E.N.T

General

External Auditory meatus

Cartilage ------outer 1/3
rd

Bone ------- Inner 2/3rds

Length 24 mm

8 mm

16 mm

2. Eustachian tube

Length 36 mm

Cartilage -----inner 2/3

24 mm

Bone -----Outer 1/3

12 mm

3. Vocal Chords

Membraneous

Cartilaginous

Length 17- 21 mm

Anterior 2/3

Posterior 1/3

4. Speech range

Hearing discomfort

500- 2000 Hz

90- 105 db

5. Normally

One can hear from 18 ft

6. Rinne’s Positive

Is Normal

7. Rinne’s negative

Conductive hearing loss greater than 15- 20 db

8. Weber’s test

Detects hearing loss of 5 db. More sensitive for conductive deafness.

9. Secretory Otitis Media

Conductive deafness of 30- 40 db