Sternocleidomastoid muscle 465415 222445502 2008-06-29T11:21:15Z Vedran12 7322109 interwiki hr {{Muscle infobox | Name = Sternocleidomastoid | Latin = musculus sternocleidomastoideus | GraySubject = 111 | GrayPage = 390 | Image = Gray512.png | Caption = The [[triangles of the neck]]. (Anterior triangles to the left; posterior triangles to the right.) | Image2 = Sternocleidomastoideus.png | Caption2 = Muscles of the neck. Lateral view. | Origin = [[manubrium sterni]], [[medial portion of the clavicle]] | Insertion = [[mastoid process of the temporal bone]], [[superior nuchal line]] | Blood = [[occipital artery]] and the [[superior thyroid artery]] | Nerve = motor: [[accessory nerve]]<BR>sensory: [[cervical plexus]]| Action = Acting alone, tilts head to its own side and rotates it so the face is turned towards the opposite side. Acting together, flexes the neck, raises the sternum and assists in forced inspiration. | DorlandsPre = m_22 | DorlandsSuf = 12550942 | }} In [[human]] [[anatomy]], the '''sternocleidomastoid''' (pronounced {{IPA|/ˌstɚ.noˌkli.dəˈmæs.tɔɪ̯d/}}) '''muscle''', also known as '''sternomastoid''' and commonly abbreviated as '''SCM''', is a paired muscle in the [[superficial]] layers of the [[anterior]] portion of the [[neck]]. It acts to flex and rotate the head. It also acts as an accessory muscle of inspiration, along with the [[scalene muscles]] of the neck. ==Etymology== It is given the name ''sternocleidomastoid'' because it originates at the manubrium of the [[sternum]] (''sterno-'') and the [[clavicle]] (''cleido-''), and articulates with the [[mastoid process]] of the [[temporal bone]] of the [[skull]]. ==Origin and insertion== The sternocleidomastoid passes obliquely across the side of the neck. It is thick and narrow at its central part, but broader and thinner at either end. * The '''medial''' or '''sternal head''' is a rounded [[fasciculus]], tendinous in front, fleshy behind, which arises from the upper part of the anterior surface of the [[manubrium sterni]], and is directed superiorly, laterally, and posteriorly. * The '''lateral''' or '''clavicular head''', composed of fleshy and [[aponeurotic]] fibers, arises from the superior border and anterior 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, 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]]. ==Nerve supply== The sternocleidomastoid is innervated by the ipsilateral [[accessory nerve]]. It supplies only motor fibres. The cervical plexus supplies sensation including proprioception. ==Variations== The sternocleidomastoid varies much in the extent of its origin from the clavicle: in some cases the clavicular head may be as narrow as the sternal; in others it may be as much as 7.5 cm 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 (also known as the wing and named after a large prehistoric bird) and passes behind the Sternocleidomastoid to the upper surface of the clavicle. ==Relations== 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]]). Anterior to sternocleidomastoid is the anterior cervical triangle. Posterior to it is the posterior cervical triangle. Many important structures relate to the sternocleidomastoid, including the common carotid artery, accessory nerve, and brachial plexus. ==Cultural significance== * [[Tom Wolfe]]'s [[The Bonfire of the Vanities]] featured a [[lawyer]] fond of clenching his '''sternocleidomastoid muscles. ''' * In the Portuguese movie [[A Canção de Lisboa]], the main character, Vasco, who is studying Medicine, is asked in his final exam where the Sternocleidomastoid muscle is located. The name of the muscle became famous in Portugal after this movie. ==Additional images== [[Image:Scm_posterior.PNG|thumb|left|350px|Muscles connecting the upper extremity to the vertebral column. The posterior surface of sternocleidomastoid muscle is labeled.]] <gallery> Image:Gray115.png|Anterior surface of sternum and costal cartilages. Image:Gray129.png|Occipital bone. Outer surface. Image:Gray137.png|Left temporal bone. Outer surface. Image:Gray187.png|Base of skull. Inferior surface. Image:Gray200.png|Left clavicle. Superior surface. Image:Gray384.png|Section of the neck at about the level of the sixth cervical vertebra. Image:Gray507.png|Superficial dissection of the right side of the neck, showing the carotid and subclavian arteries. Image:Gray557.png|Veins of the head and neck. Image:Gray558.png|The veins of the neck, viewed from in front. Image:Gray790.png|The nerves of the scalp, face, and side of neck. Image:Gray1194.png|Anterolateral view of head and neck. Image:Gray1195.png|Front view of neck. </gallery> ==External links== * {{MuscleLoyola|scm}} * {{GPnotebook|436600910}} * {{SUNYAnatomyFigs|24|01|03}} * {{eMedicineDictionary|Sternocleidomastoid+muscle}} * {{RocheLexicon|25420.000-1}} {{Gray's}} {{Muscles of neck}} [[Category:Muscular system]] [[de:Musculus sternocleidomastoideus]] [[es:Esternocleidomastoideo]] [[fr:Muscle sterno-cléido-mastoïdien]] [[hr:Prsnoključnosisasti mišić]] [[it:Sternocleidomastoideo]] [[hu:Fejbiccentő izom]] [[la:Musculus sternocleidomastoideus]] [[nl:Musculus sternocleidomastoideus]] [[ja:胸鎖乳突筋]] [[pl:Mięsień mostkowo-obojczykowo-sutkowy]] [[pt:Esternocleidomastoideu]] [[sr:Стерноклеидомастоидни мишић]] [[fi:Päännyökkääjälihas]] [[sv:Sternocleidomastoideus]] [[th:กล้ามเนื้อสเตอร์โนไคลโดมาสตอยด์]] [[zh:胸鎖乳突肌]]