86 DISSECTION OF THE DOG 



M. QUADEiCEPS FBMOEis.— Although named the quadriceps muscle of the 

 thigh, only three heads can be satisfactorily demonstrated in the dog. These 

 are the two vasti muscles (m. vastus mediahs and m. vastus lateralis) akeady 

 dissected, and the straight muscle of the thigh (m. rectus femoris) now to be 

 examined. It seems possible that the fourth head (m. vastus intermedius) is 

 blended with the lateral vastus muscle. 



M. EECTUS FEMOEis. — The rectus femoris muscle is the middle member 

 of the quadriceps group, and clothes the anterior aspect of the femur. Its 

 origin is from an eminence on the cranial edge of the acetabulum and its 

 insertion is into the patella. 



M. CAPSXJLAEis. — The capsular muscle is small and flat and lies on the 

 lateral face of the capsule of the hip-joint. 



Dissection. — Cut across the sciatic nerve on a level ^^ith the sacro-tuberous 

 Ugament, and the femoral vessels at the hip-joint. Remove the remains 

 of those muscles which are attached in the close vicinity of the hip-joint, 

 and clean the outer surface of the joint-capsule. 



Aeticulatio cox.e. — The joint-capsule (capsula articularis) of the hip- 

 joint is in the form of a roomj^ double-mouthed sac, one end of which is 

 attached to the margin of the acetabulum and the fibrous appendage 

 thereto, and the other is fixed to the neck of the femur a little distance from 

 the articular margin. The strongest part of the capsule is lateral and oral. 



Dissection. — Cut through the joint-capsule and examine its contents. 



The joint is formed by the acetabulum and the head of the femur. The 

 whole of the acetabulum is not articular, inasmuch as its medial half contains 

 a depressed non-articular fossa acetabuli. Opposite the fossa the continuity 

 of the cavity is broken by the incisura acetabuli. Surrounding the acetabular 

 margin is a ring of fibro-cartilage, the labrwm glenoidale, continued across the 

 incisura acetabuli by a hgamentous bridge, the transverse ligament (ligamentum 

 transversum). 



Passing from the fossa acetabuli to the non-articular and slightly depressed 

 area on the head of the femur is the strong round ligament (ligamentum teres). 

 When this is divided by the dissector the limb will be separated from the body. 



Dissection. — The examination of the limb should be continued by the 

 dissection of the regions in front of the tibia and about the fibula. With 

 this it is necessary to combine the dissection of the dorsum of the pes. 

 Before proceeding to an examination of the deep fascia and muscles of 

 the leg, it is well to foUow the superficial structures of the metatarsus 

 and digits. The removal of the skin must be conducted with great care. 



