Unit 5: Second Order

Head and Neck

Zygomaticus major M Origin

Zygomatic bone

Zygomaticus major M Insertion

Skin at superolateral edge of mouth

Zygomaticus major M Action

Elevates corner of the mouth (“smile” muscle)

Zygomaticus major M Innervation

CN VII (facial nerve)

Buccinator M Origin

Alveolar processes of mandible and maxillae

Buccinator M Insertion

Orbicularis oris

Buccinator M Action

Compresses cheek; holds food between teeth during chewing (“trumpet-blowing” muscle)

Buccinator M Innervation

CN VII (facial nerve)

Sternohyoid M Origin

Manubrium of sternum and medial end of clavicle

Sternohyoid M Insertion

Hyoid bone

Sternohyoid M Action

Depresses hyoid bone

Sternohyoid M Innervation

Cervical spinal nerves C1–C3 through ansa cervicalis (from cervical plexus)

Sternocleidomastoid M (sternal & clavicular

heads) Origin

Manubrium and sternal end of clavicle

Sternocleidomastoid M (sternal & clavicular

heads) Insertion

Mastoid process of temporal bone

Sternocleidomastoid M (sternal & clavicular

heads) Action

Unilateral action: Lateral flexion, rotation of head to opposite side

Bilateral action: Flexes neck

Sternocleidomastoid M (sternal & clavicular

heads) Innervation

CN XI (accessory nerve)

Hyoglossus M Origin

Hyoid bone

Hyoglossus M Insertion

Inferolateral side of tongue

Hyoglossus M Action

Depresses and retracts tongue

Hyoglossus M Innervation

CN XII (hypoglossal nerve)

Genioglossus M Origin

Mental spines of mandible

Genioglossus M Insertion

Inferior region of tongue; hyoid bone

Genioglossus M Action

Protracts tongue

Genioglossus M Innervation

CN XII (hypoglossal nerve)