Anatomy 2300 Muscles of the Head and Neck

Muscles of facial expression

Originate on the surface of the skull and insert into the superficial fascia and dermis of skin

When they contract, they move the skin

Innervated by CN VII Facial

Frontalis m.

Draws scalp anteriorly

Raises eyebrows

Wrinkles forehead

Occipitalis m.

Draws scalp posteriorly

Epicranial aponeurosis

What connects the frontalis and occipitalis muscles to form the occipitofrontalis muscle?

Orbicularis oculi m.

Encircles the eye

Closes the eye

Buccinator m.

Presses cheeks against teeth and lips

Orbicularis oris m.

Encircles the mouth

Closes and protrudes lips (duck face)

Platysma m.

Draws out part of lower lip inferiorly and posteriorly (pouting)

Tenses skin of neck

Very thin

Muscles of Mastication

Origin and insertion on bone

Innervated by mandibular division of CN V Trigeminal

Temporalis m.

Runs from the temporal fossa to the coronoid process of the mandible

Elevates (closes) and retracts the mandible

Masseter m.

Runs from the zygomatic arch to the ramus and coronoid process of the mandible

Elevates the mandible

Lateral pterygoid m.

Runs from the lateral side of the lateral pterygoid plate to the condyle of the mandible

Depresses (opens), protracts, and moves the mandible side to side

Medial pterygoid m.

Runs from the medial side of the lateral pterygoid plate to the medial surface of the angle of the mandible

Elevates, protracts, and moves the mandible side to side

The muscle shown in green in the picture

Neck muscles

Region of muscles innervated by CN XI Accessory

Trapezius m.

Elevates and retracts the scapula

Sternocleidomastoid m.

Originates on the sternum and medial portion of the clavicle

Inserts onto the mastoid process

Bilaterally, flexes cervical portion of the vertebral column

Unilaterally, rotates head to the opposite side

Suprahyoid muscles

Superior to hyoid bone, depresses the mandible and elevates the hyoid bone

Infrahyoid muscles

Inferior to hyoid bone, stabilizes the hyoid bone