Estilohyoid Muscle: Origin and Insertion and Functions

He stylohyoid muscle It is a small, thin and bilateral muscle that is located in the neck and extends in front and above the digastric muscle; this gives it a particular characteristic. Because of its location it belongs to the previous group of neck muscles, topographically divided into muscles of the deep plane and the superficial plane.

The muscles of the superficial plane are separated by the hyoid bone in a suprahyoid group (those located above the hyoid bone), and an infrahyoid group (located below the hyoid bone). The muscles of the suprahyoid region are four: digastric, stylohyoid, mylohyoid and genihoid.

This group of muscles has the function of lowering the jaw by contraction, supported with the counterpart of the group of infrahyoid muscles, thus allowing the balance of the hyoid bone. Its name reveals the origin and insertion of the same, since it originates in the styloid process and is inserted in the lateral area of ​​the body of the hyoid.

It is part of the muscular and ligamentous group called riolanus corsage, which is made up of the stylopharyngeal, stylo- gosous, stylohyoid muscles and the stylomaxillary and stylohyoid ligaments, all of which are inserted into the styloid process of the temporal bone in the shape of a corsage.

Its lower end is divided into an eyelet that allows the passage of the common tendon of the digastric muscle, which gives it a unique feature among the muscles of the neck. The stylohyoid muscle pulls the hyoid bone back during swallowing and lengthens the floor of the mouth.

Origin and insertion

It is located or has its origin in the posterior and lateral surface of the styloid process, near the base; When passing down and forward, it is inserted into the body of the hyoid bone, at the junction between the body and the greater horn.

The styloid process is a pointed part of the temporal bone of the skull, which lies just below the ear and functions as an anchoring point for a series of muscles. In general, the stylohyoid muscle is divided near its insertion by the digastric tendon.

Relations of the stylohyoid muscle

It accompanies the posterior belly of the digastric muscle throughout its path, situating itself laterally and then behind it.

Medially it is related to the styloglossus muscle, from which it is separated by a space occupied by the external carotid artery from the retroestílea region to the parotid region.

The facial artery passes under the posterior belly of the digastric muscle and the stylohyoid muscle, and penetrates above these into the submaxillary cell.

Functions

The stylohyoid muscle initiates the action of swallowing by pulling the hyoid bone posteriorly and superiorly; that is, it retracts and elevates the hyoid bone.

Raises the tongue and lengthens the floor of the mouth; therefore it is considered that it helps to swallow and elevates the larynx.

Irrigation

The vascularization of the stylohyoid muscle is given by various arteries and arterioles of the external carotid artery according to its surface. For this, the stylohyoid muscle is divided into three thirds.

The first and second third receive the blood supply of a pair of arterioles of the posterior auricular artery, which is a branch of the external carotid artery.

The third third is irrigated by the hyoid branch of the lingual artery, which in turn is a collateral branch of the external carotid artery.

Innervation

The stylohyoid muscle grows from the second pharyngeal arch and, therefore, its innervation is supplied by the facial nerve (VII cranial nerve), which is a mixed cranial nerve.

The facial nerve exits the skull through the stylomastoid orifice, and gives nerve branches to the digastric and stylohyoid muscles. They can be independent branches or through a common trunk.

The stylohyoid muscle branch can be inconstant, not because of its presence or absence but because of the difficulty in dissecting it, since it is very small and its location is complex and never exact.

Impacts

There are few conditions that can affect this muscle. However, if the nerves surrounding the stylohyoid become irritated or damaged, the result may be chronic pain in the face, neck, and head.

Although there is no known cure for it, the prescription of non-steroidal anti-inflammatory drugs (aspirin and ibuprofen) can reduce pain and inflammation. In very severe cases, the injections are used to numb the affected area.

Differences between the stylohyoid muscle and the stylopharyngeus muscle

While both muscles have the similarity of suspending the larynx, they have some differences between them.

- The stylolohyoid muscle is associated with the stylohyoid ligament, while the stylopharyngeus muscle has no associated ligament.

- The stylopharyngeus muscle is necessary to contract and suspend the larynx; In the case of the stylohyoid muscle, it does not need to be contracted because it rests on the ligament for it.

- The stylopharyngeus muscle hangs and contracts to change the position of the larynx, while the stylohyoid muscle contracts to change the position of the hyoid bone.

References

1. Anatomy, Head and Neck, Muscles._ Muscles of the Neck._ Taken from earthslab.com.
2. Drake R.L., Vogl A., Mitchell, A.W.M. GRAY. Anatomy for students + Student Consult. Elsevier Madrid. P. 954 - 959
3. Healthline (2015)._ Stylehioid._ Taken from healthline.com
4. US National Library of Medicine National Institutes of Health._ Hyoid muscle dystonia: A distinct focal dystonia syndrome._ Taken from ncbi.nlm.nih.gov
5. The Infrahyoid muscles. Taken from teachmeanatomy.info.