Tragus

The tragus is a small, cartilaginous projection situated anteriorly to the external auditory meatus.

Relations

The tragus is positioned anteriorly to the external auditory meatus and is surrounded by other components of the external ear, including the antitragus and the helix.

Arterial Supply

The tragus receives its blood supply from the posterior auricular artery and the superficial temporal artery, both of which are branches of the external carotid artery.

Venous Drainage

Venous drainage of the tragus is facilitated through the superficial temporal vein and the posterior auricular vein.

Innervation

The tragus is innervated primarily by the auriculotemporal nerve, a branch of the mandibular nerve (V3). There is also some sensory supply by the great auricular nerve, which is derived from the cervical spinal nerves C2 and C3 ¹.

Action

Although the tragus does not facilitate any particular action, it plays a passive role in directing sound into the ear.

Variant Anatomy

The size, shape, and angle of the tragus can vary widely among individuals, with no standard or "normal" morphology. Some individuals may also present with a bifid or "split" tragus, which is usually a congenital variation ².

Radiographic features

Plain radiograph

The tragus may not be clearly visible on plain radiographs due to its small size and cartilaginous composition.

Ultrasound

On high-resolution ultrasound, the tragus appears as a hypoechoic structure with a thin, bright echogenic rim representing the overlying skin and subcutaneous tissue.

CT

On computed tomography, the tragus appears as a soft tissue density anterior to the external auditory canal. It may be better appreciated on reconstructed images.

MRI

On magnetic resonance imaging, the tragus is seen as a cartilaginous structure with signal intensity similar to other cartilaginous structures of the body.

Development

The tragus, like the rest of the external ear, develops from the six hillocks of His, which are derived from the first and second pharyngeal arches. Specifically, the tragus arises from the first pharyngeal arch ¹.

History and etymology

The term "tragus" is derived from the Greek word "tragos," which means "goat." This term was likely chosen due to the tuft of hair often present on the tragus, resembling a goat's beard ².

Clinical importance

The tragus plays a crucial role in several medical procedures, primarily in ear examination and surgery. In otoscopy, the tragus is often pushed downward to straighten the external auditory canal for better visualization.

The tragus is also a common site for body piercing, and knowledge of its vascular and nervous supply is necessary to minimize risks and complications. Furthermore, the tragus has been implicated in certain clinical conditions such as otalgia and referred pain in trigeminal neuralgia ³.