Omohyoid muscle

Omohyoid muscle
Side of neck, showing chief surface markings. (Omohyoideus visible at center.)
File:Musculus omohyoideus.png
Muscles of the neck. Anterior view. Omohyoid is labeled on both sides.
Latin	musculus omohyoideus
Gray's	subject #112 392
Origin:	Upper border of the scapula
Insertion:	Hyoid bone
Artery:
Nerve:	Ansa cervicalis
Action:	Depresses the larynx and hyoid bone. Also carries hyoid bone backward and to the side.
Dorlands/Elsevier	m_22/12549956

The omohyoid muscle is a muscle at the front of the neck that consists of two bellies separated by an intermediate tendon. It belongs to the group of infrahyoid muscles.

Structure

It arises from the upper border of the scapula, and occasionally from the superior transverse scapular ligament which crosses the scapular notch, its extent of attachment to the scapula varying from a few millimetres to 2.5 cm.

From this origin, the inferior belly forms a flat, narrow fasciculus, which inclines forward and slightly upward across the lower part of the neck, being bound down to the clavicle by a fibrous expansion; it then passes behind the sternocleidomastoideus, becomes tendinous and changes its direction, forming an obtuse angle.

It ends in the superior belly, which passes almost vertically upward, close to the lateral border of the sternohyoideus, to be inserted into the lower border of the body of the hyoid bone, lateral to the insertion of the sternohyoideus.

The central tendon of this muscle varies much in length and form, and is held in position by a process of the deep cervical fascia, which sheaths it, and is prolonged down to be attached to the clavicle and first rib; it is by this means that the angular form of the muscle is maintained.

Triangles

The inferior belly of the Omohyoideus divides the posterior triangle of the neck into an upper or occipital triangle and a lower or subclavian triangle.

Its superior belly divides the anterior triangle into an upper or carotid triangle and a lower or muscular triangle.

The Omohyoid muscle is proximally attached to the scapula and distally attached to the hyoid bone.

Variations

Doubling; absence; origin from clavicle; absence or doubling of either belly.

Innervation

The omohyoid is innervated by a branch of the cervical plexus, and mostly acts to stabilise the hyoid bone.

Additional images

• 

  Hyoid bone. Anterior surface. Enlarged.

• 

  Left scapula. Dorsal surface.

• 

  Section of the neck at about the level of the sixth cervical vertebra. Showing the arrangement of the fascia coli.

• 

  Muscles of the neck. Lateral view.

• 

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

• 

  The veins of the neck, viewed from in front.

• 

  Hypoglossal nerve, cervical plexus, and their branches.

• 

  The right brachial plexus with its short branches, viewed from in front.

The omohyoid muscle is innervated by the ansa cervicalis from the cervical plexus (C1-3)

External links

• -1335164848 at GPnotebook
• SUNY Labs 24:06-0100
• SUNY Figs 24:01-09
• LUC omo
• Norman/Georgetown lesson6

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.

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