The origin of the stylohyoid muscle is from the middle of the posterior surface of the styloid process of the temporal bone near its base. The styloid process is a thin pointed bone just below the ear projecting downward and forward from the inferior surface of the petrous temporal bone. It runs in an anteroinferior direction and inserts at the junction of the body and greater cornu of the hyoid bone immediately superior to the omohyoid muscle. This muscle connects to the posterior belly of the digastric muscle in its path.

The muscle lies anteromedial to the superior margin of the posterior belly of the digastric muscle. The styloglossus muscle lies medially, and anterior to the stylohyoid muscle The stylopharyngeal muscle is located between the stylohyoid and the styloglossus muscle Near its insertion at the hyoid bone, the intermediate tendon of the digastric muscle runs in the center of the tendon of the stylohyoid muscle. This muscle confines the posteroinferior boundary of the digastric or submandibular triangle. The facial artery after arising from the external carotid artery travels upwards on the superior constrictor muscle deep towards stylohyoid muscle. The posterior auricular artery runs superficially towards the stylohyoid. 

There lies an intermuscular space between the stylohyoid muscle and the styloglossus muscle. This space gives passage to the external carotid artery superiorly and the facial artery inferiorly as it courses from the retrostyloid area to the prestyloid area.[1]

The stylohyoid muscle may be absent in some individuals. Physiological variation in its insertion area may also exist.  It may insert into the mylohyoid muscle or omohyoid muscles.

In the lesion of the marginal mandibular nerve, which results in asymmetrical lips, surgical intervention is required to improve the aesthetic and functions. Stylohyoid muscle transfer is a possible surgical option when the digastric muscle is not an option. 

The stylohyoid muscle is a part of a significant anatomical structure known as stylopharyngeal septum/styloid diaphragm. This septum is considered as an important surgical landmark when attempting to enter the pharyngeal spaces. The septum divides the space into two compartments (prestyloid and retrostyloid compartment) based on its relationship with the septum. Partial ossification of the ligament of stylohyoid muscle may lead to Eagle syndrome, also known as the stylohyoid syndrome.[2] This condition results in sharp shooting pain unilaterally in the jaw. The pain may radiate into the throat, tongue, or ear, which causes difficulty in deglutition, sore throat, and tinnitus.[2] Surgical resection of the ligament is required as it compresses the underlying structures.[3]

The facial nerve has a significant contribution to the oropharyngeal phase of deglutition through various muscles. It innervates the stylohyoid muscle in association with other muscles, such as the buccinator muscle, perioral muscles, and the posterior belly of digastrics muscle.  In patients with peripheral facial palsy, there are reports of difficulty in swallowing.[4] Paralysis or weakness of the stylohyoid may occur if the facial nerve gets damaged. The intracranial lesion of the facial nerve (before its exit from the stylomastoid foramen) may occur due to some middle ear pathology (tumor or infection). An extracranial lesion of the facial nerve can occur due to an infection of the nerve such as herpes virus, compression during forceps delivery (since incomplete development of the neonatal mastoid process leaves the nerve unprotected), or it can be idiopathic. Pathologic conditions associated with the stylohyoid muscle may result in cervical and pharyngeal symptoms such as neck pain laterally in the area of the angle of the mandible, submandibular space, and anterior upper neck. The pain may get exacerbated by movements such as speaking, swallowing, yawning, or head-turning. Myofascial pain syndrome can result in severe pain in the stylohyoid muscle; treatment includes nonsteroidal anti-inflammatory drugs to reduce pain and inflammation. Severe cases may require injections to numb the affected area.

In children, the stylohyoid muscle is nearly horizontal. With age, there occurs a change in length and shape of the muscle and the stylohyoid process, and thus, in adults, the course of the stylohyoid becomes more vertical.

Stylohyoid muscle can be palpated by placing the fingers along the direction of the muscle fiber under the chin and superiorly to the hyoid bone. Palpation is done laterally from the hyoid bone towards the ear lobe along the anterior border of the sternocleidomastoid muscle while the patient is asked to swallow or place the tongue against the roof of their mouth and push against it.