Shoulder

Brachium

Antebrachium

Facial and Masticatory Muscles

Thorax and Heart

Brain

Body Wall

Hip and Thigh

Shank and Foot

Digestive System

Urinary and Reproductive Systems

Hip and Tail

Hip and Thigh of the Cat (Felis catus)

Photos and text by Adam Hartstone-Rose

Introduction:

The cat is a quadrupedal mammalian cursor that captures its prey by stalking stealthily and then either sprints or leaps onto its quarry [1].  As such, it has the typical mammalian quadrupedal thigh musculature with an emphasis on powerful propulsion.  The muscular and vascular arrangement is straightforward to an anatomist with a basic understanding of the mammalian condition (even an understanding of the highly modified bipedal arrangement present in humans is sufficient to understanding feline anatomy).  This region of anatomy is particularly important for the locomotion of the cat.

Dissection Technique:

Remove the skin by retracting it skin with forceps, nicking it with a scalpel or scissors, making sure not to damage the tissues below, and loosening it from the underlying muscles by breaking the loose connective tissue with a blunt probe.  The skin overlying the thigh of the cat, like that over the much of the rest of the cadaver, is loosely connected to the underlying musculature and should not require much effort to remove.

Neurovascular structures:

As is the case for the dissection of the brachium, the dissection of the thigh reveals some major and obvious neurovascular structures worth noting (see medial thigh figure).  Namely the femoral artery, vein and nerve, the sciatic nerve and saphenous vein are readily visible and easily identified.

Musculature:

The musculature of the thigh acts between two joints, the hip and knee, and the muscles of the thigh span one or both of these.  As is true of the arm, the thigh muscles generally can be split into anterior and posterior groups that are responsible for extension or flexion of the joints respectively.  And as in the arm, this pattern is only general and is violated in several instances.

Table 1.  Thigh musculature.  Adapted from [2].

Conclusion:

It is clear that there are far more muscles than the individual actions they perform.  That is, there are 25 muscles listed above and together they perform only adduction, abduction, rotation of the thigh and flexion or extension of the thigh and or leg.  What is the reason for all of this seeming redundancy?  Surely it has to do with both the evolutionary origin of each of these muscles (they did not always perform the same actions in the ancestor in which they evolved, and therefore were not necessarily redundant) and also, more importantly for the living cat, probably has something to do with the fine motor control necessary for complex of actions they are recruited for.  Could all of the actions performed by the cat be controlled by fewer muscles?  Probably, but living species are confined by the state of their ancestors, and unless there is some evolutionary advantage for losing these muscles to, in effect, stream line the firing pattern involved in the action, there is no reason to expect this type of reduction.

References:

1. Turner, A. 1997.  The Big Cats and Their Fossil Relatives.  New York: Columbia Univ.

2. Reighard, J. & Jennings H.S. 1935.  Anatomy of the Cat.  New York: Henry Holt and Co.