anatomy and physiology of ear , nose and paranasal sinus for physical examination For More Medicine Free PPT - http://playnever.blogspot.com/

1. THE EAR AND NOSE
SAPKOTA RAJITA

3. Anatomy and Physiology
The ear has three compartments:
a) External ear,
b) The middle ear, and
c) The inner ear.

5. The External Ear
• Consists of:
▫ Auricle (pinna)
 Made of elastic cartilage
 Helix
 Antihelix
 Lobule (ear lobe)
 Tragus
▫ External auditory canal
 Lies within temporal bone
& connects to ear drum
(tympanic membrane)
 Approximately 24 mm long.
 Contains ceruminous
glands which secrete ear
wax
 At the end of the ear canal
lies the tympanic
membrane (marking the
lateral limit of middle ear)

6. The Middle Ear
The middle ear is an air-filled
cavity that transmits sound by
way of three tiny bones, the
ossicles.
• Ossicles (smallest bones in
body)
▫ Malleus
 Attaches to ear drum
 two chief landmarks- the
handle and the short process.
 Articulates with incus
▫ Incus
 Articulates with stapes
▫ Stapes (stirrup)
 Footplate of stapes fits into
oval window
• Opening to Eustachian tube

7. • The cone of light-a light
reflection where the eardrum
meets the tip of the malleus.
• Above the short process lies a
small portion of the eardrum
called the pars flaccida.
• The remainder of the drum is the
pars tensa.
• Anterior and posterior
malleolar folds- extend
obliquely upward from the short
process, separate the pars flaccida
from the pars tensa but are
usually invisible unless the
eardrum is retracted.

8. The Inner Ear (Labyrinth)
• Bony labyrinth
▫ Contains perilymph
▫ Semicircular canals
 Anterior, posterior, and
lateral
 Lie right angles to each
other
▫ Vestibule
 Oval portion
▫ Cochlea
 Looks like a snail
 Converts mechanical energy
into electrical energy
• Membranous labyrinth
▫ Contains endolymph, high in
K+ ions

9. Pathways of Hearing
• Vibrations of sound pass through the air of the
external ear and are transmitted through the
eardrum and ossicles of the middle ear to the
cochlea, a part of the inner ear.
• The cochlea senses and codes the vibrations, and
nerve impulses are sent to the brain through the
cochlear nerve.

10. Conductive phase (The first part of this pathway)
• From the external ear through the middle ear.
• Disorder here causes conductive hearing loss.
Sensorineural phase (The second part of the
pathway)
• Involving the cochlea and the cochlear nerve.
• Disorder here causes sensorineural hearing loss.

12. The Nose
• The nose consists of the
external nose and the nasal
cavity,
• Both are divided by a septum
into right and left halves.
• Upper one third – supported by
Bone.
• Lower two third- supported by
cartilage

13. External Nose
• The external nose has two elliptical
orifices called the naris
(nostrils), which are separated
from each other by the nasal
septum.
• The lateral margin, the ala nasi, is
rounded and mobile.
• Air enters the nasal cavity by way of
the anterior naris on either side,
then passes into a widened area
known as the vestibule and on
through the narrow nasal passage
to the nasopharynx.

14. The Medial Wall of Nasal Cavity
• The medial wall of each nasal
cavity is formed by Nasal
Septum.
• Divides the nasal cavity into
right and left halves
• Supported by both bone and
cartilage.
• Nasal septum consists of the
perpendicular plate of the
ethmoid bone (superior), the
vomer (inferior) and septial
cartilage (anterior)

15. The Lateral Walls of Nasal Cavity
Marked by 3 projections:
▫ Superior turbinate
▫ Middle turbinate
▫ Inferior turbinate
• The space below each concha
or turbinate is called a meatus,
each named according to the
turbinate above it.

16. The Paranasal Sinuses
• The paranasal sinuses are
cavities found in the
interior of the maxilla,
frontal, sphenoid, and
ethmoid bones .
• They are lined with
mucos membrane and
filled with air.
• They communicate with
the nasal cavity through
relatively small apertures.

17. • Only the frontal and maxillary sinuses are
readily accessible to clinical examination.