SUPRAHYOID MUSCLES
SUPRAHYOID MUSCLES
- The suprahyoid muscles are four muscles located above the hyoid bone in the neck.
- They are the digastric, stylohyoid, geniohyoid, and mylohyoid muscles.
- Anterior belly of digastric, Mylohyoid dervied from 1st branchial arch
- Second branchial arch give rise to stylohyoid, posterior belly of digastric muscles
- They are all pharyngeal muscles, with the exception of the geniohyoid muscle.
- The digastric is uniquely named for its two bellies eg Muscle fibers in the ligament of Treitz, Omohyoid, Occipitofrontalis
| Muscle | Origin | Insertion | Innervation |
|---|---|---|---|
| Digastric (anterior belly) | Digastric fossa of Mandible | Intermediate Tendon | Mylohyoid nerve – branch of CN V3 (Mandibular division of Trigeminal nerve) |
| Digastric (posterior belly) | Mastoid notch | Intermediate Tendon | Facial nerve |
| Geniohyoid | Inferior mental spine of Symphysis menti | Hyoid | C1 via the hypoglossal nerve (XII) |
| Stylohyoid | Temporal styloid process | Hyoid | Facial nerve |
| Mylohyoid | Mylohyoid line of mandible | Hyoid | Mylohyoid nerve – branch of CN V3 (Mandibular division of Trigeminal nerve) |
FUNCTIONS:
- These four muscles have different actions, but in general assist in elevating the hyoid bone and widening the esophagus during swallowing.
- Submandibular gland is divided into superficial and deep parts by mylohyoid.
- When the two bellies of the digastric contract, they pull upward on the hyoid bone; but if the hyoid is fixed from below, the digastric assists in extreme opening of the mouth such as yawning or taking a large bite of an apple.
- Stylohyoid & digastric are elevators of larynx.
- The mylohyoid elevates the hyoid bone, tenses the floor of the mouth.
- The Geniohyoid pulls the hyoid bone anterosuperiorly, shortening the floor of the mouth and widening the pharynx during swallowing.
- The Stylohyoid elevates and retracts the hyoid bone, elongating the floor of the mouth during swallowing
Exam Question
- Digastric muscles refers to muscles with two bellies are Muscle fibers in the ligament of Treitz, Omohyoid, Occipitofrontalis.
- Posterior belly of digastric is supplied by Facial nerve.
- Mylohyoid nerve – branch of CN V3 (Mandibular division of Trigeminal nerve) innervates anterior belly of trigeminal nerve.
- Second branchial arch give rise to stylohyoid, posterior belly of digastric muscles.
- Stylohyoid & digastric are elevators of larynx.
- Stylohyoid muscle is supplied by Facial nerve.
- Submandibular gland is divided into superficial and deep parts by mylohyoid.
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