PATELLA TIBIA. 12J 



condyloid extremity during the last month of foetal life ;* in the head to- 

 wards the end of the first year ; in the greater trochanter between the 

 third and the fourth year ; in the lesser trochanter between the thirteenth 

 and fourteenth. The epiphyses and apophyses are joined to the diaphysis 

 in the reverse order of their appearance, the junction commencing after 

 puberty and not being completed for the condyloid epiphysis until after 

 the twentieth year. 



Articulations. With three bones ; with the os innominatum, tibia, and 

 patella. 



Attachment of Muscles. To tioenty-three ; by the greater trochanter, to 

 the gluteus medius and minimus, pyriformis, gemellus superior, obturator 

 internus, gemellus inferior, obturator externus, and quadratus femoris ; by 

 the lesser trochanter, to the common tendon of the psoas and iliacus. By 

 the linea aspera, its outer lip, to the vastus externus, gluteus maximus, 

 and short head of the biceps ; by its inner lip, to the vastus internus, pec- 

 tineus, adductor brevis, and adductor longus ; by its middle to the ad- 

 ductor magnus ; by the anterior part of the bone, to the cruraeus and 

 subcrurseus; by its condyles, to the gastrocnemius, plantaris, and 

 popliteus. 



PATELLA. The patella is a sesamoid bone, developed in the tendon 

 of the quadriceps extensor muscle, and usually described as a bone of the 

 lower extremity. It is heart-shaped in figure, the broad side being di- 

 rected upwards and the. apex downwards, the external surface convex, 

 and the internal divided by a ridge into two smooth surfaces, to articulate 

 with the condyles of the femur. The external articular surface corres- 

 ponding with the external condyle is the larger of the two, and serves to 

 indicate the leg to which the bone belongs. 



Development. By a single centre, at about the middle of the third 

 year. 



Articulations. With the two condyles of the femur. 



Attachment of Muscles. To four ; the rectus, crurseus, vastus internus, 

 and vastus externus, and to the ligamentum patellae. 



TIBIA. The tibia is the inner and larger bone of the leg ; it is pris- 

 moid in form, and divisible into a shaft, an upper and lower extremity. 



The upper extremity, or head, is large, and expanded on each side into 

 two tuberosities. Upon their upper surface the tuberosities are smooth, to 

 articulate with the condyles of the femur ; the internal articular surface 

 being oval and oblong, to correspond with the internal condyle ; and the 

 external broad and nearly circular. Between the two articular surfaces is 

 a spinous process ; and in front and behind the spinous process a rough 

 depression, giving attachment to the anterior and -posterior crucial liga- 

 ments. Between the two tuberosities, on the front aspect of the bone, is 

 a prominent elevation, the tubercle, for the insertion of the ligamentum 

 patellae, and immediately above the tubercle a smooth facet, corresponding 

 with the bursa. Upon the outer side of the external tuberosity is an arti- 

 cular surface, for the head of the fibula ; and upon the posterior part of 

 the internal tuberosity a depression, for the insertion of the tendon of the 

 semimembranosus muscle. 



* Cruveilliier remarks that this centre is so constant in the last fortnight of foetal life 

 that it may be regarded as an important proof of the foetus having reached its full term 

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