Anatomy chapters
Surface anatomy of the lower limb
Locate the major bones, pulses, tendons and nerve test sites, then relate the surface findings to the spaces beneath them.
- The femoral pulse lies at the mid-inguinal point, not the ligament midpoint.
- Behind the medial malleolus lie long flexors, posterior tibial vessels and tibial nerve.
- Use one motor and one sensory test to assess a peripheral nerve.
On this page
Overview
Surface anatomy lets you locate deeper structures using bones, tendons and folds visible or palpable on the limb. A useful landmark must be connected to a function: finding a pulse, testing a tendon or explaining a sensory deficit.
Examine corresponding sites on both limbs. Position matters: relaxing the knee helps assess the popliteal pulse, while resisted movement brings a tendon into view. Skin creases alone do not reliably identify the exact underlying joint line.
Pelvic and gluteal landmarks
The iliac crest is subcutaneous and can be followed to the anterior superior iliac spine. Posterior superior iliac spines correspond approximately to the skin dimples on the lower back. The ischial tuberosity becomes easier to feel with the hip flexed.
The greater trochanter is the prominent lateral proximal femoral landmark. It moves with hip rotation and receives the hip abductors and several short rotators. The gluteal fold is a skin fold, not an exact outline of the lower border of gluteus maximus.
Snell describes gluteal injection in the well-forward upper outer quadrant to avoid the underlying sciatic nerve. This is a traditional landmark principle; actual injection placement also depends on the selected site and local technique guidance.
The sciatic nerve runs deep to gluteus maximus and towards the posterior thigh between the ischial tuberosity and greater trochanter. It should not be treated as a superficial structure to find by firm repeated pressure.
Groin points and femoral triangle
The inguinal ligament joins the anterior superior iliac spine to the pubic tubercle. Its midpoint differs from the mid-inguinal point, which uses the pubic symphysis as the medial endpoint.
The femoral artery passes beneath the ligament at the mid-inguinal point. At the upper triangle, structures lie from lateral to medial as femoral nerve, artery, vein and femoral canal/lymphatic compartment.
Femoral pulse: halfway from ASIS to pubic symphysis, not halfway from ASIS to pubic tubercle.
| Feature | Anatomical landmark | Deep relationship | Examination use |
|---|---|---|---|
| Triangle superior border | Inguinal ligament | Roof over proximal femoral vessels | Locate upper arterial pulse |
| Lateral border | Medial edge of sartorius | Femoral nerve branches lie within triangle | Distinguish muscle edge from vessel course |
| Medial border | Medial edge of adductor longus | Forms medial triangular boundary | Adduction makes the tendon prominent |
| Floor | Iliopsoas laterally, pectineus and adductor longus medially | Femoral vessels lie on deep muscles | Explains depth and support |
| Roof | Skin, superficial fascia and fascia lata | Superficial veins and nodes above deep vessels | Saphenous opening admits great saphenous vein |
NAVEL, lateral to medial: nerve, artery, vein, empty space, lymphatics. “Empty” is only a memory label; the canal contains fat and lymphatic structures.
The femoral nerve lies outside the sheath. The sheath contains artery, vein and femoral canal.
Femoral canal and adductor canal
The femoral ring is bounded anteriorly by inguinal ligament, medially by lacunar ligament, posteriorly by pectineal ligament/superior pubic ramus and laterally by femoral vein.
A femoral hernia neck therefore lies below and lateral to the pubic tubercle. It is not located within the femoral vein, despite the close relationship.
The adductor canal lies beneath sartorius in the middle thigh. Vastus medialis forms its lateral wall and adductors its posterior wall. It contains femoral vessels, saphenous nerve and the nerve to vastus medialis in the standard regional description.
The vessels pass through adductor hiatus to the popliteal fossa. The saphenous nerve leaves medially before that opening, so it does not follow the artery into the posterior knee.
Knee and popliteal landmarks
Palpate the patella, patellar ligament, tibial tuberosity and medial/lateral tibiofemoral joint lines. The fibular head lies posterolaterally below the knee; common fibular nerve winds around its neck.
Pes anserinus tendons attach to upper medial tibia, distal to the joint line. Sartorius, gracilis and semitendinosus form this group. Medial bursal pain here is anatomically distinct from pain directly on the meniscal joint line.
Popliteal-fossa boundaries are biceps femoris superolaterally, semimembranosus/semitendinosus superomedially and gastrocnemius heads inferiorly. Its floor includes the posterior femur, posterior capsule and popliteus region.
The central tibial nerve, popliteal vein and popliteal artery lie in that superficial-to-deep order. Common fibular nerve follows the lateral boundary.
The artery is often difficult to feel because it is deep, not because every absent palpable pulse means occlusion.
Popliteal nerve–vein–artery order is superficial to deep; the artery lies closest to the joint.
Pulses and superficial veins
| Name | Origin/roots | Supply/action | Clinical note |
|---|---|---|---|
| Femoral artery | External iliac continuation | Thigh inflow | Pulse just below ligament at mid-inguinal point |
| Popliteal artery | Femoral at adductor hiatus | Knee and leg inflow | Palpate deeply with knee relaxed and flexed |
| Posterior tibial artery | Popliteal terminal pathway | Posterior leg and sole | Pulse behind medial malleolus towards heel |
| Dorsalis pedis | Anterior tibial continuation | Dorsal foot and deep plantar connection | Pulse lateral to EHL tendon |
| Great saphenous vein | Medial dorsal venous network | Superficial medial return | Anterior to medial malleolus with saphenous nerve |
| Small saphenous vein | Lateral dorsal network | Posterior calf return | Behind lateral malleolus with sural nerve |
Extend the great toe gently to identify extensor hallucis longus, then relax it before palpating the dorsal pulse. A variant arterial course may alter the expected point; compare perfusion findings as well as pulse palpation.
Ankle tendons and the foot
The medial malleolus is distal tibia; the lateral malleolus is distal fibula and extends further distally. Tibialis anterior becomes visible at the anterior medial ankle during dorsiflexion and inversion.
Behind the medial malleolus, anterior to posterior, lie tibialis posterior, flexor digitorum longus, posterior tibial vessels, tibial nerve and flexor hallucis longus. The flexor retinaculum spans medial malleolus to calcaneum over them.
Tom, Dick And Very Nervous Harry recalls tibialis posterior, digitorum longus, artery, veins, nerve and hallucis longus.
Behind the lateral malleolus run fibularis brevis and longus tendons, with brevis nearer the bone anteriorly. Their retinacula retain them against the ankle/hindfoot.
The navicular tuberosity is palpable on the medial midfoot and receives tibialis posterior. The fifth metatarsal tuberosity is palpable laterally and receives fibularis brevis. The Achilles tendon reaches the posterior calcaneum.
Assess the medial arch while standing, then compare a non-weight-bearing position if needed. Flexibility distinguishes some flexible flatfoot patterns from fixed deformity.
Motor and sensory test sites
| Name | Origin/roots | Supply/action | Clinical note |
|---|---|---|---|
| Femoral | L2–L4 | Resisted knee extension; anterior thigh/medial leg sensation | Patellar reflex adds information |
| Deep fibular | Mainly L4–S1 | Dorsiflexion/toe extension; first dorsal web space | Test great-toe extension separately |
| Superficial fibular | Mainly L5–S2 | Eversion; most dorsal foot skin | First web space is excluded |
| Tibial | L4–S3 | Plantarflexion/toe flexion; plantar sensation | Heel and sole branches may differ by lesion level |
| Superior gluteal | L4–S1 | Hip abduction and pelvic stability | Observe unsupported pelvic side during stance |
Clinical relevance
Trendelenburg sign
How it happens: abductor failure, hip displacement or an ineffective femoral-neck lever prevents stance-side pelvic support.
What you see: the unsupported side drops. The sign does not prove a superior gluteal lesion without the rest of the examination.
Fibular-neck compression
How it happens: a cast edge or external pressure loads the superficially placed common fibular nerve.
What you see: dorsiflexion and eversion weakness with dorsal sensory disturbance; inversion may remain relatively strong.
Tarsal tunnel compression
How it happens: tibial fibres are compressed beneath the medial ankle flexor retinaculum.
What you see: plantar burning or tingling with possible intrinsic weakness. The exact sensory pattern depends on branch origin and compression site.
Identify the correct endpoints before locating a pulse or drawing the femoral region. Learn femoral-triangle and popliteal-fossa boundaries, then place their contents in the correct depth or side-to-side order. Connect each malleolar tendon and nerve to a movement or sensory test.
Quick revision
- Femoral pulse uses the ASIS–pubic symphysis midpoint.
- Femoral nerve lies lateral to the artery and outside the sheath.
- Femoral hernia neck is below and lateral to pubic tubercle.
- Popliteal artery is deepest of the central neurovascular bundle.
- Great saphenous is anterior to medial malleolus; sural follows small saphenous laterally.
- Dorsalis pedis lies lateral to extensor hallucis longus.
Sources: Snell's Clinical Anatomy by Regions, supplied Lower Limb regional anatomy and pulse descriptions; supplementary standard surface landmarks and examination conventions. UHS PGET Paper I MBBS TOS. Picture links are visual study resources. Text and tables written independently for The House Job.
FAQ
Is the midpoint of the inguinal ligament the femoral pulse point?
No. The pulse uses the mid-inguinal point between ASIS and pubic symphysis. The ligament ends at the pubic tubercle.
Which nerve accompanies the great saphenous vein near the ankle?
The saphenous nerve. The small saphenous vein accompanies the sural nerve behind the lateral malleolus.
Does the saphenous nerve pass through the adductor hiatus?
No. It leaves the canal medially before the femoral vessels pass through the hiatus.
What lies immediately behind the medial malleolus in the tendon sequence?
Tibialis posterior is the most anterior tendon in the sequence, followed by flexor digitorum longus, the vessels, tibial nerve and flexor hallucis longus.