Anatomy 434: Hand and Wrist Anatomy

Hand and Wrist Anatomy

• Anatomy Team 434 created this study guide
• Contact information is provided for complaints and suggestions
• Anatomy 434 is the course number

Objectives

• Students should be able to describe deep fascia of the wrist and hand (flexor and extensor retinacula and palmar aponeurosis)
• Students should be able to list structures superficial and deep to the flexor retinaculum
• Students should be able to describe the anatomy of the insertion of long flexor and extensor tendons
• Students should be able to describe the anatomy of the small muscles in the hand (origin, insertion, action and nerve supply)

Retinacula

• The flexor retinaculum is anterior and the extensor retinaculum is posterior
• These structures are formed from the deep fascia at the wrist
• Retinacula hold the long tendons in position at the wrist
• Medial attachments include the pisiform and hook of hamate
• Lateral attachments include the tubercle of the scaphoid, trapezium, and distal end of the radius

Structures Superficial to Flexor Retinaculum

• These structures are listed from medial to lateral
• Tendon of flexor carpi ulnaris
• Ulnar nerve
• Ulnar artery
• Palmar cutaneous branch of ulnar nerve
• Palmaris longus tendon
• Palmar cutaneous branch of median nerve

Carpal Tunnel

• Formed by the concave anterior surface of the carpus, covered by the flexor retinaculum
• Important contents (from medial to later):
  • Tendons of flexor digitorum superficialis and profundus.
  • Median nerve.
  • Flexor pollicis longus.
  • Flexor carpi radialis
• Causes of carpal tunnel syndrome include compression of the median nerve within the carpal tunnel
• Manifestations include burning pain (pins and needles) in the lateral three and a half fingers, no paresthesia over the thenar eminence, weakness or atrophy of the thenar muscles (ape hand), and inability to oppose the thumb

Palmar Aponeurosis

• Triangular in shape, occupies central area of the palm
• Apex is attached to the distal border of the flexor retinaculum, receiving the insertion of the palmaris longus tendon
• The base divides into four slips that pass into the fingers
• Functions include improving grip, protecting underlying tendons, vessels, and nerves
• Gives origin to the palmaris brevis

Short Muscles of Thumb and Little Finger

• Detailed descriptions of the origin, insertion, nerve supply, and action of short muscles of the hypothenar and thenar eminences(3 each)
• Descriptions of actions include abduction, flexion, opposition, and adduction.

Insertion of Flexor Digitorum Superficialis & Profundus

• Flexor digitorum superficialis divides into two halves that pass around the profundus tendon
• The two halves meet on the posterior aspect and fuse
• Flexor digitorum superficialis divides again into two slips attached to the borders of the middle phalanx
• Flexor digitorum profundus inserts into the base of the distal phalanx

Fibrous Flexor (Digital) Sheath

• Strong fibrous sheath covering the anterior surface of the fingers and attached to the sides of phalanges
• The proximal end is open
• The distal end is closed to form an osteofibrous tunnel for long flexor tendons
• Common synovial sheath (ulnar bursa) contains tendons of flexor digitorum superficialis and profundus
• Medial portion of the sheath extends distally to the little finger tendon/
• The lateral portion of the sheath stops at the middle of the palm
• Distal ends of the long flexor tendons to the index, middle, and ring fingers acquire digital synovial sheaths.
• The flexor pollicis longus tendon has its own radial bursa

Lumbrical Muscles, Palmar Interossei, and Dorsal Interossei

• Detailed descriptions of origin, insertion, nerve supply, and actions of lumbrical muscles, palmar interossei, and dorsal interossei muscles
• These muscles are essential for fine hand movements

Extensor Expansion

• Formed from the expansion of extensor digitorum tendons at the proximal interphalangeal joints
• The tendon splits into three parts: One central part inserts into the base of the middle phalanx
• Two lateral parts insert into the base of the distal phalanx
• The expansion receives insertions from corresponding interosseous muscles (on each side) and the lumbrical muscle (on the lateral side)

Multiple Choice Questions (MCQs)

• Questions testing knowledge of hand anatomy and related nerves/muscle/structures.

This quiz covers the essential anatomy of the hand and wrist, including the deep fascia, flexor and extensor retinacula, and the small muscles of the hand. Students will be tested on their understanding of tendon insertions and the anatomical relationships of these structures. Prepare to demonstrate your knowledge of critical anatomical details necessary for a comprehensive understanding of hand and wrist function.