MedicoPlexus

Limb’s assignment 

Muscles 

The  muscles of the anterior thigh are innervated by the femoral nerve, and the function of them is to extend the leg at the knee joint. There are a few key muscles in this region which are: 

• Psoas major and iliacus muscles which form the iliopsoas muscle which is the one of the most important muscles in terms of hip flexion at the hip joint. The key movements allow for standing, walking and running. The psoas major joins with the iliacus at the same level as the inguinal ligament, and inserts into the smaller trochanter on the femur. The innervation for this muscle is split between the anterior rami of L1 to L3 for the psoas major and the femoral nerve for the iliacus. The arterial blood supply comes from the medial femoral circumflex artery as well as the iliolumbar artery.

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Quadriceps femoris muscle group – which consists of four muscles such as the three vastus muscles as well as the rectus femoris. Blood supply comes through the femoral artery and the femoral nerve is responsible for innervation. They combine to form the main portion of the thigh, and attach to the patella through the quadriceps tendon. These muscles work as the main extensors of the knee :

• Vastus lateralis originates from the greater trochanter and along the line of asperea of the femur bone. Blood supply comes through the lateral circumflex femoral artery and innervation is from the femoral nerve. 
• Vastus medialis attaches from the interochanteric line and the medial lip of the line of asperea of the femur bone.  The fibres converge onto the inner part of the quadriceps tendon and the medial border of the patella. 
• Vastus intermedius attaches from the anterior and the lateral surfaces of the femur , with the fibres sitting underneath the rectus femoris, with the fibres converging to form a aponeurosis, which helps from part of the deep part of the quadriceps femurs tendon. As the this muscle is deepest in the quadricep group it is most difficult to stretch during maximum knee flexion. 
• Rectus femoris arises from two tendons with the first being the anterior inferior iliac spine and the second arising from a groove located above the acetabulum. Both meet and form an aponeurosis passing down the anterior surface of the muscle and the muscle ends by forming another aponeurosis that is much flatter than the muscle and inserts into the base of the patella. The function of this quadriceps muscle differs slightly to the others a it extends much higher crossing both the hip and knee joints resulting in flexure at the hip joint causing extension at the knee joint. Blood supply for this muscle comes from the defending branch of the lateral femoral circumflex artery. 

• The sartorius is a thin muscle running the length of the thigh in the anterior aspect. It originates on the anterior superior iliac spine and runs obliquely across the upper and anterior part of the thigh in the inferomedial direction. The muscle ends by passing behind the medial condyle of the femur and forming a tendon, which travels anteriorly to join the tendons of the gracilis and semitendinosus muscles and inserting into the superomedial surface of the tibia. The muscles functions by being able to move the knee and hip joints , but because it has weak actions it’s known as a synergist muscle, helping stabilise the movement around the joints. When looking from the hip it can have abduct and laterally rotate the thigh quite weakly and at 

the knee it can flex the leg, and also medially rotate the leg when the knee is flexed. The blood supply is received from the femoral artery and innervation is provided through the femoral nerve. 

• The pectineus muscle forms the base of the femoral triangle and transitions between the anterior and medial thigh compartments. It originates from the pectineal line of the anterior surface of the pelvis and attaches to the pectineal line on the posterior line of the femur. It is the most anterior adductor of the hip, and can adduct and laterally rotate the thigh but the main function of the muscle is to flex the hip. The innervation comes from the femoral nerve but it can also receive a branch from the obturator nerve. Blood supply comes from the obturator artery. 

Blood vessels 

The largest artery in the anterior region of the thigh is the femoral artery which enters the thigh behind the inguinal ligament and is a continuing of the external iliac artery. Then the femoral artery gives a branch called the profunda femoris artery which originates posterio-laterally. The profunda femoris artery produces three main branches with the first being perforating branches which perforate the adductor magnus and provide arterial blood supply to muscles of the posterior and medial thigh. Then there is the lateral femoral circumflex artery which wraps around the anterior lateral side of the femur and supplies muscles on the lateral aspect of the thigh. Also there is the medial femoral circumflex artery which wraps around the posterior head of the femur and supplies the head and neck of the bone. 

In the anterior aspect the artery lies superficial and is covered by skin and fascia while on the upper part of its course, and on the lower part it passes behind the sartorial muscle. The superficial femoral artery continues distally to the level of the adductor hiatus where it terminates as the popliteal artery. When the superficial femoral artery travels through the adductor canal it produces minor branches to supply muscles of the anterior thigh.

Veins in the lower limb are split between deep veins of the lower limb and the superficial veins of the lower limb:

Deep veins

The femoral vein travels anteriorly with the femoral artery, so that the arterial pulsations can help to return the venous blood flowing back. There is also the profunda femurs vein which drains blood from the thigh muscles and empties back into the femoral vein. The femoral vein then leaves the thigh underneath the inguinal ligament where it forms the external iliac vein. 

There are two key superficial veins in the lower limb which are the long saphenous vein and the short saphenous vein. The long saphenous vein ends in the femoral vein and has multiple tributaries including the postero-medial vein of the thigh and the anterior femoral cutaneous vein. These tributaries join near the thigh close to the junction with the femoral vein.