出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/12/28 06:27:55」(JST)
| Sternocleidomastoid | |
|---|---|
|
Neck muscles, with the sternocleidomastoid shaded.
|
|
|
The two heads of the sternocleidomastoid are visible here, with the activation of the right SCM it is to cause the face to turn to the person's left.
|
|
| Details | |
| Latin | Musculus sternocleidomastoideus |
| Origin | Manubrium and medial portion of the clavicle |
| Insertion | Mastoid process of the temporal bone, superior nuchal line |
|
Artery
|
Occipital artery and the superior thyroid artery |
|
Nerve
|
Motor: accessory nerve sensory: cervical plexus |
| Actions |
Unilaterally; cervical rotation to opposite side, cervical lateral flexion to same side Bilaterally; cervical flexion, raises the sternum and assists in forced inhalation. |
| Identifiers | |
| Gray's | p.390 |
| Dorlands /Elsevier |
m_22/12550942 |
| TA | A04.2.01.008 |
| FMA | 13407 |
| Anatomical terms of muscle | |
In human anatomy, the sternocleidomastoid muscle (/ˌstɜrnɵˌklaɪdɵˈmæstɔɪd/), also known as sternomastoid and commonly abbreviated as SCM, is a paired muscle in the superficial layers of the side of the neck. It is one of the largest and most superficial cervical muscles. The primary actions of the muscle are rotation of the head to the opposite side and flexion of the neck. The sternocleidomastoid is innervated by the accessory nerve.
It is given the name sternocleidomastoid because it originates at the manubrium of the sternum (sterno-) and the clavicle (cleido-), and has an insertion at the mastoid process of the temporal bone of the skull.
The sternocleidomastoid originates from two locations, the manubrium of the sternum and the clavicle. It travels obliquely across the side of the neck and inserts at the mastoid process of the temporal bone of the skull. The sternocleidomastoid is thick and narrow at its centre, and broader and thinner at either end.
The sternal head is a round fasciculus, tendinous in front, fleshy behind, arising from the upper part of the front of the manubrium sterni. It travels superiorly, laterally, and posteriorly.
The clavicular head is composed of fleshy and aponeurotic fibers, arises from the upper, frontal surface of the medial third of the clavicle; it is directed almost vertically upward.
The two heads are separated from one another at their origins by a triangular interval (supraclavicular fossa) but gradually blend, below the middle of the neck, into a thick, rounded muscle which is inserted, by a strong tendon, into the lateral surface of the mastoid process, from its apex to its superior border, and by a thin aponeurosis into the lateral half of the superior nuchal line of the occipital bone.
The sternocleidomastoid is innervated by the accessory nerve of the same side. It supplies only motor fibres. The cervical plexus supplies sensation, including proprioception, via the ventral primary rami of C2 and C3.
The clavicular origin of the sternocleidomastoid varies greatly: in some cases the clavicular head may be as narrow as the sternal; in others it may be as much as 7.5 centimetres (3.0 in) in breadth.
When the clavicular origin is broad, it is occasionally subdivided into several slips, separated by narrow intervals. More rarely, the adjoining margins of the sternocleidomastoid and trapezius are in contact. This would leave no posterior triangle.
The supraclavicularis muscle arises from the manubrium behind the sternocleidomastoid and passes behind the sternocleidomastoid to the upper surface of the clavicle.
The function of this muscle is to rotate the head to the opposite side or obliquely rotate the head. It also flexes the neck. When both sides of the muscle act together, it flexes the neck and extends the head. When one side acts alone, it causes the head to rotate to the opposite side and flexes laterally to the same side (ipsilaterally).
It also acts as an accessory muscle of respiration, along with the scalene muscles of the neck.
The sternocleidomastoid is within the investing fascia of the neck, along with the trapezius muscle, with which it shares its nerve supply (the accessory nerve). It is thick and thus serves as a primary landmark of the neck, as it divides the neck into anterior and posterior cervical triangles (in front and behind the muscle, respectively) which helps define the location of structures, such as the lymph nodes for the head and neck.[1]
Many important structures relate to the sternocleidomastoid, including the common carotid artery, accessory nerve, and brachial plexus.
It is given the name sternocleidomastoid because it originates at the manubrium of the sternum (sterno-) and the clavicle (cleido-), and has an insertion at the mastoid process of the temporal bone of the skull.
Examination of the sternocleidomastoid muscle forms part of the examination of the cranial nerves. It can be felt on each side of the neck when a person moves their head to the opposide side.[1]
This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)
| Wikimedia Commons has media related to Sternocleidomastoid muscles. |
|
||||||||||||||||||||||||||||||||||||||||||||||||||||
全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.
| リンク元 | 「下顎呼吸」「sternocleidomastoid」 |