MUSCLES OF NECK

Muscles not attached to Hyoid bone (Atlas Fig. 8.5, 8.6, 8.7)

MUSCLE

ORIGIN

INSERTION

ACTION

NERVE

Sternocleidomastoid

Two heads

1) Sternum - Manubrium

2) Clavicle - medial 1/3

Both heads to

Temporal bone - Mastoid process

Acting on both sides - flex neck;

Acting singly - rotate head so face is directed to opposite side

Accessory nerve (XI)

Scalenus anterior and Scalenus medius

Vertebra- transverse processes of upper cervical

Rib 1

Flex neck and elevate rib 1

branches of ventral rami of cervical spinal nerves

Infrahyoid muscles (Atlas Fig. 6.26A, 8.12, 8.13)

MUSCLE	ORIGIN	INSERTION	ACTION	NERVE
Omohyoid (Muscle has two bellies connected by an intermediate tendon)	Inferior belly from Scapula - medial to suprascapular notch (Intermediate tendon - linked to clavicle and rib 1) Superior belly - continues to insertion	Hyoid Bone	Depresses hyoid bone	Ansa cervicalis
Sternohyoid	Sternum - manubrium Clavicle	Hyoid bone	Depresses hyoid bone	Ansa cervicalis
Sternothyroid	Sternum - manubrium	Thyroid cartilage	Depresses thyroid cartilage, indirectly depresses hyoid bone, larynx	Ansa cervicalis
Thyrohyoid	Thyroid cartilage	Hyoid bone	Depresses hyoid bone, elevates larynx	C1 via branch hitch-hiking with Hypoglossal nerve (XII)

Suprahyoid muscles (Atlas Figs. 8.16, 8.13, 8.22, 8.62)

MUSCLE	ORIGIN	INSERTION	ACTION	NERVE
Digastric (has two bellies)	Posterior belly from Temporal bone - mastoid notch (medial to mastoid process) Anterior belly from Mandible - inner side	Hyoid Bone - via intermediate tendon	Elevates hyoid bone, Depresses mandible	Posterior belly - Facial nerve (VII) Anterior belly - Trigeminal nerve (V3)
Stylohyoid	Temporal bone - styloid process	Hyoid bone	Elevates hyoid bone	Facial nerve (VII)
Mylohyoid	Mandible - mylohyoid line	Hyoid bone	Elevates hyoid bone, Raises floor of mouth during swallowing	Trigeminal nerve (V3)
Geniohyoid	Mandible - inner side	Hyoid bone	Elevates hyoid bone, draws hyoid forward	C1 via branch hitch-hiking with Hypoglossal nerve (XII)