Ascending Pathways

Question 1

five special senses

Answer 1

• olfaction
• vision
• taste
• hearing
• balance

Question 2

cranial nerve for olfaction

Answer 2

olfactory nerve (I)

Question 3

cranial nerve for vision

Answer 3

optic nerve (II)

Question 4

cranial nerve for taste

Answer 4

facial (VII) and glossopharyngeal (IX) nerves

Question 5

cranial nerve for hearing

Answer 5

vestibulocochlear nerve (VIII)

Question 6

cranial nerve for balance

Answer 6

vestibulocochlear nerve (VIII)

Question 7

three types of general senses

Answer 7

• interoception
• exteroception
• proprioception

Question 8

interoception

Answer 8

pain, temperature, touch pressure of viscera

Question 9

exteroception

Answer 9

pain, temperature, touch pressure of external world

Question 10

proprioception

Answer 10

position sense from joints/ligaments/tendons

Question 11

5 types of sensory receptor for general senses

Answer 11

• nociceptors
• thermoreceptors
• mechanoreceptors
• chemoreceptors
• Baroreceptors

Question 12

what do nociceptors do

Answer 12

monitor tissue change

Question 13

what do thermoreceptors do

Answer 13

monitor temperature - found in skin, liver muscle, and hypothalamus

Question 14

what do mechanoreceptors do

Answer 14

monitor contact and pressure, found mostly in the skin

Question 15

what do chemoreceptors do

Answer 15

monitor chemical compositition of body fluids

Question 16

what do baroreceptors do

Answer 16

• subset of mechanoreceptors
• monitor changes in pressure of tubular organs (vessels, ureters, bowel)

Question 17

dermatome

Answer 17

area of skin supplied by a specific spinal nerve
each corresponds to an entry or exit point of ventral (motor) and dorsal (sensory) rootlets

Question 18

how many dermatomes are there

Answer 18

31

Question 19

dermatone pathology

Answer 19

symptoms that follow a dermatome (rash, pain) may indicate pathology involving the nerve root eg. shingles

Question 20

where are somatosensory axons relayed to

Answer 20

post central gyrus (primary somatosensory cortex)

Question 21

1st order neurons

Answer 21

• PNS
• found in dorsal root ganglia

Question 22

2nd order neurons

Answer 22

• CNS
• found in spinal cord

Question 23

3rd order neurons

Answer 23

• CNS
• found in thalamus

Question 24

three different types of ascending somatosensory pathways in spinal cord

Answer 24

• Spinothalamic (STT)
• Medial Lemniscus (MLT)
• Spinocerebellar

Question 25

what does the STT relate to

Answer 25

pain, temperature, crude touch

Question 26

what does the MLT relate to

Answer 26

fine touch and conscious proprioception

Question 27

what does the spinocerebellar tract relate to

Answer 27

proprioception

Question 28

what does the trigeminal nerve innervate

Answer 28

face and oral cavity

Question 29

what does the facial nerve innervate

Answer 29

skin around ear

Question 30

what does the glossopharyngeal nerve innervate

Answer 30

upper pharynx and posterior 1/3 of tongue

Question 31

what does the vagus nerve innervate

Answer 31

external auditory meatus and tympanic membrane

Question 32

four cranial nerves involved in the trigeminothalamic tract

Answer 32

- trigeminal - facial - glossopharyngeal - vagus

Question 33

trigeminal tract pathway

Answer 33

- four cranial nerves enter brainstem - these synapse at the trigeminal nucleur complex (midbrain, pons, and medulla) - they decussate here - then ascend to post central gyrus

Question 34

nine periperac receptors and sensation structures served by trigeminal system

Answer 34

- cornea - muscoctaneous tissues around nose and mouth - oral and nasal mucosae - paranasal sinuses - tongue (anterior 2/3) - teeth and gums - dura of anterior and middle cranial fossae - skin of face to vertex except angle of jaw - parts of external ear

Question 35

primary sensory neurons | trigeminothalamic tract

Answer 35

unipolar neurons similar to dorsal root ganglion cells

Question 36

what nerve roots give rise to primary sensory neurons

Answer 36

- ophthalmic CN V-1 - maxillary CN V-2 - mandibular CN V-3

Question 37

where do second order neurons originate

Answer 37

two brain stem nuclei: principle trigeminal nucleus spinal trigeminal nucleus

Question 38

principle trigeminal nucleus

Answer 38

- mediates fine touch stimuli (two point discrimination), joint position and vibration - located in the middle of the pons just lateral to the motor nucleus of trigeminal nerve

Question 39

what is neuritis

Answer 39

inflammation of PNS

Question 40

five causes of neuritis

Answer 40

- physical injury - infection (herpes, shingles, leprosy, guillain-barre syndrome, lyme disease, bells palsy) - chemical injury - radiation - nutritional deficiencies

Question 41

what two types of sensory function damage can occur | neuritis

Answer 41

- loss of function (numbness, tremor, gait abnormality) - gain of function (tingling, itching, crawling, pins and needles)

Question 42

dissaociated sensory loss

Answer 42

deficit in modality of pain/temperature or touch/proprioception

Question 43

STT lesion

Answer 43

contralateral loss of pain/temperature sensation below the level of the lesion

Question 44

MLP lesion

Answer 44

ipsilateral loss of touch/proprioception below the level of the lesion

Question 45

what is syringomyelia

Answer 45

disruption of the decussating fibres of the spinothalamic system (usually in cervical and upper thoracic regions) but not usually the ascending fibres of the dorsal column-medial lemniscal system

Question 46

syringomyelia symptoms

Answer 46

cape like distribution of loss of pain, temperature and crude touch sensation from above the lesion

Question 47

what is Brown-Sequard Syndrome

Answer 47

incomplete spinal cord lesion characterised by a hemisection of the spinal cord

Question 48

causes of Brown-Sequard Syndrome

Answer 48

- spinal cord tumour - trauma (puncture wound to neck or back) - ischemia (obstruction of bloos vessel) - infection/inflammatory diseases (TB or MS)

Question 49

Brown-Sequard Syndrome symptoms

Answer 49

contralateral loss of pain and temperature sensation (STT) ipsilateral loss of position and vibrating sensation, as well as parasthesia (ML)

Question 50

neuropathic pain

Answer 50

complex, chronic pain state that is usually accompanied by a tissue injury affecting the STT

Question 51

causes of central neuropathic pain

Answer 51

- spinal cord injury - MS - some strokes

Question 52

what is referred pain

Answer 52

pain perceived at a location other than the site of the painful stimulus