Altered Somatic and Special Sensory Function

Nociception

pain/itch

Proprioception

body position

Somatosensory System

• The 5 senses”: taste, touch, hearing, smell, and sight

• Nociception

• Proprioception

• Temperature

• Pressure

• Balance

Somatosensory Cortex

Located in the parietal lobe

Cortex processes and fine-tunes
sensory input to determine:

• Location

• Intensity

• Perception of sensation

Sensory signals travel

periphery->spinal cord->thalamus >somatosensory cortex

Somatosensory System Processing

How sensory information from the skin, muscles, joints, and internal organs is

Received Sensors

mechanoreceptors, thermoreceptors, nociceptors,etc

Transmitted Sensors

sensory neurons->dorsal root ganglia->sensory
pathway

Interpretation Sensors

occurs in the thalamus and somatosensory
cortex

General somatic afferent neurons

wide distribution with distribution throughout the body

• senses pain, touch, temperature

Special somatic afferent neurons

distributed throughout muscles, tendons, and joints

• senses position and body movement

General visceral afferent neurons

distributed throughout visceral structures

• senses fullness and discomfort

Somatosensory System

Relay information thorough out the body from the periphery to the central nervous system (CNS) using:
Sensory receptors—-Ascending Pathways—-Processing Centers

Chemoreceptors

oxygen, pH, organic molecules, osmoreceptors

Mechanoreceptors

vibration/acceleration/sound, baroreceptors

Thermoreceptors

cold and warm receptors

Photoreceptor

specialized cells located in the retina of the eye that detect light and convert it into electrical signals that are sent to the brain; rods and cones

Somatosensory Neuronal Organization

1. First-order neurons (out of peripheral axon to CNS)

2. Second-order neurons (CNS to the brainstem)

3. Third-order neurons (thamalus to somatosensory cortex)

Somatosensory Neurotransmission

Dorsal root ganglia fibers:

• Depends on the diameter and
  nerve fiber myelination

• Nerve fibers involved are type
  A-alpha, A-beta, A-delta, & C
   

A-alpha fibers

Large, Heavy myelination, Very fast, Proprioception

A-beta fibers

Large, Heavy myelination, Fast, Touch and
pressure

A-delta fibers

Small, Light myelination, Moderate
speed;  Sharp, localized pain and
temperature

Anterolateral (reflexes)

• Pain, temperature, crude touch

• Triggers autonomic responses

Discriminative (specified sensation)

• Fine touch, proprioception

• Allows localization
  

C fibers

Very small,No myelination, Slow; Dull, aching,
burning pain and temperature

Dermatome Innervation

a single spinal nerve root, which transmits sensory information from that skin area to the spinal cord

Neurogenic/neuropathic pain

Originates within the CNS

Nociceptive pain

Noxious stimulus of pain fibers initiated in skin, joints, muscles, bones, or other internal organs

Transduction

Tissue-damaging stimuli activate nerve endings

Transmission

Message is carried from the site of injury to
the brain

Modulation

Reduces activity of transmission system

Perception

Subjective awareness (sensory, emotional,
and subjective reactions to stimuli

How do we know to feel pain?

A pain message is transmitted to the brain by specialized nerve cells known as nociceptors, or pain receptors

How do we know where the pain is?

signal of pain receptors is processed by the brain, the thalamus identifies the location and nature of the pain before sending a response back to the body to indicate the source

Pain Locations

• Cutaneous

• Deep

• Visceral

• Referred

Pain Quality

Sharp, burning, stabbing, aching, etc.

Pain Duration

• Acute

• Chronic

Myopia

nearsightedness

Hyperopia

farsightedness

Astigmatism

blurred vision, from irregular curve of the cornea or lens

Presbyopia

farsightedness associated with aging

Cataract

blurred vision, from clouding of the lens

Vision Function

light comes through cornea reflects on retina, rods (dim light, peripheral vision) and cones (bright light, color perception)

Vitamin C Foods

Citrus fruits, Strawberries, Kiwi, Berries ,Papaya, Mango, Cantaloupe, Bell peppers , Broccoli, Brussels sprouts, Cauliflower, Tomatoes, Potatoes, Spinach, and Kale

Vitamin A Foods for vision improvement

Carrots, Spinach, Sweet potatoes, Egg, Bell pepper, Beef liver, Mango, Apricot, Cantaloupe

Strabismus

cross-eyed, from lack of eye muscle coordination

Nystagmus

rapid, uncontrolled eye movement, involuntary

Inner Ear Alterations in Hearing

• Cochlear hair cell damage
  • Tinnitus
  • Sensorineural hearing loss (presbycusis)

• Equilibrium disruption
  • Meniere disease

Hearing Function

outer ear gathering sound waves, the middle ear amplifying them with tiny bones, and the inner ear translating them into nerve signals

External and Middle Ear Alterations in Hearing

• Obstruction
  • Cerumen impacted
  • Mass

• Inflammation
  • Otitis externa/media

• Barotrauma

Fibromyalgia Patho

• Condition of soft tissues and
  muscles

• Common in AFAB, especially older
  adults (60-70 years old)

• Unknown cause

Cochlear implants

bypasses damage hearing cells (cochlea) caused by congenital or environmental loss

Meniere Disease

causes vertigo, neuronal hearing loss, tinnitus

Otitis externa/media

ear infection

Barotrauma

caused by a difference in pressure between a body cavity and the surrounding environment

Fibromyalgia Symptoms

• Fatigue

• Pain

• Depression

• Malaise

Fibromyalgia Diagnosis

• No diagnostic test exists

• Subjective assessment

• History of fatigue

• Chronic musculoskeletal pain for
  at least 3 months

• 12/18 tender point sites

• Trigger points (tight bands of muscle fibers)

Migraines Patho

• Recurrent headaches (HA), mod-
  severe that last 1-2 days

• Accompanied with nausea, vomiting, and sensitivity to noise and light

• Exact cause unknown

Migraine phases: Prodrome

mood changes, food cravings, neck stiffness in hours to days before HA

Migraine phases: Aura

not common, visual disturbances preceding the HA

Migraine phases: Headache

pain, unilateral, pulsing, throbbing

Migraine phases: Postdrome

fatigue, inability to concentrate, depressed or euphoric mood

Migraines Diagnosis

• History

• Physical exam

• MRI/CT (rule out masses or lesions in brain)

Meniere Disease Patho

• Altered vestibular function

• Membranous labyrinth swelling (compresses bony labyrinth)

• Increased volume of endolymph
  causes dilation altering hearing and
  balance

• Unilateral occurrence

Meniere Disease Clinical Manifestations

Vertigo, nausea and vomiting, sensorineural hearing loss, pressure/pain, tinnitus and
nystagmus

Meniere Disease Diagnosis

• History

• Physical exam

• Auditory and visual tests

Macular Degeneration Patho

• Degeneration of the fovea

• Distorted central vision

• Drusen deposits

• Choroidal neovascularization

Dry (atrophic) Macular Degeneration

slow progression of symptoms

Wet (exudative) Macular Degeneration

typically rapid and severe vision loss

Macular Degeneration Clinical Manifestations

• Difficulty reading, recognizing faces, or colors

• Blindness

• seeing detail

• severity—loss of vision

Macular Degeneration Risk Factors

• 60 years or older

• Smoking

• Hypertension

• Being overweight or obese

• Family history

Macular Degeneration Diagnosis

Vision screenings

• Ophthalmoscopic exam

• Leakage (wet)

• Bulging macula (wet)

• Drusen deposition (dry)