Anatomy Fall 2011 Appendicular Musculature

Front 1

Muscles acting on the scapula(anterior group).

Back 1

The pectoralis minor attaches the coracoid process of the scapula. The serratus anterior attaches to the anterior aspect of the medial border of the scapula (long thoracic nerve). Both act to protract the scapula and the serratus anterior acts to rotate the scapula so that glenoid fossa is oriented cranially. (key muscle to lifting arm above head).

Front 2

Muscles acting on the scapula(posterior group).

Back 2

The trapezius attaches to the spine of the scapula (accessory nerve cn XI). The rhomboids attach to the medial border of the scapula. The levator scapulae attaches to the superior aspect of the medial border of the scapula and elevates it. Rhomboids and trapezius retract and elevate the scapula, trapezius can also depress scapula.

Front 3

Muscles acting on the humerus

Back 3

Nine muscles cross the shoulder joint to insert on the humerus. The pectoralis major(anteriorly), and the latissmus dorsi(posteriorly) bear the primary role for attaching the upper limb to the trunk. It adducts and medially rotates the humerus. The deltoid wraps around the top of the shoulder like a semicircular cap with anterior and posterior aspects. It is innervated by axillary n. It raises the upper limb to 90 degrees. Teres major and rotator cuff mm are both posterior.

Front 4

Muscles acting on the humerus continued.

Back 4

The biceps brachii is a superficial flexor of the elbow and the major supinator of the forearm. Note its two superior heads both attach to the scapula. the long head to the supraglenoid tubercle and the short head to the coracoid process. The coracobrachialis also attaches to the coracoid process. Both biceps and the coracobrachialis are innervated by the musculocutaneous n. Both are prime flexors of the shoulder.

Front 5

Rotator Cuff Muscles

Back 5

4 scapular muscles: supraspinatus, infraspinatus, teres minor, subscapularis. (SITS). Supraspinatus and infraspinatus is innervated by the suprascapular nerve. The teres minor is innervated by the axillary nerve and the subscapularis is innervated by the subscapular nerve. Only the subscapularis is on the anterior side.

Front 6

Muscles acting on the forearm

Back 6

The elbow and forearm exhibit 4 motions: flexion/extension; supination/pronation. The prime movers for flexion of the forearm are the biceps brachii and the brachialis muscles. They are both innervated by the musculocutaneous nerve.

Front 7

Muscles acting on the posterior arm and forearm

Back 7

The prime mover for extension of the arm and forearm is the triceps brachii located on the posterior side of the humerus. There are three heads, only one of which crosses shoulder to insert on scapula. This is the only head that extends the arm at the shoulder. Innervated by the radial nerve from the brachial plexus.

Front 8

Muscles of the forearm

Back 8

Supinator, pronator teres and pronator quadratus. Pronator teres and pronator quadratus are both on anterior aspect and innervated by median nerve. The supinator comes from the posterior aspect and wraps around the forearm. Because of this it is innervated by the radial nerve.

Front 9

Muscles acting on the wrist and hand

Back 9

Flexor carpi radialis is the flexor of the wrist on the thumb side and pulls hand away from midline (abduction). The flexor carpi ulnaris is the flexor of the wrist on the little finger side that pulls the hand toward the midline (adduction). Palmaris longus weakly flexes the wrist but tenses the palmar aponeurosis. Flexor carpi radialis and palmaris longus are innervated by the median nerve(thumb side) and the flexor carpi ulnaris is innervated by the ulnar nerve(little finger side).

Front 10

Flexor digitorum superficialis

Back 10

Muscle found underneath other three forearm anterior muscles. This muscle flexes the wrist, metacarpalphalangeal joints and the proximal and interphalangeal joint of digits II through V (NOT the thumb) and as such is inserted into the medial epicondyle of the humerus. It is a weak flexor of the elbow. This muscle is also innervated by the median nerve.

Front 11

Deep Layer of anterior compartment of wrist and hand

Back 11

The flexor pollicis longus is the long flexor of the thumb. It is innervated by the median nerve. Flexor digitorum profundus flexes the wrist, metacarpalphalangeal joints and all interphalangeal joints of digits II through V. This muscle as a dual innervation. Both median and ulnar nerves.

Front 12

Posterior Component of the superficial layer of muscles of the wrist and hand

Back 12

Muscles are predominantly wrist and finger extensors that share a common attachment to the lateral epicondyle of the humerus. The muscles are extensor carpi radialis longus, extensor carpi radialis brevis, extensor carpi ulnaris, extensor digitorum and extensor digiti minimi. All these muscles are innervated by the radial nerve.

Front 13

Deep layer of posterior component of wrist and hand muscles

Back 13

Muscle that extends the index finger is the extensor indicis. The muscles that act on the thumb are the abductor pollicis longus, extensor pollicis longus, and extensor pollicis brevis. All these muscles of the deep posterior layer are innervated by the radial nerve.

Front 14

Intrinsic Muscles of the Hand

Back 14

Assist the flexors and extensors of the forearm and make finger movements more precise. There are three groups: thenar(base of thumb), hypothenar(base of little finger), midpalmar group (in between).

Front 15

Thenar Muscles

Back 15

Comprise the fleshy bulge at the base of the thumb. 4 muscles: abductor pollicis brevis, adductor pollicis, flexor pollicis brevis, opponens pollicis. All are innervated by median nerve except for adductor pollicis which is innervated by the ulnar nerve.

Front 16

Hypothenar Muscles

Back 16

Form fleshy mass at the base of little finger. Three muscles: abductor digiti minimi, flexor digiti minimi brevis, opponens digiti minimi. All innervated by the ulnar nerve

Front 17

Midpalmar Muscles

Back 17

Span the hollow palm. Includes the dorsal interosseimm(DAB) which abduct fingers, the palmar interosseimm (PAD) which adduct fingers, and the lumbrical mm. which flex the metacarplaphalangeal joints and extend interphalangeal joints. All innervated by ulnar nerve except for 1st and 2nd lumbricals, which are innervated by median nerve

Front 18

The Carpal Tunnel

Back 18

As the median nerve passes down into the hand, it crosses under the thick flexor retinaculum(roof of carpal tunnel) that keeps the flexor muscle tendons from bowstringing across the wrist. Compression of the median nerve in this relatively narrow space results from pain and wasting of the thenar muscles (carpal tunnel syndrome).