Lateral process of nasal septal cartilage

At a glance

English

Lateral process of nasal septal cartilage

Latin (TA2)

Processus lateralis cartilaginis septi nasi

System

Cartilage

Region

Head

Side

Paired, left and right

About the lateral process of nasal septal cartilage

The lateral process of the septal cartilage, better known as the upper lateral cartilage, is a thin triangular plate on each side of the middle third of the nose. It lies immediately below the lower edge of the nasal bone and fills the gap between that bone and the alar cartilage of the nostril. Although it is often described as a separate cartilage, it is really a wing of the septal cartilage: towards the top its front edge is fused with the dorsal border of the septum, so that the two together form a T-shaped or gabled roof along the bridge.

Its edges each have their own connection. The upper margin is tucked under the nasal bone and fixed there and to the maxilla's frontal process. The front margin is thicker than the back one; it merges with the septum above but is parted from it lower down by a narrow cleft. The lower margin is joined by fibrous tissue to the lateral crus of the major alar cartilage. At this junction the edge of the upper lateral cartilage often rolls outwards while the alar cartilage curls inwards, and the two interlock in a fold known as the scroll.

The angle between the lower edge of the upper lateral cartilage and the septum marks the internal nasal valve, the narrowest part of the airway in the nose. Air entering the nostril must pass through this slit, so small changes in its shape have a large effect on breathing. During a strong breath in, a weak or poorly supported cartilage can be drawn inwards and narrow the valve further.

Injury, ageing or reduction of the bony hump in rhinoplasty can let the cartilage collapse inwards at the valve, causing a blocked nose on one or both sides. Surgeons support it with spreader grafts placed between it and the septum, or with flaring sutures, to keep the valve open. A pinched look just below the nasal bones, called an inverted V deformity, shows when the cartilage has fallen away from the bone after surgery.

Attachments and function

Attaches from

Its upper margin is attached beneath the lower border of the nasal bone and to the adjoining maxillary frontal process.

Attaches to

Its front margin is fused above with the dorsal border of the septal cartilage, and its lower margin is joined by fibrous tissue to the lateral crus of the major alar cartilage.

Function

Forms and stiffens the side wall of the middle third of the nose and, with the septum, bounds the internal nasal valve.

Nerve supply

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

Blood supply

Branches of the facial artery (lateral nasal artery) and the dorsal nasal branch of the ophthalmic artery supply the covering tissues.