Cat Dissection 4

Cat Dissection 4 Muscles of the Hip and Thigh A. Superficial Medial Thigh Muscles Instruction for Dissection Almost the entire medial surface of the thigh is covered by two ribbon like muscles separated proximally by a triangular area (the femoral triangle) in which you see blood vessels and a nerve. Remove any fat and fascia which obscures these vessels and the underlying muscles. The blood vessels are the femoral artery (injected red) and femoral vein (injected blue). The large nerve running parallel to the blood vessels is the femoral nerve. The thin, wide muscle located laterally is the sartorius. Loosen it between origin and insertion. The thin, wide muscle located medially is the gracilis. The muscles lying in the triangular area will be considered in the next section. B. Superficial Thigh Muscles and Hip Muscles, lateral View Instructions for Dissection Turn the cat over so that the lateral surface is facing out. In the hip region, which is covered with heavy fascia, are the gluteal muscles. Remove this heavy fascia by cutting as much of it off as is necessary to expose the gluteus medius and posterior to it the gluteus maximus. Note that the gluteus maximus is the smaller of the two, contrary to the condition in the human. Lying within the same mass of fascia which you have just removed and below the gluteus medius is the tensor fasciae latae. The tensor is an irregularly shaped muscle which not only originates in a heavy fascia, but also inserts by a long broad fascia (fascia latae), almost completely covering the vastus lateralis. Loosen the fascia latae and transect it so that you can see the entire vastus lateralis. Posterior to the fascia latae and the gluteus maximus is the caudofemoralis ( a muscle not found in the human), which tapers to its insertion by a very fine tendon. Separate it from the large biceps femoris whose mass covers most of the lateral surface of the thigh. C. Deep Thigh Muscles, Medial View Instruction for Dissection In order to see this important group of muscles it will be necessary to transect both the sartorius and the gracilis muscles. Lay their ends back as far as possible and begin your observations at the lateral border. Covering about one-half the area of the thigh is a large muscle named the quadriceps femoris. It is so large that the four muscles which make it up must be considered separately, as they are in the human. The quadriceps separates readily into 3 distinct bundles: (*1) a large lateral muscle, the vastus lateralis, (2) a middle muscle, the rectus femoris, and (3) a medial muscle, the vastus medialis. The fourth muscle of the group, the vastus intermedius, may be seen by separating the rectus femoris from either adjacent muscle, or be transecting the rectus femoris and laying back its cut ends. Dissect away the femoral artery, fermoral vein, and femoral nerve so that you are better able to see the group of muscles beneath them. Most lateral of the group is the iliopsoas (composed of two muscles, the iliacus and the psoas major, but seen as one muscle in this dissection). Medial to the iliopsoas is the pectineus, and medial to it is the adductor longus. The remaining two medial muscles are considerably larger, the adductor femoris and medial to it the semimembranosus. Two other muscles, which can be seen in this view, the tensor fasciae latae and the semitendinosus, are studied with the lateral thigh muscles. D. Deep Thigh Muscles, Lateral View Instructions for Dissection Separate the biceps femoris from the tissue below it with your finger and a probe. Before making a transection, locate a very small muscle, the tenuissimus, (not found in the human leg), and locate the sciatic nerve. When you have done this, carefully transect the biceps femoris and draw each end to its origin and insertion. In addition to the sciatic nerve, observe the semimembranosus already seen in the ventral view. Medial to it is the semitendinosus. The vastus lateralis and the adductor femoris are also prominent in this view.