Suprahyoid Muscles

The suprahyoid muscles are a group of four muscles:
- Located superior to the hyoid bone of the neck
They all act to elevate the hyoid bone:
- An action involved in swallowing
The arterial supply to these muscles:
- Is via branches of the facial artery, occipital artery, and lingual artery
Stylohyoid muscle:
- Is a thin muscular strip:
  - Which is located superiorly to the posterior belly of the digastric muscle
- Attachments:
  - Arises from the styloid process of the temporal bone
  - Attaches to the lateral aspect of the hyoid bone
- Actions:
  - Initiates a swallowing action:
    - By pulling the hyoid bone in a posterior and superior direction
- Innervation:
  - Stylohyoid branch of the facial nerve (CN VII)
    - This arises proximally to the parotid gland

The digastric muscle:
- Is comprised of two muscular bellies:
  - Which are connected by a tendon:
    - In some cadaveric specimens, this tendon can be seen to pierce the stylohyoid muscle
- Attachments:
  - The anterior belly arises from the digastric fossa of the mandible
  - The 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:
  - The anterior belly is innervated by the inferior alveolar nerve:
    - A branch of the mandibular nerve:
      - Which is derived from the trigeminal nerve, CN V
  - The posterior belly:
    - Is innervated by the digastric branch of the facial nerve
Mylohyoid muscle:
- Is a broad, triangular shaped muscle
- It forms the floor of the oral cavity and supports the floor of the mouth
- Attachments:
  - Originates from the mylohyoid line of the mandible
  - 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 nerve:
      - Which is derived from the trigeminal nerve
Geniohyoid muscle:
- Is located either side of the midline of the neck:
  - Deep to the mylohyoid muscle
- Attachments:
  - Arises from the inferior mental spine of the mandible
  - It 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