The Suprahyoid Muscles

• This group of muscles is located superior to the hyoid bone and connects to this bone and the skull.
• This group includes the mylohyoid, geniohyoid, stylohyoid and digastric muscles.

The Mylohyoid Muscles 

• These are thin, flat triangular muscles that form a sling inferior to the tongue.
• They form the floor of the mouth.
• Role of these muscles in grinding the food in the mouth.

• Superior attachment: mylohyoid line of mandible.
• Inferior attachment: raphe and body of hyoid bone.
• Innervation: mylohyoid nerve, a branch of the inferior alveolar nerve.

• It elevates the hyoid bone, floor of the mouth and the tongue during swallowing and speaking.

Geniohyoid Muscles 

• These are short narrow muscles that contact each other in the median plane.
• They are located superior to the mylohyoid muscles, where they reinforce the floor of the mouth.

• Superior attachment: inferior mental spine of mandible.
• Inferior attachment: body of hyoid bone.
• Innervation: C1 via the hypoglossal nerve (CN XII).

• It pulls the hyoid bone anterosuperiorly, and shortens the floor of the mouth and widens the pharynx.

The Stylohyoid Muscles 

• These muscles form a small slip on each side, which is nearly parallel to the posterior belly of the digastric muscle.

• Superior attachment: styloid process of the temporal bone.
• Inferior attachment: body of hyoid bone.
• Innervation: Stylohyoid branch of facial nerve (CN VII).

• It elevates and retracts the hyoid bone, thereby elongating the floor of the mouth.

The Digastric Muscles 

• Each of the strap-like muscles has two bellies (G. gaster, belly) that descend toward the hyoid bone.
• They are joined by an intermediate tendon that is connected to the body and the greater horn of the hyoid bone by a strong loop or sling of fibrous connective tissue.
• This fibrous pulley allows the intermediate tendon to slide anteriorly and posteriorly.

• Superior attachment: anterior belly-digastric fossa of mandible, posterior belly-mastoid notch of temporal bone.
• Inferior attachment: intermediate tendon to body and greater horn of hyoid bone.
• Innervation: anterior belly-mylohyoid nerve, a branch of the inferior alveolar nerve, posterior belly-facial nerve (CN VII).

• It depresses the mandible and raises the hyoid bone. Also, it steadies the hyoid bone during swallowing and speaking.

 

Mylohyoid muscle alnwith lingual nerve and submandibular and sunlingual gland