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

Depressor Labii Inferioris

Musculus depressor labii inferioris

Origin

Inferior border of the mandible, between the symphysis and the mental foramen

Insertion

Skin and mucosa of the lower lip, interweaving with the contralateral muscle

Function

Pulls the lower lip downward and slightly laterally, as in mockery or irony

Innervation

Marginal mandibular branch of the facial nerve (CN VII)

Movement & chain

Pulls the lower lip downward and slightly laterally; a mimetic movement.

Palpation

Palpable between the chin and lower vermilion border deep to depressor anguli oris.

Clinical

Part of the same marginal-mandibular-branch group as the depressor anguli oris; loss of function causes an asymmetric lower lip during speech or smiling.

Segmental innervation

CN VII, motor.

In clinical practice

Depresses and everts lower lip; targeted training to restore oral continence during drinking and oral hygiene.

Region in the model

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