brachii (distal end of humerus)

Function: flex the forearm (pulls on the ulna, while biceps brachii pulls on the radius)