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Phalanges of the Hand

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(Redirected from Distal Phalanx (Hand))

Introduction

Labeled illustration of the phalanges of the hand
Radiographs of the hand bones labeled[1]
Coronal section through the left hand at the level of the interossei muscles (dorsal aspect). 1 Radius 2 Radiocarpal joint 3 Scaphoid (navicular) bone 4 Radial artery 5 Trapezoid bone 6 Trapezium bone 7 First metacarpal bone 8 Metacarpophalangeal joint of thumb 9 Interossei muscles 10 Proximal phalanx of thumb 11 Proximal phalanx of fingers 12 Interphalangeal joints 13 Middle phalanx 14 Distal phalanx 15 Ulna 16 Distal radio-ulnar joint 17 Articular disc 18 Lunate bone 19 Triquetral bone 20 Capitate bone 21 Hamate bone 22 Carpometacarpal joints 23 Abductor digiti minimi muscle 24 Fifth metacarpal bone 25 Metacarpophalangeal joint 26 Adductor pollicis muscle 27 Proper palmar digital arteries 28 Metacarpal joint 29 Opponens pollicis muscle 30 Ulnar collateral ligament 31 Pisiform bone[2]

General

  • Group of small bones which compromise the bony core of the fingers of the hand
  • Each finger has a proximal, middle and distal except the thumb

Osteology

  • Classified as long bones due to structural characteristics
  • Phalanx consists of a shaft, distal head and a proximal base
  • Base: concave in order to articulate with the head of the proximal metacarpal or phalanx
  • Distal phalanx is distally tuberos and rough on the flexor side for the digital fat pad[3]

Distribution

  • There are 14 total phalanges of the hand
  • Digits 2-5 (Medial four) have three phalanges (proximal, middle, distal)
  • Digit 1 (Thumb) has only two (proximal, distal)

Sesamoid Bones

  • Can sometimes be found at the metacarpal heads, especially 2nd and 5th
  • Contained within the palmar capsule of the metacarpophalangeal joint
  • Less commonly, at the interphalangeal joints

Proximal Phalanges

  • Largest compared to middle, distal phalanx
  • Proximal phalanx of the thumb is shorter and more stout compared to the rest
  • Base articulates with the metacarpal head, forms metacarpophalangeal joint
  • Body forms dorsal and extensor surface for muscle/tendon attachments
  • Head articulates with the middle phalanx to form proximal interphalangeal joint
  • Ligament attachments: digital fascial complex, metacarpophalangeal ligaments, collateral interphalangeal ligaments, extensor expansion of hand
  • Very mobile within the MCP joints
  • Movement: capable of flexion/extension and abduction/adduction
    • Thumb has circumduction and rotation as well

Middle Phalanges

  • Four total for digits 2 to 5, absent in the thumb
  • Anatomy: base, body and head
  • Head articulates with distal phalanx to form Distal interphalangeal joint
  • Ligament attachments: digital fascial complex, collateral interphalangeal ligaments, extensor expansion of hand
  • Movement: flexion/extension

Distal Phalanx

  • Five total, shorter and thicker compared to proximal/ middle
  • Base articulates with the middle phalanx (2-4), proximal phalanx (1)
  • Head: irregular, curved, anchor point for the digital pulp
  • Ligament attachments: fascial complex, collateral interphalangeal ligaments and extensor expansion of hand
  • Movement: flexion/extension

Actions

Joints

Flexor Muscles Attachments

Extensor Muscles Attachments

Vascular Supply

  • Nutrient rami to phalanges, stem from the palmar digital arteries

Innervation

  • Needs to be updated

Clinical Significance

See Also

References

  1. ↑ Image courtesy of radiologymasterclass.co.uk
  2. ↑ Rohen, Johannes W., Chihiro Yokochi, and Elke Lutjen-Drecoll. Photographic atlas of anatomy. Lippincott Williams & Wilkins, 2020.
  3. ↑ McMinn. Lasts Anatomy Regional and Applied. CHURCHILL LIVINGSTONE. (2003) ISBN:B0084AQDG8.
Created by:
John Kiel on 22 August 2024 02:39:00
Authors:
Last edited:
22 August 2024 17:15:29
Category:
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