The Suprahyoid Muscles PDF

THE SUPRAHYOID MUSCLES • The suprahyoid muscles are a group of 4 muscles, located superiorly to the hyoid bone of the neck. • They all act to elevate the hyoid bone – an action involved in swallowing. • The arterial supply to these muscles is via branches of the facial artery, occipital artery and...

THE SUPRAHYOID MUSCLES • The suprahyoid muscles are a group of 4 muscles, located superiorly to the hyoid bone of the neck. • They all act to elevate the hyoid bone – an action involved in swallowing. • The arterial supply to these muscles is via branches of the facial artery, occipital artery and lingual artery. (1) Stylohyoid • The stylohyoid muscle is a thin muscular strip, which is located superiorly to the posterior belly of the digastric muscle. Attachments: • Arises from the styloid process of the temporal bone and attaches to the lateral aspect of the hyoid bone. (1) Stylohyoid Actions: • Initiates a swallowing action by pulling the hyoid bone in a posterior and superior direction. Innervation: • Stylohyoid branch of the facial nerve (CN VII). • This arises proximally to the parotid gland. (2) Digastric • The digastric is comprised of two muscular bellies, which are connected by a tendon. • In some cadaveric specimens, this tendon can be seen to pierce the stylohyoid muscle. Attachments: • The anterior belly arises from the digastric fossa of the mandible. • The posterior belly arises from the mastoid process of the temporal bone. • The two bellies are connected by an intermediate tendon, which is attached to the hyoid bone via a fibrous sling. (2) Digastric Actions: • Depresses the mandible and elevates the hyoid bone. Innervation: • The anterior belly is innervated by the inferior alveolar nerve, a branch of the mandibular nerve (which is derived from the trigeminal nerve, CN V). • The posterior belly is innervated by the digastric branch of the facial nerve. (3) Mylohyoid • The mylohyoid is a broad, triangular shaped muscle. • It forms the floor of the oral cavity and supports the floor of the mouth. Attachments: • Originates from the mylohyoid line of the mandible, and attaches onto the hyoid bone. (3) Mylohyoid • Actions: • Elevates the hyoid bone and the floor of the mouth. • Innervation: • Inferior alveolar nerve, a branch of the mandibular nerve (which is derived from the trigeminal nerve). (4) Geniohyoid • The geniohyoid is located close to the midline of the neck, deep to the mylohyoid muscle. Attachments: • Arises from the inferior mental spine of the mandible. • It then travels inferiorly and posteriorly to attach to the hyoid bone. (4) Geniohyoid Actions: • Depresses the mandible and elevates the hyoid bone. Innervation: • C1 nerve roots that run within the hypoglossal nerve.