The fifth metacarpal bone (metacarpal bone of the little finger or pinky finger) is the most lateral metacarpal.

Surfaces

It presents on its base one facet on its superior surface, which is concavo-convex and articulates with the hamate, and one on its radial side, which articulates with the fourth metacarpal.

On its ulnar side is a prominent tubercle for the insertion of the tendon of the extensor carpi ulnaris muscle

Extensor carpi ulnaris muscle

In human anatomy, the extensor carpi ulnaris is a skeletal muscle located on the ulnar side of the forearm. It acts to extend and adduct at the carpus/wrist.Being an extensor muscle, extensor carpi ulnaris is on the posterior side of the forearm....

.

The dorsal surface of the body is divided by an oblique ridge, which extends from near the ulnar side of the base to the radial side of the head.

The lateral part of this surface serves for the attachment of the fourth Interosseus dorsalis

Dorsal interossei of the hand

The dorsal interossei of the hand are muscles that occupy the space between the metacarpals.-Structure:There are four dorsal interossei in each hand...

; the medial part is smooth, triangular, and covered by the Extensor tendons of the little finger

Little finger

The little finger, often called the pinky in American English, pinkie in Scottish English , or small finger in medicine, is the most ulnar and usually smallest finger of the human hand, opposite the thumb, next to the ring finger.-Muscles:There are four muscles that...

.

Clinical significance

This is the most common bone to be injured when throwing a punch. (See Boxer's fracture

Boxer's fracture

A "Boxer's fracture" is the second and/or third metacarpal transverse neck fracture that is more likely to occur from a straight punch. The "Boxer's" designation is suggestive of the generally well tolerated way of striking a hard object with the closed fist, with the second and third metacarpal...

)

See also

• Metacarpus
• First metacarpal bone
  First metacarpal bone
  The first metacarpal bone or the metacarpal bone of the thumb is the first bone of the thumb. It is connected to the trapezium of the carpus at the first carpometacarpal joint and to the proximal thumb phalanx at the first metacarpophalangeal joint....
  
  
• Second metacarpal bone
• Third metacarpal bone
  Third metacarpal bone
  The third metacarpal bone is a little smaller than the second.The dorsal aspect of its base presents on its radial side a pyramidal eminence, the styloid process, which extends upward behind the capitate; immediately distal to this is a rough surface for the attachment of the extensor carpi...
  
  
• Fourth metacarpal bone
  Fourth metacarpal bone
  The fourth metacarpal bone is shorter and smaller than the third.The base is small and quadrilateral; its superior surface presents two facets, a large one medially for articulation with the hamate, and a small one laterally for the capitate.On the radial side are two oval facets, for articulation...