The mylohyoid muscle is a muscle

Muscle

Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...

 running from the mandible to the hyoid bone

Hyoid bone

The hyoid bone is a horseshoe-shaped bone situated in the anterior midline of the neck between the chin and the thyroid cartilage. At rest, it lies at the level of the base of the mandible in the front and the third cervical vertebra behind.Unlike other bones, the hyoid is only distantly...

, forming the floor of the oral cavity. It is named for its two attachments, with the prefix "mylo" coming from the Greek word for "molar". These muscles are mesodermal in origin. The mylohyoid muscle is derived from the first pharyngeal arch.

Structure

The mylohyoid muscle is flat and triangular, and is situated immediately above the anterior belly of the digastric muscle

Digastric muscle

The digastric muscle is a small muscle located under the jaw. so digastric muscles are muscle fibers in ligament of treitz ,omohyoid , occipitofrontalis....

. It forms, with its fellow of the opposite side, a muscular floor for the cavity of the mouth

Mouth

The mouth is the first portion of the alimentary canal that receives food andsaliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth....

.

It arises from the whole length of the mylohyoid line of the mandible, extending from the symphysis in front to the last molar

Molar (tooth)

Molars are the rearmost and most complicated kind of tooth in most mammals. In many mammals they grind food; hence the Latin name mola, "millstone"....

 tooth behind. The posterior fibers pass inferomedially to insert into the body of the hyoid bone

Hyoid bone

The hyoid bone is a horseshoe-shaped bone situated in the anterior midline of the neck between the chin and the thyroid cartilage. At rest, it lies at the level of the base of the mandible in the front and the third cervical vertebra behind.Unlike other bones, the hyoid is only distantly...

. It thus belongs to the suprahyoid muscles

Suprahyoid muscles

The term suprahyoid refers to the region above the hyoid bone in the neck. The suprahyoid muscles include digastric, stylohyoid, geniohyoid, and mylohyoid...

.

The middle and anterior fibers are inserted into a median fibrous raphé

Raphé

Raphé can refer to:* Rafe, a diacritic ֿ a short horizontal overbar placed above certain letters to indicate that they are to be pronounced as fricatives* Raphe, scientific term...

 extending from the symphysis menti

Symphysis menti

The external surface of the mandible is marked in the median line by a faint ridge, indicating the symphysis menti, mandibular symphysis, or line of junction of the two pieces of which the bone is composed at an early period of life....

 to the hyoid bone

Hyoid bone

The hyoid bone is a horseshoe-shaped bone situated in the anterior midline of the neck between the chin and the thyroid cartilage. At rest, it lies at the level of the base of the mandible in the front and the third cervical vertebra behind.Unlike other bones, the hyoid is only distantly...

, where they joint at an angle with the fibers of the opposite muscle. This median raphé

Median raphe

The term Median raphe can refer to one of two different anatomical structures:* The pharyngeal raphe* The perineal raphe, also known as the "median r. of perineum"...

 is sometimes absent; the fibers of the two muscles are then continuous.

Innervation

Along with the anterior belly of the digastric muscle

Digastric muscle

The digastric muscle is a small muscle located under the jaw. so digastric muscles are muscle fibers in ligament of treitz ,omohyoid , occipitofrontalis....

, the mylohyoid muscle is innervated by the mylohyoid nerve

Mylohyoid nerve

The mylohyoid nerve is a nerve that innervates the mylohyoid muscle and the anterior belly of the digastric muscle.-Structure:...

, a branch of the inferior alveolar nerve

Inferior alveolar nerve

The inferior alveolar nerve is a branch of the mandibular nerve, which is itself the third branch of the trigeminal nerve .-Path:...

, which is a branch of the mandibular nerve

Mandibular nerve

The mandibular nerve is the largest of the three branches of the trigeminal nerve.-Roots:It is made up of two roots:* a large sensory root proceeding from the inferior angle of the trigeminal ganglion....

, a division of the trigeminal nerve

Trigeminal nerve

The trigeminal nerve contains both sensory and motor fibres. It is responsible for sensation in the face and certain motor functions such as biting, chewing, and swallowing. Sensory information from the face and body is processed by parallel pathways in the central nervous system...

.

Actions

The mylohyoid depresses the mandible and elevates the hyoid, the floor of the oral cavity, and the tongue. This is particularly important during swallowing and speaking.

Variations

It may be united to or replaced by the anterior belly of the digastric muscle

Digastric muscle

The digastric muscle is a small muscle located under the jaw. so digastric muscles are muscle fibers in ligament of treitz ,omohyoid , occipitofrontalis....

; accessory slips to other hyoid muscles are frequent.