There are four Infrahyoid muscles and four Suprahyoid muscles:
Infrahyoids: sternohyoid, sternothyroid, thyrohyoid, omohyoid
Suprahyoids: Digastric, stylohyoid, mylohyoid, geniohyoid
Most of the attachments of the hyoids are indicated in their names:
- As a group, the infrahyoids attach superiorly into the hyoid bone.
- As a group, the suprahyoids attach inferiorly into the hyoid bone and superiorly into the mandible.
- Note: The sternothyroid does not directly attach into the hyoid bone; and the stylohyoid does not attach into the mandible.
- Note: there are two bellies to the omohyoid and two bellies to the digastric.
- As a group, the infrahyoids depress the hyoid bone and assist in flexing the neck at the spinal joints.
- As a group, the suprahyoids elevate the hyoid bone and assist in flexing the neck at the spinal joints.
- The digastric, mylohyoid, and geniohyoid also depress the mandible at the temporomandibular joints.