Clinical anatomy of the external ear
The human external ear consists of the auricle (auricula) and the external acoustic meatus. The auricle is formed by cartilage and the lobule (lobulus), which is a cutaneous duplication containing adipose tissue without cartilage. On the anterior surface, the skin is firmly fused with the perichondrium, while on the posterior surface, it is mobile.
The anatomical elements of the auricle include:
- Helix (helix)
- Anthelix (anthelix)
- Tragus (tragus), covering the entrance to the acoustic meatus
- Antitragus (antitragus)
- Triangular fossa (fossa triangularis) and scapha (scapha)
Anatomy is of great diagnostic significance. For example, the symptom of pressure on the tragus in adults indicates inflammation of the external acoustic meatus, whereas in infants, it indicates acute otitis media due to the short acoustic meatus and the transmission of pressure to the tympanic membrane.
Etiology and pathways of infection entry
Middle ear inflammation is predominantly caused by cocci, such as Streptococcus and Pneumococcus. Infection can penetrate the middle ear via the following pathways:
- Tubal pathway (main) — from the nasopharynx through the auditory tube.
- Hematogenous pathway — via the bloodstream in infectious diseases, including measles, scarlet fever, and influenza.
- Traumatic pathway — through a damaged tympanic membrane.
Development of the disease is facilitated by young age, adenoids, chronic pathologies of the nose and paranasal sinuses, as well as general weakening of the body.
Stages of acute middle ear infection and treatment
In its course, acute otitis media goes through three successive stages: pre-perforative, perforative, and reparative.
In the first (pre-perforative) stage, patients complain of ear fullness, sleep disturbance, and severe constant pain radiating to the temple, teeth, or occiput. Otoscopy reveals crimson coloration of the tympanic membrane, disappearance of landmarks, and its bulging.
Treatment at this stage includes:
- Prescribing vasoconstrictor nasal drops to restore auditory tube function.
- Using ear drops and warming compresses on the mastoid process area.
- Systemic administration of painkillers and antibiotics.
If there is no effect within two days or if symptoms worsen, paracentesis is performed — an incision of the tympanic membrane in the posteroinferior quadrant to evacuate the exudate.
In infants, pressing on the tragus transmits pressure directly to the eardrum: pain means otitis media!
Class and exam questions
What are the main pathways of infection penetration into the middle ear?
The main pathway is the tubal pathway from the nasopharynx via the auditory tube. The hematogenous pathway in infectious diseases and the traumatic pathway through a damaged eardrum are also distinguished.
Why is pressing on the tragus painful in otitis in children?
In infants, the external acoustic meatus is short and lacks a bony part, so pressure on the tragus is directly transmitted to the inflamed tympanic membrane.
Where and why is paracentesis of the tympanic membrane performed?
The incision is made in the posteroinferior quadrant of the tympanic membrane when conservative therapy fails. This relieves inflammation, prevents spontaneous rupture, and ensures smooth healing.
What else to study on this topic
- Clinical physiology of the auricle (ototopics, protective, and acoustic functions)
- Second (perforative) and third (reparative) stages of acute otitis media
- Features of the course and complications of otitis in measles and scarlet fever
- Diagnostic capabilities and types of bronchoscopy in general practice
- Methods of local and systemic antibacterial therapy in ENT pathologies
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