Syndesmosis

[1] The syndesmoses found in the forearm and leg serve to unite parallel bones and prevent their separation.

In the forearm, the wide gap between the shaft portions of the radius and ulna bones are strongly united by an interosseous membrane.

However, a syndesmosis does not prevent all movement between the bones, and thus this type of fibrous joint is functionally classified as an amphiarthrosis.

Thus in contrast to the stability provided by the tibiofibular syndesmosis, the flexibility of the antebrachial interosseous membrane allows for the much greater mobility of the forearm.

If the fracture site is not properly immobilized with a cast or splint, contractile activity by these muscles can cause improper alignment of the broken bones during healing.