Canine Phalanges - Anatomy & Physiology

Bones

The arrangement of the metatarsals are similar to those of the metacarpals.
They are rod shaped bones, numbered from I to V. The 1st is the most medial and is very small, the 3rd and 4th are the longest.
The proximal base articulates with it's corresponding carpal bone and the adjacent metacarpal.
The distal end is it's head, which is transversely cylindrical and articulates with the proximal phalanx.
Metacarpals II - V possess a sagittal ridge on their palmar aspects.

Proximal phalanx - of the main digits (II - V) they have a concave articular surface proximally. The palmar border has a groove to accomodate the articular surface of the metacarpus when the joint is fixed. The distal head has two convex areas seperated by a groove.
Middle phalanx - roughly two-thirds the length of the proximal, its base has a sagittal ridge on the articular surface, which articulates with the groove of the proximal phalanx. The head resembles that of the proximal.
Distal phalanx - made up of a cone-shaped ungual process with a distinct collar, ungual crest. The deep ungual groove distal to the crest provides attachment for the proximal border of the claw. It articulates with the middle phalanx via a small sagittal crest.
A bony sesamoid bone is found on the dorsal aspect of the metacarpophalangeal joint.
The 'dew claw', metacarpal I, is normally present in the forelimb but often not in the hindlimb. It normally only consists two phalanges that resemble the proximal and distal ones.