Support for weightbearing is provided primarily by the tibia.
The tibia has a thick cortex, and significant force is required
to fracture it. Proximally, the tibia splays out to form the medial
and lateral plateaus that articulate with the femoral condyles.
The lateral plateau is higher and smaller than the medial and is
more susceptible to fracture. The distal tibia articulates with
the fibula laterally and the talus inferiorly. The tibia and fibula
are connected by a dense interosseous membrane. The distal tibial
articulation is supported by the ankle syndesmosis, a series of
ligaments inferior to the interosseous membrane. The fibula has
a small diameter and lies lateral and posterior to the tibia. It
bears little weight but is more easily fractured than the tibia.
The lower leg is divided into four compartments, each coursing
parallel to the tibia (Figure 272-1). The
compartments are enclosed by nonexpandable bones and connective
tissue that limit the compartment size and prevent compartment expansion
if its volume increases. Each compartment contains muscles and nerves
that may sustain permanent damage with elevated tissue compartment
pressure (Table 272-1). (See also Chapter 275, Compartment Syndrome.)
Table 272-1 Lower Leg Anatomy |Favorite Table|Download (.pdf)
Table 272-1 Lower Leg Anatomy
|Anterior||Lateral||Superficial Posterior||Deep Posterior|
|Muscles||Dorsiflex foot and ankle||Plantarflex and evert foot||Flex knee and ankle||Plantarflex toes, inversion foot|
|Nerve||Deep peroneal||Superficial peroneal||Sural||Posterior tibial|
|Sensation||First dorsal webspace||Dorsum of foot||Lateral aspect of foot and distal calf||Sole of foot|
|Artery||Anterior tibial||—||—||Posterior tibial|
A cross-section at the midcalf level shows the anterior compartment enclosed
by the tibia, interosseous membrane, and anterior crural septum
(Table 272-1 and Figure
272-1). Muscles in the anterior compartment group dorsiflex
the foot and ankle. The deep peroneal nerve courses within the anterior
compartment and exits to provide sensation to the dorsal web space
between the first and second toes.
The lateral compartment is bordered by the anterior crural septum,
the fibula, and the posterior crural septum. Its muscles plantarflex
and evert the foot. The superficial peroneal nerve in this compartment
provides sensation to the dorsum of the foot. The superficial posterior
compartment contains muscles that flex the knee and the tibiotalar
joints. Its sural nerve provides sensation for the lateral aspect
of the foot and the distal calf. The muscles of the deep posterior
compartment plantarflex the foot and toes and invert the foot. The
posterior tibial nerve that exits this compartment provides sensation
to the sole of the foot.
Leg injuries are initially evaluated with a directed history,
including the mechanism of injury. The history may ...