Femoral cutaneous nerves
The femoral cutaneous nerves are sensory nerves that arise from the lumbar (L1-L4) and sacral (L4-S4) nervous plexuses. They include the lateral femoral cutaneous nerve (L2-L3), posterior femoral cutaneous nerve (S1–S3) and the anterior femoral cutaneous nerves (L2–L4).
The main function of these nerves is to provide cutaneous innervation to most of the skin of the thigh, knee, and proximal leg. Compared to the other two nerves, the posterior femoral cutaneous nerve supplies the largest area of skin.
This article will discuss the anatomy and functions of the femoral cutaneous nerves.
- Lateral femoral cutaneous nerve
- Posterior femoral cutaneous nerve
- Anterior femoral cutaneous nerves
- Clinical relations
Lateral femoral cutaneous nerve: lumbar plexus (L2–L3)
Posterior femoral cutaneous nerve: sacral plexus (S1–S3)
Anterior femoral cutaneous nerves: lumbar plexus via femoral nerve (L2–L4)
Lateral femoral cutaneous nerve: skin of anterolateral aspects of thigh
Posterior femoral cutaneous nerve: skin of posterior thigh and popliteal fossa
Anterior femoral cutaneous nerve: skin of anteromedial aspects of thigh
Lateral femoral cutaneous nerve
The lateral femoral cutaneous nerve, also referred to as the lateral cutaneous nerve of the thigh, is formed by fibers of the posterior divisions of the anterior/ventral rami of spinal nerves L2 and L3. It emerges from the lateral border of the psoas major muscle and courses inferolaterally to enter the iliac fossa. Here, it crosses anterior to the iliacus muscle, and supplies the parietal peritoneum of the iliac fossa.
The nerve passes behind the cecum on the right and the descending colon on the left. It continues into the anterolateral thigh by passing either below or through the inguinal ligament, emerging just medial to the anterior superior iliac spine and anterior to the sartorius muscle.
Branches and innervation
In the thigh, the lateral femoral cutaneous nerve gives rise to two branches:
- The anterior branch supplies the skin of the anterolateral thigh (along the iliotibial tract) to the knee.
- The posterior branch innervates the skin of the lateral aspect of the greater trochanter to the mid-thigh region and sometimes the gluteal region as well.
Posterior femoral cutaneous nerve
The posterior femoral cutaneous nerve, also known as the posterior cutaneous nerve of the thigh, is formed within the pelvic cavity by fibers from both the anterior and posterior divisions of anterior/ventral rami of spinal nerves S1–S3. Specifically, the fibers that contribute to this nerve arise from the anterior divisions of the anterior rami of spinal nerves S2 and S3 and the posterior divisions of spinal nerves S1 and S2.
The nerve exits the pelvic cavity to enter the gluteal region via the greater sciatic foramen, inferior to the piriformis muscle, and accompanied by the inferior gluteal vessels. Here, it descends deep to the gluteus maximus muscle and lies either posterior or medial to the sciatic nerve. The posterior femoral cutaneous nerve continues inferiorly into the posterior thigh, coursing superficial to the long head of biceps femoris muscle and deep to the fascia lata. The nerve terminates close to the mid-calf region after perforating the deep fascia of the posterior knee.
Branches and innervation
The posterior femoral cutaneous nerve gives rise to branches that innervate the gluteal region, perineum, posterior thigh and proximal posterior leg:
- The three or four gluteal branches (inferior clunial nerves) innervate the skin of the gluteal fold region.
- The perineal branch supplies the skin of the superomedial thigh and part of the external genitalia in both sexes.
- The perforating cutaneous branches arise from the main part of the nerve and pierce the fascia lata to innervate the skin overlying the posterior thigh, popliteal fossa and proximal region of the posterior leg.
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Anterior femoral cutaneous nerves
The anterior femoral cutaneous nerves are also called the anterior cutaneous branches of femoral nerve. They arise from the lumbar plexus via the femoral nerve which is formed by the posterior divisions of the anterior rami of spinal nerves L2-L4.
The nerves consist of two sensory nerves which are the medial femoral cutaneous nerve of thigh and intermediate femoral cutaneous nerve of thigh. These nerves emerge from the anterior branch of the femoral nerve in the femoral triangle. From their origin, they descend along the path of the sartorius muscle, piercing the fascia later to supply the skin of the anteromedial aspects of the thigh.
Meralgia paresthetica is a disorder that usually presents as tingling, numbness, pain, burning sensation and sensory loss of the lateral thigh region. It is caused by entrapment of the lateral femoral cutaneous nerve, often causing compression of the nerve.
The condition is associated with tight clothing, obesity, pregnancy, local trauma, hip surgery or metabolic diseases such as diabetes mellitus. It is normally treated with conservative measures such as the wearing of loose clothing, weight loss and medications that relieve nerve compression symptoms.
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