ANATOMY

Depressor Labii Inferioris Muscle is located in the jaw area. This muscle originates from oblique line of Mandible. It ends on the skin of the lower lip and blends with the Orbicularis Oris Muscle (circular muscle). At the start the Depressor Labii Inferioris fibers are in continuation with the fibers of Platysma Muscle (superficial muscle overlapping muscle of neck). Fibers of this muscle are lined with yellow fat.

INNERVATION

Mandibular division of the Facial Nerve, Cranial Nerve VII innervates this Muscle.

BLOOD SUPPLY

Interior Labial branch of the Facial Artery supplies the blood to the Depressor Labii Inferioris Muscle.

FUNCTION

The main function of this muscle is to depress the lower lip. It allows Facial expressions like playing of trumpet and kissing. It pulls the lower lip downward slightly to the lateral side. It also helps in eversion (turning inside out) of lip.

CLINICAL SIGNIFICANCE

Depressor Labii Inferioris Muscle is affected by variety of medical disorders which are as follows.

• Myalgia

• Stroke

• Myopathy

• Strain

• Bell’s Palsy

• Tear

• Contusions

• Neuromuscular diseases

The symptoms related to any of the before mentioned disease include decrease movements of lip, loss of muscle control, paralysis and Muscle spasms.