ANATOMY IN A NUTSHELL. 147 



the inner surface of shaft of that bone. At its insertion it gives off a prolonga- 

 tion to the deep fascia of the leg. 



Action. — Flexes leg on thigh and rotates it inward. 



Nerve Supply. — First, second, and third sacral through great sciatic. 



Blood Supply. — Perforating branches of the profunda. 



Semimembranosus. — Description. — (Plate LXY.) — This muscle is mem- 

 branous above and muscular below. It is situated at the back part and inner 

 side of the thigh. At its origin the aponeurosis covers the upper and anterior 

 part of the muscle, and from this aponeurosis muscular fibers arise and con- 

 verge to another aponeurosis which covers the lower part of its posterior sur- 

 face and contract into the tendon of insertion. 



Origin. — (Plate XLIII.) — By thick tendon from upper and outer impress- 

 sion on back part of tuberosity of ischium above and to the outer side of the 

 Biceps and Semitendinosus. 



Insertion. — (Plate L.) — Groove on inner and back part of inner tuber- 

 osity of tibia, beneath the internal lateral ligament. At its insertion fibrous 

 expansions are given off; one of these, of considerable size, passes upward and 

 outward to be inserted into the back part of outer condyle of femur, forming 

 part of posterior ligament of knee-joint; a second is continued downward to the 

 fascia which covers the Popliteus muscle. The tendon also sends a few fibers 

 to join the internal lateral ligament. 



Action. — Flexes leg and rotates it inward. 



Nerve Supply. — Pdrst. second and third sacral through the great sciatic. 



Blood Supply. — Perforating branches of the profunda. 



LESSON XXXIX. 



Femur. 



The femur (Plates XLYIII-XLIX) is about one-fourth the length of the 

 body and is the longest and strongest as well as the largest bone in the body. 

 When one is standing it inclines inward and a little backward. The main part 

 is the shaft or diaphysis. Its upper part has a head, neck, a greater tro- 

 chanter, and a LESSER TROCHANTER. Its lower part is expanded into TWO 

 CONDYLES — an external one and an internal one. Above each one of these is a 

 SUPRACONDYLAR LINK. 



The neck makes an angle of 12.") degrees with the diaphysis. It i> directed 

 upward. inward and a little forward, bein^ broad and compressed at the base Inn 

 becomes rounded at its junction with the head. It is longer below and behind 

 than above and in front. Posteriorly and above where it joins the greater tr< - 

 chanter is a depression (digital fossa) for the insertion of the Obturator exter- 

 nals. Where it joins the shaft between the two trochanters is tile POSTERIOR 

 INTERTROCHANTERIC LINE. About half an inch above this line the capsular lig- 

 ainent of the hip-joint is attached to the neck. 



The bead is an expanded portion of the neck, and forms more than a hem- 

 isphere. It articulates witli the acetabulum of the innominate bone. The 



Fossa CAPITIS is a depression a little below and behind the center of the head. 



