Overview
The suprahyoid muscles are a group of four paired muscles located superior to the hyoid bone of the neck, which acts to elevate the hyoid bone during swallowing.
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Muscles
Stylohyoid
The stylohyoid muscle is a thin muscular strip 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
- Actions: Initiates swallowing action by pulling the hyoid bone in a posterior and superior direction
- Innervation: Stylohyoid branch of the facial nerve (arises proximally to the parotid gland)
Digastric
The digastric consists of two muscular bellies connected by an intermediate tendon
- Attachments:
- Anterior belly arises from the digastric fossa of the mandible
- 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
- Actions: Depresses the mandible and elevates the hyoid bone.
- Innervation:
- Anterior belly – inferior alveolar nerve, a branch of the mandibular division of the trigeminal nerve
- Posterior belly – digastric branch of the facial nerve
Mylohyoid
The mylohyoid is a broad, triangular shaped muscle which forms and supports the floor of the oral cavity
- Attachments: Originates from the mylohyoid line of the mandible, and attaches onto the hyoid bone
- Actions: Elevates the hyoid bone and the floor of the mouth
- Innervation: Inferior alveolar nerve, a branch of the mandibular division of the trigeminal nerve
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, then travels inferiorly and posteriorly to attach to the hyoid bone
- Actions: Depresses the mandible and elevates the hyoid bone
- Innervation: C1 nerve roots that run within the hypoglossal nerve
Variants
- Tendon of digastric pierces the stylohyoid muscle.