Veterinary Gross Anatomy-II

MUSCLES OF THE NOSTRILS

• Levator naso labialis
• Dilator naris lateralis
• Dilator naris apicalis
• Dilator naris superioris (dorsal part )
• Dilator naris inferioris (ventral part)

Levator naso labialis

• The muscle is thin and extensive and extends in oblique direction from the inferior border of the frontalis muscle to the nostril and the upper lip. It is elongated from above downwards and covers the external face of the nasal region.
• Origin: Frontal and nasal bones.
  • The muscle divides below into two layers-superficial and deep. The superficial part passes over the lateral face of the levator labi superioris proprius and dilator naris lateralis. The deep division is thin, aponeurotic and passes beneath the above said muscles.
• Insertion: Upper lip and lateral part of the nostril.
• Action: To elevate the upper lip and dilate the nostril.
• Blood supply: Facial, dorsal, labial and malar arteries.
• Nerve supply: Facial nerve.

Dilator naris lateralis (Caninus)

• This a narrow band placed between the levator labii superioris proprius and depressor labii superioris muscles.
• Origin: Facial tuberosity.
• Insertion: Lateral wing of the nostril.
• Action: To dilate the nostril.
• Blood supply: Superior labial artery.
• Nerve supply: Facial nerve.

Dilator naris apicalis

• It is situated in the muzzle.
• Origin: Body of the premaxilla.
• Insertion: Medial wing of the nostril.
• Action: To dilate the nostril.
• Blood supply: Naso labial arteries.
• Nerve supply: Facial nerve

Dilator naris superioris (dorsal part)

• It is very small, short thin muscle.
• Origin: Alar cartilage of the nostril.
• Insertion: Medial wings of nostril.
• Action: To dilate the nostril.
• Blood supply: Facial and infra orbital arteries.
• Nerve supply: Facial and infraorbital nerves.

Dilator naris inferioris (ventral part)

• This muscle is arranged in two layers
• Origin: Nasal process of premaxilla.
• Insertion: Lateral wing of the nostril.
• Action: To dilate the nostril.
• Blood supply: Facial and infra orbital arteries.
• Nerve supply: Facial and infraorbital nerves.