DISSECTION OF THE POSTERIOR LIMB. 65 



3. A few inches below the point of the hip a cutaneous branch derived 

 from one of the posterior gluteal nerves appears from between the biceps 

 and semitendinosus, and separates into a number of radiating filaments. 



4. On a level with the stifle-joint the peroneal-cutaneous branch of the 

 external popliteal nerve comes out through the biceps, and is distributed 

 on the outer side of the leg. 



Directions. — The dissector should, in the next place, direct his 

 attention to the strong fascia covering the muscles in this region, after , 

 which the fascia must be removed, and the muscles cleaned and separated. 



Gluteal Fascia and Fascia Lata. The gluteal fascia forms a 

 bluish-white covering over the muscles of the hip, and by its deep 

 face affords origin to many fibres of the superficial and middle gluteal 

 muscles. It is fixed above to the summits of the sacral spines and 

 to the external angle of the ilium, and between these points it is 

 •continuous forwards with the tendon of the latissimus dorsi. It is 

 prolonged downwards over the muscles of the thigh, where it takes 

 the name of the fascia lata. This fascia lata receives in front the 

 insertion of the tensor vaginae femoris muscle, and it should not be 

 removed until that muscle has been examined. It forms a sheath for 

 the muscles of the thigh, and is prolonged downwards over the leg. 

 From its inner face a septum is sent in between the vastus internus and 

 the biceps, to join the tendon of the superficial gluteal muscle and 

 be inserted into the femur. 



The Tensor Vaginae Femoris (Plate 15). This muscle is situated at 

 the forepart of the thigh, in front of the superficial gluteal muscle, from 

 which it is somewhat difficult to separate it. It arises from the external 

 angle of the ilium, and is inserted into the fascia lata. 



Action. — It flexes the hip-joint. It also keeps the fascia lata tense 

 and mechanically aids in keeping the stifle-joint extended. 



Directions. — The gluteal fascia and the fascia lata are now to be 

 removed. It is a matter of some difficulty to remove the former, as its 

 deep face has the muscular fibres taking origin from it, and these are 

 therefore exposed w T ith a rough surface when it is removed. 



The Superficial Gluteus (Gluteus externus of Percivall, part of the 

 gluteus maximus of human anatomy) (Plate 15). The outline of this 

 muscle is not distinctly recognisable until the gluteal fascia has been 

 removed. It is then seen to have some resemblance to the letter V, 

 having in its upper border an indentation that divides into an 

 anterior and a posterior branch. The anterior branch arises from 

 the external angle of the ilium ; the posterior from the gluteal fascia. 

 Both converge to a common tendon, which is inserted into the third 

 trochanter of the femur (trochanter minor externus). From the posterior 

 branch of the muscle an aponeurotic layer passes backwards beneath the 

 biceps, to be inserted into the sacro-sciatic ligament and the tuber ischii. 



F 



