Anatomy · MU Sofia

Topographic · 262. Wrist Region

Covers the wrist and hand regions in topographic detail: the posterior forearm with its superficial and deep muscle layers, and the anterior wrist with the carpal canals, the ulnar (Guyon's) canal and the carpal tunnel, including boundaries and contents. It then describes the anatomical snuff box and the extensor retinaculum, and finishes with the palmar skin, its three deep lines and their functional significance.

Inside: 6 sections · 5 labelled pictures · 16 flashcards · 6 min

Topic 237 of 264 in the MU Sofia syllabus for Anatomy (Dental Medicine, Year 2). The free AceMed note covers it in 6 sections, about 806 words (6 min of reading), with 16 flashcards.

In this note

  1. WRIST Region
  2. Posterior Region of the forearm:
  3. Anterior Region:
  4. Posterior Region
  5. Posterior Region:
  6. PALMAR Region.

Posterior Region of the forearm:

  1. 1. The skin in this area is thicker and may have variable hair.
  2. 2. The superficial fascia is thin and loosely attached to the deep fascia.
  3. 3. Veins (e.g., cephalic and basilic veins) cross this region on their way to the anterior antebrachial region.
  4. 4. Cutaneous innervation is provided by the posterior antebrachial cutaneous nerve and branches from the medial antebrachial cutaneous nerve.
  5. 5. Muscles in the Superficial Layer:
  • Extensor muscles (from radius to ulna):
  • Extensor carpi radialis (longus and brevis)
  • Extensor digitorum
  • Extensor digiti minimi
  • Extensor carpi ulnaris
  1. 6. Muscles in the Deep Layer:
  • Supinator muscle
  • Muscles for the thumb and index finger:
  • Abductor pollicis longus
  • Extensor pollicis brevis
  • Extensor pollicis longus
  • Extensor indicis

Fascial Separation:

  • The two muscle layers are separated by a fascial space, with deep vessels and nerves situated between them.

Anterior Region:

  1. 1. Skin Characteristics:
  • Very fine and smooth.
  • Devoid of hair.
  1. 2. Superficial Fascia:
  • Contains very little fat.
  • Fixed to the deep fascia, especially around os pisiforme.
  1. 3. Deep Fascia:
  • Continuous with the antebrachial fascia.
  • Thickened by transverse fibrous strands forming a thick 1.5-2 cm wide transverse band.
  • Fuses with the retinaculum mm. flexorum.

The Retinaculum transforms the carpal groove into carpal canals:

  • It's radial end sends a thin fibrous septum inwards that inserts onto the bones & forms Radial Carpal Canal.
  • u medial end forms Ulnar Carpal canal (lateral to the bones btw the retinaculum & superficial fascia)
  • In the middle forms Carpal tunnel.

The ulnar canal (Guyon's canal) is a passage through the split layers of the flexor retinaculum located on the medial side of the wrist.

Boundaries

  1. 1 Medially: pisiform bone
  2. 2 Laterally: hamulus (hook) of hamate bone
  3. 3 Dorsally: flexor retinaculum
  4. 4 Superficially: palmaris brevis and part of flexor retinaculum

Content

  1. 5 Ulnar artery
  2. 6 Ulnar veins
  3. 7 Ulnar nerve

The carpal tunnel is formed by the carpal bones and a thick ligament called the flexor retinaculum. These walls do not allow expansion of this space. This causes the median nerve to be more susceptible to compression as it courses through the carpal tunnel. Compression of the median nerve in the carpal tunnel is known as carpal tunnel syndrome and is the most common entrapment syndrome. The carpal canal is subdivided by a fibrous septum into two subspaces: the smaller radial region and the larger ulnar region.

Boundaries

  1. 1 Medially: ulnar eminence of the wrist
  2. 2 Laterally: radial eminence of the wrist

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