ANA - W13

Question 1

What does the external and middle ear consist of?

Answer 1

External: auricle and external acoustic meatus

Internal: tympanic cavity and auditory tube

Question 2

what is the structur eof auricle and what does it connect?

Answer 2

elastic cartilage - connected to the temporal bone by the ligaments

• extrinsic auricular muscles - connect the auricle to the skull and scalp and
  move the auricle as a whole
• intrinsic auricular muscles connect the different parts of the auricle
• skin – firmly connected to the cartilage – more on the lateral side than on the
  medial side, this skin contains sebaceous glands and hairs

Question 3

How does the auricle collect the sound

Answer 3

its elevation and depressions collect the sound and act as a funncel, amplyfing the sound toward the EAM

Question 4

Where does the EAM extend and pass?

Answer 4

it extends from the concha of the
auricle to the tympanic membrane
* it is S-shaped - in transverse
section
* it passes ventromedially and
upwards, then posteromedially and
again ventromedially with a slight
descent

Question 5

Superior and inferior wall of EAM

Answer 5

superior wall
– runs almost horizontally
- shorter than inferior due
to the oblique position of the
tympanic membrane

• inferior wall – is convex and
  longer than superior wall

Isthmus: narrowest part-in the body-cartilagineous junction

Question 6

What two parts does EAM consist of?

Answer 6

cartilagineous part
– lateral part of EAM, cca 8mm
*

osseous part
– medial part of EAM, cca16 mm
- formed by temporal bone
– superior wall squamous part of the
temporal bone;
- inferior wall by the tympanic part
of the temporal bone
*

Question 7

what is EAM lined by?

Answer 7

EAM is lined by the skin
containing tragi (hairs)
and ceruminous glands
– producing ear wax - cerumen

Question 8

EAM relations

Answer 8

middle cranial fossa – above EAM

• mastoid process – behind EAM
• temporomandibular joint – in front of EAM
• middle ear – tympanic cavity – medial to EAM

Question 9

What does the tympanic membrane form?
How does the centre of membrane look?
what does it have on external surface

Answer 9

• grey membrane
• oval in form, its circumference is thickened and forms fibrocartilaginous !!!ring which is fixed in tympanic sulcus of temporal bone

-Centre of membrane is drawn inwards by attachment of handle of malleus-convexity of inner ruface is named UMBO

• small fold on ext surface called ANT AND POST MALLEAR FOLDS-border trinagylar part of tympanic membrane-PARS FLACCIDA-is thin and lax part of membrane
• PARS TENSE-the rest major part-is tense-taught part

Question 10

nerve supply of auricle/external ear

Answer 10

• sensory innervation is supplied by auriculotemporal nerve (mandibualr nerve V3) - IN FRONT OF EAR
• the cervial plexus (great auricular nerve-C2,C3, Lesser occipital nerve-C2) - REGION BEHIND AND BELOW (great is more below)
• facial nerve (VII) - for auricle itself
• Vagus (X) - for entrance to EAM

Question 11

blood supply of externla ear

Answer 11

By external carotid artery and its branches:

• posterior auricular a->auricular and perforating a
• occipital a ?
• superficial temporal a–>anterior auricular branches

Question 12

Examination of EAM

Answer 12

• pull sup, pst and a bit laterally—>straighten
• normal membrane: translucent, gray-redisht ting, handle of malleus is visible near the center, a cone of light is always demonstrated
• acute otitis media–>membrane is bright red and bulging with loss of the normal light reflection

Question 13

perforation of tympanic membrane

Answer 13

• MYRINGOPLAST/TYMPANOPLASTY
• trauma and infection
• myringoplast: surgical, uses connective tissue scaffold or graft (temporal fascia) to support healing of perforation

Question 14

what is the tympanic cavity and what levels do we have?

Answer 14

in temporal bone, biconcave lens

EPITYMPANUM-epitympanic recess-the part of tympanic cavity above the lvl of the roof of EAM
- suspension apparatus
- majority of ossicles
. through mastoid antrum-connect with mastoid cells

MESOTYMPANUM
- handle of malleus
-lenticular process of incus
-tendon of tensor tympanic

HYPOTYMPANUM
- leads into auidtory tube

Question 15

Boundaries of tympanic cavity

Answer 15

lateral wall - membranous wall- by tympanic membrane

medial wall-labyrinthine wall - promontory, fenestra cochleae, fenestra vestibuli

floor- jugular wall

rood-tegmental wall-tegmen tympani

posterior wall - mastoid wall-the entrnce into mastoid antrum-cells

anterior wall - thin layer of bone that separates the tympanic cavity from the internal carotid a

Question 16

relations of tympanic cavity

Answer 16

anterior: carotid canal
posterior: mastoid process

Superiro: middle cranial fossa
inferior: jugular fossa

mediall wall: labrrinth
lateral: tympanic membrane

Question 17

the auditry ossicles

Answer 17

Auditory ossicles transmit
vibrations of the tympanic
membrane to the inner
ear
* malleus - hammer - is
attached to tympanic
membrane

• incus – anvil – is
  interposed between
  malleus and stapes
• stapes - stirrup – is
  ancored into the fenestra
  vestibuli - ovale

Question 18

tympanic cavity-muscles

Answer 18

tensor tympani muscle
F: its contraction pulls the handle of the
malleus medially, this way it tenses the
tympanic membrane,
- its contraction reduces the force of
vibrations in response to loud noises -
protection of the internal ear
I: trigeminal nerve -[V3]

• stapedius muscle
  F: it pulls the stapes posteriorly and
  prevents excessive oscillation, its
  contraction is usually in response to
  loud noises - protection of the internal
  ear
  I: facial nerve

Question 19

blood and nerve supply of tympanic cavity

Answer 19

blood supply
branches of:
maxillary a.
posterior auricular a.
middle meningeal a.
ascending pharyngeal a.

• nerve supply:
  tympanic plexus – composed of:
  glossopharyngeal n. (sensory
  and pararasympathetic),
  caroticotympanic nerves
  (sympathetic)
• relations to the nerves:
  facial nerve in facial canal –
  related to the tympanic cavity
  chorda tympani runs through
  the tympanic cavity

Question 20

mastoid antrum

Answer 20

• aditus to the mastoid
  antrum (from tympanic
  cavity)
• the mastoid cells

Question 21

THE AUDITORY TUBE –
THE PHARYNGOTYMPANIC
TUBE

parts

Answer 21

it connects the tympanic cavity with the
nasal part of the pharynx
* it equalizes pressure on both sides of thetympanic membrane
* it directs ventromedially and inferiorly

It consists of 2 parts:
* bony part (in temporal bone)
- the one-third nearest the middle ear
- begins in the anterior wall of the tympanic
cavity – in the tympanic opening of the
auditory tube

*cartilagineous part
- the remaining two-thirds
- formed by curved fibrocartilaginous plate
which ends on the lateral wall of the
nasopharynx - in pharyngeal opening of
auditory tube