168 ANATOMY IN A NUTSHELL. 



is for the origin of the Tibialis posticus. A nutrient foramen is on this portion 

 of the bone and is directed towards the distal extremity. 



The lower portion of the bone is broad transversely, and extends downward 

 internally to form the inner malleolus. On the posterior portion of this malleo- 

 lus is a groove for the tendon of the Tibialis posticus, and externally to this is 

 one for the tendon of the Flexor longus hallucis. The fibula articulates with the 

 external portion of the lower extremity of the bone in a concave surface, which 

 is rough for the attachment of ligaments, except along its lower border. The 

 lower end of the tibia has an articular surface which is concave, being broader 

 in front than behind. It articulates with the astragalus. In the middle of 

 thi> surface is a slight elevation separating two lateral depression-. 



The tibia is a very vascular bone. The nutrient artery for the shaft is 

 furnished by the posterior tibial, it enters the bone near the interosseous border 

 at the junction of the upper and middle third, and is directed downward. The 

 head of the bone receives numerous branches from the inferior articular arteries 

 of the popliteal, and the recurrent branches of the anterior and posterior tibial 

 arteries. The lower extremity receives twigs from the posterior and anterior 

 tibial, the anterior peroneal, and the internal malleolar arteries. 



Ossificatiox. — From three centers. The center for the shaft appears in 

 the eighth week of intra-uterine life. The center for the proximal extremity 

 appears at the end of the ninth month of intra-uterine life, and joins the shaft 

 at the twenty-first year or even later. The center for the distal extremity ap- 

 pears during the second year and unites with the shaft at the eighteenth year. 



Articulation. — With three bones; femur, fibula and astragalus. 



Attachment of Muscles. — Twelve; to the inner tuberosity, the Semi- 

 membranosus; to the outer tuberosity, the Tibialis anticus and Extensor longus 

 digitorum and Biceps; to the shaft, its internal surface, the Sartorius, Gracilis, 

 and Semitendinosus; to its external surface, the Tibialis anticus; to its posterior 

 surface, the Popliteus, Soleus, Flexor longus digitorum, and Tibialis posticus; 

 to the tubercle, the hgamentum patellae. 



LESSON XLY. 

 The Patella. 



The sesamoid bone which is developed in the tendon of the Quadriceps 

 extensor muscle is the patella (knee-pan.) Its anterior surface is pierced by 

 vascular foramina. h> superior border has the Rectus and Crureus attached 

 to it. The posterior margin of this border is higher than the anterior margin. 



The externa] part of the posterior surface is concave transversely, and the 

 interna] pari i- convex. When the leg is extended the lower one-sixth of 

 articular surface is in contact withthe femur. When it is mid-flexed the middle 

 three-sixths of the articular surface is in contact with the femur. When fully 

 flexed the upper two-sixths of the articular surface is in contact with the femur, 

 also in this position the marginal facet is in contact with the inner condyle. 

 The Ugamentum patellae springs from the apex. If the patella is placed upon a 



