Unit 6 Question Bank
Sourcing: items tagged TMU 2021–22 come from the real final paper. Items tagged
Slide come from the TMU lecture. Items tagged Gray's are built from the textbook to cover
examinable content. Nothing here is invented; answers are verifiable against the cited page — check against
the official marking scheme where one exists.
0 / 20 answered
1The posterior wall of the axilla is formed by the ( ).
Answer: B
Subscapularis, teres major and latissimus dorsi. The pectorals form the anterior wall, serratus anterior the medial wall, and the intertubercular groove with coracobrachialis the lateral wall.TMU Lecture 7 Slide 21 · Snell's 10e Ch.3
2The axillary artery is divided into three parts by the ( ).
Answer: C
Pectoralis minor crosses the artery: the first part is proximal to it, the second behind it, the third distal to it. The first rib and teres major mark the artery's beginning and end, not its subdivisions.TMU Lecture 7 Slide 13
3How many branches arise from the third part of the axillary artery?
Answer: D
Three — subscapular, anterior circumflex humeral and posterior circumflex humeral. The rule is easy: part 1 has one branch, part 2 has two, part 3 has three.TMU Lecture 7 Slide 20
4The musculocutaneous nerve arises from the ( ) cord.
Answer: A
The lateral cord gives the musculocutaneous nerve and the lateral root of the median nerve. The medial cord gives the ulnar nerve and the medial root of the median nerve.TMU Lecture 7 Slide 18
5Winging of the scapula results from injury to the ( ).
Answer: B
The long thoracic nerve (C5, C6, C7 — from the roots) supplies serratus anterior, which holds the medial border of the scapula against the chest wall. Injury lets the scapula wing away when the patient pushes against a wall.TMU Lecture 7 Slide 9
6Which nerve arises directly from the ROOTS of the brachial plexus?
Answer: C
The long thoracic nerve (and the dorsal scapular nerve) come off the roots themselves, before the trunks form. All the named limb nerves come from the cords.TMU Lecture 7 Slide 18
7The thoracodorsal nerve supplies the ( ).
Answer: D
The thoracodorsal nerve, from the posterior cord, supplies latissimus dorsi. It runs down the posterior wall of the axilla with the thoracodorsal artery and is at risk during axillary node clearance.TMU Lecture 7 Slide 17
8The cords of the brachial plexus are named according to their relation to the ( ).
Answer: A
They are named lateral, medial and posterior by their position around the second part of the axillary artery — which is why finding the artery lets you identify every cord.Gray's 4e p.736, Fig. 7.53
9Which artery is the largest branch of the axillary artery?
Answer: B
The subscapular artery, from the third part, which immediately divides into the circumflex scapular and thoracodorsal arteries.TMU Lecture 7 Slides 19–20
10The median nerve is formed from ( ).
Answer: C
It has a lateral root from the lateral cord and a medial root from the medial cord, which straddle the axillary artery like a letter M — the landmark for identifying the cords in dissection.TMU Lecture 7 Slide 14
11Most lymph from the breast drains first to which axillary node group?
Answer: D
The pectoral group along the lateral thoracic vessels. This is the anatomical basis of sentinel node biopsy in breast cancer.Gray's 4e p.744, Fig. 7.57
12The axillary sheath is a prolongation of the ( ).
Answer: A
It is a downward extension of the prevertebral layer over the first rib into the axilla, enclosing the axillary vessels and brachial plexus — which is what makes a single-injection brachial plexus block possible.Snell's 10e Ch.3 · Gray's 4e p.999
13The axillary artery becomes the brachial artery at the ( ).
Answer: B
It begins at the outer border of the first rib and becomes the brachial artery at the lower border of teres major. Names change at anatomical doorways.Gray's 4e p.729
14Which structures form the apex of the axilla?
Answer: C
The apex — the doorway to the neck — is bounded by the clavicle, first rib and upper border of the scapula. Skin and axillary fascia form the base.TMU Lecture 7 Slide 21 · Gray's 4e p.717
15Branches of the second part of the axillary artery are the ( ).
Answer: D
Part 2 has two branches: thoracoacromial and lateral thoracic. Part 1 has one (superior thoracic); part 3 has three.TMU Lecture 7 Slide 20
16The lateral wall of the axilla is formed by the ( ).
Answer: A
The intertubercular (bicipital) groove of the humerus, with coracobrachialis and the short head of biceps lying on it.TMU Lecture 7 Slide 21
17Which nerve pierces coracobrachialis?
Answer: B
The musculocutaneous nerve pierces coracobrachialis on its way into the anterior compartment of the arm, which it supplies (biceps, brachialis, coracobrachialis).TMU Lecture 7 Slides 10–11
18The medial wall of the axilla is formed by ( ).
Answer: C
Serratus anterior covering the upper four ribs and their intercostal muscles — literally the chest wall. The long thoracic nerve runs on its surface here.TMU Lecture 7 Slide 21
19After axillary lymph node clearance, chronic arm swelling is called ( ).
Answer: D
Lymphoedema — chronic swelling from destroyed lymphatic drainage. Avoiding it is the reason sentinel node biopsy replaced routine full clearance.Gray's 4e p.744 (clinical application)
20The posterior cord gives all of the following EXCEPT the ( ).
Answer: A
The ulnar nerve comes from the medial cord. The posterior cord gives the radial, axillary, thoracodorsal and the upper and lower subscapular nerves.Gray's 4e p.743, Fig. 7.56
1 Axillary fossa (axilla) — homework · 4′+
A pyramidal space between the upper arm and the chest wall, transmitting all structures passing between the neck and the upper limb.
Apex: clavicle, first rib, upper border of the scapula.
Base: skin and axillary fascia.
Anterior wall: pectoralis major and minor.
Posterior wall: subscapularis, teres major, latissimus dorsi.
Medial wall: serratus anterior over ribs 1–4 and intercostals.
Lateral wall: intertubercular groove of the humerus with coracobrachialis.
Contents: axillary artery and vein · brachial plexus cords and branches · axillary lymph nodes · axillary sheath and fat.TMU Lecture 7 Slide 21 · Gray's 4e p.717
Apex: clavicle, first rib, upper border of the scapula.
Base: skin and axillary fascia.
Anterior wall: pectoralis major and minor.
Posterior wall: subscapularis, teres major, latissimus dorsi.
Medial wall: serratus anterior over ribs 1–4 and intercostals.
Lateral wall: intertubercular groove of the humerus with coracobrachialis.
Contents: axillary artery and vein · brachial plexus cords and branches · axillary lymph nodes · axillary sheath and fat.TMU Lecture 7 Slide 21 · Gray's 4e p.717
2 Axillary sheath — 3′+
A fascial sleeve enclosing the axillary vessels and the brachial plexus, formed as a downward prolongation of the prevertebral layer of deep cervical fascia over the first rib.
Clinical: allows a brachial plexus block from a single injection — the distal sheath is compressed and anaesthetic massaged along it, with the third part of the axillary artery as the landmark.Snell's 10e Ch.3 — Axillary Sheath and Brachial Plexus Nerve Block
Clinical: allows a brachial plexus block from a single injection — the distal sheath is compressed and anaesthetic massaged along it, with the third part of the axillary artery as the landmark.Snell's 10e Ch.3 — Axillary Sheath and Brachial Plexus Nerve Block
3 Axillary artery — 3′+
The continuation of the subclavian artery from the outer border of the first rib to the lower border of teres major, where it becomes the brachial artery. Divided into three parts by pectoralis minor.
Part 1 (1 branch): superior thoracic.
Part 2 (2 branches): thoracoacromial, lateral thoracic.
Part 3 (3 branches): subscapular (→ circumflex scapular + thoracodorsal), anterior circumflex humeral, posterior circumflex humeral.TMU Lecture 7 Slide 20
Part 1 (1 branch): superior thoracic.
Part 2 (2 branches): thoracoacromial, lateral thoracic.
Part 3 (3 branches): subscapular (→ circumflex scapular + thoracodorsal), anterior circumflex humeral, posterior circumflex humeral.TMU Lecture 7 Slide 20
4 Long thoracic nerve — 2′+
A nerve arising directly from the roots C5, C6 and C7 of the brachial plexus, descending on the surface of serratus anterior, which it supplies.
Injury — in axillary surgery, mastectomy with node clearance, or a blow to the side of the chest — causes winging of the scapula and inability to raise the arm fully above the head.TMU Lecture 7 Slide 9
Injury — in axillary surgery, mastectomy with node clearance, or a blow to the side of the chest — causes winging of the scapula and inability to raise the arm fully above the head.TMU Lecture 7 Slide 9
5 Winged scapula — 2′+
Protrusion of the medial border of the scapula away from the chest wall, seen when the patient pushes against a wall, caused by paralysis of serratus anterior following injury to the long thoracic nerve.TMU Lecture 7 Slide 9
6 Axillary lymph nodes — 3′+
Approximately 20–30 nodes in the axillary fat, described in five groups: pectoral (anterior), subscapular (posterior), humeral (lateral), central and apical.
They receive most of the lymph from the breast and the upper limb, drain finally through the apical group into the subclavian lymph trunk, and determine the staging of breast cancer.Gray's 4e p.744, Fig. 7.57
They receive most of the lymph from the breast and the upper limb, drain finally through the apical group into the subclavian lymph trunk, and determine the staging of breast cancer.Gray's 4e p.744, Fig. 7.57
1
Summarise the four walls of the axilla and its main contents.
8′
Set as homework in TMU Lecture 7.
Shape
A pyramidal space between the upper arm and the chest wall.
Boundaries
- Apex: clavicle, first rib and upper border of the scapula — the gateway to the neck
- Base: skin and axillary fascia
- Anterior wall: pectoralis major and pectoralis minor (with subclavius)
- Posterior wall: subscapularis, teres major, latissimus dorsi
- Medial wall: upper part of serratus anterior over the first four ribs and their intercostal muscles
- Lateral wall: intertubercular groove of the humerus, with coracobrachialis and the short head of biceps
Contents
- Axillary artery and its branches
- Axillary vein and its tributaries
- Cords and branches of the brachial plexus
- Axillary lymph nodes (five groups)
- Axillary sheath and fat; tendon of the long head of biceps crossing the space
Marking guide: apex and base 1 · four walls 4 (1 each) · contents 3.
2
Summarise the branches of the brachial plexus and of the axillary artery.
10′
Set as homework in TMU Lecture 7.
Brachial plexus — organisation
Roots (C5–T1) → three trunks → anterior and posterior divisions → three cords named by their relation to the second part of the axillary artery → branches.
Branches by cord
- From the roots: long thoracic nerve (C5–7); dorsal scapular nerve
- From the upper trunk: suprascapular nerve; nerve to subclavius
- Lateral cord: musculocutaneous nerve; lateral root of the median nerve; lateral pectoral nerve
- Medial cord: ulnar nerve; medial root of the median nerve; medial pectoral nerve; medial cutaneous nerves of arm and forearm
- Posterior cord: radial nerve; axillary nerve; thoracodorsal nerve; upper and lower subscapular nerves
Axillary artery — three parts, divided by pectoralis minor
- Part 1: superior (supreme) thoracic artery
- Part 2: thoracoacromial artery; lateral thoracic artery
- Part 3: subscapular artery (→ circumflex scapular and thoracodorsal); anterior circumflex humeral; posterior circumflex humeral
Mnemonic for the branch count: 1, 2, 3 by part number.
Marking guide: plexus organisation 2 · branches by cord 4 · root branches 1 · three arterial parts 1 · six arterial branches 2.
3
A patient develops a winged scapula after axillary surgery. Explain the anatomy.
6′
Nerve and muscle
The long thoracic nerve, arising directly from the anterior rami of C5, C6 and C7, descends on the outer surface of serratus anterior on the medial wall of the axilla, and supplies it.
Normal function
Serratus anterior holds the medial border of the scapula flat against the chest wall and rotates the scapula upward, allowing the arm to be raised above the head.
Effect of injury
- The medial border of the scapula lifts away from the chest wall — most obvious when the patient pushes against a wall
- The patient cannot abduct the arm fully above the horizontal, because scapular rotation is lost
Why it happens here
The nerve lies superficially on the medial wall of the axilla and is easily divided during axillary node clearance or mastectomy. The thoracodorsal nerve, on the posterior wall, is at risk in the same operation — which is why both are deliberately identified and preserved.
Marking guide: nerve and root value 2 · muscle and normal function 2 · sign of injury 1 · surgical context 1.
4
Describe the axillary lymph nodes and their clinical importance.
6′
Groups
- Pectoral (anterior) — along the lateral thoracic vessels; receive most breast lymph
- Subscapular (posterior) — along the subscapular vessels
- Humeral (lateral) — along the axillary vein; drain the upper limb
- Central — in the axillary fat, receiving from the above three
- Apical — at the apex, receiving from all groups
Drainage runs pectoral / subscapular / humeral → central → apical → subclavian lymph trunk.
Clinical importance
- They receive around 75% of the lymph from the breast, so their status determines the staging and treatment of breast cancer
- Sentinel node biopsy: tracer injected into the breast identifies the first node reached — usually pectoral. If clear, full clearance can often be avoided
- Lymphoedema: full clearance destroys lymphatic drainage of the arm and causes chronic swelling
- The long thoracic and thoracodorsal nerves lie on the medial and posterior walls and must be preserved during clearance
Marking guide: five groups 2.5 · drainage sequence 1 · breast staging 1 · sentinel node 1 · lymphoedema 0.5.
5
Describe the axillary artery — its extent, parts and branches.
7′
Extent
Begins as the continuation of the subclavian artery at the outer border of the first rib, and becomes the brachial artery at the lower border of teres major.
Parts
Divided into three parts by pectoralis minor: the first proximal to the muscle, the second behind it, the third distal to it.
| Part | Branches |
|---|---|
| First (1 branch) | Superior (supreme) thoracic artery |
| Second (2 branches) | Thoracoacromial artery · lateral thoracic artery |
| Third (3 branches) | Subscapular artery (→ circumflex scapular + thoracodorsal) · anterior circumflex humeral · posterior circumflex humeral |
Points worth adding
- The subscapular artery is the largest branch
- The posterior circumflex humeral artery passes through the quadrangular space with the axillary nerve
- The circumflex scapular artery passes through the triangular space and contributes to the scapular anastomosis, which provides collateral flow if the axillary artery is occluded
Marking guide: extent 2 · division by pectoralis minor 1 · six branches 3 · one anastomotic or relational point 1.