Advanced Quadrangular Space Quiz

Q1. Compression of structures within the quadrangular space most directly threatens which nerve?

• Musculocutaneous nerve
• Axillary nerve
• Median nerve
• Ulnar nerve

Q2. Which vessel can be compressed together with the axillary nerve in quadrangular space syndrome?

• Posterior circumflex humeral artery
• Circumflex scapular artery
• Superior ulnar collateral artery
• Deep brachial artery

Q3. Weakness of which shoulder movement may occur with significant axillary nerve compression in the quadrangular space?

• Pronation of the forearm
• Extension of the wrist
• Flexion of the distal interphalangeal joints
• Abduction of the arm

Q4. Sensory loss from axillary nerve injury is classically assessed over which region?

• Dorsal first web space of the hand
• Skin over the lower deltoid region
• Palmar surface of the index finger
• Tip of the little finger

Q5. Why can a fracture of the surgical neck of the humerus injure structures associated with the quadrangular space?

• The ulnar nerve is attached directly to the greater tubercle
• The brachial artery passes through the glenohumeral joint
• The median nerve passes through the medullary cavity of the surgical neck
• The axillary nerve and posterior circumflex humeral vessels wind around the surgical neck

Q6. Which common shoulder injury can place the axillary nerve at risk because of its close relationship to the inferior glenohumeral region and quadrangular space?

• Anterior dislocation of the shoulder
• Distal radioulnar joint sprain
• Scaphoid fracture
• Posterior elbow dislocation

Q7. Atrophy of which muscle may become visually apparent after a severe chronic axillary nerve lesion?

• Biceps brachii
• Flexor carpi ulnaris
• Deltoid
• Pronator teres

Q8. Which additional muscle may be weakened by an axillary nerve lesion involving the quadrangular space?

• Supraspinatus
• Teres minor
• Teres major
• Subscapularis

Q9. A patient has deltoid weakness, impaired sensation over the lower deltoid region, and preserved elbow extension. Compression in which anatomical space best fits these findings?

• Cubital tunnel
• Triangular interval
• Carpal tunnel
• Quadrangular space

Q10. Which description best summarizes the anatomical importance of the quadrangular space?

• It transmits the ulnar nerve and artery into the hand
• It transmits the median nerve and brachial artery into the forearm
• It transmits the axillary nerve and posterior circumflex humeral vessels into the posterior shoulder region
• It transmits the radial nerve and deep brachial artery into the posterior arm