PINNA
P)inna is made of yellow elastic cartilage which is again covered by skin .Skin is closely attached to cartilage on lateral surface but loose on medial ( back ) surface .
Nerve supply of pinna : Lobule of pinna : Greater auricular nerve . Medial surface : Lesser occipital nerve . Lateral surface : Auriculotemporal nerve . Concha of pinna : Auricular branch of vagus and few fibres of facial nerve .
Cauliflower are or boxer's ear : Post traumatic deformity = Subperichondrial hemorrhage
External Auditory Canal :: 24 mm in length . Outer 8mm cartilagenous , inner 16 mm bony .
EAC is lined by skin . Outer part has hair follicles and ceruminous gland .
EAC skin migrated outwards and hence brings the dead skin and tissues out . If this migration is absent , it leads to accumulation of dead tissues and wax in EAC as a large expansile mass
It can damage facial nerve too . This condition is called keratosis obturans . Treatment is cleaning of EAC in every 6 months .
Blockage of EAC due to wax =30 db hearing loss . Tratment= Syringing . Direction of syringing is = Postero superior .
Live insect in Eac , what to do ? 1st : Oil in EAC to kill it then remove it .
Isthmus of EAC is the narrowest part . It lies 6 mm laterla to tympanic membrane . Any foreign body lying beyond isthmus will get impacted .
Fissure of Santorini : Natural defect in cartilagenous EAC . Clinical importance = infection can travel from EAC to parotid gland .
Fissure of Huschke : Natural defect in bony EAC .
Directon of EAC = Inward Downward and Forward . SO Direction of pulling = Upward , Outward and Backward .
NERVE SUPLLY OF EAC : Anterior wall and roof : Auriculotemporal nerve .
Posterior wall and floor : Auricular branch of vagus ( Also called Arnold's or Alderman's nerve , stimulation of this nerve leads to cough .)
Posterosuperior part : Sensory divison of facial nerve ( nerve of Wrisberg )
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