Fascial compartment

On the human body, the limbs can be divide into segments, such as the arm and the forearm of the upper limb, and the thigh and the leg of the lower limb.

If these segments are cut transversely, it is apparent that they are divided into multiple sections. These are called fascial compartments, and are formed by tough connective tissue septa.

These compartments usually have a separate nerve and blood supply to their neighbours. The muscles in each compartment will often all be supplied by the same nerve.

Compartment syndrome

Knowledge of these compartments not only simplifies the learning of innervation, it is also important in situations where pressure can build up in one compartment, potentially damage the contents.

This problem is called compartment syndrome and have happen acutely in a bleed (possibly caused by a fracture), or gradually, as with an athelete's overuse of a muscle.

Increased pressure within the compartment compresses the nerves, and it also decreases blood perfusion. In an acute situation it can cut off blood supply completely, leading to necrosis of the tissues in that compartment.

Compartment syndrome can be treated by a fasciotomy, where the septum enclosing the compartment is cut to relieve the pressure.

Fascial compartments of the body

The thigh is usually divided into three compartments:

• Anterior - supplied by the femoral nerve, contains the knee extensors and hip flexors.
• Medial - supplied by the obturator nerve, contains the hip adductors.
• Posterior - supplied by the sciatic nerve, contains the knee flexors and hip extensors.

The (lower) leg is divided into three compartments also:

• Anterior - supplied by the deep peroneal nerve and anterior tibial artery, contains the dorsiflexors.
• Lateral - supplied by the superficial peroneal nerve, contains the evertors of the foot.
• Posterior - supplied by the tibial nerve, contains the plantar flexors.

The (upper) arm is divided into:

The forearm is divided into two compartments: