Bones Of Hand- Carpal

Bones Of Hand- Carpal


CARPAL BONES

  • Short bones, eight in number.
  • Arranged in two proximal and distal, each row presenting four bones.
  • From lateral to medial side, bones of proximal row are scaphoid, lunate, triquetrum and pisiform.
  • bones of distal row are trapezium, trapezoid, capitate and hamate. 

OSSIFICATION:

  • Ossification of carpal bones appear after birth in a spiral manner as follows:

CARPAL  BONE

   OSSIFICATION  (in yrs)

Capitate

1

Hamate

2

Triquetrum

3

Lunate

4

Scaphoid

5

Trapezium

6

Trapezoid

7

Pisiform

12

  Note: The scaphoid bone is a small carpal bone on the thumb side (radial side) of the wrist. It is the most commonly fractured carpal bone.

  • This is probably because it actually crosses two rows of carpal bones, forming a hinge.

Articulations:

CARPAL BONE

ARTICULATING WITH

Scaphoid

Radius, trapezium, trapezoid, lunate, capitate

Lunate

Radius, capitate, hamate, scaphoid, Triquetral

Triquetrum

Hamate, lunate, pisiform

Pisiform

Triquetral

[Minimum articulation with only 1 bone]

Trapezium

Scaphoid, trapezoid, 1st & 2nd metacarpal

Trapezoid

Scaphoid, trapezium, capitate, 2nd metacarpal

Capitate

Scaphoid, lunate, trapezoid, hamate, 2nd 3rd & 4th metacarpals

[Maximum articulation with 7 bones]

Hamate

Lunate, capitate, Triquetral, 4th & 5th metacarpals

  BONY PILLARS:

  • There are four bony pillars at the four corners of the carpus.
  • All attachments are to these four pillars:
1. The tubercle of the scaphoid:
  • The flexor retinaculum
  • A few fibers of the abductor pollicis brevis
2. The pisiform gives:
  • Flexor carpi ulnaris
  • Flexor retinaculum and its superficial slip
  • Abductor digiti minimi
  • Extensor retinaculum
3. The trapezium:
  • The crest gives origin to the abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis. These constitute muscles of thenar eminence.
  • The edges of the groove give attachment to the two layers of the flexor retinaculum.
  • The lateral surface gives attachment to the lateral ligament of the wrist joint.
  • The groove lodges the tendon of the flexor carpi radialis.
4. The hamate:
  • The tip of the hook gives attachment to the flexor retinculum.
  • The medial side of the hook gives attachment to the flexor digiti minimi and the opponens digiti minimi. 
APPLIED ANATOMY:
 
  1. Kienbock’s disease is osteochondritis of lunate.
  2. Capitate is the largest carpal bonefirst carpal bone to ossify and articulates with maximum number of bones.
  3. Lunate is the most commonly dislocated carpal bone.
  4. Scaphoid is the most commonly fractured carpal bone.
  • The scaphoid bone is a small carpal bone on the thumb side (radial side) of the wrist. It is the most commonly fractured carpal bone.
  • This is probably because it actually crosses two rows of carpal bones, forming a hinge.
Exam Question
 
  • 4th carpal bones (Lunate) are present at 4 yrs of age.
  • Carpal bones articulate with radius are Scaphoid and lunate.
  • Carpal bone which fracture commonly is Scaphoid.
  • The commonly injured carpal bone next to scaphoid is Trapezium.
  • Lunate carpal bone fracture causes median nerve involvement.
Don’t Forget to Solve all the previous Year Question asked on Bones Of Hand- Carpal

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