Tibia and Fibula - Overview
The bones of the lower leg are the tibia and fibula. Between them, at the top and bottom are joints (the proximal and distal tibiofibular joints) and an interosseous membrane runs down their length.
Around and between the muscles of the lower leg are fascia and intermuscular septa that divide the lower limb into compartments.
The tibia is suitable for interosseous infusion in children. The bone is triangular in cross section with a sharp anterior border. One of the standard positions for interosseous needle placement is on the anterior surface of the tibia, 2-3 cm below the tibial tuberosity. Another is on the femur, anterolateral, 3 cm above the lateral condyle.
On the lateral side of the lower leg, below the knee joint, you can feel the head of the fibula and, just distal to this, be able to roll the common peroneal nerve (L4,5 S1,2) as it winds round the neck of the fibula.
This is a vulnerable site and the nerve can be damaged by pressure on this area – whether by a tight plaster cast or pressure on the lateral side of the leg from lithotomy stirrups. As the common peroneal nerve supplies sensation and motor innervation to the foot and ankle abductors and evertors, damage will leave the patient with foot drop, foot inversion and anaesthesia on the anterior leg and foot.
The fact that the common peroneal nerve is superficial as it winds round the fibular neck, also means that it can be used for nerve stimulation to assess neuromuscular blockade. Stimulation causes dorsiflexion of the foot.