Compartments of the Thigh
Anatomical Organization
The thigh contains three primary muscular compartments separated by the fascia lata (deep fascia): anterior, medial, and posterior compartments. 1
The fascia lata is a robust aponeurotic structure with variable thickness across regions (anterior: 556.8 ± 176.2 µm; medial: 820.4 ± 201 µm; lateral: 1112 ± 237.9 µm reinforced by the iliotibial tract; posterior: 730.4 ± 186.5 µm), forming distinct compartmental boundaries. 1
Anterior (Extensor) Compartment
Muscles
- Quadriceps femoris group:
- Rectus femoris
- Vastus lateralis
- Vastus medialis
- Vastus intermedius
- Sartorius
- Iliopsoas (enters compartment from pelvis)
Nerve Supply
- Femoral nerve (L2-L4) - primary motor and sensory innervation 2
Vascular Supply
- Femoral artery - supplies anterior and anteromedial thigh surfaces, palpable below the inguinal ligament midway between the anterior superior iliac spine and symphysis pubis 2
- Femoral vein - accompanies the artery
Function
- Knee extension (quadriceps)
- Hip flexion (rectus femoris, iliopsoas, sartorius)
Medial (Adductor) Compartment
Muscles
- Adductor longus
- Adductor brevis
- Adductor magnus (also receives posterior compartment innervation)
- Gracilis
- Obturator externus
Nerve Supply
- Obturator nerve (L2-L4) - primary innervation
- Tibial portion of sciatic nerve - supplies hamstring portion of adductor magnus
Vascular Supply
- Obturator artery - primary supply
- Profunda femoris artery - perforating branches
- Medial circumflex femoral artery
Function
- Hip adduction
- Hip flexion (adductor longus, brevis)
- Hip extension (adductor magnus posterior fibers)
Posterior (Flexor) Compartment
Muscles
- Biceps femoris (long and short heads)
- Semitendinosus
- Semimembranosus
- Hamstring portion of adductor magnus
Nerve Supply
- Sciatic nerve (L4-S3) - divides into:
- Tibial division - supplies all hamstrings except short head of biceps femoris
- Common peroneal division - supplies short head of biceps femoris
Vascular Supply
- Profunda femoris artery - perforating branches
- Inferior gluteal artery - proximal supply
- Popliteal artery - distal supply
Function
- Knee flexion
- Hip extension
- Tibial rotation (medial hamstrings) and fibular rotation (biceps femoris)
Fascial Architecture and Clinical Significance
The popliteal fascia acts as a three-layered retinaculum for the hamstring muscles, with the superficial layer interwoven with the epimysium of biceps femoris laterally and semimembranosus medially, ensuring proper muscle positioning during knee movement. 3
Compartment Syndrome Risk
The rigid fascial compartments of the thigh predispose to compartment syndrome when intracompartmental pressure rises, particularly following trauma, vascular injury, or reperfusion. 2 The inflammatory response can cause compartmental pressure to exceed capillary pressure, leading to ischemic tissue necrosis. 2
Pain out of proportion to injury and pain with passive muscle stretch are the earliest and most sensitive clinical findings requiring immediate fasciotomy when compartment pressures reach ≥30 mmHg or differential pressure (diastolic BP minus compartment pressure) ≤30 mmHg. 4, 5
Infection Spread Patterns
In diabetic foot infections, understanding compartmental anatomy is critical as infections spread along fascial planes and tendons within compartments, moving from higher to lower pressure areas. 2 The compartmental architecture fosters proximal spread of infection, requiring surgical knowledge of these planes for proper drainage and debridement. 2