Axilla and Brachial Plexus

Question 1

What structures form the anterior border of the axilla?

Answer 1

Pectoralis major and minor.

Question 2

What structures form the medial border of the axilla?

Answer 2

Serratus anterior + thoracic wall.

Question 3

What structures form the posterior border of the axilla?

Answer 3

Subscapularis, teres minor + latissimus dorsi.

Question 4

What structures form the apex of the axilla?

Answer 4

Superior margin of scapula.
Clavicle.
First rib.

Question 5

State the contents of the axilla.

Answer 5

Axillary vessels (axillary artery + vein). 
Axillary lymphatics (drain upper limb + breast). 
Brachial plexus.

Question 6

What are the lymph node groups of the axillary lymphatics?

Answer 6

Lateral. 
Subscapula (posterior). 
Pectoral. 
Central. 
Apical.

Question 7

What are the roots of the brachial plexus?

Answer 7

Ventral primary rami of spinal nerves:

C5, C6, C7, C8, T1.

Question 8

What are the trunks of the brachial plexus?

Answer 8

Superior, middle, inferior.

Question 9

What are the divisions of the brachial plexus?

Answer 9

Superior trunk splits into anterior and posterior divisions.
Middle trunk splits into anterior and posterior divisions.
Inferior trunk splits into anterior and posterior divisions.

Question 10

Name the cords of the brachial plexus.

Answer 10

Lateral (anterior division of superior + middle trunks), medial (anterior division of inferior trunk), posterior (posterior divisions of superior, middle and inferior trunks).

Question 11

Name the major terminal branches of the brachial plexus + state where they arise from.

Answer 11

Musculocutaneous (arises from lateral cord).
Median (arises from lateral and medial cords).
Ulnar (arises from medial cord).
Radial (arises from posterior cord).
Axillary (arises from posterior cord).

Question 12

Finish the sentence:

The dorsal root of the spinal cord is…

Answer 12

Sensory fibres.

Question 13

Finish the sentence:

The ventral root of the spinal cord is…

Answer 13

Motor fibres.

Question 14

Posterior nerves supply which types of muscles?

Answer 14

Extensors and abductors.

Question 15

Ventral nerves supply which type of muscles?

Answer 15

Flexors and adductors.

Question 16

Describe the sensory and muscular innervation of musculocutaneous nerve.

Answer 16

S: Anterolateral forearm.
M: Ventral compartment flexors of upper arm (brachilais, biceps brachia, coracobrachialis).

Question 17

Describe the sensory and muscular innervation of median nerve.

Answer 17

S: Lateral 2/3rds of hand.
M: Ventral compartment- flexors of forearm + few muscles of hand (radial side).

Question 18

Describe the sensory and muscular innervation of ulnar nerve.

Answer 18

S: Medial 1/3rds of hand.
M: Ventral compartment- flexors of forearm + hand (ulnar side).

Question 19

Describe the sensory and muscular innervation of radial nerve.

Answer 19

S: Posterior aspect of lateral forearm + wrist, posterior arm.
M: Dorsal compartments- extensors. All back of arm- triceps, extensors, abductors.

Question 20

Describe the sensory and muscular innervation of axillary nerve.

Answer 20

S: Lateral portion of shoulder + upper arm.
M: Deltoid.

Question 21

Describe the cutaneous ulnar nerve innvervation of the hand.

Answer 21

Superior portion of little finger on palmer + dorsal side of hand is exclusive to ulnar nerve.

On palmer surface + dorsal aspect of hand: little finger + half of ring finger.

Question 22

Describe the cutaneous radial nerve innvervation of the hand.

Answer 22

Dorsal aspect of hand: thumb + bottom half of index and middle finger + on palmer side, lateral aspect of thumb.

Question 23

Describe the cutaneous median nerve innvervation of the hand.

Answer 23

Superior portion of index and middle finger on both palmer + dorsal aspect of hand is exclusive to median nerve.

Palmer aspect of hand: thumb, index, middle and half of ring finger.

Dorsal aspect: top half of index, middle + half index, middle and ring finger.

Question 24

How would a radial nerve injury manifest itself?

Answer 24

Describe the cutaneous ulnar innervation of the hand.

Loss of sensation over dorsal web between thumb + index finger.

Question 25

How would an ulnar nerve injury manifest itself?

Answer 25

Ulnar claw: inability to extend 4th + 5th digits. Loss of sensation over medial aspect of the palm, little finger and middle of ring finger.

Question 26

How would an median nerve injury manifest itself?

Answer 26

Hand of Benediction when patient attempts to make a fist. Loss of sensation over palm, thumb, index and middle finger.

Question 27

What is a dermatome?

Answer 27

An area of skin (sensory) supplied by a single spinal nerve and its dorsal root ganglion.

Question 28

What is Erbs Palsy and what are the consequences of it?

Answer 28

Brachial plexus is stretched due to traction on delivery. Specifically tears C5- affects upper myotomes + dermatomes. Effects: inability to abduct shoulder and arm remains pronated (hand tilted backwards).

Question 29

What is Klumpke's paresis and what are the consequences of it?

Answer 29

Tear to T1 which affects lower myotomes and dermatomes. Paralysis of intrinsic muscles of hand- claw hand. Numbness of C8-T1.

Question 30

What nerve innervates intrinsic muscles of the hand?

Answer 30

T1.

Question 31

What nerves allow flexion of the fingers + thumb.

Answer 31

C7, C8.

Question 32

What nerves allow extension of the fingers + thumb.

Answer 32

C7, C8.

Question 33

What nerves allow flexion of the wrist?

Answer 33

C6, C7.

Question 34

What nerves allow extension of the wrist?

Answer 34

C6, C7.

Question 35

What nerve enables pronation of the forearm?

Answer 35

C6.

Question 36

What nerve enables supination of forearm?

Answer 36

C6.

Question 37

What nerves enable flexion of the elbow?

Answer 37

C5, C6.

Question 38

What nerves allow extension of the elbow?

Answer 38

C7, C8.

Question 39

What nerve enables the shoulder to abduct +laterally rotate?

Answer 39

C5.

Question 40

What nerves enable the shoulder to abduct and medially rotate?

Answer 40

C6, C7, C8.