Special senses 👁️

How many cranial nerves are there

12

How many spinal nerves are there

31 pairs

What are the cranial nerves involved in special senses

Optic, Facial, Glossopharyngeal, vestibulocochlear, Olfactory

What is the role of optic nerve

Vision

What is the role of facial and glossopharyngeal

taste

What is the role of vestibulocochlear

Balance (through hearing)

What is the role of olfactory nerve

Smell

What are the eyes primarily made up of

Water and electrolytes

What is the function of the eye

To detect light and colour, convert it into an impulse and will be transmitted to the brain for processing and interpretation

What location of the eye is aqueous humour produced

Anterior and posterior chambers of the eye

What produces aqueous humour

ciliary bodies

What is the purpose of ciliary humour

Protect the eye, maintains pressure within the eye, provides nutrients to the eye

(pressure protect, provide)

What is vitreous humour - what is its role

A gel mainly comprised of water, found at the back of the eye between the lens and retina

it contains phagocytes which detect any debris in the eye

What is the structure called at the back of the eye

The retina

What is the role of the retina

Light sensitive layer of tissue

What is contained within the retina - what do they do

Rods and cones

rods - black and white vision

cones - coloured vision

What does the optic nerve do

Takes impulses from the optic nerve, into the optic chiasm, then optic tract to the optic radiation then the occipital lobe.

Where are tears produced

The lacrimal gland

Why are tears produced

To lubricate movement

To remove debris

What is the movement of tears and where do they drain into

Lateral to medial and drain into nose

What structure drains tears from lacrimal gland into the nose

Nasolacrimal duct

List the bones of the face orbit

Sphenoid

Zygomatic

Frontal

Maxilla

Lacrimal

Palatine

Ethmoid

What are the sinuses

Orbital, nasal, oral cavities

What are the types of paranasal sinuses

Maxillary

Ethmoid

Sphenoid

Facial

What is the role of the sinuses

Reduce weight of skull

Circulation of mucous

Contribute to the resonance of sounds

Where is the maxillary sinus found

Under the eyes

Where is the facial sinus found

the forehead

Where is the sphenoid and ethmoid sinuses found

Posterior to the nose

What cranial nerves are responsible for eye movements

Oculomotor

Trochlear

Abducens

How many extraocular muscles are there

7

List the types of extraocular muscles

Superior rectus

Inferior rectus

Medial rectus

Lateral rectus

Superior oblique

Inferior oblique

What is the function of the nasal cavity

To warm, humidify and filter air

Why is the nasal cavity suitable for its function

It has a rich, superficial blood supply

Has mucous for moisture

Mucous and hairs trap particles

What is the role of olfaction

Converts chemical information to electrical

Has a defence mechanism

What is the role of turbulence

To warm, humidify and filter air

What are the roles of the tongue

Swallow

speech

taste

mastication

What are the two parts of the the tongue

Oral part

Pharyngeal

What is the gland which provides saliva

Sublingual gland - this produces saliva

What is the muscle called that is found at the floor of the mouth

mylohyoid

What epithelia is found in the mouth

Stratified squamous

Where is the buccal surface f the mouth found

Side of the mouth where the surface is towards the cheeks as a surface of the teeth

Where is the lingual surface of the surface

The surface that faces the teeth

Role of the epiglottis

helps to close over the trachea when swelling so prevents food going into the trachea

Role of foramen caecum

The embryological remnant of the thyroid gland and the primitive tract where the thyroglossal duct was

Filiform papillae

Rough and abrasive surface - no taste buds

Helps with speaking, chewing and cleaning the oral cavity

Role of the fungiform papillae

front 2/3rd of the tongue

has taste buds

Role of vallate papillae

Has a few taste buds and salivary glands

where do the chorda tympani branch from

the facial nerve

What is the role of the chorda tympani

To carry taste fibres from front 2/3 of tongue through the middle ear

What nerve does the chorda tympani branch with

Lingual nerve

Where does the lingual nerve come from

Mandibular division of the trigeminal nerve

What does the mandibular division of the trigeminal nerve carry

carries sensory information from the 2/3rd of the tongue

What are the structures found superficial to deep in the ear

ear canal, tympanic membrane, malleus, incus, stapes, semi circular canal, cochlea

What are the 3 bones of the ear

Malleus

Incus

Stapes

What is an ear ossicle

Transmit vibrations through the bones of the ear

What are the regions to the tympanic cavity

lateral

medial

cochlear window

What is the lateral wall

The tympanic membrane

what is the medial wall

the oval window

opening into vestibule of inner ear

closed by base of stapes

what is cochlear wall

round window

opening into cochlear

What is the function of cochlea

Sound amplification

What is the function of semicircular canals

Balance

What is the nerve supply of the semi circular canals

Vestibulocochlear

What is the nerve supply of the cochlea and how does this differ

Vestibulocochlear

Vibration into electrical signals

What cranial nerves are responsible for taste

V3, VII, IX

What is the stimulant for sweet

glucose

What is the stimulant for salt

Sodium chloride

What is the stimulant for bitter

Alkaloid

What is the stimulant for sour

Hydrogen ions

What is the stimulant for savoury

Glutamate

Why does the body have a specific response to bitter foods

Bitter is typically associated with poison, unrippened or food that has gone off

The body has been made so that if the body comes into contact with any of these “dangers” it has been programmed to spit it out

Foods like coffee have specific chemicals in them which makes us think that the coffee is bad and poison

What are the muscles involved in the movement of the tongue

Genioglossus

Hyoglossus

Styloglossus

What is the role of the genioglossus

pull the tongue forward

What is the role of the styloglossus and hyoglossus

pull the tongue back

What muscles are responsible for the ability to role the tongue

Intrinsic muscles

Where are tastebuds found

Fugiform papillae and Vallate papillae

What are the receptors of saliva

gustatory

Outline the process of saliva and nerve impulse

Substance is broken down using saliva

The saliva goes into taste pore

Becomes bound to gustatory receptor - causes depolarisation in response to substance

GPCR

Nerve impulse sent to the brain via afferent nerve

What are the nerve innervations of the tongue

Lingual - taste and sensation in the anterior 2/3 of tongue

(conflicting information that taste here is due to chorda tympani)

Glossopharyngeal - taste and sensation in the posterior 1/3 of the tongue

Where do the nerves of the tongue go to in the brain

solitary nucleus of the medulla, thalamus, gustatory cortex

What structures of the gustatory complex do nerves go to

Anterior insula and inferior frontal gyrus

What are the other sensory inputs

Pungency

Coolness

Fattiness

Temperature

Texture

What is flavour mainly due to

Smell

What is the relation between flavour and smell called

Retronasal olfaction

What are the structures of the nose which are responsible for warming, humidifying and filtering the air

Septum, inferior turbinate and middle turbinate

(think - this process is called turbination hence the name)

What does quiet breathing involve

Laminar airflow over the inferior turbinate

What does sniffing involve

Turbulence which mixes the air and send odourant to the roof of the nose

Where are the olfactory receptors found

In the epithelia of the cribriform plate

Outline the process of smell

Odorant molecules in the air dissolve in nasal mucus

Detected by rhodopsin like detectors on dendrites of olfactory cells

GPCR

What can the olfactory nerve link to

Amygdala

Hippocampus

for emotion and memory

What is the purpose of a fever

To kill pathogens

Increased metabolic rate which causes healing to increase

Rapid increase in defense mechanism

What device is used a tympanic ear exam

Otoscope

What can be visualised with an otoscope

The tympanic membrane

What is the function of the tympanic membrane

To vibrate in response to air pressure changes and transmit these vibrations to the ossicles

What is otitis media

Inflammation or infection of the middle ear

What is effusion

Fluid present

What may we see in a patient who has otitis media when doing a physical exam

Red/yellow/cloudy tympanic membrane

Bulging tympanic membrane

Perforation

Decreased motility of the tympanic membrane

Why are ear infections more likely in children

Small eustachian tube

When children get a cold and there is a build up of mucus and inflammation this eustachian tube may not be able to drain causing a build up of fluid

What are eustachian tubes

Tube that connects the ear to the throat

What is the most common cause of otitis media

Bacteria most common strep pneumoniae.

What does paracetamol inhibit

COX enzymes