Page 98 - Edited - Webster HEAD AND NECK - part 2-Merge PDF

HN 292 THE OUTER EAR (1) HN 292

CORONAL SECTIONS (C) ADULT
PINNA
TEMPORALIS MUSCLE

SQUAMOUS
TEMPORAL

MIDDLE (B) NEWBORN/INFANT
ELASTIC FOSSA
CARTILAGE NOTICE that the EXTERNAL
SKELETON MEATUS IS RELATIVELY
SHORT & ENTIRELY
TYMPANIC CARTILAGINOUS
CAVITY

CONCHA
OF PINNA

TYMPANIC
BONE
TYMPANIC
K.E.W. THIS FORMS THE LOWER EXTERNAL MEMBRANE
LOBULE & ANTERIOR PART OF THE AUDITORY
EXTERNAL MEATUS MEATUS

TYMPANIC
K.E.W. BONE (“RING”)

(A) PARTS OF THE PINNA (AURICLE)

AURICULAR
TUBERCLE
(of DARWIN)

HELIX

ANTI-
TRAGUS HELIX

CONCHA

ANTI-
TRAGUS

LOBULE

Fig. A. The pinna (see Fig. C) is an elastic cartilage structure continuous with the outer cartilaginous part of
the external auditory (acoustic) meatus. In adults, the external meatus is ~2.5 cms long. Note in Fig. B that in
the newborn/infant the tympanic plate is poorly developed (no more than part of a thin ring) and the tympanic
membrane is therefore very near the external surface of the ear: care is needed in inserting an auroscope. The
head of the mandible lies immediately in front of the cartilaginous external meatus, which is distorted by
mandibular movements (try sticking your little finger in you ear and opening and closing your mouth).

The skin of the outer part of the meatus is hairy and provided with special sebaceous glands which secrete "ear
wax". This is either quick drying or wet (which variety you are blessed with is genetically determined). If it
accumulates on the ear drum or gets wet and swells when on the drum, it causes deafness. These ceruminous
glands are embedded in dense connective tissue: if they become infected the “boils” are very painful!

kewteach\ear/nodes