Tympanic Membrane

The average thickness of the T.M is...

0.74 mm (.003 in)

Describe the lever advantage...

1.3:1; Long distance needs less pressure/force - short distance needs high pressure/force

Describe the areal advantage...

17:1; "Thumb-tack." The T.M. is 17 times larger than the oval window.

(Eustachian tube) Carilaginous portion is __, osseous portion is __?

2/3; 1/3

How long is the eustachian tube?

35 mm

The outer ear collects sound and provides pathway because...

Concha is larger than the T.M. The outer ear acts like a funnel and slightly increases SPL at T.M.

Describe the mastoid process of the temporal bone...

Contains air cells

Describe the pinna...

Covered with skin and composed mostly of cartilage with the exception of the lobe

Decussate

Cross over

Describe ectoderm...

Cutaneous - continuous with the EAM

What passes through the petrous-squamosal suture in children directly to the meninges of the temporal lobe of cortex?

Inflammatory conditions of the middle ear

What is the function of pars tensa?

Inserts into boney groove in the tympanic bone

The densest bone in the body is...

The temporal bone

The facial nerve (VII) innervates what?

Chorda tympani, stapedial muscle, and location behind the medial wall

Describe the opening of the eustachian tube...

"Milking" action - tensor palatini pulling on the side of the eustachian tube, opening the tube

Distal

(Distance) Away from a reference point

What is cholesteatoma?

A middle ear tumor; not cancerous. Could turn into Mastoiditus if pushed back toward the mastoid section of your ear.

The ossicles are held in place by...

A series of ligaments, tendons, and joints

Undulations and differences in cartilage of pinna cause...

A sound shadow as well as antiresonances between 6000-12000Hz.

What is the function of the middle ear?

Acts as an impedance matching device between the air-borne sound waves and the fluids of the inner ear

What structures are located within the posterior wall?

Aditus, pyramidal eminence, posterior iter, jugular wall, and the jugular vein

What is the difference between afferent and efferent?

Afferent - Up, towards; Efferent - Down, away

Pars Flaccida contains what?

All layers of the T.M. EXCEPT the fibrous one

Pars Tensa contains what?

All three layers of the T.M.

Describe an adult's E.T...

Angle: about 40 degrees; Length: about 35 mm; Flaccidity: Little to none

Describe a child's E.T...

Angle: more horizontal; Length: shorter than 35 mm; Flaccidity: very flaccid in children

What is epitympanic recess?

Anything above the eardrum

What is hypotympanium?

Anything below the eardrum

How long is the EAM?

Approx. 2.5 cm (1 in) from entrance of concha to T.M.

The incus consists of what structures?

Articular facet, short process, head, long process, and lenticular process

In adults, the T.M. is...

At a 55 degree angle

EAM terminates where?

At the typmanic membrane

Lateral

Away from the midline

Binaural

Both ears

Bilateral

Both sides

(Resonance of middle ear) Effects of increased mass is...

Downward shift of resonant frequency

What are the three layers of the T.M.?

Ectoderm, Mesoderm, and Endoderm

What structures are located within the medial wall?

Facial nerve, promentory of the lateral semi-circular canal, oval window, promentory of the basal turn of the cochlea, and the round window

Describe mesoderm...

Fibrous - Radial fibers and Concentric Fibers

Describe the zygomatic process of the temporal bone...

Forms the zygomatic arch. Connects with the zygomatic bone.

Coronal plane

Frontal view. Cut body in half between front and back

What causes glomus jugularis?

Glomus bodies can push up through the jugular wall from the jugular vein

The malleus consists of what structures?

Head, lateral process, articular facet, anterior process, neck, and manubrium

The stapes consists of what structures?

Head, neck, anterior crus, posterior crus, annular ligament, footplate, and obturator foramen

What is the function of atrium and where is it located?

Help increase the capacity, which in turn, increases the amount of blood it can hold. Located posterior to the aditus

Describe the squamous portion of the temporal bone...

Helps enclose the cranial cavity

In newborns, the T.M. is...

Horizontal

Posterior

In back

Anterior

In front

Where is cerumen made?

In the sebacious and cerumenous glands of the EAM

Where is the jugular vein located?

Inferior to the jugular wall

If the chorda tympani is damaged, what can happen?

It can change your taste buds

How does the outer ear protect the T.M.?

Its S shape provides a physical protection, cerumen and sweat lubricate the EAM and help expel debris, and hair follicles are tilted to concha to discourage debris from entering

Describe the petrous portion of the temporal bone...

Located at the base of the skull between the sphenoid and the occipital bones. Houses inner ear and internal auditory canal.

Describe the styloid process...

Located on the medial/inferior portion of the temporal bone. Attaches to several pharyngeal muscles

Inferior

Lower or below

The eustachian tube consists of what structures?

Lumen, cartilage, tensor palatini, levator palatini, and the temporal bone

What are the three smallest bones in the body?

Malleus, Incus, and Stapes (aka - Ossicles)

Describe endoderm...

Mucous - continuous with the T.M.

What structures are located within the anterior wall?

Muscular-tubal canal, carotid artery, and the anterior iter.

What is impedance mismatch?

Occurs when you have two mediums of differing impedance's. Occurs between gas (air) and fluid of inner ear.

(Eustachian tube) the osseous portion is usually ___, and the cartilaginous portion is usually ___?

Open; closed

Contralateral

Opposite side

What is impedance?

Opposition to the flow of energy

The make of of the T.M. consists of what structures?

Pars Tensa, Pars Flaccida, Manubrium, Umbo, Annulus, Incus, Cone of Light, and Notch of Rivinus

What is the cone of light?

Part of the T.M. that is perpendicular to the light from the ossiscope. Shiney = Healthy

What is the aditus?

Passage or opening for entrance

The tegmen separates the tympanic cavity from the...

Posterior cranial fossa

What is the function of the eustachian tube?

Pressure equalization and drainage

The EAM is what shape?

S shaped

Unilateral

Same side

What is the function of the manubrium?

Serves as an attachment point

Sagittal plane

Side view. Cut body into right and left parts

The EAM is angled which direction?

Slightly forward

What are sebaceous glands important for?

Sweating

Name the walls of the tympanic cavity...

Tegman, Anterior, Jugular, Posterior, and Medial

The outer ear keeps the T.M at a constant ___ and ___.

Temperature; humidity

The posterior cranial fossa houses the...

Temporal lobe

What muscle secures the pinna to the head?

Temporalis muscle

What two muscles help open the E.T.?

Tensor palatini, and the levator palatini

The trigeminal nerve (V) innervates what?

Tensor tympani

What is very thin and translucent (wax paper like)?

The Tympanic Membrane

What structure is eliptically shaped?

The Tympanic Membrane. -- vertically .9 cm and horizontally .8 cm

The internal auditory canal connects inner ear with what?

The brainstem

Where are hair follicles found in the outer ear portion?

The cartilaginous portion of the ear canal

What muscle is attached to the petrous portion?

The levator palatini

The eustachian tube begins at the tympanic cavity and teminates in...

The nasopharynx

The temporal bone contains...

The outer, middle, and inner ear

The ossicles connect the T.M with what?

The oval window

The temporal bone articulates with...

The parietal, occipital, frontal, and sphenoid bones

What are the two main parts of the outer ear?

The pinna (auricle) and the external auditory meatus (EAM aka ear canal)

What is the function of the outer ear?

To collect sound and provide pathways, protect the T.M., keep a constant temperature, help us localize on a vertical plane, and resonate in high frequencies

What is the function of the annulus/annular ligament?

To help hold the T.M. in place.

What is the function of the ossicular chain?

To sound transmission to oval window and to protect cochlea from intense vibrations by changing axis of rotation of stapes.

Transverse plane

Top or horizontal view. Cut body into upper and lower halves

Proximal

Towarda reference point

Medial

Towards the midline

Superior

Upper or above

(Resonance of middle ear) Effects of increased stiffness is...

Upward shift in resonant frequency

Ossification of the EAM causes...

changes in the angle of the T.M., until about age 5 when it reaches adult position