Section 2 Flashcards
Another name for the Auricle
pinna
Temporal Bone
The portion of the cranium that houses a portion of the external ear; as well as the middle ear, inner ear and includes the cochlea and vestibular apparatus and the 7th and 8th nerves.
External Auditory meatus
also called the auditory canal. Located anterior to the mastoid process of the temporal bone.
HOw many bones does each temporal bone articulate with?
5 occipital bone parietal bone sphenoid bone zygomatic bone The mandible
What portions make up the temporal bone?
Squamous
Mastoid
Petrous
Tympanic
Squamous Portion of Temporal Bone
thin and translucent. forms anterior and upper portion of the bone.
Fan shaped, contains mandibular fossa (place of articulation for the condylar process of the mandible). SUPERIOR to the EAM.
Zygomatic Process
The arched process that articulates with the zygomatic bone. Pretty sure its part of the squamous portion.
Mandibular fossa
a shallow depression that articulates with the mandibular condylar process. located on squamous portion.
Tympanic portion
The portion that surrounds the external auditory meatus(EAM).
EAM
external auditory meatus. the circular external opening into the auditory/ ear canal.
Styloid process
part of the tympanic portion. narrow projection of bone that angles downward and gives attachment to a ligament and 3 muscles.
Mastoid portion
Lies below squamous portion and behind the typanic portion. Contains the mastiod process.
Mastoid process
The large prominence located posteriorly to the EAM.
Petrous portion
Solid wedge of bone that forms most of the posterior and inferior portions of temporal bone. located medial to EAM. Houses the IAM that transmits the 8th nerve from the internal ear to the brain. Houses most of the ear.
petrous portion of the ear houses what three movable bones?
The three ossical bones
M, I ,S
Auricle
aka pinna. directs sound into the EAM.
Composed of elastic fibro-cartilage.
Helix
Ridged rim along the posterior and superior part of the pinna. Originates at the crus of the helix and terminates superior to the lobule.
Lobe/ Lobule
Devoid of cartilage, highly elastic, most inferior part of the pinna.
Tragus
The cartilaginous flap that partially covers the opening of the ear canal
Antihelix
A ridge located anterior to the scaphoid fossa. Essencially runs parallel to the helix In the upper portion it slips into two segments called the crura of the antihelix (Superior and inferior).
Cruz of the helix
origination point of the helix.superior to opening of the EAM. birdbeak
crura of antihelix
two anterior and superior elevations of the auricle located on the upper portion of the Antihelix and form two sides of the triangular fossa. Inferior crura forms the roof of the concha.
Concha
a deep depression of the auricle, divided into to portions. The cymba concha and cavum concha. both are Bordered by the antihelix, tragus and antitragus.
Cymba cochae
deep depression located between the inferior antihelix and cruz of the helix.
Cavum conchae
larger inferior portion of the conchea. kinda “c” shaped,flat portion of ear that touches the helix cruz and targus.
Intertragic notch/intertragalincisure
notch separating the targus and antitargus
scaphoid fossa/scapha
long narrow groove that runs in between the helix and the antihelix
antitragoinsisure
separates the tail of the helix and the antihelix (cartilage view)
Auricular muscles
Extrinsic- connect the auricle to the hear. vestigial- serve little or no function and innervated by fracial nerve 7. 3 muscles- superior, anterior and inferior.
Intrinsic- connct auricle parts together, makes small changes to the pinna, no real purpose other than holding the shape and innervated by facial nerve 7.
Ear canal/ EAM
About an inch long. Wider a the opening and then becomes more narrow. At the end of the EAM is the isthmus. The tube is not a perfect cylinder, but rather an elongated/lazy “s”. Runs roughly perpendicular to the head.
Structure of the EAM and slope
At either end the EMa slopes downward- this helps minimize the retention of water in the ear for adults. kids are more susceptible.
Near the opening the first 1/3 or 1/2 of the EMA is carlaginous and slightly malleable. the last 1/2 or so is boney as it passes through the temporal bone.
Boney portion of EAM is formed by three main structures….?
The tympanic portion of the temporal bone, squamous portion and the condoyal of the mandible.
Is there are osseous/boney portion to the EAM in humans at birth?
Nope! it develops over several years.
Ear canal is covered by an epidermal lining..
closely adheres to the supportive structures of the canal. covers the length of the and eventually forms the lateral most layer of the tympanic membrane and the medial (inside) portion of the EAM.
The outer lining contains hair cells and glands that secrete a waxy substance called cerumen.
Cerumen
Ear wax…Serves protective functions for the peripheral hearing system. Protects ear canal from drying out and has an acidic pH
Sebaceous glands
Contribute to production of cerumen. these cells are located close the the hair follicles. produce an oily substance that lubricates the ear canal. Made up of broken down cells.
Cerumenous glands
The cells that create the wax-like substance that mixes with the oily substance from the sebaceous glands. Eventually forming earwax.
Differences in cerumen…
Varies depending on the contribution of oily and waxy substance and varies by race as well.
Asian- more likely to have flakey
Caucasian, african american, latino- more likely to have wet and sticky.
ho does cerumen come out the the ear?
The outer layer of skin migrates out
Protective functions of cerumen
slightly antibacterial/anti-fungal. may repel or discourage insects from entering.
Isthmus
A constriction which marks the junctions of the cartilaginous and body framework of the EAM.
Medial portion of the ear canal
lacks glands or hair cells and is extremely sensitive. attaches to periosteum.
Lateral portion of the ear canal
Contains hair follicles and glands that produce cerumen.
Which nerves innervate the epidermal lining?
5th, 7th, 9th and 10th
Arnold’s reflex. What is it?
Coughing resulting from stimulations of the auricular or Arnold’s branch of 10th nerve (innervates posterior portion of EAM).
another name for 10th nerve
vegas nerve
Pinna purpose, function, localization
- primary purpose is to collect sound
- shape causes this pinna to become a resonator for high frequency sound
- the presence of he head aids in localization and helps us determine which side sound is coming from
- less effective from behind. best for anterior and lateral sound
EAM function
- carries sound to the middle ear
- resonates high frequency much more than pinna
- helps determine localization
- resonance is centered mostly at 2500-2700 HZ and specifically voice sounds.
Middle ear basic definition
an airfilled space in the temporal bone- sometimes called the tympanum.
What is the lateral wall of the middle ear?
The ear drum/ tympanic membrane.
What is the medial wall of the middle ear
The petrous portion of the temporal bone
Important structures within the middle ear
ossicles- 3 smallest bones in the body Eustachian tube tympanic membrane facial nerve tendons and ligments
tympanic membrane physical properties
oval shaped smooth pearl gray translucent (NOT TRANSPARENT) concave
What is the normal mass of the tympanic membrane?
14 mg
What is the angle of the TM in adulthood
Starts off as flat when a child and as the EAM lengthens it sits at a 140 degree angle.
T or F the TM is grown to full size in infanthood
true
Is the TM concave or convex?
Concave. the center is more medial than the rim.
What are the 3 layers of tissue of the TM
Lateral Cutaneous (cuticular) layer Intermediate fibrous layer Internal mucous (or medial or mucoid) layer
Lateral Peripheral Cutaneous (cuticular) layer
Lateral epithelial lining continuous with the external layer of the EAM
Intermediate Fibrous layer
largely responsible for the compliance of the eardrum. Two types of fibo elastic fibers- radial (superficial and look like spokes of a bike) and circular (deep and form rings). These fibers are unevenly distributed through the TM.
Internal (medial, mucous, and mucoid) serous layer
continuous with the lining of the tympanic membrane.
Where are the fibers in the TM most dense?
Near the center and outside edge (peripheral)
Where are the middle layer fibers of the TM least dense?
In the pars flaccida (shrapnell’s membrane)
Pars Flaccida
Also called shrapnell’s membrane. The superior portion of the TM located in a triangular portion formed by malleolar folds. Fibers of the middle layer are more sparse and not organized.
Pars Tensa
The remainder of the ear drum (aside from pars flaccida) that is divided into quadrants Anterior inferior anterior superior posterior superior posterior inferior
Tympanic annulus
a thickened rind around the TM that holds the TM in place. The tympanic annulus is thicker inferiorly and thin above the pars Flaccida.
Tympanic Sulcus
a groove in the bony wall of the meatus that accommodates the tympanic annulus.
notch of rivinus
Located on the superior portion of the TM. IT marks an opening the the tympanic sulcus caused by a tiny interuption.
Malleolar stria
opaque/whitish streak. superior and slightly anterior. formed by the attachment of the manubrium of the malleus.
Extends from the center to periphery.
What position is the malleolar stria in when looking in the right ear?
1 o clock
What position is the malleolar stria in when looking in the left ear?
11 o clock
Malleolar prominence
located in the upper portion of the malleolar stria. formed by the attachment of the lateral process of the malleus to the TM/ear drum.
Anterior and posterior malleolar folds
ligamentous bands that run from the superior portion of the malleolar prominence and attach to the notch of rivinus. this forms the triangular area the par flaccida/shrapnell’s membrane.
Umbo
Latin for “boss” meaning a rounded or projection eminence. The point of attachment of the inner TM to the manubrium. It is the end of the malleolar stria.
- draws the TM inward
- forms the tip of the cone.
This is the spot from which the cone light radiates.
When viewing the TM with an otoscope, what will you be able to see?
The manubrium of the malleus ( part os the malleolar stria)
Long process of the incus (if the TM is translucent enough)
Annular ligament/tympanic annulous (rim area)
The cone of light
Cone of light
A reflection from the light of the otoscope that will appear on the anterior/ inferior portion of the TM. Radiates from the umbo. Not an actual landmark of the ear but is a hallmark of a health ear drum. In right ear the reflection is at 5oclock, in left ear it is at 7 o clock.
otoscope
used to examine the ear.
effective moveable area of the TM
55mm^2
TM quadrants- how are they separated?
forms kind of an X shape.
one line is drawn and extends from the malleolar stria to separate anterior and posterior.
a 2nd line is drawn the opposite direction and goes through the umbo to separate superior and inferior.
The occicles
3 bones within the middle ear.
Most lateral- Malleus is attached to the eardrum/TM
Middle- Incus
3rd- Stapes
These three bones make up the ossicular chain
Malleus- parts
First of three bones in the chain
Head- bulb shaped portion that projects upward from the manubrium
Three processes:
- manubrium: attaches firmly to TM at umbo
-anterior process: a spine like process that can be seen in the region of the juncture of the manubrium and the head
-lateral process: in the same area as the anterior process but projects laterally and attaches to the upper portion of the TM.
How much space does the Malleus head occupy in the epitympanic recess?
About 1/2 the space
Where is the neck of the malleus?
in between the head and manubrium
What is the articular facet on the malleus
The point of articulation with the incus bone on the posterior side of the muscle.
What muscle attaches to the small projection at the point where the neck and manubrium of the malleus meet?
Tensor tympani muscle.
Incus
Consists of a body and 2 arms/processes/cura
Body of Incus
On the anterior surface of the body is an articular facet that serves as the contact point for the incus connection to the malleus
Short process of incus
Projects posteriorly in a roughly horizontal plane
occupys epitympanic recess
Incus Long process
Courses in a vertical direction almost parallel to the manubrium of the malleus.
Lenticular process of the incus
Located at the inferior most end of the long process. the process makes a medial turn and ends with a rounded part that articulates with the head of the stapes.
Stapes
3rd bone is ossicular chain. SMALLEST BONE IN THE HUMAN BODY.
Consists of a head, neck, 2 crura and a footplate
Head of stapes (where)
Superior part of bone, round, articulates with incus.
Neck of Stapes
constriction between the head and the crura
Anterior and posterior crura-
2 delicate but strong struts on the stapes. The anterior crus is more slender, shorter, and less curved than the posterior.
Footplate of stapes
Part osseous (bone) and part cartilaginous. occupies the oval window.
Obturator Foramen of the stapes
the triangular space formed by the crura and footplate.
Head/neck of the stapes has a small projection that connects to what tendon?
stapedius muscle tendon
Where are the three ligaments on the malleus and where do they attach?
Superior- origin: head insertion: roof of tympanic cavity
Lateral- origin: neck of malleus insertion: lateral wall near superior TM
Anterior: O: anterior process. I: anterior wall of middle ear
What are the two ligaments located on the Incus?
Superior: o- body of incus i: epitympanic reces
Posterior: o- tip of short process i: fossa incudous in tympanic recess
What is the ligament that attaches to the stapes?
Annular ligament of the stapes
-binds the footplate to the oval window
Larger anteriorly and smaller/tighter posteriorly.
What type of joint does the malleus and incus form? what is it called?
Incudomalleal joint
type: Diarthroidial (double saddle) joint
What type of joint does the incus and stapes form? what is it called?
Incudostapedial joint
type: ball and socket. possibly also called a syndesmosis joint (slightly movable).
T or F the ossicle mass above and below are about equal
True. once sound vibrations cease. the vibrations of the bones terminate abruptly. this lessens sound distortion.
