UE Neurology

Question 1

• nerve that is derived from cervical plexus (anterior rami of C1-4)
• specifically derived from C3 and C4, travels inferiorly from the nerve point of the neck, cutaneous innervation to the skin over neck and shoulder
• gives rise to lateral, middle, and medial branches

Answer 1

supraclavicular N.

Question 2

• anterior rami of C5-T1, divided along their course, from proximal to distal, into roots, trunks, divisions, cords, and terminal branches
• the roots, trunks, and divisions are all supraclavicular, while the cords and terminal branches are all infraclavicular

Answer 2

brachial plexus

Question 3

What are the roots of the brachial plexus?

Answer 3

(roots are the 5 anterior rami of spinal nerve C5-T1, travel between anterior and middle scalene Ms. w/ the subclavian A.)

• dorsal scapular N. (C5, innervates the rhomboids, contributes to innervation of levator scapulae)
• long thoracic N. (C5-7, innervates serratus anterior M.)
• muscular branches: anterior scalene M. (C4-7), middle scalene M. (C3-7), posterior scalene M. (C5-7), and longus colli M. (C2-6)

Question 4

What are the trunks of the brachial plexus?

Answer 4

(three trunks form when the superior two roots and inferior two roots converge in the inferior part of the neck and form the superior, middle, and inferior trunks, travel over the 1st rib under the clavicle w/ the subclavian A.)

• superior trunk (anterior rami of C5-6): gives rise to suprascapular N. and subclavian N.
• middle trunk (anterior ramus of C7)
• inferior trunk (anterior rami of C8 and T1)

Question 5

What nerves does the superior trunk of the brachial plexus give rise to?

Answer 5

(anterior rami of C5-6)

• suprascapular N. (C5-6, travels w/ the suprascapular A., the artery travels over the transverse scapular L., while the nerve travels under the transverse scapular L., through the suprascapular foramen, innervates the supraspinatus M., sends branches through the greater scapular notch to innervate the infraspinatus M.)
• subclavian N. (C5-6, travels anteriorly to innervate the subclavius M.)

Question 6

• injury to the superior part of the brachial plexus that typically affects C5-6 anterior rami
• usually the result of dramatically increasing angle between neck and shoulder
• can stretch, rupture, or avulse spinal roots off spinal cord
• individuals w/ this injury will have adducted and medially rotated arm and an extended elbow, also known as Erb-Duchenne palsy or “waiter’s tip position”

Answer 6

upper plexus injury

Question 7

• injury to the inferior part of brachial plexus (less common that superior injury)
• usually the result of dramatically increasing the angle between the trunk and upper limn
• typically affects short muscle of the hand and results in “claw hand” when individual tries to make a fist, also known as Klumpke paralysis

Answer 7

lower plexus injury

Question 8

• region of the brachial plexus
• each trunk divides into an anterior and posterior portion
• produces six portions that will converge to form three cords
• there are no branches off of this very short portion of the brachial plexus

Answer 8

divisions

Question 9

What are the chords of the brachial plexus?

Answer 9

• superior and middle trunks’ anterior divisions form the lateral cord
• inferior trunks’ anterior division forms the medial cord
• posterior divisions form all three trunks from the posterior cord

(cords tend to space themselves evenly arround the axillary A., w/ the posterior cord behind the axillary A. and the medial and lateral cords medial and lateral to axillary A. respectively)

Question 10

What nerves does the lateral cord give rise to?

Answer 10

(anterior rami of C5-7, formed by the anterior divisions of the superior and middle trunk)

• lateral pectoral N. (C5-7, courses superior to the pectoralis minor M. to appear in the pectoral region deep to pectoralis major M., innervates pectoralis major M., there is often a communicating branch to medial pectoral N. that passes anterior to the axillary A.)

Question 11

What nerves does the medial cord give rise to?

Answer 11

(anterior rami of C8 and T1, formed by the anterior division of the inferior trunk)

• medial pectoral N. (C8 and T1, pierces the pectoralis minor M. to appear in the pectoral region, innervates the pectoralis minor and major Ms.)
• medial brachial cutaneous N. (C8 and T1, sensory cutaneous innervation from the medial aspect of the distal 2/3rds of the brachium)
• medial antebrachial cutaneous N. (C8 and T1, travels w/ the ulnar N., then travels through the deep fascia w/ the basilic V. before dividing into anterior/posterior branches, sensory cutaneous innervation from anterior and medial aspect of antebrachium)

Question 12

What nerves does the posterior cord give rise to?

Answer 12

(anterior rami of C5-T1, formed by the posterior divisions of the superior, middle, and inferior trunks)

• superior (upper) subscapular N. (C5-6, travels posteriorly into the subscapularis M., innervates the superior portion of subscapularis M.)
• thoracodorsal N. (C6-8, originates between superior and inferior subscapular Ns., travels inferolaterally to latissimus dorsi M.)
• inferior (lower) subscapular N. (C5-6, travels inferolaterally deep to subscapular A., innervates inferior portion of subscapularis M. and teres major M.)

Question 13

• usually results from prolonged periods of working w/ upper limb extended over the head
• results in pain radiating down the arm, loss of sensation, tingling of the arms, and weakness of hands

Answer 13

brachial plexus cord compression

Question 14

What are the terminal branches of the brachial plexus?

Answer 14

(five terminal branches arise from distal end of three cords)

• lateral cord produces musculocutaneous N.
• medial cord produces ulnar N.
• both lateral and medial cords send fibers that meet together to form median N.
• posterior cord divides into smaller axillary N. and radial N.

Question 15

What nerves does the musculocutaneous N. give rise to?

Answer 15

(C5-7. terminal branch of the lateral cord, travels through the coracobrachialis M., between the biceps brachii and brachialis M., innervates the coracobrachialis, biceps brachii, and the brachialis Ms., continues distally as the lateral antebrachial cutaneous N.)

• lateral antebrachial cutaneous N. (C6-7, sensory cutaneous innervation from the lateral aspect of the antebrachium, typically splits into anterior and posterior branches)

Question 16

• rare nerve injury
• occurs w/ blunt force trauma and renders the anterior brachial muscles paralyzed

Answer 16

musculocutaneous N. injury

Question 17

What nerves does the axillary N. give rise to?

Answer 17

(C5-6, terminal branch of the posterior cord, travels posteriorly through the quadrangular space w/ the posterior humeral circumflex A., produces the superior lateral brachial cutaneous N., travels around the surgical neck of the humerus to the deep aspect of the deltoid M., innervates the deltoid and teres minor Ms. and sensory innervation from the glenohumeral joint)

• superior lateral brachial cutaneous N. (C5-6, sensory cutaneous innervation from superior half of the lateral aspect of brachium)

Question 18

• nerve injury
• results in atrophy of the deltoid M. and loss of sensation over the superolateral arm, where the superior lateral brachial cutaneous N. exists

Answer 18

axillary N. injury

Question 19

What nerves does the median N. give rise to?

Answer 19

(C5-T1, union of two terminal branches from the medial and lateral cords, travels through the brachium w/ the brachial A., enters the cubital fossa by passing between the heads of the pronator teres M., travels through the antebrachium between the flexor digitorum profundus and superficialis Ms., travels through the carpal tunnel to central compartment of the palm)

• articular branches
• muscular branches
• anterior interosseous N.
• palmar cutaneous branch of the median N.
• recurrent branch of the median N.
• medial branch of the median N.
• lateral branch of the median N.

Question 20

Name the following branches of the median N. based upon their description:

a) sensory innervation from the elbow joint
b) several unamed muscular branches in the antebrachium that innervate the pronator teres M., flexor carpi radialis M., and flexor digitorum superficialis M.
c) travels along the anterior surface of the interosseous membrane w/ the anterior interosseous A., innervates the lateral half of the flexor digitorum profundus M., flexor pollicis longus M., and pronator quadratus M., then sends sensory articular fibers to innervate wrist joint
d) originates from the median N. before it enters te carpal tunnel, travels superficial to the flexor retinaculum to the palmar surface of the hand, sensory cutaneous innervation from the central palm
e) C8-T1, travels proximally to the thenar muscles, innervates the abductor pollicis M., opponens pollicis M., and superficial head of the flexor pollicis brevis M.

Answer 20

a) articular branches (elbow joint)
b) muscular branches (pronator teres M., flexor carpi radialis M., and flexor digitorum superficialis M.)
c) anterior interosseous N. (lateral half of the flexor digitorum profundus M., flexor pollicis longus M., and pronator quadratus M.; wrist joint)
d) palmar cutaneous branch of the median N. (central palm)
e) recurrent branch of the median N. (abductor pollicis M., opponens pollicis M., and superficial head of the flexor pollicis brevis M.)

Question 21

a) branch off the median N. that innervates the 2nd lumbrical M., becomes the medial two common palmar digital Ns.
b) travel through the palm to the base of the proximal phalanges where they branch into proper palmar digital Ns.
c) sensory cutaneous innervation from the palmar surface and distal dorsal surface of the 1st, 2nd, 3rd, and lateral half of the 4th digits

Answer 21

a) medial branch of the median N.
b) common palmar digital Ns.
c) proper palmar digital N.

Question 22

a) innervates the 1st lumbrical M., becomes the lateral two common palmar digital Ns.
b) travel through the palm to the base of the proximal phalanges where they branch into proper palmar digital Ns.
c) sensory cutaneous innervation from the palmar surface and distal dorsal surface of the 1st, 2nd, 3rd, and lateral half of the 4th digits

Answer 22

a) lateral branch of the median N.
b) common palmar digital Ns.
c) proper palmar digital N.

Question 23

• nerve injury in the wrist that results in an adducted thumb and thenar eminence atrophy, known as ape’s hand
• injury to the same nerve at the elbow inhibits flexion of 2nd and 3rd digits, known as hand of benediction, also has the symptoms of ape’s hand

Answer 23

median N. injury

Question 24

What nerves does the ulnar N. give rise to?

Answer 24

(C7-T1, terminal branch of the medial cord, travels distally through the medial brachium, passes through the groove for the ulnar N. posterior to the medial humeral epicondyle, passes between the two head of the flexor carpi ulnaris M., travels through the antebrachium between the flexor carpi ulnaris and flexor digitorum profundus Ms., becomes superficial as it enters the hand passing over the flexor retinaculum)

• articular branches
• muscular branches
• palmar cutaneous branch of the ulnar N.
• dorsal cutaneous branch of the ulnar N.
• deep ulnar N.
• superficial ulnar N.

Question 25

Name the following branches of the ulnar N. based upon their description: a) sensory innervation from the elbow b) unnamed branches occurring in the antebrachium, innervate flexor carpi ulnaris M. and medial half of flexor digitorum profundus M. c) travels w/ the ulnar A., become superficial, sensory cutaneous innervation from distal most anterior antebrachium and medial 1/3rd of the palm d) travels to the dorsum of the hand at the wrist, produces 2 to 3 dorsal digital Ns., sensory cutaneous innervation to the medial half of the dorsum of the hand dd) 2 to 3 branches form the dorsal branch of the ulnar N., produces digital branches ddd) sensory cutaneous innervation from the dorsal aspect of the 4th and 5th digits e) branches from the ulnar N., distal to the wrist, innervates abductor digiti minimi M., flexor digiti minimi M., opponens digiti minimi M., 3rd and 4th lumbrical Ms., dorsal/palmar interossei Ms., adductor pollicis M., and deep head of flexor pollicis brevis M. f) branches into two common palmar digital Ns. ff) travel through the palm to the bases of the proximal phalanges where they branch into proper palmar digital Ns. fff) sensory cutaneous innervation from the palmar surface of the medial half of the 4th and 5th digits

Answer 25

a) **articular branches** (elbow joint) b) **muscular branches** (flexor carpi ulnaris M. and medial half of flexor digitorum profundus M.) c) **palmar cutaneous branch of the ulnar N.** ( distal most anterior antebrachium and medial 1/3rd of the palm) d) **dorsal (cutaneous) branch of the ulnar N.** (medial half of the Dorsum of the Hand) dd) **dorsal digital N.** ddd) **digital branches of dorsal digital Ns.** (dorsal aspect of the 4th and 5th digits) e) **deep ulnar N.** (abductor digiti minimi M., flexor digiti minimi M., opponens digiti minimi M., 3rd and 4th lumbrical Ms., dorsal/palmar interossei Ms., adductor pollicis M., and deep head of flexor pollicis brevis M.) f) **superficial ulnar N.** ff) **common palmar digital Ns.** fff) **proper palmar digital N.** (palmar surface of the medial half of the 4th and 5th digits)

Question 26

Where are the typical 4 places the ulnar N. gets injured? What symptoms does this injury produce?

Answer 26

- injury can occur: posterior to the medial humeral epicondyle, between the ulnar and humeral heads of the flexor carpi ulnaris M. (cubital tunnel), at the wrist, or in the hand - symptoms: extensive loss of sensory and motor control in the hand, and when an individual tries to make a fist it appears as a **"claw hand"** also known as **Klumpke paralysis**

Question 27

- ulnar N. compression that occurs when pressure is placed on the hamulus of the hamate B., like when riding a bike - produces sensory loss on the medial side of the hand and weakness of the intrinsic hand muscles

Answer 27

handlebar neuropathy

Question 28

What branches does the radial N. give rise to?

Answer 28

(C5-T1, **largest branch of the plexus,** terminal branch of the posterior cord, travels to the posterior aspect of the humerus w/ the deep brachial A., passes between the lateral and medial heads of the triceps brachii M., divide in the cubital fossa into the deep and superficial radial Ns.) - posterior brachial cutaneous N. - posterior antebrachial cutaneous N. - muscular branches - deep radial N. - posterior interosseous N. - superficial radial N.

Question 29

Name the following branches of the radial N. based upon their descriptions: a) C5-8 sensory cutaneous innervation from the posterior aspect of the brachium b) C5-8 sensory innervation from the posterior aspect of the antebrachium, variably produces inferior lateral brachial cutaneous N. (sensory cutaneous innervation from inferior aspect of lateral brachium) c) unnamed branches from the radial N. proximal to its division into deep and superficial radial N., innervates the triceps brachii M., anconeus M., brachioradialis M., and extensor carpi radialis longus M. d) C7-8, terminal branch of the radial N., innervates extensor carpi radialis brevis and supinator Ms., passes between two heads of supinator M. and continues on as posterior interosseous N. e) continuation of the deep radial N. distal to the supinator M., innervates the extensor digitorum M., extensor digiti minimi M., extensor carpi ulnaris M., extensor incidis M., abductor pollicis longus M., extensor pollicis longus M., and extensor pollicis brevis M. f) sensory to numerous joints in the hand and wrist, sensory cutaneous innervation from the lateral half of the dorsum of the hand, produces 3 to 4 dorsal digital branches ff) 3 to 4 branches from the superficial radial N., produces terminal branches at the bases of the proximal phalanges fff) sensory cutaneous innervation from the dorsal aspect of the pollux and the proximal aspect of the dorsum of the 2nd, 3rd, and lateral half of the 4th digits

Answer 29

a) **posterior brachial cutaneous N.** (posterior aspect of the brachium) b) **posterior antebrachial cutaneous N.** (posterior aspect of the antebrachium) c) **muscular branches** (triceps brachii M., anconeus M., brachioradialis M., and extensor carpi radialis longus M.) d) **deep radial N.** (extensor carpi radialis brevis and supinator Ms.) e) **posterior interosseous N.** (extensor digitorum M., extensor digiti minimi M., extensor carpi ulnaris M., extensor incidis M., abductor pollicis longus M., extensor pollicis longus M., and extensor pollicis brevis M.) f) **superficial radial N.** ff) **dorsal digital N.** fff) **digital branches of dorsal digital Ns.** (dorsal aspect of the pollux and the proximal aspect of the dorsum of the 2nd, 3rd, and lateral half of the 4th digits)

Question 30

- nerve injury - results in "wrist drop", impairment of elbow extension and thumb adducton/extension

Answer 30

radial N. injury

Question 31

- lateral cutaneous branch of the 2nd intercostal N. (T2) - travels laterally to provide sensory cutaneous innervation to the uppermost medial aspect of the brachium

Answer 31

intercostobrachial N.

Question 32

What portion of the UE do these dermatomes innervate? a) C5 b) C6 c) C7 d) C8 e) T1 f) T2

Answer 32

a) C5 - over deltoid M. b) C6 - lateral antebrachium and hand, including pollux c) C7 - central portion of hand and posterior antebrachium, including 3rd digit d) C8 - medial hand and antebrachium, including 5th digit e) T1 - medial brachium f) T2 - anterior border of axilla

Question 33

Summary of UE cutaneous innervation | (good study tool)

Answer 33