Overview of the neck muscle anatomyCredit: http://www.anatomyatlases.org/atlasofanatomy/plate09/02rneckmuscles.shtml
The neck muscle anatomy is made up of muscles that support the head, move the head in so many directions like rotation, flexion and extension.
The neck muscle anatomy is divided into 2 major groups, the superficial muscles and the deep muscles
|*suprahyoid muscles||*Anterior vertebral muscles|
Platysma: Originates from subcutaneous skin over deltoid-pectoral region (from the thoracic fascia). It functions to depress the mandible and lower lip, tenses the skin under the neck and prevents the subcutaneous veins from compressing.Credit: http://commons.wikimedia.org/wiki/File:Musculi_coli_sternocleidomastoideus.svg
Sternocleidomastoid muscle: It has two heads; one originates from the manubrium of the sternum and the other from the sternal end of the clavicle. The two head both terminate at the mastoid process and superior nuchal line. It functions to rotate the face in the opposite direction, bilaterally flexes the neck, elevates the head and maintains the head above the vertical positions.
They are five muscles that make up this group;
- Digastric muscle.
- Stylohoid muscle.
- Myohyoid muscle.
- Geniohyoid muscle.
- Hyoglosus muscle.
Digastric muscle: It originates from the mastoid notch of the temporal bone (posterior belly) and digastric fossa of the internal mandible (anterior belly). Both bellies meet and insert at the lateral aspect of the body of hyoid by a pulley tendon. The muscle functions to opens the mouth by depressing the mandible, flexes the hyoid bone for infrahyoid action if mandible is flexed.Credit: http://commons.wikimedia.org/wiki/File:Musculi_colli_mylohyoideus.svg
Mylohyoid muscle: It originates from the mylohyoid line of the mandible and inserts at the body of the hyoid bone (posterior fiber) and along the midline at myohyoid raphe.
Action: It depresses the mandible, and pulls the hyoid bone upwards (if mandible is fixed) and elevates the hyoid. It forms the muscular floor of the mouth.Credit: http://commons.wikimedia.org/wiki/File:Musculi_colli_stylohyoideus.svg
Stylohyoid muscle: It originates from the styloid process of the temporal bone and inserts at the hyoid bone. It functions to pull the hyoid bone upwards and backwards.Credit: http://commons.wikimedia.org/wiki/File:Geniohyoid_muscle.PNG
Geniohyoid muscle: This muscle is paired, it originate from mental spine of the mandible and inserts at the body of the hyoid bone.
It functions to pull the tongue and depress the mandible (if hyoid is fixed).Credit: http://en.wikipedia.org/wiki/File:Hyoglossal_muscle.PNG
This group of muscle consists of four muscles;
- Sternohyoid muscle.
- Omohyoid muscle.
- Sternothyroid muscle.
- Thyrohyoid muscle.
Sternohyoid muscle: It originates from posterior surface of the manubrium and sternal end of the clavicle. It then inserts at the body of hyoid. It functions to depress the hyoid and larynx, acts eccentrically with the suprahyoid muscle to provide them with a stable base.Credit: http://commons.wikimedia.org/wiki/File:Musculi_colli_omohyoideus.svg
Omohyoid muscle: The superior belly originates from the hyoid bone and inferior belly from the superior scapular border (notch). Both bellies meet at clavicle and held to clavicle by a pulley tendon.
It functions to compress jugular vein, same roll as sternohyoid. And it pulls pretracheal fascia.Credit: http://www.healthline.com/human-body-maps/sternothyroid-muscle
Sternothyriod muscle: It originates from posterior surface of the manubrium sterni and first rib and inserts on the oblique line of thyroid cartilage. It has same function as stenohyoid.Credit: http://commons.wikimedia.org/wiki/File:Thyrohyoid_muscle.PNG
Thyrohyoid muscle: It originates from oblique line of the thyroid cartilage and inserts on the body of hyoid bone. It functions depresses the hyoid and may also help in larynx and thyroid gland elevation.
Deep muscles of the neck
Scalene muscles (stria): It originates from transverse processes of cervical vertebrae, scalenus anterior and medius insert into the first rib, whereas the scalenus posterior attach to the second rib.
There are three scalenus muscles;Credit: http://commons.wikimedia.org/w/index.php?title=Special%3ASearch&profile=default&search=Scalenus+anterior&fulltext=Search
- Scalenus anterior: originates from the anterior tubercles of transverse processes of C3 to C4.Credit: http://commons.wikimedia.org/wiki/File:Scalenus_medius.png
- Scalenus medius: originates from posterior tubercle of transvers process of all cervical vertebrae.Credit: http://commons.wikimedia.org/wiki/File:Scalenus_posterior.png
- Scalenus posterior: originates from the posterior tubercle of the transverse processes of C4 to C6.
Action of scalenus muscle: if transverse processes are fixed they elevate the ribs for respiration, if ribs are fixed they rotate head to side opposite of contraction, flextion and bending the cervical region of the spine.
Paravertebralis (anterior vertebral muscles)
They lie in the groove between the vertebral bodies and their transverse processes. They have two groups;Credit: http://commons.wikimedia.org/wiki/File:Longus_colli.png
a) Longus colli muscle: it originates from the lower anterior vertebral bodies and transvers processes. Insertion: same place as origin but below.Credit: http://commons.wikimedia.org/wiki/File:Longus_capitis.png
b) Longus capitis muscle: originates upper anterior vertebral bodies and transverse processes. Insertion: anterior vertebral bodies and transverse processes several segments above at the base of the occipital bone.
All muscles that make up the neck muscle anatomy receive their blood supply from the branches of the axillary artery and are innervated by the posterior rami of spinal nerves.