Corpus: Triceps surae muscle

The triceps surae muscle belongs to the superficial calf muscles and consists of two parts that have the Achilles tendon as their common tendon: the gastrocnemius muscle and the soleus muscle. The plantaris muscle is seen inconsistently in the literature as a further, third component.

Musculus gastrocnemius[Bearbeiten]

from Greek: gaster - stomach and kneme - leg

The two-headed gastrocnemius muscle originates from the distal femur. Its caput laterale originates from the lateral femoral epicondyle, the caput mediale from the medial femoral epicondyle. It borders the popliteal fossa from the caudal side. Its two muscle bellies merge caudally and their tendon fibres radiate into the Achilles tendon.

Musculus soleus[Bearbeiten]

from Latin: solea - sandal, sole

The soleus muscle ("clod muscle") originates from the upper third of the tibia and fibula. It lies under the gastrocnemius muscle and swells out laterally under it. Distally, its tendon joins with that of the gastrocnemius muscle to form the Achilles tendon.

Musculus plantaris[Bearbeiten]

from Latin: planta - sole of the foot

Some authors regard the plantaris muscle as a separate entity, while others categorise it as part of the triceps surae muscle. It originates from the linea supracondylaris lateralis of the thigh bone and the joint capsule of the knee joint. In humans, it is only of minor functional importance. Its fibres radiate into the fascia of the soleus muscle and the Achilles tendon. Occasionally it can insert on the medial side of the calcaneal tuberosity.

The triceps surae muscle is innervated by the tibial nerve, which is a branch of a main branch of the sacral plexus.

The triceps surae muscle is the most powerful foot flexor (plantar flexion). It presses the sole against the ground and enables the toes to stand and the foot to lift off the ground when walking or jumping. It also causes an inversion of the hindfoot and is therefore one of the supinators. The gastrocnemius muscle can also cause flexion in the knee joint.

Whether the length of the calcaneus has a significant influence on the force transmission of the triceps surae muscle has not been conclusively clarified. More recent studies assume that the height of the bone is particularly relevant.<ref>Suga T et al: Calcaneus height is a key morphological factor of sprint performance in sprinters, Scientific Reports volume 10, Article number: 15425 (2020)</ref

A non-functional or paralysed triceps surae muscle can be recognised diagnostically by the fact that the patient cannot stand on their toes (see plantar flexion function).

See also: Tiptoe stance