Plantaris muscle
| Plantaris muscle |
|---|
|
| Plantaris muscle and tendon (red) |
| origin |
|
Linea supracondylaris lateralis (lower lateral part of the femur ) |
| approach |
| Posterior surface of the calcaneus over the Achilles tendon |
| function |
| Knee flexion, internal rotation of the lower leg |
| Innervation |
| Tibial nerve |
| Spinal segments |
| L5, S1-2 |
The plantaris muscle ( Latin for "sole muscle ") is a skeletal muscle and is one of the superficial flexors on the lower leg . It is a small, receded muscle, which is still very strongly developed in lower monkeys and semi-monkeys and in them radiates over the heel hump into the aponeurosis plantaris , which was decisive for the name.
It consists of a muscle belly and a long, thin tendon. With a length of 30 to 45 cm, it is the longest tendon in the human body. Without this tendon, the plantaris muscle is 5 to 10 cm long. This muscle is completely absent in 8 to 12 percent of the population.
function
The plantaris muscle is functionally almost insignificant, but is involved in the flexion of the knee and the inward rotation of the flexed lower leg. Some sources also mention weak plantar flexion and supination of the foot as additional functions. Since the tendon of the plantaris muscle attaches medial to the Achilles tendon at the heel hump, this information also appears plausible.
It also prevents compression of the posterior tibial vessels ( vasa tibialia posteriora ) when the knee is flexed .
Innervation
The muscle is innervated by the tibial nerve , a branch of the sciatic nerve in the lumbosacral plexus . The signal for contraction comes from the precentral gyrus in the frontal lobe.