The two muscles are in contact with each other proximally (close to their origin), but diverge distally (towards their insertions).
Origin The sternothyroid arises from the posterior surface of the
manubrium of the
sternum from the midline to the notch for the first rib (inferior to the origin of the
sternohyoid muscle), and the posterior margin of the
first costal cartilage.
Insertion It inserts onto the oblique line of the lamina of
thyroid cartilage.
Innervation The sternothyroid muscle receives motor innervation from branches of the
ansa cervicalis (ultimately derived from
cervical spinal nerves C1-C3).
Relations The sternothyroid muscle is shorter and wider than the
sternohyoid muscle and is situated deep to and partially medial to it.
Variations The muscle may be absent or doubled. It may issue accessory slips to the
thyrohyoid muscle,
inferior pharyngeal constrictor muscle, or the
carotid sheath.
Actions/movements The sternothyroid muscle indirectly depresses the hyoid bone by means of pulling the thyroid. When the hyoid bone is fixed, it instead elevates the larynx (producing an increased voice
pitch). ==Clinical significance==