The digital or interphalangeal articulations are hinge-joints, and each has a palmar and two collateral ligaments. The arrangement of these ligaments is similar to those in the metacarpophalangeal articulations. The extensor tendons supply the places of dorsal ligaments.

Movements.-The only movements permitted in the interphalangeal joints are flexion and extension; these movements are freer between the proximal and middle phalanges than between the middle and distal. The amount of flexion is very considerable, but extension is limited by the palmar ligaments.

Muscles producing the movements:

Flexion.-Flexores digitorum sublimis et profundus, Flexor pollicis longus.
Extension.-Lumbricales, Interossei; dorsal and palmar, Extensores pollicis longus et brevis.

Figure 543
Metacarpophalangeal and digital joints palmar view - Figure 543
Figure 544
Metacarpophalangeal and digital joints medial view - Figure 544


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