Plantaris muscle
Encyclopedia
Plantaris is a vestigial structure
and one of the superficial muscle
s of the posterior crural compartment of the leg.
It is innervated by the tibial nerve
(S1, S2) .
It is composed of a thin muscle belly and a long thin tendon. It is approximately 2-4 inches long, and is absent in 7-10% of the human population. It is one of the plantar flexors in the superior compartment of the leg along with the gastrocnemius, and soleus. The plantaris is considered an unimportant muscle and mainly acts with gastrocnemius.
at a position slightly superior to the origin of the lateral head of gastrocnemius.
Also, it may arise from the oblique popliteal ligament
.
Passing inferomedially posterior to the knee joint, it becomes tendinous while passing distally to insert into the tendo calcaneus, or occasionally separately inserting into the medial side of the calcaneus.
Plantaris may also provide proprioceptive
feedback information to the central nervous system
regarding the position of the foot. The unusually high density of proprioceptive receptor end organs supports this notion.
Its motor function is so minimal that its long tendon can readily be harvested for reconstruction elsewhere with little functional deficit. Often mistaken for a nerve by new medical students (and thus called the "freshman nerve"), the muscle was useful to other primates for grasping with their feet.
Vestigial structure
Vestigiality describes homologous characters of organisms that have seemingly lost all or most of their original function in a species through evolution. These may take various forms such as anatomical structures, behaviors and biochemical pathways. Some of these disappear early in embryonic...
and one of the superficial muscle
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
s of the posterior crural compartment of the leg.
It is innervated by the tibial nerve
Tibial nerve
The tibial nerve is a branch of the sciatic nerve. The tibial nerve passes through the popliteal fossa to pass below the arch of soleus.In the popliteal fossa the nerve gives off branches to gastrocnemius, popliteus, soleus and plantaris muscles, an articular branch to the knee joint, and a...
(S1, S2) .
It is composed of a thin muscle belly and a long thin tendon. It is approximately 2-4 inches long, and is absent in 7-10% of the human population. It is one of the plantar flexors in the superior compartment of the leg along with the gastrocnemius, and soleus. The plantaris is considered an unimportant muscle and mainly acts with gastrocnemius.
Origin and insertion
It arises from the inferior part of the lateral supracondylar line of the femurFemur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
at a position slightly superior to the origin of the lateral head of gastrocnemius.
Also, it may arise from the oblique popliteal ligament
Oblique popliteal ligament
The oblique popliteal ligament is a broad, flat, fibrous band, formed of fasciculi separated from one another by apertures for the passage of vessels and nerves....
.
Passing inferomedially posterior to the knee joint, it becomes tendinous while passing distally to insert into the tendo calcaneus, or occasionally separately inserting into the medial side of the calcaneus.
Functions
Plantaris acts to weakly:- plantarflex the ankle joint
- flex the knee joint
Plantaris may also provide proprioceptive
Proprioception
Proprioception , from Latin proprius, meaning "one's own" and perception, is the sense of the relative position of neighbouring parts of the body and strength of effort being employed in movement...
feedback information to the central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
regarding the position of the foot. The unusually high density of proprioceptive receptor end organs supports this notion.
Its motor function is so minimal that its long tendon can readily be harvested for reconstruction elsewhere with little functional deficit. Often mistaken for a nerve by new medical students (and thus called the "freshman nerve"), the muscle was useful to other primates for grasping with their feet.