1GG OSTEOLOGY. 



oblong elevation of large size, the tubercle of the tibia ; the lower half of this 

 tubercle is rough, for the attachment of the ligamentum patellae ; the upper half 

 is a smooth facet corresponding, in the recent state, with a bursa which separates 

 the ligament from the bone. Posteriorly, the tuberosities are separated from 

 each other by a shallow depression, the popliteal notch, which gives attach- 

 ment to the posterior crucial ligament. The posterior surface of the inner 

 tuberosity presents a deep transverse groove, for the insertion of the tendon of 

 the Semi-membranosus ; and the posterior surface of the outer one, a flat articular 

 facet, nearly circular in form, directed downwards, backwards, and outwards, for 

 articulation with the fibula. The lateral surfaces are convex and rough; the 

 internal one, the most prominent, gives attachment to the internal lateral 

 ligament. 



The Shaft of the tibia is of a triangular prismoid form, broad above, gradually 

 decreasing in size to the commencement of its lower fourth, its most slender part, 

 where fracture most frequently occurs, and then enlarging again towards its lower 

 extremity. It -presents for examination three surfaces and three borders. 



The anterior border, the most prominent of the three, is called the crest of the 

 tibia, or, in popular language, the shin ; it commences above at the tubercle, and 

 terminates below at the anterior margin of the inner malleolus. This border is 

 very prominent in the upper two-thirds of its extent, smooth and rounded below. 

 It presents a very flexuous course, being curved outwards above, and inwards 

 below ; it gives attachment to the deep fascia of the leg. 



The internal border is smooth and rounded above and below, but more promi- 

 nent in the centre ; it commences at the back part of the inner tuberosity, and 

 terminates at the posterior border of the internal malleolus ; its upper third gives 

 attachment to the internal lateral ligament of the knee, and to some fibres of the 

 Popliteus muscle ; its middle third, to some fibres of the Soleus and Flexor longus 

 digitorum muscles. 



The external border is thin and prominent, especially its central part, and gives 

 attachment to the interosseous membrane ; it commences above in front of the 

 fibular articular facet, and bifurcates below, to form the boundaries of a triangular 

 rough surface, for the attachment of the interosseous ligament, connecting the 

 tibia and fibula. 



The internal surface 'is smooth, convex, and broader above than below; its 

 upper third, directed forwards and inwards, is covered by the aponeurosis derived 

 from the tendon of the Sartorius, and by the tendons of the Gracilis and Semi- 

 tendinosus, all of which are inserted nearly as far forwards as the anterior 

 border ; in the rest of its extent it is subcutaneous. 



The external surface is narrower than the internal; its upper two-thirds present 

 a shallow groove for the attachment of the Tibialis anticus muscle ; its lower third 

 is smooth, convex, curves gradually forwards to the anterior part of the bone, 

 and is covered from within outwards by the tendons of the following muscles : 

 Tibialis anticus, Extensor proprius pollicis, Extensor longus digitorum, Peroneus 

 tertius. 



The posterior surface (fig. 110) presents at its upper part a prominent ridge, 

 the oblique line of the tibia, which extends from the back part of the articular facet 

 for the fibula, obliquely downwards, to the internal border, at the junction of its 

 upper and middle thirds. It marks the limit for the insertion of the Popliteus 

 muscle, and serves for the attachment of the popliteal fascia, and part of the 

 Soleus, Flexor longus digitorum, and Tibialis posticus muscles ; the triangular 

 concave surface, above, and to the inner side of, this line, gives attachment to 

 the Popliteus muscle. The middle third of the posterior surface is divided by a 

 vertical ridge into two lateral halves ; the ridge is well marked at its commence- 

 ment at the oblique line, but becomes gradually indistinct below ; the inner and 

 broadest half gives attachment to the Flexor longus digitorum, the outer and 

 narrowest, to part of the Tibialis posticus. The remaining part of the bone is 

 covered by the Tibialis posticus, Flexor longus digitorum and Flexor longus 



