Major alar cartilage

At a glance

English

Major alar cartilage

Latin (TA2)

Cartilago alaris major

System

Cartilage

Region

Head

Side

Paired, left and right

About the major alar cartilage

The major (greater) alar cartilage is the main cartilage of the lower third of the nose. Right and left cartilages lie side by side and together give the tip its form. Each is a thin, springy plate of hyaline cartilage bent sharply on itself into a narrow U, so that it wraps around the front of the nostril. The bend forms a dome, and the two domes lying side by side make up the tip of the nose, with a slight notch between them that can sometimes be felt.

The plate has two limbs. The medial crus runs back in the columella, the strip of tissue between the nostrils, lying against its partner from the other side and in front of the lower edge of the septal cartilage. The lateral crus is broader and curves outwards and backwards in the ala, the wing of the nostril, but does not reach the lower edge of the ala, which is made of fibrofatty tissue. Its upper border is linked to the lower edge of the upper lateral cartilage by fibrous tissue, and further back it is joined to the edge of the piriform aperture by small minor alar cartilages set in a fibrous membrane.

By forming both the inner and the outer wall of each nostril, the cartilage keeps the entrance of the nose open and resists collapse when air is drawn in quickly. It frames the external nasal valve, the nostril opening itself, and so governs how freely air reaches the internal valve further up. Small muscles of the nose, the dilator naris and depressor septi, act on the alar tissues to widen or narrow the opening.

In some people the lateral crus is weak or concave and the nostril sucks inwards on breathing in. Surgeons reshape or support the cartilage with grafts or with techniques such as the sliding alar cartilage method, which restructures the lateral crus to stiffen the tip. The shape, angle and spacing of the domes are also the main targets when the nasal tip is refined in rhinoplasty.

Attachments and function

Attaches from

The medial crus lies in the columella against its partner, near the lower border of the septal cartilage.

Attaches to

The lateral crus is attached by fibrous tissue to the upper lateral cartilage above and, through minor alar cartilages, to the margin of the piriform aperture behind.

Function

Shapes the nasal tip and nostril, holding the naris open and resisting inward collapse on breathing in.

Nerve supply

The overlying skin is supplied by the external nasal branch of the anterior ethmoidal nerve and the infra-orbital nerve.

Blood supply

The lateral nasal and superior labial branches of the facial artery, through the alar and columellar vessels.