📚 Question Bank

Correct Answer: C

Around the middle of the arm, the ulnar nerve leaves the anterior compartment. It pierces through the tough medial intermuscular septum to enter the posterior compartment. It is accompanied by the superior ulnar collateral artery (SUCA).

Correct Answer: C

The lesser tubercle is reserved exclusively for the subscapularis muscle. Because the subscapularis is the primary internal rotator of the shoulder, tearing off its bony attachment will severely weaken internal rotation.

Correct Answer: B

If you must ligate the main brachial artery, you must ensure blood can bypass the block. The profunda brachii artery is the largest proximal branch. If you ligate the brachial artery distal to it, blood will shunt into the profunda and use the elbow collateral network to reconnect with the forearm.

Correct Answer: C

The deep fascia has different names depending on where it is. In the arm, it is called the brachial fascia. It forms a strong, inelastic cylinder around the biceps and triceps, helping to contain muscle expansion.

Correct Answer: C

Let's clear up a common point of confusion! Structurally, the articular surfaces of the sternoclavicular (SC) joint are saddle-shaped. However, functionally, it acts as a ball-and-socket joint.

Why? Because the presence of a strong intra-articular disc allows the clavicle to move in three distinct planes: elevation/depression, protraction/retraction, and axial rotation. This extensive, multiaxial movement is the hallmark of a ball-and-socket joint.

Correct Answer: C

While the acromioclavicular ligament wraps the joint itself, it is actually quite weak. The true heavy lifter here is the coracoclavicular (CC) ligament, which sits slightly medial to the joint.

Composed of two parts (the conoid and trapezoid ligaments), the CC ligament firmly anchors the clavicle down to the coracoid process of the scapula. It acts as the primary suspensory ligament of the entire upper limb, preventing the shoulder from sagging away from the clavicle.

Correct Answer: C

Think of the elbow as the hinge of a door. The elbow joint complex primarily involves the humeroulnar and humeroradial articulations.

The tight grip of the trochlear notch of the ulna around the trochlea of the humerus strongly restricts movement to just one plane: flexion (bending) and extension (straightening) of the forearm.

Correct Answer: C

A pivot joint allows a bone to rotate around a central, longitudinal axis.

At the proximal radioulnar joint, the cylindrical head of the radius is held against the ulna by the ring-like annular ligament. When the muscles pull, the radial head spins freely within this ring. This spinning action crosses the radius over the ulna, producing the movements of pronation (palm down) and supination (palm up).

Correct Answer: D

This is a critical clinical distinction!

• A shoulder dislocation usually refers to the humerus popping out of the glenoid fossa (glenohumeral joint).
• A shoulder separation specifically refers to a sprain or tear of the ligaments at the Acromioclavicular (AC) joint.

Correct Answer: C

The shoulder joint trades stability for extreme mobility. It is formed by the large, spherical head of the humerus articulating with the much smaller, shallow glenoid fossa (or cavity) on the lateral angle of the scapula.

Because the socket is so shallow (often compared to a golf ball sitting on a tee), it relies heavily on muscles and ligaments to stay in place.

Correct Answer: C

Also known as 'nursemaid's elbow', a pulled elbow occurs when a child is suddenly jerked by the hand or wrist. The radial head slips partially out of its primary restraint: the annular ligament.

This strong, fibrous band forms a collar around the radial head, holding it securely in the radial notch of the ulna while still allowing it to spin during pronation and supination.

Correct Answer: C

The radiocarpal joint is the true wrist joint, connecting the forearm to the hand. The concave distal end of the radius articulates directly with the convex surfaces of the scaphoid (laterally) and the lunate (medially).

Note: The ulna does NOT directly articulate with the carpal bones; it is separated from the triquetrum by the triangular fibrocartilage complex (TFCC).

Correct Answer: B

The thumb is special! The first CMC joint, located between the trapezium and the base of the first metacarpal, is the premier example of a saddle joint in the human body.

The opposing surfaces are concave in one direction and convex in the other (like two interlocking saddles). This unique shape permits flexion, extension, abduction, adduction, and the crucial combined movement of opposition.

Correct Answer: B

Because the bony socket of the shoulder is so shallow, static ligaments aren't enough. The joint relies on 'dynamic' stability—muscles that actively adjust their tension to hold the joint together during movement.

The four rotator cuff muscles (Supraspinatus, Infraspinatus, Teres minor, Subscapularis) act as a muscular sleeve. When the arm moves, these muscles contract to pull the humeral head tightly into the center of the glenoid fossa.

Correct Answer: B

Stand in the true anatomical position: arms down by your sides, elbows straight (extended), and palms facing forward (supinated).

You will notice your forearms angle slightly away from your body. This lateral deviation of the ulna relative to the humerus is the carrying angle. It allows your arms to swing past your wide hips without hitting them while walking.

Correct Answer: B

Sesamoid bones are bones that grow embedded within a tendon (like the patella/kneecap). The pisiform is a small, pea-shaped bone on the ulnar side of the wrist.

It develops entirely within the tendon of the flexor carpi ulnaris muscle, acting as a pulley to improve the muscle's mechanical advantage.

Correct Answer: B

Try this: Keep your fingers completely straight (extended) and try to spread them apart (abduct). Easy! Now, make a tight fist (flex the MCP joints) and try to spread your fingers. You can't!

This is because the collateral ligaments on the sides of the knuckles are eccentrically attached. They are slack when the fingers are straight, allowing side-to-side movement. But when you flex your fingers to grip something, the ligaments stretch tightly over the cam-shaped metacarpal heads, locking the fingers in place for a solid grip.

Correct Answer: B

The Ulnar Collateral Ligament (UCL), also known as the medial collateral ligament, spans the inside of the elbow joint.

It originates on the medial epicondyle of the humerus and fans out to attach firmly to two landmarks on the ulna: the coronoid process anteriorly and the olecranon posteriorly. It does not attach to the radius.

Correct Answer: C

The radius and ulna articulate at both their proximal (near the elbow) and distal (near the wrist) ends. These joints work together mechanically.

When you supinate (turn palm up) or pronate (turn palm down), the radial head spins at the proximal joint, while the distal end of the radius swings entirely around the relatively fixed head of the ulna at the distal joint.

Correct Answer: C

When a patient presents with a visible 'step off' at the AC joint after trauma, it indicates a severe AC joint separation. The AC ligament itself is torn, but more importantly, the massive Coracoclavicular (CC) ligament is completely ruptured.

Because the CC ligament is the main tether holding the clavicle down to the scapula, its failure allows the trapezius muscle to pull the clavicle visibly upward.

Correct Answer: B

The glenoid fossa is remarkably shallow, covering only about a third of the humeral head. To help remedy this, a wedge-shaped ring of tough fibrocartilage called the glenoid labrum attaches around the rim of the fossa.

It effectively deepens the socket by about 50%, providing a 'chock-block' effect to prevent the humeral head from sliding out, and serving as the anchor point for the glenohumeral ligaments and the long head of the biceps.

Correct Answer: D

A true anatomical joint requires two bony surfaces covered in cartilage, enclosed by a fibrous capsule lined with synovium.

The scapulothoracic articulation lacks these features. It is simply the anterior surface of the scapula gliding over the posterior rib cage, separated only by muscles and bursae. Despite not being a 'true' joint, its smooth movement is absolutely essential; without it, you could not raise your arm above your head.

Correct Answer: D

When the shoulder dislocates anteriorly (which happens 95% of the time), the humeral head is driven forward and downward.

The axillary nerve wraps intimately around the surgical neck of the humerus, right at the inferior margin of the joint capsule. As the bone dislocates, it can severely stretch or crush the axillary nerve, leading to deltoid weakness and numbness over the 'regimental badge' area of the outer shoulder.

Correct Answer: C

The TFCC is the meniscus of the wrist. Located on the ulnar side, it acts as a crucial shock absorber and stabilizer.

• It physically binds the distal radius to the distal ulna, stabilizing the distal radioulnar joint (DRUJ) during rotation.
• Because the ulna doesn't directly touch the carpal bones, the TFCC acts as a cushion to transmit about 20% of the axial load from the hand into the ulnar shaft.

Correct Answer: C

This injury is termed 'terrible' because it completely destroys the stability of the elbow, making treatment notoriously difficult.

The elbow relies on bony congruence for stability. In this injury, the joint dislocates posteriorly, shearing off the two primary bony buttresses preventing backward movement: the radial head (the lateral stabilizer) and the coronoid process of the ulna (the primary anterior stabilizer).