Head and neck muscles (chewing, facial, and throat muscles)

Orbicularis oris

Musculus orbicularis oris

Origin

Partly intrinsic, formed by crossing fibers of surrounding facial muscles, with a small bony anchor at the incisive fossa of the maxilla and mandible near the midline

Insertion

Skin and mucosa of the lips, converging at the modiolus at the corners of the mouth

Function

Closes and purses the lips; essential for speech (articulation of labial sounds), sucking, whistling and holding food/liquid in the mouth

Innervation

Facial nerve (CN VII), buccal branches and the marginal mandibular branch

Movement & chain

Works together with the radiating muscles of the mouth (e.g. buccinator, levator/depressor anguli oris) via the modiolus as a central anchor point for facial expression and speech movement

Palpation

Directly felt and seen around the lips when pursing or tensing the mouth.

Clinical

Paralysis in a peripheral CN VII palsy (e.g. Bell's palsy) causes asymmetric drooping of the mouth corner and drooling on the affected side.

Segmental innervation

Facial nerve (VII), motor.

In clinical practice

Oral sphincter muscle; myofunctional therapy and lip closure training in Bell's palsy to restore oral competence and prevent drooling.

Region in the model

Head and neck muscles (chewing, facial, and throat muscles)