Brachial Plexus And Axilla

Question 1

What do we call the different parts of the nerves from the neck downwards?

Answer 1

Roots, Trunks, Divisions, Cords and Branches

Question 2

What are the roots of the brachial plexus?

Answer 2

C5-T1

Question 3

How many trunks are there and what are they called?

Answer 3

3: superior, middle and inferior

Question 4

What are the roots of each trunk?

Answer 4

Superior trunk = joining of C5 and C6
Middle trunk = continuation of C7
Inferior trunk = joining of C8 and T1

Question 5

At which stage do the nerve fibres pass into the axilla?

Answer 5

When they are divisions

Question 6

What do we call the divisions?

Answer 6

Anterior and posterior divisions

Question 7

How many cords are there and what are they called?

Answer 7

3: lateral, posterior and medial

Question 8

What are each of the cords made up of?

Answer 8

Lateral = joining of the anterior divisions of the superior and middle trunks 
Posterior = formed by the posterior divisions of all 3 trunks
Medial = anterior division of the inferior trunk

Question 9

How many branches are there and what are they called?

Answer 9

5 branches: musculocutaneous, axillary, median, radial and ulnar

Question 10

What are the roots of each of the branches?

Answer 10

Musculocutaneous: C5, C6 and C7
Axillary: C5 and C6
Median: C5-T1
Radial: C5-T1
Ulnar: C8 and T1

Question 11

What is Erb’s Palsy?

Answer 11

Damage to roots C5 and C6 due to excessive increase in angle between the neck and shoulder. It affects all the nerves derived from C5 and C6 and produces the “waiter’s tip” deformity.

Question 12

What is Klumpke’s Palsy?

Answer 12

A nerve injury caused by excessive abduction of the arm. This affects the nerves derived mainly from T1 (ulnar and median) and paralyses the small muscles of the hands. Sensory loss along the medial side of the arm is common.

Question 13

What is the axilla?

Answer 13

A pyramid shaped area under the shoulder and between the thorax and upper limb that contains nerves, vascular and lymphatic structures.

Question 14

How many borders does the axilla have and what are their general names?

Answer 14

5 borders: apex, lateral, medial, anterior and posterior.

Question 15

What makes up the apex of the axilla?

Answer 15

1st rib, clavicle and superior edge of subscapularis

Question 16

What makes up the lateral border of the axilla?

Answer 16

Intertubercular groove of the humerus

Question 17

What makes up the medial border of the axilla?

Answer 17

Serratus anterior and thoracic wall

Question 18

What makes of the anterior border of the axilla?

Answer 18

Pectoralis major, pectoralis minor and subclavius

Question 19

What makes up the posterior border of the axilla?

Answer 19

Subscapularis, teres major and latissimus dorsi

Question 20

What is the brachial plexus?

Answer 20

A network of nerves supplying the skin and muscles in the upper limb that passes through the axilla.

Question 21

When can long thoracic nerve injury occur and what does it cause?

Answer 21

Can be damaged in axillary node clearance and leads to paralysis on serratus anterior and the scapula protrudes (particularly when the patient pushes on a wall) - winged scapula

Question 22

What does the musculocutaneous nerve innervate?

Answer 22

Brachialis, biceps brachii and coracobrachialis muscles.

A cutaneous branch of it innervates the anterio-lateral forearm.

Question 23

What does the axillary nerve innervate?

Answer 23

Deltoid, teres minor and long head of biceps brachii.

Question 24

Some divisions of the axillary nerve wrap around which structure and why can this be dangerous?

Answer 24

Wrap around the upper humerus, dangerous because fractures around this site can lead to damage to this nerve and cause paralysis of the deltoid.

Question 25

What does the median nerve innervate?

Answer 25

Most of the flexor muscles in the forearm. Supplies to the palm and the anterior side of the lateral 3 and a half fingers.

Question 26

Which sites of fracture can damage the median nerve?

Answer 26

Elbow and wrist

Question 27

What does the radial nerve innervate?

Answer 27

The triceps and extensor muscles in the posterior forearm. It supplies to the posterior arm and forearm as well as the posterior lateral aspect of the hand.

Question 28

Injuries in the axilla most commonly occur from what?

Answer 28

Shoulder dislocation

Question 29

What does the ulnar nerve innervate?

Answer 29

Muscles of the hand and the anterior and posterior surfaces of the medial one and a half fingers.

Question 30

How might we injure the axillary nerve?

Answer 30

Dislocation of shoulder or fracture at surgical neck of humerus

Question 31

How do we test for axillary nerve damage?

Answer 31

Loss of sensation over regimental badge area of skin

Do NOT test motor function as could cause more damage

Question 32

At which point does the subclavian artery become the axillary artery?

Answer 32

After passing the 1st rib

Question 33

At which point does the axillary artery become the brachial artery?

Answer 33

After passing teres major

Question 34

Where are the ulnar and radial arteries formed?

Answer 34

within the cubital fossa