Harvey's Garden

Muscles of the hip and leg

2 min read

Gluteal Region

  • Gluteus Maximus
    • Action: Primary hip extensor (e.g., standing up from chair, climbing stairs).
    • Innervation: Inferior Gluteal N. (L5-S2).
    • Note: Injury leads to difficulty rising from seated position.
  • Gluteus Medius & Minimus
    • Action: Hip abduction; stabilizes pelvis during stance phase of gait.
    • Innervation: Superior Gluteal N. (L4-S1).
    • Clinical: Injury causes Trendelenburg Sign (pelvis drops to the contralateral side when standing on the affected leg).
  • Tensor Fasciae Latae (TFL)
    • Action: Abduction/Flexion.
    • Innervation: Superior Gluteal N.
  • Piriformis
    • Action: External rotation.
    • Clinical: Piriformis Syndrome (hypertrophy/inflammation can compress the Sciatic N.).

Thigh: Anterior Compartment (Extensors)

  • Iliopsoas (Iliacus + Psoas Major)
    • Action: Primary hip flexor.
    • Innervation: Lumbar plexus (L1-L3) / Femoral N.
    • Clinical: Psoas Abscess (can result from vertebral TB/Pott disease; presents with fever + back pain + limitation of hip extension).
  • Quadriceps Femoris (Rectus Femoris, Vastus Lat/Med/Intermed)
    • Action: Knee extension; Rectus femoris also flexes hip.
    • Innervation: Femoral N. (L2-L4).
    • Clinical: Patellar Reflex (L3-L4). Injury leads to inability to extend knee against resistance.
  • Sartorius
    • Action: Flexes, abducts, laterally rotates hip (FABER position - cross-legged).
    • Innervation: Femoral N.

Thigh: Medial Compartment (Adductors)

  • Adductor Longus, Brevis, Magnus & Gracilis
    • Action: Hip adduction.
    • Innervation: Obturator N. (L2-L4).
    • Clinical: Injury (e.g., pelvic surgery, fetal head compression) presents as gait instability and lateral swinging of leg.

Thigh: Posterior Compartment (Hamstrings)

  • Biceps Femoris, Semitendinosus, Semimembranosus
    • Action: Hip extension, Knee flexion.
    • Innervation: Sciatic N. (Tibial division; Short head of Biceps is Common Peroneal div).
    • Clinical: Origin is the Ischial Tuberosity (avulsion fractures common in sprinters/hurdlers).

Leg: Anterior Compartment (Dorsiflexors)

  • Tibialis Anterior
    • Action: Dorsiflexion and Inversion.
    • Innervation: Deep Peroneal (Fibular) N.
    • Clinical:
      • Nerve compression/trauma (fibula neck fracture affects common peroneal) Foot Drop.
      • Gait: Steppage gait (patient lifts leg high to clear toes).
  • Extensor Hallucis Longus (EHL)
    • Action: Big toe extension.
    • Clinical: Used to test L5 nerve root motor function.

Leg: Lateral Compartment (Evertors)

  • Peroneus (Fibularis) Longus & Brevis
    • Action: Eversion and Plantarflexion.
    • Innervation: Superficial Peroneal (Fibular) N.
    • Clinical: Loss of sensation over dorsum of foot (spares webspace between 1st/2nd toes).

Leg: Posterior Compartment (Plantarflexors)

  • Gastrocnemius & Soleus (Triceps Surae)
    • Action: Plantarflexion.
    • Innervation: Tibial N. (S1-S2).
    • Clinical: Achilles Reflex (S1). Rupture feels like being “kicked in the back of the leg” + inability to tiptoe.
  • Tibialis Posterior
    • Action: Inversion and Plantarflexion.
    • Innervation: Tibial N.
  • Popliteus
    • Action: Unlocks the knee joint (laterally rotates femur on fixed tibia) to initiate flexion.

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