The thyrohyoid muscle depresses the hyoid bone and elevates the larynx during swallowing.

[1] Its inferior attachment[note 2][1] is the oblique line of the thyroid cartilage (alongside the sternothyroid muscle[1]).

[2][1][3]: 538 The thyrohyoid muscle is innervated (along with the geniohyoid muscle[1][3]: 457, 709 ) by a branch of the cervical plexus[4][3]: 538  - the nerve to thyrohyoid muscle (thyrohyoid branch of ansa cervicalis)[4] - which is formed by fibres of the cervical spinal nerve 1 (C1)[1][2][3]: 538  (and - according to some sources - cervical spinal nerve 2 as well[4][3]: 457 ) that join and travel with the hypoglossal nerve (CN XII)[2] before splitting away from it[1][2] distal to the superior root of ansa cervicalis.

[1] The thyrohyoid muscle forms the inferior boundary of the carotid triangle.

[6] This article incorporates text in the public domain from page 394 of the 20th edition of Gray's Anatomy (1918)