Okay, so the femoral triangle is this anatomical triangle found in the upper thigh at the junction between the anterior abdominal wall and the muscles of the upper thigh. It’s important to know about because some important structures pass through it, but first I’ll just talk about the boundaries of the triangle.
Laterally, you’ve got the medial border of the sartorius, say this border here. Medially, you’ve got the medial border of the adductor longus muscle and superiorly, you’ve got the inguinal ligament. The inguinal ligament runs from the anterior superior iliac spine (ASIS) to the pubic tubercle.
You can see it on this model here, the anterior superior iliac spine is here and the pubic tubercle, so the inguinal ligament runs from ASIS to the pubic tubercle. That’s the base of the triangle or the superior border.
This is the triangle here. Superiorly, you’ve got the inguinal ligament, the medial border is the medial border of the adductor longus muscle and the lateral border is the medial border of the sartorius muscle (this muscle which runs all the way down here).
This is the femoral triangle. The flow of the triangle is made up of these three muscles that you can see here. Laterally, we’ve got the iliopsoas muscle, which is a combination of the iliacus, the psoas major and minor muscles, which originate in the abdomen. And then you’ve got these two muscles medially, the pectineus muscle and obviously, the adductor longus muscle. These muscles make up the floor of the femoral triangle.
We’ve got a few things that pass through the femoral triangle. We’ve got arteries, veins, nerves and lymphatics.
Laterally, we’ve got the femoral branch of the genitofemoral nerve. We’ve got the femoral nerve. Medial to that, we’ve got the femoral artery. Medial to that, we’ve got the femoral vein. And not shown here, we’ve also got lymphatics, so lymph nodes and lymph vessels. We’ve got femoral nerve, femoral artery, femoral vein and then we’ve got some lymphatics.
The artery, the nerve and the lymphatics are actually enclosed in a fascial sheath. This is the femoral sheath. The femoral sheath has three compartments. It’s got the compartment for the artery, a compartment for the vein and a compartment for the lymphatics.
The compartment that contains the lymphatics, which again aren’t shown in this model, is called the femoral canal. It’s important to know because the abdominal contents can actually herniate into the femoral canal. This is a femoral hernia.
The fascial sheath has three compartments, which contain the femoral artery, vein and the lymphatics. Each of these is obviously enclosed in one, big femoral sheath.
The femoral nerve lies outside the femoral sheath. A way of remembering the contents of the femoral triangle is the mnemonic NAVY – nerve, artery, vein y-fronts (as in briefs or pants, whatever, underwear for men). Nerve, artery, vein from lateral to medial.
And you’ve also got this branch of the femoral artery, the profunda femoris. If I just zoom in a little bit, there’s a branch here which comes off and that’s also contained in the femoral triangle. This is the deep artery of the femur. Profunda femoris, ‘profunda’ meaning ‘deep’ in Latin, so the ‘deep artery of the thigh’. That runs closer to the femur. You can just see that. This is the profunda femoris artery, which lies deeper.
There’s also a mnemonic for remembering the borders of the femoral triangle and that’s SAIL. S, sartorius (the medial border of the sartorius); A, the medial border of the adductor longus; and IL, inguinal ligament.
SAIL to remember the borders of the femoral triangle and NAVY to remember the contents (femoral nerve, femoral artery, femoral vein y-fronts). That’s the femoral triangle.