The short muscles of the toes in the sole of the foot are arranged in four layers beneath the plantar fascia. Starting at the outermost layer, they areFirst layer: Abductor halluces, flexor brevis digitorum, abductor minimi digiti.

Second layer: Lumbricales and accessorius, and the tendons of the long flexor muscles.

Third layer: Flexor brevis halluces, adductores halluces, flexor brevis minimi digiti.

Fourth layer: Interossei (plantar and dorsal) and tendons of peroneus longus and tibialis posticus.

Fig. 24. - Short Muscles and Arteries of Foot.

The Deep Fascia of the lower limb is continuous with that of the trunk, and that of the thigh is attached to the crest of the ilium, the pubic arch and symphysis, the great sciatic ligament, and Poupart's ligament; below it is attached to the patella, the tuberosities of the tibia, and the head of the fibula.

On the front of the thigh it is very thick, especially over the region of Scarpa's triangle, where there is an opening for the internal saphenous vein. On the outer surface of the thigh there is a strong band in the fascia, the ilio-tibial band, attached above to the iliac crest, and below to the outer tuberosity of the tibia. At the knee it forms the lateral ligaments of the patella attached to the patella and the tuberosities of the tibia. Just above the knee the deep fascia sends in expansions, intermuscular septa, which are attached to the supra-condyloid ridges. On the back of the thigh the fascia is especially thick over the popliteal space, where it is pierced by the external saphenous vein.

Femoral Sheath

A facial investment for the femoral vessels, formed by the deep fascia covering Scarpa's triangle above, and an expansion of the internal fascial lining of the abdominal wall which goes down deep to the vessels, so enclosing them between two layers of fascia. It is divided into three compartments-the outer one for the artery, the intermediate one for the vein, and the inner one for a lymphatic gland; this latter division is known as the crural canal.

The deep fascia of the leg is continuous with that of the thigh, and passing down the leg sends in septa between the muscles. At the ankle it is attached to the malleoli and the os calcis, and forms the annular ligament.

The Internal Annular ligament is attached to the internal malleolus and the tuberosity of the os calcis. A number of important structures pass beneath it - viz., tendon of tibialis posticus, tendon of flexor longus digitorum, post tibial artery, post, tibial nerve, tendon of flexor longus halluces.

The External Annular ligament is attached to the external malleolus and the os calcis, and the tendons of peroneus longus and brevis pass beneath it.

Across the front of the ankle there are usually three bands of fascia, but occasionally more are found. The extensor tendons of the ankle pass beneath the uppermost one, and the anterior tibial vessels and nerve pass over it.

In the sole of the foot the fascia forms the very important Plantar Fascia attached to the tuberosity of the os calcis; anteriorly it spreads out and divides into five slips, which are attached to the digital sheaths of the toes. From the sides a thinner layer of fascia spreads out to cover the muscles and sends in intermuscular septa. The plantar fascia is instrumental in preserving the arch of the foot.