Femoral nerve

Function

What it supplies

The femoral nerve is the biggest nerve to come off the lumbar plexus, a network of nerves in the lower back¹. It forms from the L2 to L4 nerve roots of the lower back¹. It is a mixed nerve: it supplies the muscles of the front of the thigh, skin, and the hip and knee joints³.

The nerve controls the major hip flexors and the muscles that straighten the knee¹. Sources name these muscles in its supply:

• the quadriceps, the group of four muscles on the front of the thigh that straighten the knee⁷;
• the iliacus, a muscle lining the inside of the pelvis and one of the hip flexors^8,9;
• the sartorius, a long, thin muscle that runs across the front of the thigh¹⁰;
• the pectineus, a muscle at the top of the inner thigh, in each of 100 thighs dissected from 52 cadavers (donated bodies)¹¹.

The iliacus joins the psoas major, a deep muscle that bends the hip, to form the iliopsoas. Sources disagree on what supplies the psoas major^3,8,9. One classic account and a current reference say branches of the upper lumbar nerves supply it^8,9. Another source says the femoral nerve itself gives branches to the psoas major³.

For feeling, the nerve carries sensation from the front and inner thigh, and from the inner side of the leg down to the big toe¹. It also sends sensory branches to the hip and knee joints¹⁰.

Its path from the lower back to the thigh

The nerve begins within the psoas major in the abdomen, then runs down through the pelvis¹⁰. It emerges from the outer border of the psoas major and runs between the psoas and the iliacus¹². It enters the thigh under the middle of the inguinal ligament, a band of tough tissue running across the groin¹⁰. There it lies on the outer side of the femoral artery¹².

Below the ligament, the nerve runs close to the front wall of the hip socket¹⁰. There the iliopsoas is the one structure between the nerve and the front of the hip’s joint capsule¹⁰. A joint capsule is the sleeve of tough tissue that encloses a joint.

The femoral triangle lies at the junction of the hip and thigh¹³. After entering its outer side, the nerve divides into motor branches, which carry signals to muscles¹⁰.

The nerve’s end branch is the saphenous nerve, which supplies the skin on the inner front of the knee, leg and foot¹⁰. The saphenous nerve is purely sensory: it carries feeling and has no motor function¹⁴. It runs through the adductor canal, under the sartorius, alongside the femoral vessels¹².

What a numbed nerve shows

A nerve block is an injection that numbs a nerve for a short time. One randomised, placebo-controlled crossover study of blocks analysed 11 healthy young men². In a crossover study, each person tries every option in turn. A femoral nerve block cut quadriceps strength by a mean 49% from baseline². A block in the adductor canal, further down the thigh, cut it by 8%².

In a randomised, blinded study of 16 volunteers, quadriceps strength and balance scores fell significantly after a femoral nerve block¹⁷. Hip adductor (inner thigh muscle) strength did not change¹⁷.

How it moves with the hip and knee

In 30 people without symptoms, ultrasound (a scan made with sound waves) showed the nerve sliding lengthways at the top of the thigh¹⁸. The nerve slid a mean 3.6 mm when the knee was bent lying on the back, and 1.1 mm when semi-seated¹⁸. It slid even though it ends above the knee¹⁸.

Two cadaver studies looked at the hip^19,20. In one, on 6 femoral nerves, a spring was fixed across the cut nerve¹⁹. It lengthened a mean 8.83 mm with hip extension, which means moving the thigh backward at the hip¹⁹. It lengthened 3.73 mm when the leg was pulled into traction, so tension was greatest with hip extension¹⁹.

The other study placed 5 cadavers on their side and measured strain, meaning stretch as a share of resting length²⁰. Strain in the nerve near the L4-L5 disc of the lower back fell as the hip was bent further, from 0 to 60 degrees²⁰.

Breakdown

What an injury takes away

Damage to the nerve weakens or paralyses the quadriceps, which severely limits or abolishes straightening of the knee³. A person with the injury has great difficulty with stairs or a slight slope³. They can walk with the knee straight but fall when it bends even a little³. Hip bending is typically weaker too, which is put down to paralysis of the iliacus and sartorius³. Nerve damage is also associated with reduced, lost or altered feeling over the front of the thigh and the inner knee, leg and foot³.

A retrospective review, which looks back at past records, covered 159 patients with isolated femoral neuropathy⁶. They were seen at Mayo Clinic Rochester between 1999 and 2019⁶. Their presenting symptoms were weakness in 96%, loss of feeling in 73% and pain in 53%⁶. On examination, knee straightening was moderately weak in 34% and could not be activated in 25%⁶.

Where it gets squeezed

A clinical commentary names three places where the nerve can be entrapped, meaning trapped and squeezed¹⁶:

• where it enters the femoral triangle at the inguinal ligament¹⁶;
• in the iliacus compartment¹⁶;
• in the adductor canal, where the saphenous branch is involved¹⁶.

The main feature of entrapment is quadriceps weakness¹⁶.

In sport and dance

Pelvic trauma in contact sports can lead to swelling and reduced blood flow inside the iliacus compartment, which entraps the nerve¹⁶. The nerve passes through a closed compartment with fibrous walls²¹. The iliac fascia, a sheet of tough tissue, and the ilium (the wide upper part of the hip bone) form it²¹. A haematoma is a pocket of blood that collects in tissue outside the blood vessels. As one expands inside the compartment, the nerve is compressed²¹.

Palsy is loss of power in a muscle from a nerve problem. A 2010 case report and literature review covered femoral nerve palsy from an injury-related iliacus haematoma in people without a clotting disorder²¹. It found only 16 reported cases in 40 years²¹. All were aged 12 to 24, and the vast majority followed a sports injury²¹.

In reported cases, the most common mechanism is falling on the back or buttocks²¹. A direct blow to the pelvis may tear the muscle and lead to the haematoma²¹. So may hyperextension of the hip, which is straightening it past its normal limit²¹. People first report groin pain, and nerve symptoms may begin as late as 10 days after the injury²¹.

One case report describes sudden-onset femoral nerve neurapraxia in a modern dancer⁴. In neurapraxia, signals are blocked but the nerve fibres stay whole. Repeated mild stretching of the nerve during a set dance routine, over several months, was implicated as the cause⁴.

After medical procedures

A scoping review, which maps the research on a topic, reports that up to 60% of femoral nerve injuries follow a medical or surgical procedure³. Procedure-related damage is mostly of the two milder grades of nerve injury, and complete division of the nerve is infrequent³.

The retrospective review of 159 patients at Mayo Clinic Rochester counted causes in people seen within 6 months of their first symptoms⁶. The most common were compression (40%), stretch around the time of surgery (35%) and inflammation (6%)⁶.

Procedure	What was counted	How often palsy or injury of the nerve followed
Hip replacement through the front of the hip	16,258 operations in 9 studies, in a systematic review	0.36%22
Hip arthroscopy (keyhole surgery inside a joint)	Not stated	0.1 to 0.2%3
Single-injection femoral nerve block	10,309 procedures, the largest study	0.03%3

In hip arthroscopy, the most likely cause is the prolonged pulling apart of the joint that the procedure needs³. In hip replacement through the front of the hip, excessive hip extension during the operation is among the reported contributors²².

Recovery

Why the grade of injury matters

Seddon’s classification sorts nerve injuries into three grades: neurapraxia, axonotmesis and neurotmesis²³. In axonotmesis the fibres are damaged but their wrappings stay whole. In neurotmesis the fibres and their wrappings are torn or cut apart. A review describes neurapraxia as a temporary block that clears fully within 12 weeks, after myelin is restored²⁴. Myelin is the fatty, insulating wrap around many nerve fibres.

The same review describes axonotmesis as followed by slow regrowth at about 1 mm a day, often with incomplete recovery²⁴.

What studies of this nerve report

In a study of 32 patients with femoral neuropathy, function improved in 2 out of 3 within 2 years, whatever the cause⁵. The estimated share of nerve fibres lost was the only significant predictor of outcome⁵. Everyone with an estimated loss of 50% or less improved within 1 year⁵. With a greater loss, fewer than half should be expected to improve⁵.

In the retrospective review of 159 patients with isolated femoral neuropathy, 154 had follow-up data, and 83% of them reported clinical improvement⁶. The mean time to the first improvement was 3.3 months⁶. The mean time to recovery at final follow-up was 14.8 months⁶. In that review, 48% had complete or nearly complete recovery⁶. Its authors conclude that motor recovery is common, but that improvement is often prolonged and incomplete⁶.

Group studied	What was reported
One modern dancer with neurapraxia, in a case report	The thigh muscles weakened quickly but regained strength within 3 months, and recovery was complete4
One 19-year-old woman with palsy from an iliacus haematoma that was left to resolve, in a case report	Her symptoms had gone completely 6 weeks after the injury, and she had returned to full sport21
174 reported cases of palsy from a haematoma in the iliopsoas, in a systematic review	Almost half (49%) had lasting muscle weakness at final follow-up25
Palsy after hip replacement through the front, in the 6 studies of a systematic review that gave times	79% regained full muscle function within 3 to 15 months22

A systematic review of procedure-related injuries concluded that the outlook is good in most cases²⁶. Some people need the nerve repaired or grafted, and some keep permanent deficits²⁶.

Connections

Muscles and joints

The femoral nerve supplies the quadriceps and the iliacus, one of the hip flexors^7,8,9. It supplied the pectineus, covered with the hip adductors, in each of 100 dissected thighs¹¹.

Branches of the femoral nerve supply the sartorius and the rectus femoris, the quadriceps muscle at the front of the thigh²⁷. The tensor fasciae latae, a small muscle beside them at the upper outer thigh, is supplied by the superior gluteal nerve instead²⁷.

Stretches that load it

A clinical commentary says the symptoms of entrapment are typically reproduced by extending the hip while the knee is bent¹⁶.

The prone knee bend is a test in which the knee is bent while the person lies face down with the pelvis held²⁸. It is used to assess how sensitive the femoral nerve is to movement²⁸. It also stresses the quadriceps and the front-of-thigh structures, so it can provoke pain from either²⁸. In a study of 100 people with patellofemoral pain in one knee, the test showed a sensitive femoral nerve in 36%²⁸. Patellofemoral pain is pain around or behind the kneecap.

Related stretch pages: quadriceps stretch, hip flexor stretch^19,28.

Sources

1. Refai NA, Black AC, Tadi P (2023). Anatomy, Bony Pelvis and Lower Limb: Thigh Femoral Nerve. StatPearls. PMID 32310525
2. Jaeger P, Nielsen ZJ, Henningsen MH, Hilsted KL, Mathiesen O, Dahl JB (2013). Adductor Canal Block versus Femoral Nerve Block and Quadriceps Strength. Anesthesiology. doi:10.1097/ALN.0b013e318279fa0b PMID 23241723
3. Gibelli F, Ricci G, Sirignano A, Bailo P, De Leo D (2021). Iatrogenic femoral nerve injuries: Analysis of medico-legal issues through a scoping review approach.. Annals of medicine and surgery (2012). doi:10.1016/j.amsu.2021.103055 PMID 34815865
4. Sammarco GJ, Stephens MM (1991). Neurapraxia of the femoral nerve in a modern dancer.. The American journal of sports medicine. doi:10.1177/036354659101900417 PMID 1897660
5. Kuntzer T, van Melle G, Regli F (1997). Clinical and prognostic features in unilateral femoral neuropathies.. Muscle & nerve. doi:10.1002/(sici)1097-4598(199702)20:2<205::aid-mus11>3.0.co;2-1 PMID 9040660
6. Santilli AR, Martinez-Thompson JM, Speelziek SJA, Staff NP, Laughlin RS (2024). Femoral neuropathy: A clinical and electrodiagnostic review.. Muscle & nerve. doi:10.1002/mus.27994 PMID 37941415
7. Kowalska B, Sudoł-Szopińska I (2012). Ultrasound assessment of selected peripheral nerves pathologies. Part II: Entrapment neuropathies of the lower limb.. Journal of Ultrasonography. doi:10.15557/jou.2012.0033 PMID 26673938
8. Gray H; Lewis WH (editor) (1918). Anatomy of the Human Body. Lea & Febiger, Philadelphia (20th edition). Link
9. Bordoni B, Varacallo MA (2026). Anatomy, Bony Pelvis and Lower Limb: Iliopsoas Muscle.. StatPearls. PMID 30285403
10. Patton RS, Runner RP, Lazarus D, Bradbury TL (2018). Femoral neuropathy following direct anterior total hip arthroplasty: an anatomic review and case series†.. Journal of surgical case reports. doi:10.1093/jscr/rjy171 PMID 30206472
11. Kim H, Kim WK, Kim YS, Nam YS (2021). Morphologic classification and innervation patterns of the pectineus muscle.. Anatomical science international. doi:10.1007/s12565-021-00619-6 PMID 34156649
12. Valera-Calero JA (2026). A Didactic Ultrasound Manual for identifying lumbar Plexus Peripheral Nerves in the lower limb: Lower Abdominal Wall, Groin and Thigh.. Ultrasound international open. doi:10.1055/a-2920-0129 PMID 42591916
13. Betts JG, Young KA, Wise JA, Johnson E, Poe B, Kruse DH, Korol O, Johnson JE, Womble M, DeSaix P (2022). Anatomy and Physiology 2e. OpenStax. Link
14. Mathew K, Varacallo MA (2023). Anatomy, Bony Pelvis and Lower Limb: Saphenous Nerve, Artery, and Vein. StatPearls. PMID 31082089
15. Tomaszewski KA, Popieluszko P, Henry BM, Roy J, Sanna B, Kijek MR, Walocha JA (2016). The surgical anatomy of the lateral femoral cutaneous nerve in the inguinal region: a meta-analysis.. Hernia : the journal of hernias and abdominal wall surgery. doi:10.1007/s10029-016-1493-7 PMID 27115766
16. Martin R, Martin HD, Kivlan BR (2017). NERVE ENTRAPMENT IN THE HIP REGION: CURRENT CONCEPTS REVIEW.. International journal of sports physical therapy. doi:10.26603/ijspt20171163 PMID 29234567
17. Kwofie MK, Shastri UD, Gadsden JC, Sinha SK, Abrams JH, Xu D, Salviz EA (2013). The Effects of Ultrasound-Guided Adductor Canal Block Versus Femoral Nerve Block on Quadriceps Strength and Fall Risk. Regional anesthesia and pain medicine. doi:10.1097/AAP.0b013e318295df80 PMID 23788068
18. Sierra-Silvestre E, Bosello F, Fernández-Carnero J, Hoozemans MJM, Coppieters MW (2018). Femoral nerve excursion with knee and neck movements in supine, sitting and side-lying slump: An in vivo study using ultrasound imaging.. Musculoskeletal science & practice. doi:10.1016/j.msksp.2018.06.007 PMID 29986192
19. Livingstone JP, Tamate TM, Richardson AK, Harpstrite JK (2022). A Cadaveric Study Measuring Femoral Nerve Tension During Anterior Total Hip Arthroplasty Approach.. Hawai'i journal of health & social welfare. PMID 35340935
20. OʼBrien J, Haines C, Dooley ZA, Turner AW, Jackson D (2014). Femoral nerve strain at L4-L5 is minimized by hip flexion and increased by table break when performing lateral interbody fusion.. Spine. doi:10.1097/BRS.0000000000000039 PMID 24108277
21. Murray IR, Perks FJ, Beggs I, Moran M (2010). Femoral nerve palsy secondary to traumatic iliacus haematoma--a young athlete's injury.. BMJ case reports. doi:10.1136/bcr.05.2010.3045 PMID 22791579
22. Zeiman M, Makrides A, Lee J, Yoon RS (2025). Femoral Nerve Palsy After Anterior Total Hip Arthroplasty: A Systematic Review.. Arthroplasty today. doi:10.1016/j.artd.2025.101889 PMID 41245377
23. Menorca RM, Fussell TS, Elfar JC (2013). Nerve physiology. Hand Clinics. doi:10.1016/j.hcl.2013.04.002 PMID 23895713
24. Grinsell D, Keating CP (2014). Peripheral nerve reconstruction after injury: a review of clinical and experimental therapies.. BioMed Research International. doi:10.1155/2014/698256 PMID 25276813
25. Guild TT, Crawford AM, Striano BM, Mortensen S, Wixted JJ (2023). The epidemiology and management of iliopsoas hematoma with femoral nerve palsy: A descriptive systematic review of 174 cases.. Injury. doi:10.1016/j.injury.2022.11.057 PMID 36586813
26. Moore AE, Stringer MD (2011). Iatrogenic femoral nerve injury: a systematic review.. Surgical and radiologic anatomy : SRA. doi:10.1007/s00276-011-0791-0 PMID 21328076
27. Putzer D, Haselbacher M, Hörmann R, Thaler M, Nogler M (2018). The distance of the gluteal nerve in relation to anatomical landmarks: an anatomic study.. Archives of Orthopaedic and Trauma Surgery. doi:10.1007/s00402-017-2847-z PMID 29177540
28. Zamani S, Abbaszadeh-Amirdehi M, Talebi G, Tavassoli M, Esmaeilnejadganji SM, Gholinia H (2025). Prevalence of femoral nerve neurodynamic disorder in patients with patellofemoral pain syndrome: a cross-sectional study.. BMC musculoskeletal disorders. doi:10.1186/s12891-025-08951-y PMID 40707930

Every source the library cites

Changes

• October 8, 2026 Revised to report sources added after their published corrections were read
• October 7, 2026 First published.