Anatomical Structures of the Wrist, Hand, and Fingers

Comprehensive flashcards covering the anatomical structures, joints, ligaments, nerves, and vascularity of the wrist, hand, and fingers based on lecture notes.

In terms of functional equipment, how do the purposes of the shoulder, elbow, and wrist/hand differ?

The shoulder is equipped for mobility and gross placement, the elbow for stability, and the wrist, hand, and fingers for strength and precision.

What specific bones make up the skeletal portion of the wrist, hand, and fingers?

The skeletal portion includes the distal portions of the radius and ulna, the $8$ carpal bones, $5$ metacarpals, and $14$ phalanges.

What are the anatomical landmarks on the distal radius that articulation with the ulna and assist in stabilizing the lateral border?

The distal radius contains a small ulnar notch on its medial surface to accept the ulnar head and the radial styloid process on its anterolateral border.

List the carpal bones in the proximal row from the radial to the ulnar side.

The proximal row consists of the scaphoid, lunate, triquetrum, and pisiform bones.

List the carpal bones in the distal row from the radial to the ulnar side.

The distal row is formed by the trapezium, trapezoid, capitate, and hamate bones.

Which carpal bones align with which metacarpals ($MC$) in the distal row?

The trapezium aligns with the first $MC$, the trapezoid with the second $MC$, the capitate with the third $MC$, and the hamate with the fourth and fifth $MC$.

What is the functional role of the pisiform bone?

It floats on the triquetrum acting as a sesamoid bone to improve the mechanical efficiency of the flexor carpi ulnaris muscle.

Which carpal bones are the most commonly fractured and the most commonly dislocated?

The scaphoid is the most commonly fractured, and the lunate is the most commonly dislocated carpal bone.

How do the articulating surfaces of the metacarpals differ between their proximal and distal ends?

The proximal articulating surfaces (the base) are concave to accept the convex carpals, while the distal surfaces (the head) are convex to accept the concave proximal phalanx.

What is the purpose of the two small sesamoid bones located on the palmar aspect of the first metacarpal?

They improve the mechanical line of pull of the flexor pollicis brevis, abductor pollicis brevis, and adductor pollicis muscles.

What movement is permitted at the distal radioulnar articulation, and which bones produce this motion?

It allows one degree of freedom, pronation and supination, produced by the radius gliding around the ulna.

Which bones form the radiocarpal articulation?

The joint is formed by the distal end of the radius articulating with the scaphoid and lunate bones, with the triangular fibrocartilaginous complex ($TFCC$) incorporating the triquetrum.

What is the primary function of the ulnar collateral ligament of the wrist?

It checks radial deviation (valgus force) and becomes taut at end ranges of flexion and extension.

Which ligament arises from the posterior surface of the distal radius and limits wrist flexion?

The dorsal radiocarpal ligament.

What functions does the triangular fibrocartilage complex ($TFCC$) serve?

It acts as a meniscus homolog to dissipate stress during loading, stabilizes the distal radioulnar joint, and extends the radiocarpal articulation by stabilizing ulnar side carpal bones.

Which structure is considered the most important ligament for controlling wrist stability and what are its three segments?

The palmar radiocarpal ligament, which includes the radiocapitate, radiotriquetral, and radioscaphoid segments.

Describe the classification and movement capabilities of the first carpometacarpal ($CMC$) joint.

It is a saddle joint with two degrees of freedom (flexion/extension, abduction/adduction) and an accessory rotational component for opposition and reposition.

How do the second through fourth $CMC$ joints differ from the first and fifth $CMC$ joints in terms of mobility?

The second through fourth $CMC$ joints are simple gliding joints with minimal motion (the second and third are practically immobile), while the first and fifth have two degrees of freedom.

How does the first metacarpophalangeal ($MCP$) joint differ in classification from the lateral four $MCP$ joints?

The first $MCP$ joint is a synovial hinge joint ($1$ degree of freedom), whereas the remaining four are ellipsoidal joints ($2$ degrees of freedom).

What structures provide stability for the interphalangeal ($IP$) joints against valgus and varus forces?

Pairs of collateral ligaments running obliquely from the dorsal aspect of the proximal bone to the palmar aspect of the distal phalanx.

Which nerve passes through the "tunnel of galleon" and what part of the hand does its superficial branch provide sensation to?

The ulnar nerve passes through the tunnel of galleon; its superficial branch provides sensation to the palmar surface of the little finger and the medial one half of the ring finger.

What muscles are innervated by the motor branches of the median nerve in the hand?

The motor branches supply the muscles of the thenar eminence and the lateral two lumbricals.

What are the two divisions of the radial nerve and their respective functions in the hand and wrist?

The posterior interosseous nerve provides motor innervation to the wrist and finger extensors, and the superficial radial nerve provides sensation to the dorsal aspect of the hand.

How is vascular redundancy achieved in the wrist and hand?

The radial and ulnar arteries combine at the palmar and dorsal surfaces to form a palmar arch and a dorsal arch structure.