Plantaris muscle

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Plantaris muscle
Plantaris muscle - posterior view.png
Plantaris muscle. Seen from behind.
Dissection video (1 min 23 s)
Details
Origin Lateral supracondylar ridge of femur above lateral head of gastrocnemius <link issue='' />
Insertion Tendo calcaneus (medial side, deep to gastrocnemius tendon)
Artery sural arteries
Nerve tibial nerve from anterior rami of S1-S2
Actions Plantar flexes foot and flexes knee
Antagonist Tibialis anterior muscle
Identifiers
Latin musculus plantaris
TA98 A04.7.02.049
TA2 2663
FMA 22543
Anatomical terms of muscle

The plantaris is one of the superficial muscles of the superficial posterior compartment of the leg, one of the fascial compartments of the leg.

Contents

It is composed of a thin muscle belly and a long thin tendon. While not as thick as the achilles tendon, the plantaris tendon (which tends to be between 30–45 centimetres (12–18 in) in length) is the longest tendon in the human body. Not including the tendon, the plantaris muscle is approximately 5–10 centimetres (2.0–3.9 in) long and is absent in 8-12% of the population. It is one of the plantar flexors in the posterior compartment of the leg, along with the gastrocnemius and soleus muscles. The plantaris is considered to have become an unimportant muscle when human ancestors switched from climbing trees to bipedalism and in anatomically modern humans it mainly acts with the gastrocnemius. [1]

Structure

The plantaris muscle arises from the inferior part of the lateral supracondylar ridge of the femur at a position slightly superior to the origin of the lateral head of gastrocnemius. It passes posterior to the knee joint in an inferomedial direction and becomes tendinous distally to insert into the Achilles tendon. It occasionally separately inserts into the medial side of the calcaneus.

Innervation

The plantaris muscle is innervated by the tibial nerve, a branch of the sciatic nerve in the sacral plexus. Signaling for contraction begins in the frontal lobe of the brain with the pre-central gyrus (primary motor cortex). Upper motor neurons are stimulated and send a signal through the internal capsule and down the corticospinal tract. Decussation of the lateral corticospinal tract occurs in the medullary pyramids, then the fibers continue down the contralateral side of the spinal cord. Upper motor neurons synapse with lower motor neurons at the anterior horn of the spinal cord in the sacral plexus (formed from the anterior rami of spinal nerves L4, L5, S1–4). The lower motor neuron fibers continue down the sciatic nerve and then diverge into the tibial and common fibular nerves. The tibial nerve runs medially at the knee joint. When the tibial nerve receives an action potential, the plantaris muscle contracts, providing weak plantar flexion of the foot and weak flexion of the knee. [2]

Variation

The muscle may arise from the oblique popliteal ligament. Interdigitations with the lateral head of the gastrocnemius and a fibrous extension of the muscle to the patella are not unusual. [3]

Function

The plantaris acts to weakly plantar flex the ankle joint and flex the knee joint.

The plantaris muscle 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. [4]

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's nerve"), the muscle was useful to other primates for grasping with their feet. [5]

Clinical significance

A common injury that is normally attributed to the plantaris muscle is a condition called tennis leg. Although pain in the calf can be attributed to a rupture of the plantaris muscle, recent ultrasound research has shown that tennis leg more commonly arises from tears in the musculotendinous junction of the medial gastrocnemius. In one clinical study, 94 out of 141 patients (66.7%) diagnosed with tennis leg were found with a partial rupture of the gastrocnemius muscle, while rupture of the plantaris tendon was only seen in 2 patients (1.4%). [6]

Injury may occur from running, jumping, or pushing off one leg in sports such as tennis, basketball and soccer, which require quick foot movement in a certain direction. Isolated plantaris muscle strains are rare, and ruptures normally occur in conjunction with injury to other muscles in the posterior compartment of the lower leg. [7] Symptoms of a plantaris muscle rupture may include an audible popping sound in the area during physical activity, swelling, pain in the back of the lower leg, and persistent soreness. Ankle flexion may also be painful. [8]

See also

Additional images

Related Research Articles

<span class="mw-page-title-main">Foot</span> Anatomical structure found in vertebrates

The foot is an anatomical structure found in many vertebrates. It is the terminal portion of a limb which bears weight and allows locomotion. In many animals with feet, the foot is a separate organ at the terminal part of the leg made up of one or more segments or bones, generally including claws and/or nails.

<span class="mw-page-title-main">Human leg</span> Lower extremity or limb of the human body (foot, lower leg, thigh and hip)

The leg is the entire lower limb of the human body, including the foot, thigh or sometimes even the hip or buttock region. The major bones of the leg are the femur, tibia, and adjacent fibula. The thigh is between the hip and knee, while the calf (rear) and shin (front) are between the knee and foot.

<span class="mw-page-title-main">Heel</span> Part of the foot in the back

The heel is the prominence at the posterior end of the foot. It is based on the projection of one bone, the calcaneus or heel bone, behind the articulation of the bones of the lower leg.

<span class="mw-page-title-main">Sciatic nerve</span> Large nerve in humans and other animals

The sciatic nerve, also called the ischiadic nerve, is a large nerve in humans and other vertebrate animals which is the largest branch of the sacral plexus and runs alongside the hip joint and down the lower limb. It is the longest and widest single nerve in the human body, going from the top of the leg to the foot on the posterior aspect. The sciatic nerve has no cutaneous branches for the thigh. This nerve provides the connection to the nervous system for the skin of the lateral leg and the whole foot, the muscles of the back of the thigh, and those of the leg and foot. It is derived from spinal nerves L4 to S3. It contains fibers from both the anterior and posterior divisions of the lumbosacral plexus.

<span class="mw-page-title-main">Fibularis longus</span> Superficial muscle in the lateral compartment of the leg

In human anatomy, the fibularis longus is a superficial muscle in the lateral compartment of the leg. It acts to tilt the sole of the foot away from the midline of the body (eversion) and to extend the foot downward away from the body at the ankle.

<span class="mw-page-title-main">Ankle</span> Region where the foot and the leg meet

The ankle, the talocrural region or the jumping bone (informal) is the area where the foot and the leg meet. The ankle includes three joints: the ankle joint proper or talocrural joint, the subtalar joint, and the inferior tibiofibular joint. The movements produced at this joint are dorsiflexion and plantarflexion of the foot. In common usage, the term ankle refers exclusively to the ankle region. In medical terminology, "ankle" can refer broadly to the region or specifically to the talocrural joint.

<span class="mw-page-title-main">Achilles tendon</span> Tendon at the back of the lower leg

The Achilles tendon or heel cord, also known as the calcaneal tendon, is a tendon at the back of the lower leg, and is the thickest in the human body. It serves to attach the plantaris, gastrocnemius (calf) and soleus muscles to the calcaneus (heel) bone. These muscles, acting via the tendon, cause plantar flexion of the foot at the ankle joint, and flexion at the knee.

<span class="mw-page-title-main">Calcaneus</span> Bone of the tarsus of the foot

In humans and many other primates, the calcaneus or heel bone is a bone of the tarsus of the foot which constitutes the heel. In some other animals, it is the point of the hock.

<span class="mw-page-title-main">Popliteal artery</span> Continuation of the femoral artery that supplies the lower leg

The popliteal artery is a deeply placed continuation of the femoral artery opening in the distal portion of the adductor magnus muscle. It courses through the popliteal fossa and ends at the lower border of the popliteus muscle, where it branches into the anterior and posterior tibial arteries.

<span class="mw-page-title-main">Tibialis posterior muscle</span> Muscle in the most central of all the leg muscles

The tibialis posterior muscle is the most central of all the leg muscles, and is located in the deep posterior compartment of the leg. It is the key stabilizing muscle of the lower leg.

<span class="mw-page-title-main">Soleus muscle</span> Powerful muscle in the back part of the lower leg

In humans and some other mammals, the soleus is a powerful muscle in the back part of the lower leg. It runs from just below the knee to the heel and is involved in standing and walking. It is closely connected to the gastrocnemius muscle and some anatomists consider it to be a single muscle, the triceps surae. Its name is derived from the Latin word "solea", meaning "sandal".

<span class="mw-page-title-main">Triceps surae muscle</span> Pair of muscles: gastrocnemius and the soleus

The triceps surae consists of two muscles located at the calf – the two-headed gastrocnemius and the soleus. These muscles both insert into the calcaneus, the bone of the heel of the human foot, and form the major part of the muscle of the posterior leg, commonly known as the calf muscle.

<span class="mw-page-title-main">Gastrocnemius muscle</span> Calf muscle

The gastrocnemius muscle is a superficial two-headed muscle that is in the back part of the lower leg of humans. It is located superficial to the soleus in the posterior (back) compartment of the leg. It runs from its two heads just above the knee to the heel, extending across a total of three joints.

<span class="mw-page-title-main">Tibial nerve</span> Branch of the sciatic 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.

The biceps femoris is a muscle of the thigh located to the posterior, or back. As its name implies, it consists of two heads; the long head is considered part of the hamstring muscle group, while the short head is sometimes excluded from this characterization, as it only causes knee flexion and is activated by a separate nerve.

The rectus femoris muscle is one of the four quadriceps muscles of the human body. The others are the vastus medialis, the vastus intermedius, and the vastus lateralis. All four parts of the quadriceps muscle attach to the patella by the quadriceps tendon.

<span class="mw-page-title-main">Popliteus muscle</span> Muscle responsible for unlocking the knees during walking

The popliteus muscle in the leg is used for unlocking the knees when walking, by laterally rotating the femur on the tibia during the closed chain portion of the gait cycle. In open chain movements, the popliteus muscle medially rotates the tibia on the femur. It is also used when sitting down and standing up. It is the only muscle in the posterior (back) compartment of the lower leg that acts just on the knee and not on the ankle. The gastrocnemius muscle acts on both joints.

<span class="mw-page-title-main">Sole (foot)</span> Bottom part of foot

The sole is the bottom of the foot.

<span class="mw-page-title-main">Medial knee injuries</span> Medical condition

Medial knee injuries are the most common type of knee injury. The medial ligament complex of the knee consists of:

References

  1. Sichting, Freddy; Holowka, Nicholas B.; Ebrecht, Florian; Lieberman, Daniel E. (2020-02-26). "Evolutionary anatomy of the plantar aponeurosis in primates, including humans". Journal of Anatomy. Wiley. 237 (1): 85–104. doi:10.1111/joa.13173. ISSN   0021-8782. PMC   7309290 . PMID   32103502.
  2. Saladin, Kenneth S. Anatomy and Physiology The Unity of Form and Function. 6th ed. New York: McGraw-Hill Science Engineering, 2009. Print.[ page needed ]
  3. Freeman, A. J.; Jacobson, N. A.; Fogg, Q. A. (2008). "Anatomical variations of the plantaris muscle and a potential role in patellofemoral pain syndrome". Clinical Anatomy. 21 (2): 178–81. doi:10.1002/ca.20594. PMID   18266282. S2CID   21873763.
  4. Moore, Keith L; & Dalley Arthur R (2008). Clinically Oriented Anatomy (6th ed.). Lippincott Williams and Wilkins. ISBN   978-1-60547-652-0 [ page needed ]
  5. Andor, W.J.M., Glaudemans, Rudi A.J.O. Dierckx, Jan L.M.A. Gielen, Johannes (Hans) Zwerver (2015). Nuclear Medicine and Radiologic Imaging in Sports Injuries. Springer. p. 762
  6. Delgado, Gonzalo J.; Chung, Christine B.; Lektrakul, Nitaya; Azocar, Patricio; Botte, Michael J.; Coria, Daniel; Bosch, Enrique; Resnick, Donald (2002). "Tennis Leg: Clinical US Study of 141 Patients and Anatomic Investigation of Four Cadavers with MR Imaging and US1". Radiology. 224 (1): 112–9. doi:10.1148/radiol.2241011067. PMID   12091669.
  7. Spina, A. A. (2007). "The plantaris muscle: Anatomy, injury, imaging, and treatment". The Journal of the Canadian Chiropractic Association. 51 (3): 158–65. PMC   1978447 . PMID   17885678.
  8. "Running Injuries to the Plantaris & Soleus Muscles". SportsRec. Retrieved 20 October 2020.