Anatomy chapters
Muscles of the lower limb
Learn the major compartments, their attachments and innervation, and the muscles that maintain gait and the arches of the foot.
- Femoral: anterior thigh; obturator: medial thigh; sciatic: posterior thigh.
- Deep fibular: anterior leg; superficial fibular: lateral leg; tibial: posterior leg.
- Hip abductors stabilise the pelvis; calf and intrinsic foot muscles support stance and propulsion.
On this page
Overview
Lower-limb muscles support body weight, stabilise joints and move the limb during walking. Learn their compartment first, then connect attachment, action and nerve supply.
Limb skeletal muscle develops from migrating somitic myoblasts; much of the limb skeleton and connective tissue develops from lateral plate mesoderm. Developmental medial rotation helps explain why lower-limb extensors lie mainly anteriorly.
Gluteal muscles and lateral rotators
| Name | Origin/roots | Supply/action | Clinical note |
|---|---|---|---|
| Gluteus maximus | Posterior ilium, sacrum, coccyx and sacrotuberous ligament to iliotibial tract/gluteal tuberosity | Inferior gluteal L5–S2; extends and laterally rotates hip | Powerful in rising and climbing |
| Gluteus medius/minimus | Outer ilium to greater trochanter | Superior gluteal L4–S1; abduct and stabilise pelvis; anterior fibres medially rotate | Loss causes contralateral pelvic drop |
| Tensor fasciae latae | Anterior iliac crest/ASIS to iliotibial tract | Superior gluteal L4–S1; assists flexion, abduction and medial rotation | Tensions lateral fascial support |
| Piriformis | Anterior sacrum to greater trochanter | S1–S2; lateral rotation | Landmark for gluteal neurovascular exits |
| Obturator internus and superior gemellus | Internal obturator region/ischial spine to medial greater trochanter | Nerve to obturator internus L5–S2; lateral rotation | Internus tendon crosses lesser sciatic foramen |
| Quadratus femoris and inferior gemellus | Ischial tuberosity to quadrate tubercle/medial greater trochanter respectively | Nerve to quadratus femoris L4–S1; lateral rotation | Deep muscles near posterior hip |
| Obturator externus | External obturator membrane/margins to trochanteric fossa | Obturator L3–L4; lateral rotation | Obturator rather than gluteal nerve supply |
During stance, gluteus medius and minimus on the weight-bearing side hold up the opposite pelvis.
Anterior thigh
| Name | Origin/roots | Supply/action | Clinical note |
|---|---|---|---|
| Iliacus | Iliac fossa to lesser trochanter with psoas | Femoral L2–L3; hip flexion | Acts with psoas as iliopsoas |
| Psoas major | T12–L5 bodies/discs and lumbar transverse processes to lesser trochanter | Lumbar ventral rami L1–L3; hip flexion | Not supplied by femoral nerve |
| Sartorius | ASIS to upper medial tibia | Femoral L2–L3; hip flexion, abduction, lateral rotation; knee flexion | Forms lateral femoral-triangle border |
| Rectus femoris | AIIS and ilium above acetabulum to patella, then tibial tuberosity via patellar ligament | Femoral L2–L4; knee extension and hip flexion | Crosses hip and knee |
| Vastus lateralis, medialis and intermedius | Proximal/shaft femoral surfaces to shared quadriceps mechanism | Femoral L2–L4; knee extension | Do not cross the hip |
| Pectineus | Superior pubic ramus to proximal femur | Usually femoral L2–L3; flexion and adduction | May also receive obturator supply |
Quadriceps inserts through the patella, which increases the extensor mechanism's leverage. Its contraction stabilises the knee as well as straightening it.
Medial and posterior thigh
| Name | Origin/roots | Supply/action | Clinical note |
|---|---|---|---|
| Adductor longus/brevis | Pubis to linea aspera/proximal posterior femur | Obturator L2–L4; adduction, assist flexion | Brevis separates obturator divisions |
| Gracilis | Pubic body/inferior ramus to upper medial tibia | Obturator L2–L3; adduction and knee flexion | Joins pes anserinus |
| Adductor magnus, adductor part | Ischiopubic rami to linea aspera and supracondylar region | Obturator L2–L4; adduction | Perforating vessels traverse it |
| Adductor magnus, hamstring part | Ischial tuberosity to adductor tubercle | Tibial sciatic, mainly L4; hip extension | Different nerve supply from adductor part |
| Biceps femoris | Long head ischial tuberosity; short head femoral shaft; both to fibular head | Tibial sciatic to long head; common fibular to short, mainly L5–S2; knee flexion/lateral rotation | Long head also extends hip |
| Semitendinosus | Ischial tuberosity to upper medial tibia | Tibial sciatic L5–S2; hip extension, knee flexion/medial rotation | Pes anserinus tendon |
| Semimembranosus | Ischial tuberosity to posterior medial tibial condyle | Tibial sciatic L5–S2; same principal actions | Expansion strengthens posterior knee capsule |
Pes anserinus combines sartorius, gracilis and semitendinosus at the upper medial tibia. They have three different parent nerve supplies: femoral, obturator and sciatic.
Short-head biceps is not tibial-supplied; adductor magnus is not supplied entirely by obturator.
Anterior and lateral leg
| Name | Origin/roots | Supply/action | Clinical note |
|---|---|---|---|
| Tibialis anterior | Lateral tibia/interosseous membrane to medial cuneiform and first metatarsal base | Deep fibular L4–L5; dorsiflexion and inversion | Supports medial arch |
| Extensor hallucis longus | Fibula/interosseous membrane to distal hallux phalanx | Deep fibular, mainly L5; great-toe extension/dorsiflexion | Useful L5 motor test |
| Extensor digitorum longus | Proximal tibia/fibula and membrane to lateral four extensor expansions | Deep fibular L5–S1; toe extension/dorsiflexion | Central/lateral slips reach middle/distal phalanges |
| Fibularis tertius | Distal fibula to dorsal fifth metatarsal base | Deep fibular L5–S1; dorsiflexion/eversion | Anterior-compartment evertor |
| Fibularis longus | Proximal/lateral fibula to plantar first metatarsal and medial cuneiform | Superficial fibular L5–S2; eversion and weak plantarflexion | Crosses sole and supports transverse arch |
| Fibularis brevis | Distal lateral fibula to fifth metatarsal tuberosity | Superficial fibular L5–S2; eversion and weak plantarflexion | Insertion may avulse during inversion |
Snell uses the name peroneus for these fibularis muscles. Both names refer to the same structures.
Posterior leg
All posterior-compartment muscles receive tibial innervation. Gastrocnemius, soleus and plantaris form the superficial group; popliteus and the long flexors lie deep.
| Name | Origin/roots | Supply/action | Clinical note |
|---|---|---|---|
| Gastrocnemius | Femoral condyles to calcaneum through Achilles tendon | Tibial S1–S2; plantarflexion and knee flexion | Crosses both joints |
| Soleus | Posterior proximal tibia/fibula to calcaneum through Achilles | Tibial S1–S2; plantarflexion | Works with knee flexed; postural calf pump |
| Plantaris | Lateral supracondylar femur to calcaneum | Tibial S1–S2; weak plantarflexion/knee flexion | Small contribution to power |
| Popliteus | Lateral femoral condyle to posterior proximal tibia | Tibial L4–S1; unlocks knee | Laterally rotates femur on fixed tibia |
| Tibialis posterior | Posterior tibia/fibula and membrane to navicular and neighbouring tarsal/metatarsal attachments | Tibial L4–L5; inversion/plantarflexion | Important medial arch support |
| Flexor digitorum longus | Posterior tibia to distal phalanges 2–5 | Tibial S2–S3; toe flexion | Supports longitudinal arches |
| Flexor hallucis longus | Posterior fibula to distal hallux phalanx | Tibial S2–S3; great-toe flexion | Important in push-off |
Tibialis anterior and posterior both invert, but their nerves lie in different compartments.
Intrinsic foot muscles
| Layer/group | Muscles and attachments | Supply/action | Clinical note |
|---|---|---|---|
| First plantar layer | Abductor hallucis, flexor digitorum brevis and abductor digiti minimi arise mainly from calcaneum to proximal hallux, middle toe phalanges and proximal fifth phalanx | Medial plantar supplies first two; lateral plantar supplies abductor digiti minimi | Maintain toe position and arches |
| Second layer | Quadratus plantae joins FDL; lumbricals arise from FDL tendons to medial extensor expansions | Lateral plantar except first lumbrical, which is medial plantar | Lumbricals flex MTP and extend IP joints |
| Third layer | Flexor hallucis brevis, adductor hallucis and flexor digiti minimi brevis reach proximal phalanges | Medial plantar to FHB; lateral plantar to other two | Adductor has oblique and transverse heads |
| Fourth layer | Plantar and dorsal interossei from metatarsals to proximal phalanges/expansions | Lateral plantar; adduction/abduction | Reference axis is second toe |
| Dorsum | Extensor digitorum brevis, including hallucis brevis component, from calcaneum | Deep fibular; short toe extension | Dorsal muscle bulk is lateral to long toe extensors |
DAB, PAD: dorsal interossei abduct; plantar interossei adduct. In the foot the axis is the second toe, unlike the hand's middle finger.
Clinical relevance
Superior gluteal palsy
How it happens: injury removes effective gluteus medius/minimus action.
What you see: opposite pelvic drop during single-leg stance and possible compensatory trunk lean towards the weak side.
Achilles rupture
How it happens: the shared powerful calf tendon fails.
What you see: weak push-off and impaired heel rise; calf squeeze may fail to plantarflex the foot. Other flexors can preserve some active plantarflexion.
Tibialis posterior dysfunction
How it happens: tendon failure removes an important dynamic medial arch support.
What you see: the arch may flatten, heel alignment may drift into valgus, and a single-leg heel rise becomes difficult.
Use the compartment to predict nerve supply, then check the important exceptions. Connect tendon insertion to the lost movement: FHL reaches the distal hallux, while FDL reaches distal lateral toe phalanges. Know pelvic stabilisers, pes anserinus, the two inverters and the four medial plantar intrinsic muscles.
Quick revision
- Hip abductors stabilise the pelvis on the weight-bearing side.
- Femoral supplies quadriceps; psoas receives direct lumbar branches.
- Magnus has obturator and tibial-component supply.
- Deep fibular supplies anterior leg; superficial fibular supplies lateral leg.
- Tibial supplies the entire posterior leg compartment.
- Medial plantar supplies AH, FDB, FHB and first lumbrical.
Sources: Snell's Clinical Anatomy by Regions, supplied Lower Limb muscle tables and regional text; supplementary standard root values and clinical testing detail. Limb-origin context: Duke Embryology, Limb Development, following Langman. UHS PGET Paper I MBBS TOS. Picture links are visual study resources. Original text and tables.
FAQ
Which calf muscle does not cross the knee?
Soleus. Gastrocnemius crosses the knee and ankle, so its effect depends on knee position.
Which tendon inserts at the fifth metatarsal tuberosity?
Fibularis brevis. Fibularis longus instead crosses the sole to the medial cuneiform and first metatarsal base.
Which intrinsic muscle abducts the great toe?
Abductor hallucis, supplied by medial plantar. Adductor hallucis receives lateral plantar innervation.