CorpusHuman Anatomy
RespiratoryOrgan part

External nose

Nasus externus

Also known as: nose, nares, nostrils

The pyramidal projection of the face whose bony and cartilaginous framework supports the nostrils (nares), the entry point for inspired air.

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Overview

The external nose has a bony upper third — paired nasal bones, frontal processes of the maxillae and the nasal part of the frontal bone — and a cartilaginous lower two-thirds formed by the paired lateral (upper lateral) cartilages, the major and minor alar cartilages and the septal cartilage. The alae are partly fibro-fatty. Each naris opens into a nasal vestibule lined with skin bearing coarse hairs (vibrissae) and sebaceous glands that trap large particles.

The narrowest part of the airway, the internal nasal valve (between the caudal edge of the lateral cartilage and the septum), provides up to half of total airway resistance during nasal breathing. Dilator naris muscles (supplied by the facial nerve) flare the nostrils in respiratory distress — a recognisable clinical sign in infants.

Location

Midline of the face, projecting from the anterior opening of the bony nasal cavity (piriform aperture).

Parts & subdivisions

  1. Root and dorsum
    The root lies at the nasion (frontonasal suture); the dorsum runs down to the tip (apex).
  2. Nasal bones
    Paired bones forming the bridge; the most frequently fractured facial bones.
  3. Lateral and alar cartilages
    Hyaline cartilages that shape the lower nose; the major alar cartilage has medial and lateral crura surrounding each naris.
  4. Nasal vestibule
    Skin-lined dilatation just inside each naris, with vibrissae; separated from the respiratory region by the limen nasi.

Anatomy

Innervation

Sensory: infratrochlear and external nasal branches of the ophthalmic nerve (CN V1) and infra-orbital nerve (CN V2). Motor to nasal muscles: facial nerve (CN VII).

Arterial supply

Facial artery (lateral nasal and superior labial branches); dorsal nasal branch of the ophthalmic artery; infra-orbital artery.

Venous drainage

Facial vein and ophthalmic veins; the latter communicate with the cavernous sinus.

Lymphatic drainage

Submandibular lymph nodes.

Function

  • Directs inspired air into the nasal cavity.
  • Filters large particles with vibrissae.
  • Contributes to nasal airway resistance that slows and conditions airflow.

Clinical significance

Danger triangle of the face

Infections of the skin around the nose and upper lip can spread through valveless facial and ophthalmic veins to the cavernous sinus, causing cavernous sinus thrombosis.

Nasal fracture

Common after facial trauma; always inspect for a septal haematoma, which must be drained urgently to prevent cartilage necrosis and saddle-nose deformity.

Compiled from standard anatomy and physiology references — see the Respiratory System sources. For education only; not medical advice.