Dissecting A Chicken Leg

As I said in my post on dissecting chicken wings, the dissection of higher animals gives us the opportunity to observe and probe internal structures that resemble those in our own bodies. The wing makes a nice analog to the human arm, and the chicken leg makes an equally nice analog to a human leg. In fact, chicken legs are even easier to study than wings, because they are larger, with parts that are easier to examine and work with, and the skin comes off much more easily. A drawback is that the feet aren't normally included, although you can buy those separately, as I mentioned in my post on the workings of the hand.

Supermarkets normally sell "leg quarters", which consist of a thigh and drumstick still united. This is what a leg quarter looks like:

Just as the pieces of a wing correspond to those in a human arm, the pieces of a chicken leg correspond to those in a human leg. The muscular section closest to the body is the thigh, the middle section (the drumstick) corresponds to the human lower leg, and if the foot were still attached, it would follow the drumstick. As with the wing, we need to remove the skin to discover the muscle structure underneath. Fortunately, the skin comes off of a leg much more easily than from a wing. You don't even need scissors. You can reach inside the hip end with your fingers and pry the skin free from the underlying tissue, then gradually peel the skin inside out off the ankle end, like taking off a sock. You will find only one place where the skin is hard to remove — around the ankle. This is what a skinned leg looks like:

The biceps and triceps on a chicken wing, like those in a human arm, are single, clearly identifiable muscles. The larger muscles on a chicken thigh do also correspond to the quadriceps and hamstring muscle groups in a human leg, but like the human quadriceps and hamstrings, they are muscle groups, bundles of several inter-grown muscles, and they aren't as easy to identify individually.

From this point on, I don't have a systematic procedure to offer. Think of the rest of the dissection as an exploration, in which you gradually disassemble the leg to see what you can see. I recommend paying special attention to the drumstick. Some of the things I have observed are as follows:

If you've read my post on the hand, you will recall how chicken feet and human hands work like marionettes. Similarly, the human forearm, and the chicken drumstick, are the "puppetmasters", containing an assembly of muscles with drawstrings running through the wrist/ankle out to the hand/foot. Unlike the chicken wing muscles, the muscles in the drumstick are relatively easy to pry apart from one another and examine separately. If you start from the ankle, you might be able to produce something like this:

There is a tough band of cartilaginous material around the ankle, which I assume corresponds to the retinacula around human wrists and ankles, and which contains passages through which tendons slide, much like the carpal tunnel in the human wrist. If you cut this and pull it away, and then gradually pry, squeeze, or pull apart the muscles, you should find that the drumstick is indeed constructed like a "puppetmaster", with a bundle of muscles, each pulling on a "drawstring", each running out to the foot to pull the toes into different positions. The drumstick muscles are the engines that pull on the tendons and drive the motions of the foot. Your forearms and lower legs are presumably built in the same way inside.

I have read that, if you work carefully and pay close attention as you pull the muscles of the leg apart, you should be able to discover such minute things as blood vessels, nerves, and synovial bursae. However, I haven't had much luck finding these myself. (There are some tubes that are quite easy to notice, as they are filled with red blood. I believe these are veins, rather than arteries, because the arteries are muscular and allegedly contract upon death, squeezing the blood out of them...but I'm not at all positive about this. Are there any medical students or medical examiners out there who can confirm that in cadavers, veins are full and arteries are empty?)

If you remove all muscle as much as you can down to the bone, you will find the skeleton of the chicken leg:

As with the resemblance of chicken wing to human arm, the resemblance of chicken leg to human leg is more than skin deep. The thigh contains a single large bone, which we may as well call the femur. The lower leg contains a pair of long bones, one of which is large and strong (the tibia), and the other of which is thin and frail and stuck to the first (the fibula). In a human, the fibula is a secondary "helper" bone, but at least it is still as long as the entire lower leg, and is stuck firmly to the tibia at both ends. In a chicken, the fibula is so meager that it doesn't even reach the ankle end. It is just a needle sticking down from the knee joint.

The resemblance continues if we examine the joints in more detail. The knee has a cartilagenous covering over the front, resembling a kneecap, and it has vertical ligaments on the sides of the knee, and criss-cross ligaments inside, that resemble the collateral and cruciate ligaments in a human knee. The hip is a ball-and-socket joint consisting of the rounded upper end of the femur fitting into a socket in the hip bone. Several ligaments hold the bones together, including a ligament within the socket, helping to hold the head of the femur inside the socket (the ligamentum teres).

Since chicken quarters are apparently normally produced by sawing the hipbone from the rest of the body, and since this cut apparently normally goes through the spine, your chicken quarter might also give a nice view of a longitudinal section of a spine.

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  Greg

  August 22, 2012

  Dear Mr. Krieger,

  I was curious about the muscle anatomy of a chicken leg and I came across your website as I tried to research this topic. I have searched a bit, but I can’t seem to find an answer to my question, so perhaps you can help.

  Basically, whenever I eat chicken legs, and after I eat the larger portions of meat, there is almost always a piece of edible meat that firmly sticks to the tibia. This piece of meat reminds me of the adductor muscles in clams, but I wonder whether it’s the same, as well as what function it serves in the overall muscle anatomy. In your last photograph (above the video), I believe you can see that one piece of meat still attached to the tibia near the knee. Can you help me identify and understand that piece of muscle? If not, would you be able to redirect me to a resource I can readily access online that might help?

  Thank you!

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    John Krieger

    August 25, 2012

    Greg,

    It would be nice if you could cross a doctor with a supermarket butcher, and produce someone who knows the technical anatomy of a chicken, but I don’t know of anybody like that. Such a person would have made my own research much easier. The best hope would be a veterinarian, I think, preferably a farm veterinarian rather than a pet veterinarian.

    In other words, I don’t know the answer to your question. But if you are referring to the thing that I think you are referring to in my last photograph, that is probably a scrap of tendon, from which the muscle has been cut. I would guess from the position that it was the tendon of one of the “hamstring” muscles. Many muscles grade by degrees into tendons before they stick to the bone, so after you cut (or eat) most of the muscle, you often find the severed ends as stray scraps of tough meat frayed around the joints.

    John