The sural region, commonly known as the calf, is a notable area of the lower leg.
Defining the Sural Region
The sural region refers to the posterior aspect of the lower leg, encompassing the area between the knee and the ankle. It is distinct from the anterior lower leg, known as the crural region. Its superior boundary is the popliteal fossa, the hollow space located at the back of the knee. Inferiorly, the sural region extends down to the heel and ankle, reaching the calcaneal (heel) and tarsal (ankle) regions.
Laterally and medially, the sural region is bordered by the sides of the lower leg, forming the rounded contour of the calf. Its superficial position makes it easily identifiable on the human body. This region houses a complex arrangement of muscles, nerves, and blood vessels that contribute to its diverse roles.
Key Components and Their Roles
The sural region contains structures that work together to facilitate movement and sensation. The most prominent components are the calf muscles, primarily the gastrocnemius and soleus, which together are often referred to as the triceps surae. The gastrocnemius, visible as the bulk of the upper calf, has two heads and contributes to both plantarflexion (pointing the toes downward) and knee flexion. The soleus, a flatter muscle located deeper than the gastrocnemius, is crucial for sustained plantarflexion and maintaining upright posture, especially during standing. A smaller muscle, the plantaris, also resides in this region and assists in plantarflexion and knee flexion.
The sural region is also supplied by nerves and blood vessels. The sural nerve, a sensory nerve, provides sensation to the skin of the posterolateral lower leg, the lateral foot, the heel, and the ankle. This nerve forms from branches of the tibial nerve and the common fibular (peroneal) nerve. The tibial nerve innervates the posterior leg muscles, including the gastrocnemius, soleus, and plantaris, enabling motor functions.
Blood supply to the sural region comes from branches of the popliteal artery, particularly the sural arteries, which deliver oxygenated blood to the calf muscles. The posterior tibial artery also supplies muscles in this compartment. Venous drainage is primarily handled by the posterior tibial veins and the popliteal vein, which collect deoxygenated blood from the region and return it towards the heart. This integrated system of muscles, nerves, and blood vessels allows the sural region to perform its essential functions in locomotion and maintaining balance.