Lecture 17 - Nerve and Blood Vessels Upper Limb

Question 1

Describe how the brachial plexus starts to form the dorsal and ventral rami

Answer 1

Mixed spinal nerves descend from the vertebral canal through intervertebral foramina and then branch into ventral and dorsal rami.

The dorsal rami innervates the skin and deep muscles of the back

The ventral rami has an anterior and posterior division (ventral rami are what form the plexuses in the body)

Question 2

Which division of spinal nerves innervate the extensor surface?

Answer 2

Innervated by posterior division

Question 3

What division of the spinal nerve innervates the flexor surface?

Answer 3

Innervated by anterior divisions

Question 4

Which 5 spinal nerves does the brachial plexus come from?

Answer 4

C5 - C8, Th1

Question 5

What are the 5 major peripheral nerves of the upper limb that come from the brachial plexus?

Answer 5

• Anterior:
• Musculocutaneous
• Median
• Ulnar
• Posterior
• axillary
  
  • radial

Question 6

What roots from the superior trunk?

Answer 6

C5, C6

Question 7

What roots does the middle trunk come from?

Answer 7

C7

Question 8

What trunks does the deep trunk come from?

Answer 8

C8, Th1

Question 9

Which roots contribute to the posterior cord?

Answer 9

All of them (C5-C8, Th1)

Question 10

From the trunks, we get what?

Answer 10

A lateral cord, and a medial cord.

The posterior cord is posterior to the second part of the axillary artery and originates as the union of all three posterior divisions of the trunks (trunks have an anterior and posterior division)

Question 11

Describe how the lateral, medial and posterior cord are formed?

Answer 11

Mixed spinal nerves descend from the vertebral canal through intervertebral foramen and then branch into dorsal and ventral rami.

The superior trunk is formed by the union of C5 and C6, the middle trunk is a continuation of the C7 root. And the inferior trunk is formed by the union of C8 and T1 root.

The trunks then divide into anterior and posterior divisions.

The lateral cord is formed from the union of anterior divisions the upper and middle trunks (has contributions from C5-C7)

The medial cord is medial to the second part of the axillary artery and is a continuation of the anterior division of the inferior trunk (contributions from C8 to T1)

The posterior cord occurs posterior to the second part of the axillary artery and originates as the union of all three posterior divisions (it contains contributions from all roots of brachial plexus C5-T1)

Question 12

Which nerves come from the roots?

Answer 12

Dorsal scapular nerve

Long thoracic nerve

Question 13

Which nerves come from the trunks?

Answer 13

Subclavian nerve

Suprascapular nerve

Question 14

Which nerves come from cords?

Answer 14

Pectoral nervess

Subscapular nerves

Thoracodorsal nerves

Question 15

Where in the brachial plexus does the axillary artery branch from?

Answer 15

Branch of posterior cord

Question 16

What muscles does the axillary nerve innervate, and which of its branches provides sensory innervation?

Answer 16

Provides motor innervation for the deltoid, teres minor

Sensory innervation is provided by the upper lateral cutaneous nerve

Question 17

Which injuries pose a high risk to the axillary nerve?

Answer 17

Subcapital fracture of humerus

Surgical approach to the humerus

Question 18

What cord does the radial nerve branch from?

Answer 18

Branches from posterior cord

the radial nerve is located in the posterior compartment of the arm, and passes along the spiral groove of the arm

Question 19

What muscles does the radial nerve innervate?

And which of its branches provide sensory supply?

Answer 19

Triceps brachii, and other extensors

Sensory supply comes from lateral cutaneous nerve, and posterior cutaneous branches of radial nerve

Question 20

What muscles does the deep branch of the radial nerve supply?

Answer 20

Extensor pollicis longus

Extensor pollicis brevis

Abductor pollicis longus

Question 21

The radial nerve divides into a superficial and deep branch. The deep branch passes through the supinator. Once it passes through the supinator muscle what is it called?

Answer 21

Posterior interosseous nerve, which then goes on to innervate the extensor pollicis longus and brevis, and the abductor pollicis longus

Question 22

Which cord does the musculocutaneous nerve branch from?

And which nerve branches from this and provides sensory supply to the forearm.

Answer 22

Branches off the lateral cord (is lateral of median nerve)

And then travels down the arm via coracobrachialis

Sensory supply comes from lateral cutaneous nerve

Question 23

What motor supply does the musculocutaneos nerve provide?

Answer 23

Biceps brachii

Brachialis

Coracobrachialis

Question 24

Which cord does the ulnar nerve come from, and how does it pass onto the forearm?

Answer 24

Ulnar nerve comes from medial cord, and passes onto the forearm medially via the medial epicondyle of the humerus

Question 25

Which cord does the median nerve come from?

Answer 25

The medial cord

then descends down arm followng brachial artety

Question 26

Which nerve supplies MOST muscles in the forearm?

And which muscles are not innervated by this nerve?

Answer 26

Median nerve supplies most muscles in the forearm

EXCEPT flexor carpi ulnaris and flexor digitorum profundas (innervated by ulnar nerve)

Question 27

Which nerve supplies most muscles of the hand?

Answer 27

Most muscles in the hand are supplied by the ulnar nerve

Exceptions: Muscles of thenar eminence and the lateral two lumbricals are innervated by the median nerve

Question 28

The radial (lateral) 3 1/2 digits are innervated by what nerve?

Answer 28

Median nerve provides sensory innervation to the palmar aspect of the later 3 1/2 digits

Question 29

Which nerve innervates the medial 1 1/2 digits?

Answer 29

Ulnar nerve provides sensory innervation to the palmar aspect of the medial (ulnar) 1 1/2 digits

Question 30

Which nerve supplies this area

Answer 30

Radial nerve (superficial branch)

Question 31

Which nerve supplies this area

Answer 31

Ulnar nerve

Question 32

What are some conditions caused my median nerve injuries?

And what signs are there which show the median nerve has been damaged?

Answer 32

Pronator teres syndrome

Carpal tunnel syndrome

Anterior interosseous nerve syndrome

Signs: Ape-hand deformity

Question 33

What issues arise with carpal tunnel for the patient?

Answer 33

• They get paralysis of thenar muscles, including coordination and strength of thumb (opposition)
  
  • Paralysis of lateral two lumbicals

Question 34

Which kind of fracture to the humerus most commonly causes radial nerve injuries?

And what does a radial nerve injury result in?

Answer 34

Mid-shaft fractures of humerus

Radial nerve muscle causes impairment of forearm extensors, and results in wrist drop

The patient is unable to have dorsal extension of the wrist, but interphalangeal extension still possible due to ulnar and median nerve

Question 35

When there is an ulnar nerve injury, what muscles are affected?

Answer 35

Intrinsic muscles of the hand (except 2 lateral lumbricals, thenar eminence muscles)

Question 36

What muscles can be paralysed when there is an ulnar nerve injury?

What sign is there for ulnar nerve injuries?

Answer 36

There is paralysis of:

• Flexor carpi ulnaris
• Flexor digitorum profundas to ring and little fingers
• All intrinsic muscles of the and (apart from lateral two lumbicals and thenar muscles)

Sign: Clawing of the hand

Question 37

Where are the 3 segments of the axillary artery located?

Answer 37

First part - the part of the artery above the pectoralis minor

Second part - the part of the artery that lies behind the pectoralis minor

Third part - the part of the artery below the pectoralis minor.