Movement of the head and neck

Question 1

Where are the suprahyoid muscles located? Are they paired or singular?

Answer 1

They are located superior to the hyoid bone. All the muscles are paired on the right and the left

Question 2

What is their main action(s)?

Answer 2

If the infrahyoid muscles contract first, it stabilises the hyoid bone and causes depression of the mandible
If the Suprahyoid muscles contract first, it elevates the hyoid bone and causes Swallowing.

Question 3

What is the action, innervation and position of the stylohyoid?

Answer 3

Action: Pulls the hyoid bone posteriorly and superiorly
Innervation: Facial nerve (CN VII)
Position: It originates from the styloid process and inserts onto the hyoid bone

Question 4

What is the action, innervation and position of the digastric?

Answer 4

Action: Elevate the hyoid bone and depress the mandible
Innervation: Anterior by Mandibular branch of Trigeminal Nerve (CN V3) and posterior by Facial nerve (CN VII) Lies close to the stylohyoid.
Position: Has two muscle bellies, the anterior belly is from the digastric fossa of mandible, and the posterior from the mastoid process. They both insert onto the hyoid bone.

Question 5

What is the action, innervation and position of the mylohyoid?

Answer 5

Action: Elevates the floor of the mouth and elevates the hyoid bone.
Innervation: Mandibular branch of Trigeminal Nerve (CN V3). Lies inferior to the anterior digastric.
Position: Originates from the mandible and inserts onto the hyoid bone. It is a broad wide muscle that forms the floor of the oral cavity

Question 6

What is the action, innervation and position of the geniohyoid?

Answer 6

Action: Depresses the mandible and elevates the hyoid bone
Innervation: Hypoglossal nerve (CN XI)
Position: Starts from the chin and inserts onto the hyoid bone. Sits most inferiorly, deep to the mylohyoid and close to the midline.