4.7 Special Sensory Flashcards
What are the 4 types of sensory-receptor cells?
mechanoreceptors: movement, touch, pressure, vibration, sound waves
nociceptors: pain, tissue damage
photoreceptors: light
chemoreceptors: specific molecules
What is somatic sensation? What forms does it take?
Somatic Sensation is the sensation of body surfaces, including skin, muscle and joint sensation.
Touch:
light touch, deep touch, vibration, pressure
Temperature:
heat, cold
Pain:
tissue damage, extreme heat, extreme cold, mechanical
Musculoskeletal:
muscle stretch, muscle contraction, joint position
What does the spinothalamic pathway do?
SENSORY- Pain and Temperature (less: crude touch, pressure)
What kinds of receptors are used in the spinothalamic pathway?
mechanoreceptors, thermoreceptors, nociceptors in skin areas
What is the pathway for the spinothalamic tract? Where does it cross over?
Spinal nerve to dorsal spinal cord, crosses over (decussation) to white matter of spinal cord to thalamus to primary somatosensory cortex
What is nociceptive pain? what two types of fibers are involved?
pain due to activation of bare nerve endings (nociceptors) that sense noxious thermal, mechanical, and chemical stimuli
A-delta fibers: fast, sharp pain sensation
C-fibers: slow, dull pain
What is neuropathy?
– pain due to direct damage to nerves
What is referred pain?
pain in organs/viscera perceived as originating from body surface due to shared input region
What does the medial lemniscus pathway do?
SENSORY- 2-point discrimination, fine touch, vibration, pressure, proprioception
What kinds of receptors are used in the medial lemiscus pathway?
mechanoreceptors in skin, proprioceptors in muscles, joints
What is the pathway of the medial lemiscus? Where does it cross over?
Spinal nerves, to Doral root gangion, to Posterior white column, to Medulla where CROSSES OVER to medial lemiscus in brainstem, to Thalamus, to primary somatosensory cortex
What are the special senses?
Olfactory (nose) Gustatory (tongue) Auditory (ear, cochlea) Vestibular (ear, vestibule) Visual (eye)
What is the pathway for the olfactory system?
Chemicals in through air stick to olfactory mucosa, where dissolve contact olfacotry receptors nerves pass through cribriform plate of the ethmoid bone CN I nerves contact olfactory bulb (in CNS)
Where in the CNS do olfactory signals go?
hypothalamus, limbic system, olfactory cortex for integration of smell recognition, memory, association.
What anatomical structures are involved in the gustatory sense?
tongue/taste buds
facial nerve CN VII, glossopharyngeal nerve CN IX, vagus nerve CN X
medulla oblongata, thalamus, Gustatory Cortex
What 3 types of taste buds are used for gustatory sensation?
circumvallate papilla
fungiform papilla
filiform papilla
What is the pathway of the gustatory sense?
Facial Nerve (VII), Glossopharyngeal nerve (IX), and vagus nerve (X) contact the gustatory cells on the tongue signals from the cranial nerves travel to the CNS for integration: medulla oblongata, then to the thalamus, then to the Gustatory Cortex.
What is the general pathway of the auditory sense?
Stimulus, to
CN VIII, to
Thalamus, to
Auditory cortex
How does sound travel through outer ear to CN VIII?
Outer ear, to Middle ear, to TM, to Bones, to Oval window, to Inner ear, WHERE Little hairs vibrate --> CN VIII
What is the organ of corti?
The part of the cochlea that houses the hair cells that turn the physical movement of sound waves into electrical impulses
What is conduction deafness? Some causes?
soundwaves are not properly conducted to the inner ear cerumen impaction tympanic membrane perforation chronic otitis media (ear infection) auditory tube dysfunction otosclerosis of the ossicle joints congenital malformation of external ear
What is sensorineural hearing loss? Some causes?
neural transmission from cochlea to CNS is impaired
acoustic trauma
ototoxic drugs (certain antibiotics, aspirin, chemotherapeutic agents…)
viral infections affecting cochlea, CN VIII
basilar skull fracture
tumors
Which auditory test is for conduction? Localization?
Conduction= Rinne (tuning fork in air vs mastoid) Localization= Weber (tuning fork on top of head)
What is tinnitus?
Tinnitus is the perception of sound, when no sound is present, patient will report “ringing, buzzing, or noise” in the ears
can be caused by a wide range of pressure changes in the conductive pathways, or by neural or pressure changes in the transduction pathways, lesion in any place along the pathway
can precede or be associated with hearing loss
What is the function of the vestibular system? What anatomical structures are involved?
The special sense of balance and equilibrium is in the Vestibular System.
stimulus: head movement (rotation, acceleration, position) fluid movement in inner ear
receptors: hair cells in semicircular canals and otolith organs
anatomical structures:
inner ear
Vestibulocochlear Nerve (CN VIII)
dorsal pons, medulla oblongata
cerebellum
cerebral cortex (somatosensory cortex, parieto-insular vestibular cortex, periarcuate area of frontal lobe)
What is the function of the vestibule, otolith, and semicircular canals?
Vestibule/otolith organs: respond to gravity and acceleration of head
Semicircular canals: respond to rotation of the head in 3 planes
What is notable about the tonic action potentials of the vestibular system?
always a small amount of electrical activity (unusual).. Can lead to unusual effects.
Brain is always comparing R/L side. So, if one side changes activity level, body sends signal, then strange effect
What is the vestibular pathway?
vestibular hair cells send signals along the vestibulocochlear nerve (VIII)
to the pons and medulla oblongata, then to the cerebellum, and cerebral cortex
