Special Senses Chap 15 Flashcards
Chambers of the cochlea
- Scala vestibuli
- Scala media
- Scala timpani
Area next to the Stapes
Oval window
Bones of the inner ear
- Malleus (hammer)
- Incus (anvil)
- Stapes (stirrup)
auditory tube or pharyngotympanic tube
Eustachian tube
Eustachian tube
auditory tube or pharyngotympanic tube
tube that links the nasopharynx to the middle ear
Eustachian tube
Thin, cone-shaped membrane that separates the external ear from the middle ear
Tympanic membrane
Tympanic membrane
thin, cone-shaped membrane that separates the external ear from the middle ear
Cochlea
A spiral-shaped cavity of the inner ear that resembles a snail shell and contains nerve endings essential for hearing.
A spiral-shaped cavity of the inner ear that resembles a snail shell and contains nerve endings essential for hearing.
Cochlea
An oval cavity in the inner ear that together with the semicircular canals makes up the organ that maintains equilibrium
Vestibule
Vestibule
An oval cavity in the inner ear that together with the semicircular canals makes up the organ that maintains equilibrium
Fluid behind the lens
Vitreous humor
Fluid behind the cornea
Aqueous humor
Layers of the Retina
1) Pigmented epithelium
2) Photoreceptors (Cones =7.10^6 and Rods =100.10^6)
3) Horizontal cells (lateral integration)
4) Bipolar cells
5) Amacrine cells (lateral integration) = no axon
6) Ganglion cells (their axons form the optic nerve)
Rods function
- Detect light.
- Rods handle vision in low light.
Cones function
- Acute vision
- Cones handle color vision and detail
Blind spot (name, location, characteristics)
- Optic disk
- On the nasal side
- No photoreceptors
- Passage for the optic nerve through the retina
Where is the major concentration of Cones (only cones)?
Fovia Centralis
Most acute vision
What surrounds the Fovia Centralis?
Macular Lutea (spot + Yellow)
What is the spot in the center of the retina called?
Macular Lutea (spot + Yellow) with the Fovia Centralis
What would happen to the vision with a tumor in the pituitary gland (Sella turcica of sphenoid bone)
It will press on the optic nerves and cause blindness in the temporal field. Bitemporal blindness ( bitemporal hemianopia)
Decussation or X-shaped crossing by the crossing of the optic nerves in the brain.
Optic chiasm
Name for the nerves after the optic chiasm when enter the brain
Optic tract
Meyers loop (importance)
Meyer’s loop constitutes the most anterior extension of the optic radiation in the temporal horn. Patients with intractable epilepsy may undergo temporal lobe surgery ( temporal lobectomy), and their optic tract is susceptible to potential injury. Consequently, neurosurgeons must appreciate the surgical implications of this pathway.
The vascular layer of the eye,
Choroid
Structure that changes the shape of the lens when your eyes focus on something. This process is called accommodation.
Ciliary muscles
structure in the eye that releases a transparent liquid (called the aqueous humor) within the eye.
Ciliary body
Sclera
The white outer wall of the eye. It is “white fibrous connective tissue” that extends from the cornea (the clear front section of the eye) to the optic nerve at the back of the eye. The sclera gives the eye its white color.
- Protects like the dura mater in the CNS
Modified sclera (collagenous fibers)
Cornea
Iris
+ circular muscle in the eye (constrict eyes),
+ Radial muscles (dilate the eye) responsible for controlling the diameter and size of the pupil and thus the amount of light reaching the retina.
Lens
epithelium cells that magnify
The white outer wall of the eye. It is “white fibrous connective tissue” that extends from the cornea (the clear front section of the eye) to the optic nerve at the back of the eye. It gives the eye its white color.
Sclera
Circular channel in the eye that collects aqueous humor from anterior chamber
Sclera venous sinus (canal of Schlemm)
is a circular channel in the eye that collects aqueous humor from the anterior chamber and delivers it into the bloodstream via the anterior ciliary veins
Too much accumulation of aqueous humor results in ——
Glaucoma
associated with elevated pressure in the eye (intraocular pressure). Generally, it is this elevated eye pressure that leads to damage of the eye (optic) nerve.
Cloudy lens results in —-
Cataract.
occur when there is a buildup of protein in the lens that makes it cloudy. This prevents light from passing clearly through the lens, causing some loss of vision. Since new lens cells form on the outside of the lens, all the older cells are compacted into the center of the lens resulting in the cataract.
Lens replacement.
Pupil
The pupil is a hole located in the center of the iris of the eye that allows light to enter the retina.
It appears black because light rays entering the pupil are either absorbed by the tissues inside the eye directly, or absorbed after diffuse reflections within the eye that mostly miss exiting the narrow pupil.
sensorineural hearing loss
Damage to cochlear hairs, irreversible and cannot be cured.
This type of hearing loss is sometimes referred to as sensory, cochlear, neural or inner ear hearing loss.
A permanent sensorineural hearing loss is the result of damage to the hair cells within the cochlea or the hearing nerve (or both). Damage to the cochlea occurs naturally as part of the ageing process (age-related hearing loss is known as presbycusis) – but there are many things that cause sensorineural hearing loss, or add to it, such as:
+ Regular and prolonged exposure to loud sounds.
+ Ototoxic drugs – some medicines are harmful to the cochlea and/or hearing nerve. These include drugs that are used in the treatment of seriouc diseases such as cancer but also include certain types of antibiotics.
+ Certain infectious diseases, including Rubella
+ Complications at birth
+ Injury to the head
+ Benign tumours on the auditory nerve - although rare, these can cause hearing loss
Genetic predisposition – some people are especially prone to hearing loss.
Sensorineural hearing loss not only changes our ability to hear quiet sounds, but it also reduces the quality of the sound that is heard, meaning that individuals with this type of hearing loss will often struggle to understand speech.
Conductive hearing loss
Conductive hearing loss is the result of sounds not being able to pass freely to the inner ear. This usually results from a blockage in the outer or middle ear, such as a build-up of excess ear wax or fluid from an ear infection (especially common in children). It can also happen as a result of some abnormality in the structure of the outer ear, ear canal or middle ear – or be due to a ruptured eardrum.
A condition known as otosclerosis (which results in the abnormal growth of bone in the middle ear) can cause severe conductive hearing loss. The excess bone prevents the ossicles in the middle ear from moving freely.
The result of this type of hearing loss is that sounds become quieter, although not usually distorted. Depending on its cause, a conductive hearing loss can either be temporary or permanent.
Conductive hearing losses can often be corrected with medical management, or minor surgery.
Gustatory pathway
1) The afferent fibers of the cranial nerves collect in the rostral solitary nucleus
2) Axons ascend ipsilaterally in the central tegmental tract of the brain stem and terminate in the parvocellular division of the ventral posterior medial nucleus of the thalamus
3) From the thalamus, neurons project to the insular cortex, the posterior limb of the internal capsule, and the operculum (primary gustatory areas)
Cranial nerves for Taste
1) Taste buds on the anterior tongue and palate innervated by Facial nerve (VII).
2) Posterior tongue and pharynx innervated by glossopharyngeal nerve (IX)
3) Epiglottis and larynx innervated by vagus nerve (X)
4) The afferent fibers of these cranial nerves synapse with many taste cells between single or multiple taste buds
Intermediate nerve afferents enter the brain stem at the pontomedullary junction
Glossopharyngeal and vagus nerve afferents enter the brain stem in the rostral medulla
Hair cells in gustatory apparatus
+ Projections from gustatory epithelial cells
+ Extend to the taste pore
+ Bathed by saliva
+ Sensitive portion of epithelial cells
Kinds of papillae
1) Foliate papillae - a series of folds on the sides of the tongue in the back (located on the folds)
2) Circumvallate papillae - are organized in an inverted V at the back of the tongue (tasted buds tasted buds located deep in the trenches)
3) Fungiform papillae - are found scattered across the top front and middle of the tongue (tasted buds located on the surface)
4) Filiform papillae - are found across the top of the tongue
Basic taste sensations
1) Sweet
2) Sour (acids)
3) Salty
4) Bitter
5) Umami
1) Sweet: (OH)
2) Sour (acids): (H+)
3) Salty: Na+, K+ Ca++
4) Bitter: alkaloids (caffeine, nicotine, morphine)
5) Umami: MSG mono-sodium glutamte
• Region that contains part of the system that helps maintain cerebral alertness and regulates skeletal and visceral muscle activity. (location)
Reticular Formation (medulla oblongata, pons)
Reticular Formation (location, function)
o medulla oblongata, pons, midbrain
o Region that contains part of the system that helps maintain cerebral alertness and regulates skeletal and visceral muscle activity.
