Cricoid cartilage

Cartilago cricoidea

A signet-ring-shaped cartilage at C6 — the only complete cartilaginous ring in the airway — forming the base of the larynx and marking the start of the trachea and oesophagus.

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Overview

Vertebral levelC6

The cricoid has a narrow anterior arch and a tall posterior lamina. Its upper border carries facets for the arytenoid cartilages (synovial cricoarytenoid joints, which allow rotation and gliding of the arytenoids), and its sides carry facets for the inferior horns of the thyroid cartilage (cricothyroid joints). The lower border is joined to the first tracheal ring by the cricotracheal ligament.

The lower border of the cricoid at C6 is a key landmark: here the larynx becomes the trachea, the pharynx becomes the oesophagus, the inferior thyroid artery crosses behind the carotid sheath, and the middle cervical sympathetic ganglion lies close by. Being a complete ring, it is the narrowest point of the infant airway (subglottis) and does not yield to oedema or tube cuffs.

Location: Anterior neck at C6, below the thyroid cartilage and cricothyroid membrane, above the first tracheal ring.

Parts & subdivisions

Arch
Narrow anterior part; palpable below the cricothyroid membrane.
Lamina
Broad posterior plate; posterior cricoarytenoid muscles arise from it.
Articular facets
For the arytenoids (upper border) and the inferior thyroid horns (sides).

Anatomy

Articulations: Cricoarytenoid and cricothyroid joints (synovial).
Ligaments: Median cricothyroid ligament (to thyroid), cricotracheal ligament (to first tracheal ring), conus elasticus.
Histology: Hyaline cartilage; may ossify with age.

Function

Provides a rigid base for the larynx and keeps the subglottic airway open.
Articulates with the arytenoids, allowing vocal fold abduction/adduction.
Attachment for the trachea, cricothyroid, posterior and lateral cricoarytenoid muscles and the inferior constrictor (cricopharyngeus).

Clinical significance

Cricoid pressure (Sellick manoeuvre)

Backward pressure on the cricoid during rapid-sequence induction compresses the oesophagus against C6 to reduce regurgitation; its effectiveness is debated and it can worsen the laryngoscopic view.

Subglottic stenosis

Prolonged intubation, especially of neonates, can injure the mucosa within the rigid cricoid ring and cause scarring and stenosis with stridor.

Cricoarytenoid arthritis

Rheumatoid arthritis can fix the cricoarytenoid joints, causing hoarseness and even stridor.

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