REIDER PART 224

284 Chapter 7 Lower Leg, Foot, and Ankle

Immediately posterior to the tibialis posterior ten-don lies the tendon of the flexor digitorum longus. The flexor digitorum longus tendon may be appreciated by firm palpation posterior to the tibialis posterior tendon while the patient actively flexes the toes (Fig. 7-53).

The posterior tibial artery is located immediately posterior to the flexor digitorum longus tendon. The posterior tibial pulse is usually easily felt by moderately firm palpation behind the medial malleolus using the tips of one or two digits.

The posterior tibial nerve is located immediately posterior to the posterior tibial artery. The tarsal tunnel is the name given to the spacc bounded anteriorly by the medial malleolus, laterally by the talus and calcaneus, and medially by the overlying flexor retinaculum. Compression of the posterior tibial nerve as it traverses this space is called tarsal tunnel syndrome. Possible con-tributory causes of tarsal tunnel syndrome include post-traumatic swelling, space-occupying lesions such as varicosities, ankle deformities, and severe pes planus. If tarsal tunnel syndrome is suspected, the examiner should pcrcuss the nerve with the tip of one finger in the manner used for Tinefs test of the median nerve at the wrist (Fig. 7-54). In a patient with tarsal tunnel syndrome, such per-cussion may reproduce or exacerbate the patients pain or result in sharp or electric pains that radiate distally into the foot or proximally into the calf. Prolonged digital pressure over the nerve may also inerease the symptoms or cause dysesthesias in the plantar portion of the foot, much in the same manner as Phalens test exacerbates the symptoms of carpal tunnel syndrome in the hand.

The tendon of the flexor hallucis longus is located both posterior and lateral to the posterior tibial nerve. This deep position makes it relatively difficult to palpate. Excursion of the flexor hallucis longus can usually be

Figurę 7-54. Tinefs test for tarsal tunnel syndrome.

appreciated by deep palpation posterior to the medial malleolus while passively extending the great toe or asking the patient to tlcx and extend it (Fig. 7-55). Tendcrncss of the flexor hallucis longus tendon suggests the possibility of flexor hallucis longus tendinitis, which characteristically occurs in ballct dancers. In the extreme case, enlargement of the tendon may cause palpable triggering of the tendon as it enters the fibroosseous sheath along the medial wali of the calcaneus, a condition analogous to trigger finger, which is sometimes called hattux saltans.

Foot. It is important to continue percussion of the posterior tibial nerve distally to its bifurcation into the medial and lateral plantar nerves because these divisions may become individually entrapped. In the case of the medial plantar nerve, entrapment tends to occur at the master