Learning objective
Identify the suprahyoid muscles, their attachments, actions, and innervation, and understand their role in elevating the hyoid bone during swallowing.
The suprahyoid muscles are a group of four muscles located superior to the hyoid bone. They elevate the hyoid bone, an important movement during swallowing.
The arterial supply is provided by branches of the facial artery, occipital artery, and lingual artery.
Overview of suprahyoid muscles
| Muscle | Attachments | Actions | Innervation |
|---|---|---|---|
| Stylohyoid | Origin: Styloid process of the temporal bone Insertion: Lateral aspect of the hyoid bone |
Pulls the hyoid bone posteriorly and superiorly to initiate swallowing | Stylohyoid branch of CN VII (facial nerve) |
| Digastric | Anterior belly: digastric fossa of mandible Posterior belly: mastoid process of the temporal bone Connected via an intermediate tendon attached to the hyoid bone |
Depresses mandible; elevates hyoid bone | Anterior belly: Inferior alveolar nerve (CN V3) Posterior belly: Digastric branch of CN VII |
| Mylohyoid | Origin: Mylohyoid line of the mandible Insertion: Hyoid bone |
Elevates the hyoid bone & the floor of the mouth | Inferior alveolar nerve (CN V3) |
| Geniohyoid | Origin: Inferior mental spine of mandible Insertion: Hyoid bone |
Depresses mandible; elevates hyoid bone | C1 via hypoglossal nerve (CN XII) |
Tip: The digastric tendon sometimes pierces the stylohyoid muscle in cadaveric specimens.
Key functional points
- All suprahyoid muscles elevate the hyoid bone → essential for swallowing.
- Some also assist in mandibular depression (digastric anterior belly, geniohyoid).
- Mylohyoid forms the floor of the oral cavity, supporting the tongue and mouth floor.
Clinical relevance
- Damage to the facial nerve (CN VII) can affect the stylohyoid and posterior digastric, impairing swallowing.
- Injury to C1 fibers in the hypoglossal nerve can impact geniohyoid function, leading to reduced hyoid elevation.
- Understanding these muscles is critical during submandibular or neck surgeries to avoid nerve injury.
