Musculus depressor labii superioris
Works antagonistically to the levator, pulling the upper lip downward. Important for fine motor control during selective grazing and object manipulation.
Origin: Facial crest of the maxilla
Insertion: Upper lip
Action: Depresses the upper lip
Innervation: Ventral buccal branch of facial nerve (CN VII)
Loss of fine lip control from nerve damage affects the horse's ability to sort feed and graze selectively.
Loss of fine lip control from nerve damage affects the horse's ability to sort feed and graze selectively. Signs include: Messy eating; inability to pick up small treats or grain; upper lip appears stiff or immobile; hay strands hanging from mouth.
See the Depressor of the Upper Lip on our interactive 3D horse model. Open 3D Model