TIBIA. 



Fig. 174. Right Patella. 

 Anterior Surface. 



Fig. 175. Posterior 



Surface. 



the leverage of the Quadriceps Extensor by making it act at a greater angle. 

 It presents an anterior and posterior surface, three borders, a base, and an apex. 



The anterior surface is convex, perforated by small apertures, for the passage 

 of nutrient vessels, and marked by numerous rough longitudinal striae. This 

 surface is covered, in the recent state by an expansion 

 from the tendon of the Quadriceps Extensor, and sepa- 

 rated from the integument by a bursa. It gives attach- 

 ment below to the ligamentum patellae. The posterior 

 surface presents a smooth, oval-shaped, articular sur- 

 face, covered with cartilage in the recent state, a"nd 

 divided into two facets by a vertical ridge, which de- 

 scends from the superior towards the inferior angle of 

 the bone. The ridge corresponds to the groove on the 

 trochlear surface of the femur, and the two facets to 

 the articular surfaces of the two condyles ; the outer 

 facet, for articulation with the outer condyle, being the 

 broader and deeper. This character serves to indicate 

 the side to which the bone belongs. Below the arti- 

 cular surface is a rough, convex, non-articular depres- 

 sion, the lower half of which gives attachment to the 

 ligamentum patellae ; the upper half being separated 

 from the head of the tibia by adipose tissue. 



The superior and lateral borders give attachment to 

 the tendon of the Quadriceps Extensor ; the superior 

 border, to that portion of the tendon which is derived 

 from the Rectus and Crureus muscles ; and the lateral 

 borders, to the portion derived from the External and 

 Internal Yasti muscles. 



The base, or superior border, is thick, directed up- 

 wards, and cut obliquely at the expense of its outer 



surface ; it receives the attachment, as already mentioned, of part of the Quad- 

 riceps Extensor tendon. 



The apex is pointed, and gives attachment to the ligamentum patellae. 



Structure. It consists of dense cancellous tissue, covered by a thin compact 

 lamina. 



Development. By a single centre, which makes its appearance, according to 

 Beclard, about the third year. In two instances, I have seen this bone cartila- 

 ginous throughout, at a much later period (six years). More rarely, the bone 

 is developed by two centres, placed side by side. 



Articulations. With the two condyles of the femur. 



Attachment of Muscles. The Eectus, Crureus, Vastus Internus, and Vastus 

 Externus. These muscles joined at their insertion constitute the Quadriceps 

 Extensor Cruris. 



THE TIBIA. (Figs. 176, 177.) 



The Tibia is situated at the front and inner side of the leg, and, excepting 

 the femur, is the longest and largest bone in the skeleton. It is prismoid in 

 form, expanded above, where it enters into the knee-joint, more slightly en- 

 larged below. In the male, its direction is vertical, and parallel with the bone 

 of the opposite side ; but in the female it has a slight oblique direction down- 

 wards and outwards, to compensate for the oblique direction of the femur in- 

 wards. It presents for examination a shaft and two extremities. 



The Upper Extremity, or Head, is large and expanded on each side into two 

 lateral eminences, the tuberosities. Superiorly, the tuberosities present two 

 smooth concave surfaces, which articulate with the condyles of the femur ; the 

 internal articular surface is longer than the external, and oval from before 

 backwards, to articulate with the internal condyle ; the external one being 



