- Platysma muscle
:"Platysma is also a plant taxon synonym with
Podochilus , an orchid genus."Infobox Muscle
Name = PAGENAME
GraySubject = 110
GrayPage = 387
Caption = Platysma is visible at bottom, in neck
Origin = inferiorclavicle and fascia of chest
Insertion =mandible
Blood = |inferior thyroid atery
Nerve =cervical branch of thefacial nerve (CN VII)
Action = Draws the corners of themouth inferiorly and widens it (as in expressions of sadness and fright). Also draws theskin of theneck superiorly whenteeth are clenched
Antagonist = Masseter, Temporalis
DorlandsPre = p_23
DorlandsSuf = 12646241
The platysma is asuperficial muscle that overlaps thesternocleidomastoid .It is a broad sheet arising from the
fascia covering the upper parts of thepectoralis major and deltoid; its fibers cross theclavicle , and proceed obliquely upward and medially along the side of the neck.The anterior fibers interlace, below and behind the
symphysis menti , with the fibers of the muscle of the opposite side; the posterior fibers cross themandible , some being inserted into the bone below the oblique line, others into the skin andsubcutaneous tissue of the lower part of the face. Many of these fibers blend with the muscles about the angle and lower part of the mouth.Sometimes fibers can be traced to the
zygomaticus , or to the margin of theorbicularis oculi . Beneath the platysma, the externaljugular vein descends from the angle of the mandible to the clavicle.Variations
Variations occur in the extension over the face and over the clavicle and shoulder; it may be absent or interdigitate with the muscle of the opposite side in front of the neck; attachment to clavicle, mastoid process or occipital bone occurs. A more or less independent
fasciculus , theoccipitalis minor, may extend from the fascia over thetrapezius to fascia over the insertion of thesternocleidomastoideus .Nerve
The platysma is supplied by the cervical branch of the facial nerve.
Actions
When the entire platysma is in action it produces a slight wrinkling of the surface of the skin of the neck in an oblique direction. Its anterior portion, the thickest part of the muscle, depresses the lower jaw; it also serves to draw down the lower lip and angle of the mouth in the expression of melancholy.
External links
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* [http://www.posilovani.net/foto/anatomie/krk/platysma.jpgImage]
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