Spinal Nerve And Motor Point Chart

The Peripheral Neuropathy Solution

Peripheral Neuropathy Program By Dr. Labrum

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ANTERIOR VIEW. RIGHT

Long thoracic N Serratus ant

POSTERIOR VIEW. RIGHT

lat and Mod. pectoral Ns Pectoralis major Pectoralis nta

Long thoracic N Serratus ant lat and Mod. pectoral Ns Pectoralis major Pectoralis nta

AM poll b Opp poll Fl po4> b (sup h ) I Lumbricfllts I, II

Motor Point Human Body

'Ant inter branch

Accessory N. (cran XI) Sternocleidomastoid Mid. & low. trap Upper trapezius

Suprascapular N. Supraspmatus Infraspinatus Axillary N

Oeliord Teres minor

AM poll b Opp poll Fl po4> b (sup h ) I Lumbricfllts I, II

'Ant inter branch

Palmaris brevis Abd. digiti min. Opp. digiti min. Fl. digiti min. Palmar interossei Lumbricales III. IV Dorsal interossei (se Fl. poll. b. (deep h.) Adductor pollicis

Oeliord Teres minor

Nerve Point Image

Yellow: Cords, peripheral nerves and anterior divisions from which they arise

E S J C o r d , peripheral nerves and posterior divisions from which they arise. •**: Motor points.

These illustrations facilitate interpretation of muscle test findings as recorded on the Spinal Nerve and Muscle Chart, and they aid in determining the site or level of lesion.

© 1993 Florence P. Kendall. Author grants permission to reproduce for personal use but not for sale.

MOTOR AND SENSORY

The following is a brief description of the relationship of the nerves and muscles. This material is chiefly from Gray's Anatomy (1).

Axillary: Leaves the axilla through the space bounded by the surgical neck of the humerus, teres major, teres minor, and long head of the triceps and supplies the deltoid and teres minor.

Musculocutaneous: Pierces the coracobrachialis, and supplies this muscle as well as the biceps and brachialis.

Radial: The posterior interosseous branch divides into a muscular and an articular branch. The muscular branch supplies the extensor carpi radialis brevis and the eu-pinator before passing between the superficial and deep layers of the supinator muscle. After passing through the supinator, it supplies the remaining muscles, that are innervated by the radial nerve. (See p. 251.)

Median: Passes between the two heads of the pronator teres and under the flexor retinaculum. It is distributed to the forearm and hand. (See Spinal Nerve and Muscle Chart, p. 251, for a list of muscles innervated.)

Spinal Accessory: Anatomy texts describe the spinal accessory nerve as being purely motor. A 1999 study by Bremner-Smith and Unwin, however, "shows that the spinal accessory nerve does not contain solely motor fibers, it also contains small unmyelinated C fibers associated with pain, temperature and mechanoreceptive reflex responses" (2).

Ulnar: The medial cord of the plexus terminates as the ulnar nerve. It supplies branches to the elbow joint, to the flexor carpi ulnaris and to the flexor digitorum profundus. (See p. 27 or p. 347 for a complete list of muscles supplied by the ulnar nerve).

MOTOR ONLY

For years, the senior author has been gathering information about which muscles are supplied by purely motor nerves. Some typewritten pages listing the peripheral nerves and whether they were sensory, motor, or both date back to the late 1930s, but these pages had no reference source noted. A 1932 Dorland's Medical Dictionary had a table of nerves that included this information (3); An article on serratus anterior paralysis stated, "The long thoracic nerve or external respiratory nerve of Bell is almost unique in that it arises directly from the spinal nerve roots, carries no known sensory fibers, and goes to a single muscle of which it is the sole innervation of consequence" (4). Later, a table was found in Taber's dictionary (5). The 1988 edition of Dorland's did not have the tables included in an earlier edition, but the information was found in conjunction with the description of each nerve (6). Finally, scattered bits of information have come from some of the many books and articles on nerve injuries, compression and entrapments (7-13).

Surprisingly, as the information was compiled, a very interesting pattern has developed. The chart on the following page shows that the nerves from the roots, trunks and cords of the brachial plexus to muscles are motor nerves. In addition, the anterior and posterior in-terosseous nerves, which are branches of the median and radial nerves, respectively, are purely motor to the muscles they supply (5, 11-13). Several of the nerves have sensory branches to joints. Of the suprascapular nerve, Hadley et al., state that it "gives off motor branches to the muscles and sensory branches to the shoulder and acromioclavicular joints" (8). In addition, Dawson et al., state, "Since there is no cutaneous territory for this nerve, there are no characteristic sensory symptoms or findings in any lesion of this nerve" (14). Conway et al., state that "entrapment of the posterior interosseous nerve is purely motor and has no associated sensory loss of dysesthetic pain" (15).

The lack of sensory fibers provides the explanation for the lack of sensory symptoms in the muscles supplied by nerves that are only motor. (See discussion and examples, pp. 337-339.) There may be a sensory branch to a joint or joints but not to the muscle.

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