The arytenoid cartilage

Cartilage

Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...

s are a pair of small three-sided pyramid

Pyramid

A pyramid is a structure whose outer surfaces are triangular and converge at a single point. The base of a pyramid can be trilateral, quadrilateral, or any polygon shape, meaning that a pyramid has at least three triangular surfaces...

s which form part of the larynx

Larynx

The larynx , commonly called the voice box, is an organ in the neck of amphibians, reptiles and mammals involved in breathing, sound production, and protecting the trachea against food aspiration. It manipulates pitch and volume...

, to which the vocal folds

Vocal folds

The vocal folds, also known commonly as vocal cords, are composed of twin infoldings of mucous membrane stretched horizontally across the larynx...

 (vocal cords) are attached. These allow and aid in the vocal cords' movement.

Each is pyramidal in form, and has three surfaces, a base, and an apex.

Surfaces

The posterior surface is a triangular, smooth, concave, and gives attachment to the Arytænoidei obliquus and transversus.

The antero-lateral surface is somewhat convex and rough. On it, near the apex of the cartilage, is a rounded elevation (colliculus) from which a ridge (crista arcuata) curves at first backward and then downward and forward to the vocal process

Vocal process

The anterior angle of the base of the arytenoid cartilage projects horizontally forward; it gives attachment to the vocal ligament, and is called the vocal process....

. The lower part of this crest intervenes between two depressions or foveæ, an upper, triangular, and a lower oblong in shape; the latter gives attachment to the Vocalis muscle.

The medial surface is narrow, smooth, and flattened, covered by mucous membrane

Mucous membrane

The mucous membranes are linings of mostly endodermal origin, covered in epithelium, which are involved in absorption and secretion. They line cavities that are exposed to the external environment and internal organs...

, and forms the lateral boundary of the intercartilaginous part of the rima glottidis

Rima glottidis

The rima glottidis is the opening between the true vocal cords and the arytenoid cartilages.It is normally subdivided into two parts, that between the arytenoid cartilages is called the intercartilaginous part , and that between the vocal folds the intermembranous part or glottis vocalis.It is...

.

Base and apex

The base of each cartilage is broad, and on it is a concave smooth surface, for articulation with the cricoid cartilage.

• Its lateral angle is called the muscular process

• Its anterior angle is called the vocal process
  Vocal process
  The anterior angle of the base of the arytenoid cartilage projects horizontally forward; it gives attachment to the vocal ligament, and is called the vocal process....
  
  

The apex of each cartilage is pointed, curved backward and medialward, and surmounted by a small conical, cartilaginous nodule, the corniculate cartilage.

Function

They allow the vocal folds

Vocal folds

The vocal folds, also known commonly as vocal cords, are composed of twin infoldings of mucous membrane stretched horizontally across the larynx...

 to be tensed, relaxed, or approximated.

The arytenoids articulate with the supero-lateral parts of the cricoid cartilage lamina, forming the cricoarytenoid joints at which they can come together

Adduction

Adduction is a movement which brings a part of the anatomy closer to the middle sagittal plane of the body. It is opposed to abduction.-Upper limb:* of arm at shoulder ** Subscapularis** Teres major** Pectoralis major** Infraspinatus...

, move apart, tilt anteriorly or posteriorly, and rotate.