WordNet

the muscle in the back part of the leg that forms the greater part of the calf; responsible for the plantar flexion of the foot (同)gastrocnemius_muscle

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2018/06/05 20:04:17」(JST)

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The gastrocnemius muscle (plural gastrocnemii) is a superficial two-headed muscle that is in the back part of the lower leg of humans. It runs from its two heads just above the knee to the heel, a two joint muscle. The muscle is named via Latin, from Greek γαστήρ "stomach" and κνήμη (knḗmē) "leg"; meaning "stomach of leg" (referring to the bulging shape of the calf).

Structure

The gastrocnemius is located with the soleus in the posterior (back) compartment of the leg. The lateral head originates from the lateral condyle of the femur, while the medial head originates from the medial condyle of the femur. Its other end forms a common tendon with the soleus muscle; this tendon is known as the calcaneal tendon or Achilles Tendon and inserts onto the posterior surface of the calcaneus, or heel bone. Further, it is considered a superficial muscle as it is located directly under skin, so its shape is clearly visible in a normal human being.

Deep to the gastrocnemius (farther from the skin) is the soleus muscle. Some anatomists consider both to be a single muscle, the triceps surae or "three-headed [muscle] of the calf", since they share a common insertion via the Achilles tendon. The plantaris muscle and a portion of its tendon run between the two muscles, which is involved in "locking" the knee from the standing position. Since the anterior compartment of the leg is lateral to the tibia, the bulge of muscle medial to the tibia on the anterior side is actually the posterior compartment. The soleus is superficial to the mid-shaft of the tibia.

Variation

10% to 30% of individuals have a sesamoid bone called the "fabella" in the lateral (outer) head of gastrocnemius muscle.

Function

Along with the soleus muscle, the gastrocnemius forms half of the calf muscle. Its function is plantar flexing the foot at the ankle joint and flexing the leg at the knee joint.

The gastrocnemius is primarily involved in running, jumping and other "fast" movements of leg, and to a lesser degree in walking and standing. This specialization is connected to the predominance of white muscle fibers (type II fast twitch) present in the gastrocnemius, as opposed to the soleus, which has more red muscle fibers (type I slow twitch) and is the primary active muscle when standing still, as determined by EMG studies.^[1]^[2]

Motor pathway

The plan to use the gastrocnemius in running, jumping, knee and plantar flexing is created in the precentral gyrus in the cerebrum of the brain.^[3] Once a plan is produced, the signal is sent to and down an upper motor neuron. The signal is passed through the internal capsule and decussates, or crosses, in the medulla oblongata, specifically in the lateral corticospinal tract.^[4] The signal continues down through the anterior horn of the spinal cord where the upper motor neuron synapses with the lower motor neuron. Signal propagation continues down the anterior rami (Lumbar 4-5 and Sacral 1-5) of the sacral plexus. The sciatic nerve branches off of the sacral plexus in which the tibial and common fibular nerves are wrapped in one sheath. The tibial nerve eventually separates from the sciatic nerve and innervates the gastrocnemius muscle. Thus, completing the plan the brain had originally started with, so that the actions of running, standing, and jumping could be executed.

Clinical significance

The gastrocnemius muscle is prone to spasms, which are painful, involuntary contractions of the muscle that may last several minutes.^[5]

A severe ankle dorsiflexion force may result in an injury of the muscle, commonly referred to as a "torn" or "strained" calf muscle, which is acutely painful and disabling.

Ultrasound of medial gastrocnemius strain

The gastrocnemius muscle may also become inflamed due to overuse. Anti-inflammatory medications and physical therapy (heat, massage, and stretching) may be useful.

Anatomical abnormalities involving the medial head of gastrocnemius muscle result in popliteal artery entrapment syndrome.

History

In a 1967 EMG study, Herman and Bragin concluded that its most important role was plantar flexing in large contractions and in rapid development of tension.^[2]

Additional images

Nerves, arteries and veins surrounding the gastrocnemius and soleus.
Muscle layer under the gastrocnemius
Cross section of the lower leg, showing the gastrocnemius at the back.
Gastrocnemius muscle

References

^ Clinically Oriented Anatomy. pp. 598–600. ISBN 978-1-60547-652-0.
^ ^a ^b Hamilton, Nancy; Luttgens, Kathryn (2001). Kinesiology: Scientific Basis of Human Motion (10th ed.). McGraw-Hill. ISBN 978-0-07-248910-1.
^ Freberg, Laura (2015-01-01). Discovering Behavioral Neuroscience: An Introduction to Biological Psychology. Cengage Learning. ISBN 9781305687738.
^ Saladin, Kenneth (2015). Anatomy & Physiology: The Unity of Form and Function. McGraw-Hill Education.
^ "Nighttime Leg Cramps". WebMD. August 19, 2010. Retrieved March 7, 2012.

External links

Anatomy photo:14:st-0405 at the SUNY Downstate Medical Center

UpToDate Contents

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1. アキレス腱に至らない脹脛部の傷害 calf injuries not involving the achilles tendon
2. ハムストリング筋腱損傷 hamstring muscle and tendon injuries
3. 膝内側側副靱帯損傷 medial collateral ligament injury of the knee
4. リケッチア痘瘡 rickettsialpox

English Journal

Contractile and metabolic properties of engineered skeletal muscle derived from slow and fast phenotype mouse muscle.

Khodabukus A1, Baar K.
Journal of cellular physiology.J Cell Physiol.2015 Aug;230(8):1750-7. doi: 10.1002/jcp.24848.
Satellite cells derived from fast and slow muscles have been shown to adopt contractile and metabolic properties of their parent muscle. Mouse muscle shows less distinctive fiber-type profiles than rat or rabbit muscle. Therefore, in this study we sought to determine whether three-dimensional muscle
PMID 25335966

Development and validation of a human biomechanical model for rib fracture and thorax injuries in blunt impact.

Cai Z1, Lan F, Chen J.
Computer methods in biomechanics and biomedical engineering.Comput Methods Biomech Biomed Engin.2015 Jul;18(9):974-980. Epub 2014 Jan 27.
From 1990 to approximately 50,000-120,000 people die annually of road traffic accidents in China. Traffic accidents are the main cause of death of Chinese adults aged 15-45 years. This study aimed to determine the biomechanical response and injury tolerance of the human body in traffic accidents. T
PMID 24460401

Enzyme immunoassay and proteomic characterization of troponin I as a marker of mammalian muscle compounds in raw meat and some meat products.

Zvereva EA1, Kovalev LI1, Ivanov AV1, Kovaleva MA1, Zherdev AV1, Shishkin SS1, Lisitsyn AB2, Chernukha IM2, Dzantiev BB3.
Meat science.Meat Sci.2015 Jul;105:46-52. doi: 10.1016/j.meatsci.2015.03.001. Epub 2015 Mar 6.
The skeletal muscle protein troponin I (TnI) has been characterized as a potential thermally stable and species-specific biomarker of mammalian muscle tissues in raw meat and meat products. This study proposed a technique for the quantification of TnI comprising protein extraction and sandwich enzym
PMID 25777979

Japanese Journal

Changes in the hardness of the gastrocnemius muscle during a Kendo training camp as determined using ultrasound real-time tissue elastography

The Journal of Physical Fitness and Sports Medicine 5(3), 239-245, 2016
NAID 130005165306

一過性運動が腓腹筋およびアキレス腱の硬度に及ぼす影響 : 超音波 Real-time Tissue Elastography を用いた検討

体力科學 62(3), 199-205, 2013-06-01
NAID 10031159417

The Effect of Different Rearing Conditions on Muscle Characteristics in Broilers of Two Commercial Lines : A Light Microscopic Study

The journal of poultry science 47(2), 125-132, 2010-04-25
NAID 10026253498

Related Pictures

★リンクテーブル★

リンク元	「腓腹筋」「gastrocnemial」

「腓腹筋」

Gastrocnemius muscle
Details
Pronunciation	/ˌɡæstrɒkˈniːmiəs/ or /ˌɡæstrəkˈniːmiəs/
Origin	superior to articular surfaces of lateral condyle of femur and medial condyle of femur
Insertion	tendo calcaneus (achilles tendon) into mid-posterior calcaneus
Artery	sural arteries
Nerve	tibial nerve from the sciatic, specifically, nerve roots S1–S2
Actions	plantar flexes foot, flexes knee
Antagonist	Tibialis anterior muscle
Identifiers
TA	A04.7.02.044
FMA	22541
	Anatomical terms of muscle [edit on Wikidata]