Dehiscence of anterior wall of the external auditory canal cause infection in the parotid gland

EXTERNAL ACOUSTIC (AUDITORY) CANAL The canal is divided into two pas: (i) cailaginous and (ii) bony. 1. CAILAGINOUS PA It forms outer one-third (8 mm) of the canal. Cailage is a continuation of the cailage which forms the framework of the pinna. It has two deficiencies--the "fissures of Santorini" in this pa of the cailage and through them the parotid or superficial mastoid infections can appear in the canal or vice versa. The skin covering the cailaginous canal is thick and contains ceruminous and pilosebaceous glands which secrete wax. Hair is only confined to the outer canal and therefore furuncles (staphylococcal infection of hair follicles) are seen only in the outer one- third of the canal. 2. BONY PA It forms inner two-thirds (16 mm). Skin lining the bony canal is thin and continuous over the tympanic membrane. It is devoid of hair and ceruminous glands. About 6 mm lateral to tympanic membrane, the bony meatus presents a narrowing called isthmus. Foreign bodies, lodged medial to the isthmus, get impacted, and are difficult to remove. Anteroinferior pa of the deep meatus, beyond the isthmus, presents a recess called anterior recess, which acts as a cesspool for discharge and debris in cases of external and middle ear infections. Anteroinferior pa of the bony canal may present a deficiency (foramen of Huschke) in children up to the age of four or sometimes in adults, permitting infections to and from the parotid. Ref:- Dhingra; pg num:-02