DISSECTION OF THE POSTERIOR LIMB. 61 



The Pectineus (Plate 13). This muscle has a distinctly conical 

 form. It lies posterior to the femoral vessels, and the profunda 

 artery disappears beneath it. It arises from the brim and inferior 

 surface of the pubis, and it is there penetrated by the pubio-femoral 

 ligament, from which some of its fibres take origin. Its tapering point 

 is inserted into the shaft of the femur in the neighbourhood of the 

 nutrient foramen. 



Action. — It adducts the limb, and flexes the hip. 



The Adductor Parvus (Adductor brevis of Percivall) (Plate 13) is 

 situated between the pectineus and the great adductor. It arises from 

 the inferior surface of the pubis, and is inserted into the posterior sur- 

 face of the femur about its middle. 



Action. — It is an adductor and outward-rotator at the hip-joint. 



The Adductor-Magnus (Adductor long 'us of Percivall) (Plate 13) arises 

 from the inferior surface of the ischium, and from the tendon of origin 

 of the gracilis. It has two insertions, between which the femoral artery 

 passes. 1. Its deeper fibres are inserted into the posterior surface of the 

 femur, on a quadrilateral area above the smooth groove in which the 

 femoral artery rests. 2. Its more superficial and longer fibres are 

 inserted into the forepart of the supracondyloid crest. 



Action. — It is an adductor at the hip. 



The Semimembranosus (Adductor magnus of Percivall) (Plate 13). 

 This is a muscle of large size. It arises from the lower surface of 

 the ischium, including its tuberosity, and by a small slip from the 

 fascia investing the muscles of the tail. It is inserted into the inner 

 condyle of the femur, behind the tubercle for the attachment of the 

 interna] lateral ligament of the stifle. 



Action. — Commonly, it is an adductor and extensor of the hip ; but 

 when the femur is fixed it acts as a lever of the first order, and assists 

 in rearing. 



Directions. — The foregoing muscles must now be cut and partially 

 removed as follows : — 



The semimembranosus is to be cut transversely, an inch or two above 

 its insertion. The muscle is then to be raised upwards from the semi- 

 tendinosus, on which it rests ; and, in doing this, branches of nerves 

 from the great sciatic will be found entering it in front. The central 

 portion of the muscle may then be removed, leaving a few inches at its 

 origin. The other muscles must be served in the same way, leaving 

 only short portions at the origin and insertion, except in the case of the 

 adductor parvus and upper half of the adductor magnus, whose 

 common insertion into the back of the femur is to be entirely removed. 

 Care is to be taken of the femoral artery where it rests on the bone, and 

 in performing the dissection it will be well to refer to Plate 14 as a 

 guide. In reflecting the upper portion of the great adductor, a branch 



