Femoral Triangle and Adductor Canal

Boundaries of the Femoral Triangle

The femoral triangle lies at the top of the front of the thigh. Its boundaries are:

The inguinal ligament
The medial border of sartorius
the medial border of adductor longus

Floor of the Femoral Triangle

The floor of the femoral triangle is formed by the muscles:

adductor longus
pectineus
iliopsoas (iliacus and psoas)

Contents of the Femoral Triangle

The chief contents of the femoral triangle include the:

The femoral nerve arises from the lumbar plexus (L2, 3, 4) and supplies pectineus, sartorius and the quadriceps.

It also supplies the skin on the anterio-medial side of the thigh and leg.

The femoral nerve only travels a short way into the thigh before splitting into its terminal branches.

The Femoral Sheath

The femoral vein and artery (but not the nerve) are surrounded, for a short distance, by the femoral sheath. This is a sleeve of tissue which is a continuation of fascia from within the abdomen. There is no sheath present at birth, but it is pulled down as the limb grows.

On the medial side of the vein is a space (the femoral canal) which serves to allow expansion of the vein. It also provides a potential route for the herniation of abdominal organs (e.g. a loop of small intestine). Femoral hernias are more common in women than men.

The femoral artery

The femoral artery is very superficial as it passes into the thigh, behind the inguinal ligament. Its pulse can be felt at this point.

Location of the femoral pulse

Locate the superior border of the pubis in the mid line of the body; this is the uppermost part of the pubic symphysis. Feel the anterior limit of the iliac crest. The femoral pulse can be found midway between these two bony points (the mid-inguinal point)

The artery leaves the femoral triangle at its apex, and finds itself in the adductor or subsartorial canal. This is a space which is surrounded by muscles, in which the artery lies deep to sartorius in front of the adductor muscles.

Related tutorial: Pulses of the Lower Limb

At the lower end of the adductor canal, the femoral artery passes through a hiatus in the adductor magnus. This will bring the artery to the back of the femur into the large depression behind the knee - the popliteal fossa - where it is then called the popliteal artery. If the femoral artery remained in the front of the limb, it would be stretched every time the knee flexed.

The femoral artery supplies very little in the thigh itself. The thigh is mainly supplied by a branch of the femoral artery, the profunda femoris (profunda = deep).

From the profunda arise:

Medial and lateral circumflex femoral arteries; the ascending, transverse and descending branches of which supply the front and sides of the thigh from the iliac crest to the knee.
perforating branches (there are usually 4); these pass through adductor magnus to supply the back of the thigh. The second perforator is normally the nutrient artery of the femur.

Lymph nodes

The inguinal region contains a number of major lymph nodes:

deep nodes around the femoral vein
superficial nodes - an upper group forming a chain just below the inguinal ligament and a lower group lying vertically along the terminal part of the long saphenous vein

These nodes may enlarge during infection. The superficial nodes receive lymph drainage from the buttock, anterior abdominal wall (below the umbilicus), genitalia and anal canal (upper group). The superficial tissues of the lower limb also drain to the superficial nodes (lower group), with the exception of the the back and and lateral sides of the calf, which drain to the nodes at the back of the knee.

The deep nodes receive lymph drainage from the deep tissues of the lower limb.