Week 10-Axilla and the brachial plexus

Question 1

The clavipectoral fascia acts as a suspensory ligament to the fascial floor of the axilla. What does it enclose?

Answer 1

It encloses the subclavius and pectoralis minor.

Question 2

What are the boundaries of the axilla? (Anterior, posterior, medial, lateral, roof and floor).

Answer 2

Anterior wall formed by pec major and minor, subclavius and fascia.
Posterior wall- Subscapularis, teres major, lattismus dorsi and long head of triceps brachii.
Floor- skin and into the arm
Roof- rib 1, clavicle and scapula
Lateral wall- humerus
Medial wall- serratus anterior and wall of thorax.

Question 3

What is contained within the axilla?

Answer 3

Vessels, nerves and lymphatics for the upper limb
Short head of biceps and coracobrachiallis
Lymph nodes draining both upper limb and breast
Adipose

Question 4

Which vein is continuous with the axillary vein medially and at what point does the name change?

Answer 4

The subclavian vein becomes the axillary vein at the point where it passes the lateral border of rib 1.

Question 5

At what point does the basilic vein superficial become the axillary vein? What does the basilic vein superficial drain?

Answer 5

At the lower margin of teres major the basilic vein superficial becomes the axillary vein.
The basilic vein superficial drains the posteromedial surface of the hand and forearm.

Question 6

What other veins join the axillary vein before it becomes the subclavian vein?

Answer 6

The brachial vein and cephalic vein.

medial brachial vein may join the basilic instead of axillary

Question 7

The subclavian artery is a branch of the brachiocephalic trunk coming from the heart. At what point does it bifurcate to form the subclavian artery?

Answer 7

Lateral margin of rib1.

Question 8

What is the continuation of the subclavian artery called once it passes under which point to supply the arm?

Answer 8

Brachial artery. Named this when it passes under the inferior margin of teres major.

Question 9

The axillary artery can be divided into three parts, part 1 is proximal to the pec minor, part 2 is posterior to pec minor and part 3 is distal to pec minor. What are the branches that come off at each of these points?

Answer 9

Part 1 (proximal to pec minor)- Gives off the superior thoracic artery.
Part 2- Thoracoacromial and lateral thoracic arteries
Part 3- Subscapular and anterior and posterior circumflex humeral arteries.

Question 10

What do the axillary nodes drain?

Answer 10

Upper limb, breast tissue, upper back and shoulder and lower neck.

Question 11

In the axilla, how many groups of nodes do you have?

Answer 11

5 groups of nodes.

Question 12

What are the five groups of axillary nodes called? Where can each of them be found? Which areas do each of them drain?

Answer 12

Humeral- found posterior to the axillary vein. Drains the upper limb.
Pectoral- found on the inferior margin of pec minor. Drains the thorax and breast (mammary) tissue
Subscapular- Found on the posterior axillary wall. Drain the back, shoulder and neck.
Central- found in the axillary fat- they communicate with the other nodes.
Apical- found on the superior margin of pectoralis minor. Drain other nodes and mammary tissue.

Question 13

The brachial plexus is an intertwining of nerve roots to form mixed nerves. Which nerve roots are involved?

Answer 13

C5-T1.

Question 14

The roots C5 and C6 combine to form the …… trunk?

Answer 14

Superior trunk.

Question 15

The roots C8-T1 combine to form the ….. trunk?

Answer 15

Inferior trunk

Question 16

C7 nerve root continues to form the ….. trunk?

Answer 16

Middle trunk.

Question 17

Before the nerve roots C5 and C6 join, C5 gives off several branches. State the names of these branches?

Answer 17

C5 gives off the dorsal scapular nerve (C5) and phrenic nerve (C5).
Also contributes to the long thoracic nerve.

Question 18

Which nerve roots make the long thoracic nerve?

Answer 18

C5, 6 and 7.

Question 19

When the C5 and C6 roots come together to form the superior cord, more branches are given off. What are the names of these branches?

Answer 19

Suprascapular nerve (C5,6)
Nerve to subclavius (C5,6)

Question 20

Nerve root T1 also gives off a branch before it combines with C8. What is this branch?

Answer 20

1st intercostal nerve.

Question 21

All the trunks (superior, middle and inferior) then split into two to form anterior and posterior branches. Describe how they then cross to form the cords.

Answer 21

The posterior branches all come together to form the posterior cord in the middle.
The anterior branches of the superior and middle trunk come together to form the lateral cord.
The anterior branches of the inferior trunk form the medial cord.

Question 22

The posterior cord gives off what terminal branches?

Answer 22

The axillary and radial branches.

Question 23

The lateral cord gives off what terminal branches?

Answer 23

The musculocutaneous branch and offers some fibres to the median branch.

Question 24

The inferior cord gives off what terminal branches?

Answer 24

The ulnar branch and offers some fibres to the median branch.