sternocleidomastoid muscle

Information about sternocleidomastoid muscle

Sternocleidomastoid
The triangles of the neck. (Anterior triangles to the left; posterior triangles to the right.)
Muscles of the neck. Lateral view.
Latinmusculus sternocleidomastoideus
subject #111 390
Origin:manubrium sterni, 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
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.
Dorlands/Elsevier m_22/12550942
In human anatomy, the sternocleidomastoid (pronounced /ˌstɚ.noˌkli.dəˈmæs.tɔɪ̯d/) muscles are anterior muscles in the neck that act 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 with the sternum (sterno-) and clavicle (cleido-), and articulates with the mastoid process of the temporal bone of the skull. It is also called the sternomastoid muscle.

Origins and insertions of the two heads

The Sternocleidomastoideus (Sternomastoid muscle) passes obliquely across the side of the neck.

It is thick and narrow at its central part, but broader and thinner at either end. It arises from the sternum and clavicle by two heads.
  • 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 upward, lateralward, and backward.
  • 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.

Variations

The Sternocleidomastoideus 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 Sternocleidomastoideus and Trapezius have been found in contact.

The Supraclavicularis muscle arises from the manubrium behind the Sternocleidomastoideus (also known as the wing and named after a large prehistoric bird) and passes behind the Sternocleidomastoideus to the upper surface of the clavicle.

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






Anterior surface of sternum and costal cartilages.

Occipital bone. Outer surface.

Left temporal bone. Outer surface.

Base of skull. Inferior surface.

Left clavicle. Superior surface.

Section of the neck at about the level of the sixth cervical vertebra.

Superficial dissection of the right side of the neck, showing the carotid and subclavian arteries.

Veins of the head and neck.

The veins of the neck, viewed from in front.

The nerves of the scalp, face, and side of neck.

Anterolateral view of head and neck.

Front view of neck.


External links

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.
 •  • [ e]
Muscles of head and neck: the neck
CERVICALplatysma - sternocleidomastoid
SUPRAHYOIDdigastric - stylohyoid - mylohyoid - geniohyoid
INFRAHYOID/STRAPsternohyoid - sternothyroid - thyrohyoid - omohyoid
VERTEBRAL — ANTERIORlongus colli - longus capitis - rectus capitis anterior - rectus capitis lateralis
LATERALscalene (anterior - medius - posterior)
Anatomists use the term triangles of the neck to describe the divisions created by the major muscles in the region.

The side of the neck presents a somewhat quadrilateral outline, limited, above, by the lower border of the body of the mandible, and an imaginary line
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Latin}}} 
Official status
Official language of: Vatican City
Used for official purposes, but not spoken in everyday speech
Regulated by: Opus Fundatum Latinitas
Roman Catholic Church
Language codes
ISO 639-1: la
ISO 639-2: lat
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bold refer to the diagram at right.)

In the skull (8):
  • 1-9. cranium
  • 7. mandible
''In the middle ears (6):
  • malleus
  • incus
  • stapes
In the throat (1):
  • hyoid
In the shoulder girdle (4):
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The manubrium (from Latin manubrĭum, "a handle") or manubrium sterni is the broad, upper part of the sternum. With a quadrangular shape, wider superiorly and narrower inferiorly, it articulates with the clavicles and the first two ribs.
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bold refer to the diagram at right.)

In the skull (8):
  • 1-9. cranium
  • 7. mandible
''In the middle ears (6):
  • malleus
  • incus
  • stapes
In the throat (1):
  • hyoid
In the shoulder girdle (4):
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The mastoid portion of the temporal bone forms the posterior part of the temporal bone.

Surfaces

Its outer surface is rough, and gives attachment to the Occipitalis and Auricularis posterior.
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The nuchal lines are four curved lines on the external surface of the occipital bone:
  • The upper, often faintly marked, is named the highest nuchal line, and to it the galea aponeurotica is attached.

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Arteries are muscular blood vessels that carry blood away from the heart.[1] All arteries, with the exception of the pulmonary and umbilical arteries, carry oxygenated blood.

The circulatory system is extremely important for sustaining life.
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The occipital artery arise opposite the facial artery, its path is below the posterior belly of digastic to the occipital region. This artery supplies blood to the back of the scalp and sterno-mastoid muscles. Other muscles it supplies are deep muscles in the back and neck.
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The superior thyroid artery arises from the external carotid artery just below the level of the greater cornu of the hyoid bone and ends in the thyroid gland.

Relations


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  • Accessory nerve
  • Accessory obturator nerve
  • Alderman's nerve
  • Anococcygeal nerve
  • Ansa cervicalis
  • Anterior interosseous nerve
  • Anterior superior alveolar nerve
  • Aortic plexus
  • Auerbach's plexus
  • Auriculotemporal nerve
  • Axillary nerve

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In anatomy, the accessory nerve is a nerve that controls specific muscles of the neck. As a part of it is traditionally believed to originate in the brain, it is considered a cranial nerve.
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The cervical plexus is a plexus of the ventral rami of the first four cervical spinal nerves which are located from C1 to C4 cervical segment in the neck. They are located laterally to the transverse processes between prevertebral muscles from the medial side and vertebral (m.
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Kinesiology is the scientific study of the anatomy, physiology, and mechanics of body movement, especially in humans. [1] The word kinesiology is derived the Greek "kinesis" (motion) + the suffix -ology or -logy from the greek "logos" or "logia"(meaning a field of study).
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Elsevier, the world's largest publisher of medical and scientific literature, forms part of the Reed Elsevier group. Based in Amsterdam, the company has substantial operations in the UK, USA and elsewhere.
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Anatomy (from the Greek ἀνατομία anatomia, from ἀνατέμνειν
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The scalene muscles are a group of three pairs of muscles in the lateral neck, namely the scalenus anterior, scalenus medius, and scalenus posterior. They originate from the transverse processes from the cervical vertebrae of CII to CVII and insert onto the first and second ribs.
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sternum (from Greek στέρνον, sternon, "chest" and hebrew pronounced "Shamokin" also meaning chest) or breastbone is a long, flat bone located in the center of the thorax (chest).
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Collarbone and collar bone redirect here. The eye abnormality is correctly spelled coloboma.
This article uses some professional terms to describe relative positions and directions.

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The mastoid process is a conical prominence projecting from the undersurface of the mastoid portion of the temporal bone. It is located just behind the external acoustic meatus, and lateral to the styloid process.
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The temporal bones are situated at the sides and base of the skull.

The temporal bone supports that part of the face known as the temple.

Parts

Each consists of five parts:
  • Squama temporalis
  • Mastoid portion
  • Petrous portion
  • Tympanic part

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skull is a bony structure found in many animals which serves as the general framework for the head. The skull supports the structures of the face and protects the head against injury.

The skull can be subdivided into two parts: the cranium and the mandible.
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sternum (from Greek στέρνον, sternon, "chest" and hebrew pronounced "Shamokin" also meaning chest) or breastbone is a long, flat bone located in the center of the thorax (chest).
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Collarbone and collar bone redirect here. The eye abnormality is correctly spelled coloboma.
This article uses some professional terms to describe relative positions and directions.

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Fasciculus can refer to:
  • nervous tissue
  • Arcuate fasciculus
  • Dorsal longitudinal fasciculus

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The manubrium (from Latin manubrĭum, "a handle") or manubrium sterni is the broad, upper part of the sternum. With a quadrangular shape, wider superiorly and narrower inferiorly, it articulates with the clavicles and the first two ribs.
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Aponeuroses (απο, "away" or "of", and νευρον, "sinew") are membranes separating muscles from each other. They have a shiny, whitish-silvery color, and are histologically similar to tendons, but are very sparingly supplied with blood
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Collarbone and collar bone redirect here. The eye abnormality is correctly spelled coloboma.
This article uses some professional terms to describe relative positions and directions.

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The mastoid process is a conical prominence projecting from the undersurface of the mastoid portion of the temporal bone. It is located just behind the external acoustic meatus, and lateral to the styloid process.
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