Topics

Topic

design image
Lateral femoral cutaneous nerve

The lateral femoral cutaneous nerve (LFCN) is a purely sensory branch of the lumbar plexus that supplies the skin of the anterolateral thigh. It is clinically significant due to its involvement in meralgia paresthetica, a condition caused by entrapment or compression at the inguinal ligament. Its superficial location and relation to the pelvis and groin make it an important structure in radiology, orthopedics, and anesthesia.

Synonyms

  • Femoral cutaneous nerve of thigh (lateral)

  • LFCN

  • External cutaneous nerve of the thigh

Origin, Course, and Distribution

  • Origin:

    • Arises from the lumbar plexus, formed by the dorsal divisions of the L2–L3 nerve roots

  • Course:

    • Emerges from the lateral border of the psoas major

    • Crosses the iliacus muscle obliquely, running toward the anterior superior iliac spine (ASIS)

    • Passes under, through, or sometimes above the inguinal ligament, near the ASIS

    • Enters the thigh, coursing superficially beneath the fascia lata

  • Distribution:

    • Provides sensory innervation to the skin of the anterolateral thigh, extending from the inguinal region down toward the knee

Relations

  • Medially: Psoas major muscle

  • Laterally: Iliacus muscle

  • Anteriorly: Inguinal ligament at the ASIS region

  • Posteriorly: Iliacus fascia and iliac crest

Function

  • Purely sensory: supplies cutaneous sensation to the anterolateral aspect of the thigh

  • Does not innervate any muscles

  • Provides protective sensation for the skin overlying the thigh

Clinical Significance

  • Meralgia paresthetica: compression or entrapment at the inguinal ligament leading to burning, tingling, or numbness in the anterolateral thigh

  • May be injured during pelvic surgery, hip surgery, or inguinal hernia repair

  • Can be compressed by tight belts, obesity, pregnancy, or trauma

  • Important consideration in regional anesthesia and nerve block techniques

MRI Appearance

T1-weighted images:

  • Nerve appears as a thin linear structure with low-to-intermediate signal intensity

  • Surrounded by high-signal fat, improving visibility

T2-weighted images:

  • Nerve shows low-to-intermediate baseline signal

  • Pathology (neuritis or entrapment) may cause increased T2 signal intensity

STIR (Short Tau Inversion Recovery):

  • Normal nerve remains dark or low signal

  • Pathological changes such as inflammation or entrapment appear as bright signal

T1 Fat-Sat Post-Contrast:

  • Normal nerve enhances minimally or not at all

  • Pathology may show focal or diffuse enhancement in neuritis, neuroma, or tumor infiltration

CT Appearance

Non-Contrast CT:

  • Nerve itself is not well visualized

  • Appears as a small soft tissue density within the fat plane near the ASIS and inguinal ligament

  • Indirect signs of compression may be seen (mass lesions, hematoma)

Post-Contrast CT:

  • Nerve is typically not directly enhanced

  • Surrounding inflammatory or neoplastic changes may show contrast uptake, highlighting pathology

MRI image

Lateral femoral cutaneous nerve MRI axial anatomy image-img-00000-00000_00002

MRI image

Lateral femoral cutaneous nerve MRI axial anatomy image

MRI image

Lateral femoral cutaneous nerve MRI axial anatomy image

CT image

Lateral femoral cutaneous nerve MRI axial anatomy image-img-00000-00000_00003