Page 58 - ASOP ROT Study Guide

6 . 3 Subtalar Joint

The subtalar joint is the articulation between the talus and the os calcis. This joint has an
oblique axis as shown in Figure 23.

http://moon.ouhsc.edu/dthompso/namics/labs/ankle.htm

http://moon.ouhsc.edu/dthompso/namics/labs/ankle.htm

http://moon.ouhsc.edu/dthompso/namics/labs/ankle.htm

RE 23. THE AXIS OF THE SUBTALAR JOINT SEEN FROM (A) ABOVE (B & C) REAR.

This joint allows an inward and outward rotation of the foot (about an approximately
horizontal, front to back axis) defined as follows:

♦ Inversion - rotation of the foot so that the sole faces medially
♦ Eversion - rotation of the foot so that the sole faces laterally

These movements are valuable when walking over rough ground or across a slope.
Together with the ankle the subtalar joint helps produce smooth walking, whatever the
ground is like.

6 . 4 First Metatarsophalangeal Joint

The first metatarsophalangeal joint (Figure 24) is an articulation on the medial side of the
foot between the great toe, or hallux, and the first metatarsal. It is a synovial joint in the
form of a hinge and permits dorsiflexion and plantarflexion of the toe. Although it is a
small joint it is important in walking and in particular in permitting the flexor hallucis muscle
to impart downward pressure on the ground during running, walking and jumping.

When the joint becomes worn every footstep becomes very painful and so the sufferer tends
to hold the joint stiff. This condition is known as Hallux Rigidus although the accurate