Anterior Medial Thigh

Transcription

1 Anterior Medial Thigh o Introduction: For women, however, it is a frightful evil, for with them beauty is more than life, and beauty consists especially in the roundness of limbs and figure, in the gracefully curved outlines. Anthelme Brillat-Savarin ( ) Speaking about leanness in men and women, in his book Gastronomy as a Fine Art, Brillat-Savarin makes an observation that would bankrupt the diet book industry if modern Americans held a similar view. Just like fashion, which changes with time, so to with body image perceptions. That is why when my wife asks me if I am gaining weight, I tell her that I am trying to stay ahead of the curve for when men with extra body fat are considered hot. What does all of this have to do with the anterior thigh you ask? Well, you may encounter some adipose on your way to the fascia lata in today s dissection. o Fascia of the Thigh: There is a circumferential layer of tough fascia that surrounds the muscles of lower limb like a stocking. In the thigh we call this fascia lata. Septa pass from this layer of fascia to the underlying femur effectively dividing the thigh into separate compartments. Functionally, the thigh is considered in three compartments (extensor, adductor and flexor). Anatomically the thigh is divided by one particularly strong septa, the lateral intermuscular septum and two much weaker septa. The different compartments of the leg will be addressed when we dissect inferior to the knee. You of course remember that we differentiate between the thigh and the leg. o Great Saphenous Vein: This vein begins as the union of the dorsal vein of the great toe and the dorsal venous arch of the foot. On its way up to the femoral triangle it first travels anterior to the medial malleolus then posterior to the medial epicondyle of the femur. From there you find it along the anteromedial surface of the thigh until it dives into the saphenous opening of the fascia lata to empty into the femoral vein. A portion of the great saphenous vein between the knee and ankle is commonly recovered for replacing occluded arteries in cases of peripheral vascular disease or for use in coronary artery bypass grafts. o Perforating veins: These are veins taking blood from the superficial veins of the lower extremities to the deep veins. From there it is the muscle contractions during activities like walking that force the blood superiorly towards the heart. One-way valves prevent backflow of blood through the perforating veins, meaning blood is prevented from flowing from deep veins to superficial veins. These valves are also present in both the deep and superficial veins to prevent inferior flow of blood. When these valves become incompetent, the blood pools in

2 the veins and the veins become distended and tortuous. This is what is referred to as varicose veins. Please note the spelling of the word in italics and the spelling of the word, torturous. The word tortuous describes something twisting, circuitous, or convoluted. Torturous describes something that is agonizingly painful. This is not to suggest that varicose veins are not both of these things, but as anatomists we like to be concise in our language which is why we don t use words like behind, under, over, beneath o Iliotibial band (ITB): Once we have dissected the posterior thigh, specifically the gluteal region, you will see that two muscles use the ITB as an attachment, the tensor fascia lata and the gluteus maximus. Anatomically, this tissue is a thickening of the fascia lata that is found on the lateral thigh. The ITB is prone to irritation in two places where it rests superficial to the femur. First, as it passes over the greater trochanter and more distally as it passes over the lateral epicondyle of the femur. Irritation is typically caused by one of two things; (1) altered gait mechanics as a result of an injury in some other part of the lower extremity, or (2) what is called an overuse injury. Example: You don t like the idea of training for a marathon, but decide to try and run one anyway. When the irritation is in the area of the greater trochanter, it is referred to as trochanteric bursitis. Patients will complain that something is snapping over their hip (usually when getting in and out of a car). Irritation over the lateral epicondyle is called ITB syndrome and is more common in runners that do more mileage that they are trained to do. (See aforementioned example) There is a provocation test you can do to confirm ITB Syndrome called the Renne Test. The simplicity of this test makes perfect anatomical sense when you see it. o The femoral triangle: You can find your own femoral triangle with the following maneuver. While holding on to something stable for balance, flex, abduct, and laterally rotate the thigh. The femoral triangle is the depression that appears inferior to the inguinal crease while in this position. Anatomically it is bounded by the inguinal ligament superiorly, the adductor longus medial margin medially, and the sartorius laterally. The contents of the triangle include (in order from lateral to medial) the femoral nerve, femoral artery, femoral vein and inguinal lymph node(s). Two muscles make up the floor of the femoral triangle, the adductor longus & pectineus medially and the iliopsoas laterally. o Femoral Sheath: The femoral sheath has three parts, a lateral part that contains the femoral artery, a middle part that contains the femoral vein, and a medial part where you find some fat, inguinal lymph vessels and a deep inguinal lymph node. It is the medial part of the sheath that a femoral hernia protrudes into and it is also the part known as the femoral canal. Superiorly, the femoral sheath opens as the femoral ring. o Sartorius: Look for this muscles superior attachment at the ASIS. As it descends to its inferior attachment on the medial tibia, it crosses the thigh. This muscle can move the hip into flexion, abduction and lateral rotation as well as flex the knee. This muscle is described as a synergist, meaning it is not the primary muscle moving the joint(s), rather it is helping another stronger muscle fine tune the movement(s).

3 o Subsartorial Canal: (aka Hunter s Canal 1, adductor canal) This is the space you see if you reflect the sartorius muscle, and inside you should expect to find 4 things. 1. femoral artery 2. femoral vein 3. nerve to vastus medialis (branch of femoral nerve) 4. saphenous nerve (branch of femoral nerve). The artery and vein will be in close proximity wrapped in connective tissue and if you follow them inferiorly, they will pass through the adductor hiatus. Inferior to this landmark, the femoral artery becomes the popliteal artery and the femoral vein is called the popliteal vein. The nerve to vastus medialis is located by making the observation that its distal portion dives into the muscle belly of V.M. The saphenous nerve can be traced inferiorly as it crosses the knee joint just deep to the distal portion of the sartorius muscle. o Quadriceps Femoris: All four parts of this muscle are innervated by branches of the femoral nerve. The rectus femoris portion is unique among the group because its superior attachment (AIIS) crosses the hip joint, allowing it to flex the hip. All four heads of the quadriceps extend the knee joint. Since the rectus femoris can both flex the hip and extend the knee, the rectus femoris is ideal for kicking, be it a soccer ball or the neighbor s cat. (Of course I m only joking; I don t own a soccer ball) Functionally, the quads are used for activities like going from sit to stand, or stair climbing. Incidentally these last examples are concentric contractions, as opposed to an eccentric contraction, which is what your quads do when you walk down a steep incline. Please let me know if the concentric vs. eccentric contraction is not clear and I will explain it further. Or we can run up and down some hills together, because I find that actions speak louder than words. o Tensor Fascia Lata: This is technically considered a gluteal muscle (innervation: superior gluteal nerve), however because of its anatomic position it is discussed with anterior thigh. Speaking of anatomic position, if you consider its location on the ilium and its attachment to the ITB you can see how it is capable of stabilizing the knee when the knee is extended. Remember the attachment of the ITB to the tibia is anterior to the axis of the knee joint. This muscle also helps abduct and flex the hip. o Gracilis: The most medial of the medial compartment muscles, it is the only adductor to cross the knee joint. Its insertion on the medial tibia is considered in conjunction with two other muscles attaching in close proximity (sartorius and semitendinosus). The arrangement of these attachments is collectively referred to as the pes anserine. (from the French for Goose Foot) What does the foot of a goose have to do with the tibia you may ask? Apparently when these attachments are pulled up from the tibia, the tendons resemble the foot of a goose. o Adductor Longus: You can feel the medial border of this muscle if you abduct the hip to its end range and palpate the medial aspect of the thigh. Probably not a good idea to repeatedly palpate this after a glass of wine and an evening of cinemax. But then again what college student can afford a decent bottle of wine and premium cable? (Unless you live in your parent s basement, in which case, still a bad idea.) Anyways. You will transect this muscle to see the deeper adductors of the thigh. Often times this is the muscle tendon that is strained when a person has a pulled groin.

4 o Pectineus: According to the textbook (Clinically Oriented Anatomy, 5 th Ed. Moore & Dalley) this muscle has a dual innervation from the femoral and obturator nerves. Anatomically it is located lateral to the adductor longus and is considered to make up part of the floor of the femoral triangle. o Adductor Brevis: You find this muscle in the crevis. What crevis you ask? The one between pectineus and adductor longus. o Adductor Magnus: This unique muscle has two portions, an obturator part and a hamstring part. But wait, it gets better. Each part has a different nerve supply. The obturator part is innervated by the deep branch of the obturator nerve, while the hamstring part is innervated by the tibial division of the sciatic nerve. As far as actions, both parts can adduct the thigh, the obturator part can flex the thigh and the hamstring part can extend the thigh. It is the hamstring part that is associated with the adductor tubercle on the medial epicondyle of the femur. o Femoral Nerve: (L2,L3,L4) This nerve has a wide distribution as it enters the thigh as is evidenced by its many cutaneous branches as well as its motor branches to the quads, sartorius and part of pectineus. Because of the nerves extensive branching, don t expect that it will look like that thick single nerve that you remember from the posterior abdominal wall dissection. o Obturator Nerve: (L2.L3,L4) On dissection, you will see two discrete branches of this nerve. A superficial branch that lies on the superficial surface of adductor brevis and a deep branch that lies adjacent to the deep surface of adductor brevis. This nerve is responsible for innervating the muscles of the medial compartment of the thigh. o Lateral Femoral Cutaneous Nerve: (L2,L3) Previously discussed with nerves of the posterior abdominal wall you see this nerve again (unless you reflected it with the skin) as it emerges inferior to the inguinal ligament in the area of the ASIS. Sensory to the lateral thigh. NOT a branch of the femoral nerve. o Deep Femoral Artery: Branch of the femoral artery shortly after it enters the thigh. After it branches from the femoral artery it will dive between pectineus and adductor longus muscles. Supplies muscles of all three compartments of the thigh. o Lateral Circumflex Femoral Artery: While you should expect to see this as a branch of the deep femoral artery it may be a branch directly off of the femoral artery. This branch passes deep to sartorius then rectus femoris before splitting into three named branches (ascending, transverse and descending). The descending branch travels inferiorly towards the knee to anastomose with genicular arteries. o Medial Circumflex Femoral Artery: Like the lateral circumflex femoral artery this may also come from either the femoral or deep femoral artery. The medial circumflex femoral artery travels a short distance before diving between the pectineus and iliopsoas muscles. This is the artery that supplies most of the blood to the head and neck of the femur. -T.S. 1. Hunter s canal gets its eponymous description from John Hunter, a Scottish surgeon / anatomist of the late 19 th century who developed a technique to resolve a popliteal aneurysm without having to amputate the leg. The rationale behind this

5 (at the time) innovative surgery was to ligate the femoral artery proximal to the aneurysm and allow a stronger collateral circulation to develop that would supply blood distal to the ligation. Prior to the successful outcomes experienced by Hunter s patients, this same procedure had been attempted before. The difference was that during earlier attempts the surgeon had ligated the popliteal artery. After a short time, the diseased artery would tear and the patient would meet an unpleasant end. Hunter had hypothesized that ligating the vessel more proximally would work since the arterial walls were stronger / healthier at this location. He accessed the femoral artery deep to sartorius and thus while the technique was named Hunter s operation the site of the surgery was called Hunter s canal.