OF THE FOOT 537 



Relations. By its superficial surface, with the Peroneus longus and the fascia of the leg 

 and foot; by its deep surface, with the fibula and outer side of the os calcis. 



Nerves. The Peroneus longus and brevis arf supplied by the fourth and fifth lumbar and 

 first sacral nerves through the musculocutaneous branch of the external popliteal nerve. 



Actions. The Peroneus longus and brevis extend the foot upon the leg, in conjunction with 

 the Tibialis posticus, antagonizing the Tibialis anticus and Peroneus tertius, which are Flexors 

 of the foot. The Peroneus longus also everts the sole of the foot; hence, the extreme eversion 

 occasionally observed in fracture of the lower end of the fibula, where that bone offers no resist- 

 ance to the action of this muscle. From the oblique direction of the Peroneus longus tendon 

 across the sole of the foot it is an important agent in the maintenance of the transverse arch 

 of the foot. Taking their fixed point below, the Peronei serve to steady the leg upon the foot. 

 This is especially the case when standing upon one leg, when the tendency of the superincumbent 

 weight is to throw the leg inward; the Peroneus longus overcomes this tendency by drawing 

 on the outer side of the leg, and thus maintains the perpendicular direction of the limb. 



Applied Anatomy. The student should now consider the position of the tendons of the 

 various muscles of the leg, their relation with the ankle-joint and surrounding bloodvessels, and 

 especially their action upon the foot, as their rigidity and contraction give rise to one or other of 

 the kinds of deformity known as club-foot. The most simple and common deformity, and one 

 that is rarely, if ever, congenital, is the talipes equinus, the heel being raised by rigidity and con- 

 traction of the Gastrocnemius muscle, and the patient walking upon the ball of the foot. In 

 the talipes varus the foot is forcibly adducted and the inner side of the sole raised, sometimes 

 to a right angle with the ground, by the action of the Tibialis anticus and posticus. In the 

 talipes valgus the outer edge of the foot is raised by the Peronei muscles, and the patient walks 

 on the inner ankle. In the talipes calcaneus the toes are raised by the Extensor muscles, the 

 heel is depressed, and the patient walks upon it. Other varieties of deformity are met with, 

 as the talipes equinovarus, equinovalcjus, and calcaneovalyus, whose names sufficiently indicate 

 their nature. Of these, the talipes equinovarus is the most common congenital form; the heel 

 is raised by the tendo Achillis, the inner border of the foot drawn upward by the Tibialis 

 anticus, the anterior two-thirds twisted inward by the Tibialis posticus, and the arch increased 

 by the contraction of the plantar fascia, so that the patient walks on the middle of the outer 

 border of the foot. Each of these deformities may sometimes be successfully relieved by divi- 

 sion of the opposing tendons and fascia; by this means the foot regains its proper position, 

 and the tendons subsequently heal. The operation is easily performed by putting the contracted 

 tendon upon the stretch, and dividing it by means of a narrow, sharp-pointed knife inserted 

 beneath it. Pes cavus, or hollow foot, is accentuation of the longitudinal arch. Pes planus, or 

 flat-foot, has been discussed on page 349. 



Rupture of a few of the fibres of the Gastrocnemius may take place. Rupture of the Plantaris 

 tendon not uncommonly occurs, especially in men somewhat advanced in life, from some sudden 

 exertion, and frequently occurs during the game of lawn tennis, and is hence known as lawn?- 

 tennis leg. The accident is accompanied by a sudden pain, and produces a sensation as if the 

 individual had been struck a violent blow on the part. The tendo Achillis is also sometimes rup- 

 tured. It is stated that John Hunter ruptured his tendo Achillis while dancing at the age of forty. 

 The bursa interposed between the posterior surface of the os calcis and the tendo Achillis, 

 just above the point of insertion of the tendon, may become inflamed, producing a disabling 

 pain (achillodynia, or Albert's disease). 



V. MUSCLES AND FASCIA OF THE FOOT. 



The fibrous bands, or thickened portions of the fascia of the leg, which bind down the tendons 

 in front of and behind the ankle in their passage to the foot, are termed the annular ligaments, 

 and are three in number anterior, internal, and external. 



The Anterior Annular Ligament (Fig. 393) consists of a superior or transverse 

 portion (ligamentum trans versum cruris], which binds down the Extensor tendons 

 as they descend on the front of the tibia and fibula; and an inferior or Y-shaped 

 portion (ligamentum cruciatum cruris), which retains them in connection with 

 the tarsus, the two portions being connected by a thin intervening layer of fascia. 

 The transverse portion is attached externally to the lower end of the fibula and 

 internally to the tibia; above it is continuous with the fascia of the leg; it contains 

 only one synovial sheath, for the tendon of the Tibialis anticus; the other tendons 

 and the anterior tibial vessels and nerve passing beneath it, but without any dis- 



