Page 12 of 12
AN10.1-13 | Axilla, Shoulder and Scapular region — Gate Quiz
Click any question card to reveal the correct answer.
The apex of the axilla is bounded by which three structures?
Correct! The apex of the axilla is a triangular space bounded by: the clavicle (anteriorly), the first rib (medially), and the superior border of the scapula (posteriorly). The cervicoaxillary canal passes through this apex.
Axillary apex boundaries: Clavicle (anterior) + 1st rib (medial) + Superior border of scapula (posterior). The base/floor is the axillary skin/fascia. The apex is the passageway for neurovascular structures between the neck and axilla.
Incorrect. Apex of axilla: clavicle + 1st rib + superior border of scapula. This is the passage between the neck and axilla (cervicoaxillary canal).
Click to reveal answer
Which of the following is NOT a content of the axilla?
Correct! The brachial artery is NOT an axillary content. The axillary artery (continuation of subclavian) becomes the brachial artery at the lower border of teres major, where it exits the axilla and enters the arm.
Axillary contents: 3 A's + 3 N's + lymph nodes. The axillary artery becomes the brachial artery at the lower border of teres major — this is the axillary boundary. Brachial plexus cords surround the axillary artery (lateral, medial, posterior).
Incorrect. The brachial artery begins at the lower border of teres major — outside the axilla. The axilla contains the axillary artery, brachial plexus cords, and axillary lymph nodes.
Click to reveal answer
The axillary artery is divided into three parts by which muscle?
Correct! Pectoralis minor divides the axillary artery into three parts: Part 1 (medial to pectoralis minor) — 1 branch; Part 2 (posterior to pectoralis minor) — 2 branches; Part 3 (lateral to pectoralis minor) — 3 branches. Rule of 1-2-3.
Axillary artery parts (divided by pectoralis minor): Part 1 → 1 branch (superior thoracic); Part 2 → 2 branches (thoracoacromial + lateral thoracic); Part 3 → 3 branches (subscapular + anterior/posterior circumflex humeral). Mnemonic: '1-2-3 rule.'
Incorrect. Pectoralis minor is the landmark that divides the axillary artery into three parts — giving 1, 2, 3 branches respectively (rule of 1-2-3).
Click to reveal answer
The scapular anastomosis provides collateral circulation around the shoulder. In this anastomosis, which artery connects the transverse cervical artery with the subscapular artery?
Correct! The suprascapular artery (from the thyrocervical trunk of subclavian artery) participates in the scapular anastomosis. It connects with branches of the subscapular artery (from the 3rd part of axillary artery) around the scapula, allowing collateral circulation if the axillary artery is ligated.
Scapular anastomosis: Subclavian side — suprascapular + dorsal scapular. Axillary side — subscapular + circumflex scapular. This anastomosis allows the axillary artery to be safely ligated (e.g., for aneurysm repair) as blood can reach the arm via this collateral route.
Incorrect. The scapular anastomosis involves: suprascapular + dorsal scapular (from thyrocervical trunk) connecting with subscapular + circumflex scapular (from axillary artery).
Click to reveal answer
The cords of the brachial plexus are named according to their relationship to which structure?
Correct! The three cords of the brachial plexus (lateral, medial, and posterior) are named based on their position relative to the second part of the axillary artery.
Brachial plexus cords: Lateral cord (lateral to axillary artery) → musculocutaneous + lateral root of median. Medial cord (medial to axillary artery) → ulnar + medial root of median. Posterior cord (posterior to axillary artery) → axillary + radial nerves.
Incorrect. The lateral, medial, and posterior cords are named for their relationship to the axillary artery.
Click to reveal answer
A 25-year-old patient in an emergency department in Vellore presents with an anterior shoulder dislocation. Which nerve is most at risk?
Correct! The axillary nerve winds around the surgical neck of the humerus and passes through the quadrilateral space. In anterior shoulder dislocation, the humeral head displaces anteroinferiorly and can stretch or tear the axillary nerve.
Anterior shoulder dislocation → axillary nerve injury. Tests: (1) Deltoid muscle weakness (abduction 15–90°). (2) Loss of sensation over the lateral shoulder ('regimental badge area'). Also check for axillary artery injury in elderly patients.
Incorrect. Anterior shoulder dislocation most commonly injures the axillary nerve. Test: deltoid power (C5) + sensation over the regimental badge area.
Click to reveal answer
The rotator cuff is composed of which four muscles?
Correct! The rotator cuff comprises four muscles: Supraspinatus, Infraspinatus, Teres minor, and Subscapularis — remembered by the mnemonic SITS. These muscles stabilize the glenohumeral joint by keeping the humeral head in the glenoid fossa.
SITS = rotator cuff: S-upraspinatus (initiates abduction), I-nfraspinatus (lateral rotation), T-eres minor (lateral rotation), S-ubscapularis (medial rotation). The primary function is dynamic stabilization of the glenohumeral joint against superior migration of the humeral head.
Incorrect. The rotator cuff is SITS: Supraspinatus, Infraspinatus, Teres minor, Subscapularis. Teres major is NOT a rotator cuff muscle.
Click to reveal answer
The quadrilateral space transmits which important structures?
Correct! The quadrilateral space (bounded by teres minor superiorly, teres major inferiorly, long head of triceps medially, and surgical neck of humerus laterally) transmits the axillary nerve and the posterior circumflex humeral artery.
Spaces of the shoulder: (1) Quadrilateral space — axillary nerve + posterior circumflex humeral artery. (2) Upper triangular space (medial to long head triceps) — circumflex scapular artery. (3) Lower triangular space (triangular interval) — radial nerve + profunda brachii.
Incorrect. Quadrilateral space = axillary nerve + posterior circumflex humeral artery. Triangular space (medial) = circumflex scapular artery. Lower triangular space = radial nerve + profunda brachii.
Click to reveal answer
The glenohumeral (shoulder) joint is the most mobile joint in the body but is prone to dislocation. The primary stabilizing structure that deepens the glenoid cavity is:
Correct! The glenoid labrum is a fibrocartilaginous rim that deepens the glenoid cavity by approximately 50%, increasing the contact area for the humeral head and improving joint stability. Tears of the labrum (Bankart lesion) predispose to recurrent anterior dislocations.
Glenohumeral stability: Static — glenoid labrum (deepens cavity), glenohumeral ligaments (superior, middle, inferior), coracohumeral ligament. Dynamic — rotator cuff muscles. The inferior glenohumeral ligament is the most important capsular structure against anterior instability.
Incorrect. The glenoid labrum deepens the glenoid socket. Bankart lesion = anteroinferior labrum tear = predisposes to recurrent dislocation.
Click to reveal answer
A 45-year-old woman from Pondicherry is diagnosed with breast cancer. The lymph nodes that are first to receive lymph drainage from the lateral breast are in which axillary group?
Correct! The anterior (pectoral) group of axillary lymph nodes lies along the lateral thoracic artery and receives lymph drainage from the breast (primarily the lateral and central breast) and anterior chest wall. It is the first-echelon node group in breast cancer lymphatic spread.
Axillary lymph node groups (5): Anterior (pectoral) — lateral breast. Posterior (subscapular) — posterior shoulder/back. Lateral — upper limb. Central — receives from above 3. Apical — receives all; drains to subclavian trunk. Sentinel node biopsy targets the first (sentinel) node.
Incorrect. Anterior (pectoral) nodes receive lymph first from the breast. Then → central → apical → subclavian trunk. The apical group receives from ALL other groups and drains into the subclavian trunk.
Click to reveal answer