MUSCLES OF TEE POSTEBIOR LIMBS. 351 



Belations. — This muscle is included between the three portions of the triceps 

 and the capsular ligament of the coxo-femoral articulation, to which it strongly 

 adheres. 



Action. — It appears to raise (or render tense) the capsular ligament during 

 flexion of the femur. 



B. Posterior Crural Kegion. 



This region is constituted by three muscles situated behind the thigh. These 

 are the biceps femoris, the semitendinosus, and the semimembranosus. 



Preparation. — Place the subject in the second position, allow one hind leg to lie unfastened, 

 and incline the body to the correspnniling side, leaving the other liinb attached to the sup- 

 porting bar, with the thigh slightly flexed to make these muscles tense. These preliminary 

 arrangements being adopted, proceed in the following manner : 1. Make a transverse incision 

 through the short adductor of the thigh, and turn back the two portions to the right and left, 

 so as to expose the whole of the semimembninosus, which is to he afterwards dissected from 

 the semitendinosus and the great adductor of the thigh. 2. After removing the aponeurosis 

 covering the biceps femoris and the semitendinosus, the latter is to be dissected by circum- 

 scribing as carefully as possible its two superior insertions. 3. The biceps is then to be 

 prepared. The biceps femoris and semitendinosus can be easily dissected in a limb arranged 

 as in Fig. 192. 



1. Biceps Femoris (Triceps Abductor Femoris) (Figs. 193, 5 ; 194, 7). 



'^ms. — Ischio-tibialis externus — Girard. A portion of the long vastus — Bourgelat, 

 Lafosse, Bigot. (The biceps abductor femoris of Percivall. Anterior pubio-ischio-tibialit — 

 Leyh.) 



Situation — Extent — Direction. — This muscle is situated behind the thigh and 

 the glutei muscles, and extends from the sacral spine to the superior extremity 

 of the leg. 



Form and Structure. — It is narrow at its upper extremity, and very wide and 

 thin inferiorly. 



Its muscular fibres are partly attached, by their superior extremities, to a 

 longitudinal aponeurotic layer, which gives the muscle a penniform appearance ; 

 they terminate, inferiorly, in a strong aponeurosis united to that of the fascia 

 lata. 



Attachments. — It arises, above, from the crest of the ischial tuberosity, where 

 the aponeurosis which gives it its penniform appearance is inserted. 



Its terminal aponeurosis is spread over the tibial muscles to constitute the 

 fascia of the leg, and is inserted into the tibial crest. 



Belations. — The gluteal aponeurosis, in the portion where it becomes semi- 

 elastic, adheres to the external surface of the biceps femoris. In front, the 

 muscle is related to the posterior portion of the superficial gluteus ; behind, to 

 the semitendinosus ; within, to the external muscles of the leg and the sciatic 

 nerves. 



Action. — It flexes the leg and renders tense the tibial fascia, when its fixed 

 point is the pelvis. It rocks the pelvis on the femur when the leg is fixed. 



2. Semitendinosus (Biceps Rotator Tibialis) (Figs. 193, 5' ; 194, 10). 



Synonyms — Ischio-tibialis medius or posticus — Girard. (Posterior sacro-ischio-tibialis — 

 eyh. Percivall describes this and the next muscle by the name of adductor tibialis.) 



Situation — Extent — Direction. — This muscle is situated behind the preceding 



