Peripheral Nerve Innervation

Question 1

What does the dorsal rami innervate?

Answer 1

the skin and intrinsic back muscles

Question 2

What does the ventral rami innervate?

Answer 2

remain segmental (thoracic) or form plexuses

Question 3

What are the 2 ‘roots’ of the brachial plexus?

Answer 3

dorsal scapular nerve, long thoracic nerve

Question 4

What is the dorsal scapular nerve pathway and what muscles does it innervate?

Answer 4

arises from the C5 ventral rami and pierces middle scalene, innervates levator scapulae and rhomboid minor and rhomboid major

Question 5

What is the long thoracic nerve pathway and what muscle does it innervate?

Answer 5

arises from the C5, C6 and C7 ventral rami and runs inferiorly over the serratus anterior, innervates serratus anterior

Question 6

What are the 3 ‘trunks’ of the brachial plexus?

Answer 6

superior trunk. middle trunk. inferior trunk.

Question 7

What is the suprascapular nerve pathway and what muscles does it innervate?

Answer 7

arises from the superior trunk carrying the C5 and C6 axons, innervates supraspinatus and infraspinatus

Question 8

What are the 3 ‘cords’ of the brachial plexus?

Answer 8

posterior cord. lateral cord. medial cord.

Question 9

What does the posterior cord consist of?

Answer 9

axillary nerve, radial nerve, upper subscapular nerve, thoracodorsal nerve, lower subscapular nerve

Question 10

What does the axillary nerve innervate?

Answer 10

(C5,6) innervates deltoid and teres minor

Question 11

What does the radial nerve innervate?

Answer 11

(C5-C8, T1) innervates all of posterior arm and forearm

Question 12

What does the upper subscapular nerve innervate?

Answer 12

(C5,C6) innervates subscapularis

Question 13

What does the thoracodorsal nerve innervate?

Answer 13

(C6,7,8) innervates latissimus dorsi

Question 14

What does the lower subscapular nerve innervate?

Answer 14

(C5, 6) innervates subscapular, teres major

Question 15

What does the lateral cord consist of?

Answer 15

lateral pectoral nerve and musculocutaneous nerve

Question 16

What does the lateral pectoral nerve innervate?

Answer 16

pectoralis major and minor

Question 17

What does the musculocutaneous nerve innervate?

Answer 17

(C5,6,7) innervates coracobrachialis, biceps brachii, brachialis

Question 18

What does the medial cord consist of?

Answer 18

medial pectoral nerve, medial brachial cutaneous (sensory only), medial antebrachial cutaneous (sensory only), ulnar nerve

Question 19

What does the medial pectoral nerve innervate?

Answer 19

pectoralis major and minor

Question 20

What does the ulnar nerve innervate?

Answer 20

(C7,C8,T1) innervates FCU, 1/2 FDP, all hand except those supplied by median nerve

Question 21

What nerve comes from both the medial and lateral cord? What does it innervate?

Answer 21

median nerve ((C5)C6-T1), innervates all anterior arm muscles except those supplied by ulnar nerve

Question 22

Draw the brachial plexus diagram.

Answer 22

see notes for answer

Question 23

How does a long thoracic nerve entrapment occur and what does it affect?

Answer 23

sports involving extreme or repetitive hyperabduction, prolonger hyperabduction, blunt trauma, weakness in serratus anterior- medial scapular winging (scapula medially located- adduction/protraction)

Question 24

Describe suprascapular entrapments at the suprascapular notch and spinoglenoid notch.

Answer 24

at the suprascapular notch: poorly localized posterolateral shoulder pain, supraspinatus and infraspinatus weakness- from repetitive trauma: carrying heavy objects on shoulder

at the spinoglenoid notch:
often no pain, infraspinatus weakness and wasting- repeated excessive ER in abduction- swimming, throwing, tennis