The order of structures passing through the tunnel from the anteromedial to posterolateral are the tendon of the tibialis posterior, the tendon of the flexor digitorum longus, the posterior tibial artery and associated veins, the tibial nerve, and the tendon of the flexor hallucis longus (“Tom, Dick, and a very nervous Harry”).
The tibial artery is palpable just posteroinferior to the medial malleolus on the anterior face of the visible groove between the heel and medial malleolus.
Identifying tendons around the ankle and in the foot
Numerous tendons can be identified around the ankle and in the foot (Fig. 6.134) and can be used as useful landmarks for locating vessels or testing spinal reflexes.
The tibialis anterior tendon is visible on the medial side of the ankle anterior to the medial malleolus.
The calcaneal tendon is the largest tendon entering the foot and is prominent on the posterior aspect of the foot as it descends from the leg to the heel. A tap with a tendon hammer on this tendon tests reflex activity of spinal cord levels S1 and S2.
When the foot is everted, the tendons of the fibularis longus and fibularis brevis raise a linear fold of skin, which descends from the lower leg to the posterior edge of the lateral malleolus.
The tendon of the fibularis brevis is often evident on the lateral surface of the foot descending obliquely to the base of metatarsal V. The tendons of the fibularis tertius, extensor digitorum longus, and extensor hallucis longus are visible on the dorsal aspect of the foot from lateral to medial.
Finding the dorsalis pedis artery
The nature of the dorsalis pedis pulse (Fig. 6.135) is important for assessing peripheral circulation because the dorsalis pedis artery is the farthest palpable vessel from the heart. Also, it is the lowest palpable artery in the body when a person is standing.
The dorsalis pedis artery passes onto the dorsal aspect of the foot and anteriorly over the tarsal bones where it lies between and is parallel to the tendon of the extensor hallucis longus and the tendon of the extensor digitorum longus to the second toe. It is palpable in this position. The terminal branch of the dorsalis pedis artery passes into the plantar surface of the foot between the two heads of the first dorsal interosseous muscle.
Approximating the position of the plantar arterial arch
The blood supply of the foot is provided by branches of the posterior tibial and dorsalis pedis arteries.
The posterior tibial artery enters the plantar surface of the foot through the tarsal tunnel and divides into a lateral and a medial plantar artery.
The lateral plantar artery curves laterally across the posterior half of the sole and then curves medially as the plantar arch (Fig. 6.136) through the anterior sole. Between the bases of metatarsals I and II, the plantar arch joins the terminal branch (deep plantar artery) of the dorsalis pedis artery. Most of the foot is supplied by the plantar arch.
The medial plantar artery passes anteriorly through the sole, connects with branches of the plantar arch, and supplies the medial side of the great toe.
Superficial veins in the lower limb often become enlarged. Also, because the veins are long, they can be removed and used elsewhere in the body as vascular grafts.
Superficial veins (Fig. 6.137) in the lower limb begin as a dorsal venous arch in the foot. The medial side of the arch curves superiorly anterior to the medial malleolus and passes up the leg and thigh as the great saphenous vein. This vein passes through an aperture in the fascia lata (saphenous ring) to join with the femoral vein in the femoral triangle.