Ringbrosket

Ringbrosket, or ring cartilage, refers to hyaline cartilage arranged in circular or crescent-shaped structures that reinforce certain tubular passages in the body. The most familiar example is the tracheal ring system in humans and many other mammals, which provides structural support to the airway.

Anatomically, the trachea is reinforced by C-shaped hyaline cartilage rings that surround the anterior and lateral aspects of the airway. The open posterior side is bridged by the trachealis muscle and adjacent connective tissue, allowing flexibility for swallowing and movement. The rings are connected by annular ligaments and are covered by a perichondrium. Cartilage is avascular and relies on diffusion from surrounding tissues for nutrients.

The primary function of ring cartilage is to keep the airway open and resist collapse during breathing, especially during inspiration when negative intrathoracic pressure is generated. The posterior flexible portion accommodates changes in the esophagus during swallowing, while the rigid rings maintain airway diameter. With aging, hyaline cartilage can undergo calcification, which may be visible on imaging.

Developmentally, tracheal ring cartilage arises from mesenchymal cells associated with the embryonic pharyngeal arches and differentiates into chondrocytes within a cartilaginous matrix rich in type II collagen and proteoglycans. The tissue is typically avascular, gaining nutrients by diffusion.

Clinically, weakened or improperly formed ring cartilage can lead to tracheomalacia or airway obstruction in congenital anomalies. Calcification of the rings can be observed in imaging studies of older adults and is generally a normal aging change rather than a disease.