Senses V2

somatic senses are generated by \_____

the simplest neuroreceptors and found throughout skin and viscera

NOCICEPTION

pain and other unpleasant sensations (e.g. cramping, shooting pain, burning, tearing pain, throbbing pain).

Nociception is appreciated by the

thalamus

Nociception is located by the

cerebrum

TEMPERATURE is appreciated by the

thalamus

Somatic Pain

located by cerebrum to a specific place (pinpointed) on the body (remember homunculus draped over post-central gyrus.)

Visceral Pain

located more generally by cerebrum over viscera affected and often referred to additional area on surface of body, e.g. Gall Bladder, Pancreas, Heart, Kidney Stone.

Anaesthesia

the absence of feeling, numb

Parasthesia

strange feeling, pins and needles, like a limb going to sleep

Analgesics

dampened pain, pain killers (only lessen the pain)

the cerebrum's postcentral gyrus locates and appreciates

DISCRIMINATORY TOUCH, pressure, vibration, PROPRIOCEPTION

Neuroreceptors are most concentrated

face, hands, and erogenous zones (remember homunculus).

Dermatomes

Body maps of the areas on skin where all the above senses (1-5) are detected and carried by specific cranial and spinal nerves. Used in neurological exams to identify which nerves are damaged when sensory deficits are found.

PROPRIOCEPTION

("Where are the joints and what are they doing?")This sense is carried by largest and fastest nerves. Need to know this to move and react. Position and movement of joint

PROPRIOCEPTION data travels up the neuraxis and is relayed to the

postcentral gyrus and cerebellum

Joint Load

stretch or tension on joints and muscles (lifting)

Ascending Tracts

Sensory pathways of the neuraxis. Carry a variety of information from neuroreceptors throughout body to brain

Descending Tracts

Motor pathways of the neuraxis. Deliver commands for voluntary movements

peripheral nerves to muscles in face and body are formed by

Axons of the primary motor regions of the cerebral cortex that run to cell bodies in brainstem or spinal cord

How does the brain movements precise and smooth

axons from other areas (basal ganglia, vestibular apparatus, etc.) synapse on those cell bodies in brainstem or spinal cord. (Hence, commands from many different areas of the brain and cerebellum are converging on the same motor neurons the face and body, blending their information

flow of deep tendon reflexes

Stretch of tissues around joint is detected by neuroreceptors → spinal nerve to spinal cord(sensory information) → motor neuron of anterior horn → spinal nerve to muscle → muscle jerk and joint movement

Upper Motor Neurons (UMN)

Brain to anterior horn cells

UMN Lesions cause

Spastic Weakness (muscles stiff but weak) Hyperreflexia (more than normal response)

possible UMN Lesions conditions:

CNS Tumors, Cerebral Palsy, CVA (stroke), Multiple Scorsese

Lower Motor Neurons (LMN)

Anterior horn cell axon to muscle (i.e. within the peripheral nerve

LMN Lesions cause

1. Flaccid Weakness \= Paralysis 2. Hyporeflexia (less than normal response

possible LMN Lesions conditions:

Spinal nerve damage, Polio.

Olfaction

Identification of odours. Assists in appreciation of flavours

Anosmia

loss of sense of smell (and food has little flavour)

Steps of olfaction

Olfactory cells w/hairs in nasal cavity → through cribriform plate of ethmoid → mamillary bodies \n (relays) → cerebral cortex (interprets)

The nose is innervated by CN \_____

I

Steps of gustation

Gustatory cells with hairs in Taste Buds on Papillae on tongue → cerebral cortex (interprets)

5 tastes:

Sweet, Salty, Sour, Bitter, Savoury? (brothy, meaty . . . umami)

The tongue is innervated by

VII—anterior 2/3 of tongue, IX—posterior 1/3 of tongue

Gagging is controlled by CN

IX, esp. bitter tastes

Aguesia

loss of sense of taste.

The ear is innervated by \____

VIII

Outer Ear role

collects sound waves

Outer ear consists of

Pinna or Auricle, Ext. Auditory Canal, Ceruminous glands (Cerumin)

Input collected by the outer ear

→Tympanic Membrane (connected to bones, i.e. ossicles, in middle ear), can be visualized with an Otoscope

Cerumin

ear wax

Middle Ear role

Ossicles transfer vibrations to inner ear.

How does the middle ear drain any build up

Eustacian or Auditory Tube connected to chamber from pharynx (infections and allergies)

The middle ear consists of \_______

3 Ossicles, 2 muscles

What are the 3 ossicles of the middle ear?

Malleus (attached to eardrum), Incus, Stapes (attached to inner ear)

What is the role of the muscles

to dampen loud sounds, reduce shaking

Labryrinth of inner ear:

coiled tube within a tube—fluid filled.

Roles of inner ear:

audition and equilibrium

Audition takes place in the

Cochlea (Stapes transvers vibrations into labyrinth)

Equilibrium takes place in the

Vestibular Apparatus (similar to proprioception of joints, i.e. Where is the head and what is it doing?)

how do the ears track equilibrium?

Head position and movement causes sensory devices to shift and fluid in labyrinth to flow

Vestibular Apparatus Utricule & Saccule

Static Equilibrium (head position).When head position changes, Otoliths in the sensory organ obey gravity and shift which stimulates hair cells → cerebral cortex (to know) & cerebellum (to coordinate response).

Vestibular Apparatus Semicircular Canals

Dynamic Equilibrium (head movement). Arranged in 3 planes, 90o to each other. Movement causes fluid in canals to swirl and bend sensory hairs →cerebrum, cerebellum, & CNs for eye Mm to follow head movement.

Vertigo (Vestibular Apparatus)

true dizziness room, spinning

Nystagmus (Vestibular Apparatus)

eye flickering

Ataxia (Vestibular Apparatus)

lesions send bad info to cerebellum → uncoordinated locomotion.

Cochlea: Organ of Corti

Membrane containing hair cells vibrates with vibrations of fluid. Hairs bend against a fixed membrane → cerebrum, inferior colliculi and CNs neck Mm (reflex)

Hertz (Hz)

cycles or waves per second, a measurement of frequency, pitch

How many Hz can the human ear detect?

20—20,000 Hz

Decibels (dB)

amplitude, loudness, magnitude or energy of waves. Normal conversation 60 dB, pain and damage around 100 dB

Conduction

middle ear problem. Most common hearing loss. e.g. Otosclerosis—DJD of ossicles

Sensorineural

damaged hair cells or nerve lesion causing hearing loss

Weber's test

done with a tuning fork. If you have a conduction problem, you'll hear the ringing louder in the bad ear. If its sensory-neural deafness, it's louder in the bad ear.

Hearing loss with age

lose highest Hz first. Also less able to process auditory \n information from one source when competing with other auditory input.

Meniere's Syndrome

increased fluid pressure (?) in inner ear → \n Tinnitus, Vertigo, Nausea, Hearing Loss

Otitis Media

Infection in middle ear or allergy with inflammation and fluid. 80% NOT bacterial—antibiotics no benefit.

Otitis Externa

"Swimmer's Ear" or "Red Ear", external ear canal infection

Lacrimal Glands produce

Tears (moisture, O2, lysozymes)

Nasolacrimal Duct

connects to the nasal cavity and causes the nose to drip

Conjunctivitis

inflammation usually d/t allergy or irritation of conjunctiva.

Ciliary Process

produces Aqueous Humor (bathes anterior eye)

Glaucoma

excessive intraocular pressure d/t aqueous humor → blindness

Lens has a \_____ shape

Ovoid

How do our eyes adjust to see things close to them?

Ligaments holding it taunt become slack when Ciliary m. contracts → lens becomes more spherical, thicker, bends light for near vision

Cataracts

Cloudy lens. Accumulating damage from UV light as one ages, dim vision.

Vitreous Humor

gel-like substance that fills posterior eye maintaining shape of eye and position of retina.

Pupil

controls light. Sympathetics dilate, Parasympathetics constrict.

Photoreceptor cells

neuroreceptor cells of the eye, bipolar like hair cells of other senses.

Photoreceptor cells- Rods

dim light, shapes & movement, Many:1 Rods to Ganglion cells—general info

Photoreceptor cells- cones

bright light, visual acuity (detail), color vision, 2:1 Cones to Ganglion cells—specific info

Photoreceptor cells- Müller's cells

like fibre optics, deliver specific wavelengths of light to specific photoreceptors for minimal distortion of image

Visual Pigment

derivative of Vitamin A

Visual Pigment- rods

chemically active in dim light, bleaches out in light/dark adaptation required; Night-blindness (Vitamin A deficiency)

Visual Pigment- cones

chemically active in bright light. Cells respond to red, green or blue wave lengths of light; brain mixes

Macula

round darker area of the ocular fundus that mediates vision only from the central visual field. in visual axis; only cones here (rods in periphery)

Optic Disk

convergence of axons (CN II) to brain; no rods or cones—blind spot

Opthalmascope

used to visualize Retinal artery & vein pass through that Optic Disk

Myopia

image focuses in front of retina (Nearsighted)

Hyperopia

image focuses behind retina (Farsighted)

Presbyopia

reduced elasticity of lens for accommodation to near vision

Astigmatism

irregular cornea and/or lens, blurred vision

3 ways eye accommodate near vision all CN III

(1) Thickening or rounding of lens to increase refraction, (2) Constriction of pupils, (3) Convergence of eyes, cross eyed (Medial Rectus Mm, voluntary)

Macular vision only

tunnel vision

Peripheral vision only

no central vision

Detached Retina

fallen curtain symptom

Strabismus

abnormal deviation of the eye (cross eyed)

Ambliopia

lazy eye, must patch good eye forcing lazy eye to perform

Diplopia

double vision

Abnormal Pupil Reflexes

no constriction when light shined, CN III lesion

non-convergence of Eyes

no convergence on close object, CN III lesion