Anatomy: Innervation of the Upper Limb

Question 1

How can you test the function of the musculocutaneous nerve?

Answer 1

Biceps deep tendon reflex - place the examiners thumb on the biceps tendon (within the cubital fossa) and the strike the examiners thumb briskly with a tendon hammer

Question 2

Which nerve is responsible for the cutaneous supply of the medial part of palm, little finger, medial half of ring finger?

Answer 2

Ulnar nerve

Question 3

Name the nerve roots which form the median nerve

Answer 3

C6-T1

Question 4

Name the sensory functions of the axillary nerve

Answer 4

Gives off the superior lateral cutaneous nerve of arm, which innervates the inferior region of the deltoid - ‘badge patch’ (lateral aspect of arm)

Question 5

Which nerve roots form the superior (upper) trunk of the brachial plexus?

Answer 5

C5 and C6

Question 6

Name the sensory functions of the musculocutaneous nerve

Answer 6

Gives off the lateral cutaneous branch of the forearm, which innervates the lateral half of the anterior forearm, and a small lateral portion of the posterior forearm

Question 7

Name the nerve roots which form the ulnar nerve

Answer 7

C8-T1

Question 8

Name the motor functions of the radial nerve

Answer 8

Innervates the triceps brachii

Deep branch innervates the muscles in the posterior compartment of the forearm

Question 9

Which cords of the brachial plexus contribute to the median nerve?

Answer 9

Lateral and medial

Question 10

Name the two divisions of the radial nerve which arise just anterior to the lateral epicondyle

Answer 10

Superficial and deep

Question 11

Name the sensory functions of the radial nerve

Answer 11

Innervates the posterior aspect of the arm and forearm

Superficial branch innervates the posterolateral aspect of the hand

Question 12

Which nerve wraps around the posterior aspect of the surgical neck of the humerus, making it it vulnerable to injury in shoulder dislocation or fractured neck of humerus?

Answer 12

Axillary nerve

Question 13

Which nerves are responsible for the cutaneous supply of medial posterior aspect of the arm?

Answer 13

Anterior rami of spinal nerves C8, T1 and T2

Question 14

How do the branches of the brachial plexus reach the medial arm?

Answer 14

Pass through the axilla

Question 15

What is the characteristic clinical sign of radial nerve injury?

Answer 15

Wrist drop - inability to extend the wrist and fingers due to paralysis of the posterior forearm muscles

Question 16

What is the name given to the area of skin innervated by the axillary nerve?

Answer 16

Badge patch

Question 17

Which is the most medial of the named nerves of the brachial plexus?

Answer 17

Ulnar nerve

Question 18

Which structure forms the medial cord of the brachial plexus?

Answer 18

Anterior devision of the inferior trunk

Question 19

Which cord of the brachial plexus forms the ulnar nerve?

Answer 19

Medial

Question 20

Which nerve travels in the radial groove of the humerus?

Answer 20

Radial nerve

Question 21

Which nerve forms the middle of the ‘M-shaped’ configuration of the named nerves within the axilla?

Answer 21

Median nerve

Question 22

Which nerves are responsible for the cutaneous supply of lateral posterior aspect of the arm?

Answer 22

Anterior rami of spinal nerves C5 and C6 via the axillary nerve

Question 23

Name the motor functions of the ulnar nerve

Answer 23

Innervates the muscles of the hand (apart from the thenar muscles and two lateral lumbricals), flexor carpi ulnaris and medial half of flexor digitorum profundus

Question 24

Which nerve is responsible for the cutaneous supply of the skin over anatomical snuffbox, lateral part of dorsum of hand, proximal thumb, index, middle and ring fingers?

Answer 24

Radial nerve

Question 25

Where are the divisions of the brachial plexus located?

Answer 25

Immediately posterior to the subclavian vessels in the root of the neck

Question 26

Which nerve is responsible for the cutaneous supply of the lateral aspect of the arm?

Answer 26

Radial nerve via lower lateral cutaneous nerve of arm

Question 27

Which nerve is responsible for the cutaneous supply of the skin over distal phalanges/nail beds of thumb, index finger, middle and ring fingers?

Answer 27

Medial nerve

Question 28

Which structures form the lateral cord of the brachial plexus?

Answer 28

Anterior division of the superior trunk and the anterior division of the middle trunk

Question 29

Which nerve is responsible for the cutaneous supply of the anterolateral aspect of the forearm?

Answer 29

Musculocutanous nerve via the lateral cutaneous nerve of the forearm

Question 30

How are the cords of the brachial plexus named?

Answer 30

According to their relationship with the axillary artery

Question 31

Each trunk of the brachial plexus divides into a ________ and a ________ division

Answer 31

Each trunk divides into an anterior and posterior division

Question 32

Where are the roots and trunks of the brachial plexus located?

Answer 32

Mainly between the anterior and middle scalene muscles in the root of the neck

Question 33

Name the nerve roots which form the radial nerve

Answer 33

C5-T1

Question 34

Name the sensory functions of the median nerve

Answer 34

Palmar cutaneous branch innervates the lateral part of the palm Digital cutaneous branch innervates the lateral three and a half fingers on the anterior (palmar) surface of the hand

Question 35

Which structures form the posterior cord of the brachial plexus?

Answer 35

Posterior division of all 3 trunks

Question 36

Name the nerve roots which give rise to the brachial plexus

Answer 36

Anterior rami of spinal nerves C5-T1

Question 37

Which nerve is responsible for the cutaneous supply of a strip of skin down the middle of the posterior forearm?

Answer 37

Posterior cutaneous nerve of forearm

Question 38

Name the nerve roots which form the musculocutaneous nerve

Answer 38

C5-C7

Question 39

Name the sensory functions of the ulnar nerve

Answer 39

Innervates the anterior and posterior surfaces of the medial one and half fingers, and associated palm area

Question 40

Why is the medial posterior arm a common site for cardiac referred pain?

Answer 40

Pain is referred via the intercostobrachial nerve and posterior cutaneous nerves of the arm (branch of radial nerve) and medial cutanous nerve of forearm

Question 41

Which nerve root forms the middle trunk of the brachial plexus?

Answer 41

C7

Question 42

In a mid-shaft fracture of the humerus, how could you test the function of the radial nerve?

Answer 42

Testing triceps function

Question 43

Which cord of the brachial plexus forms the musculocutanous nerve?

Answer 43

Lateral

Question 44

Why is the radial nerve vunerable to damage in a (spiral) mid-shaft fracture of the humerus?

Answer 44

Lies in the radial groove

Question 45

Which cord of the brachial plexus forms the axillary nerve?

Answer 45

Posterior

Question 46

What is the brachial plexus?

Answer 46

Collection of spinal nerves that form the peripheral nerves of the upper limb

Question 47

Name the motor functions of the median nerve

Answer 47

Anterior interosseous nerve supplies all muscles of the anterior forearm except for the flexor carpi ulnaris and the medial part of flexor digitorum profundus Recurrent branch innervates the thenar muscles Palmar digital branch innervates the lateral 2 lumbricals

Question 48

Name the nerve roots which form the axillary nerve

Answer 48

C5-C6

Question 49

Which cord of the brachial plexus forms the radial nerve?

Answer 49

Posterior

Question 50

Where are the cords of the brachial plexus located?

Answer 50

Around the axillary artery

Question 51

Name the motor functions of the axillary nerve

Answer 51

Innervates the teres minor and deltoid muscles

Question 52

Describe the structure of the brachial plexus

Answer 52

Roots → trunks → divisions → cords → branches

Question 53

Which nerve is responsible for the cutaneous supply of the skin over the base of the thumb?

Answer 53

Radial nerve

Question 54

Name the motor functions of the musculocutaneous nerve

Answer 54

Innervates the brachialis, biceps brachii and coracobrachialis muscles

Question 55

Which nerve roots form the inferior (lower) trunk of the brachial plexus?

Answer 55

C8 and T1