Spinal cord/nerves

Question 1

Protecive structures of spinal cord

Answer 1

vertebral column and meninges (continuous with cranial meninges)

• epidural space = adipose tissue
• dura mater = dense collagen
• arachnoid mater w/ subarachnoid space for CSF
• Pia mater : denticulate ligament and filum terminale

Question 2

Where are the two enlargements?

Answer 2

cervical and lumbar

Question 3

what are the two middle crevices called?

What are the white areas around the horns called?

Answer 3

Ventral/Anterior median fissure
Dorsal/Posterior median sulcus
Funiculi

Question 4

Spinal nerves: numbers for each section

Answer 4

C1-C8 = cervical
T1-T12 = Thoracic
L1-L5 = Lumbar
S1-S5 =Sacral
CO1 = coccygeal

Question 5

Connective tissue coverings of spinal nerves

Answer 5

endoneurium = around individual fibers
perineurium = bundles of nerve fibers (fasicle)
epineurium = around multiple fasicles

Question 6

Rami

Answer 6

• Dorsal rami sense and motorize dorsal side of body (mixed nerves)
• Ventral rami make up plexuses everywhere except T2-T12

Question 7

Cervical Plexus

Answer 7

C1-C5

-Includes phrenic nerve = innervates diaphragm

Question 8

Brachial Plexus

Answer 8

• C5-T1
• Shoulders and upper limbs
• roots merge into trunks which divide into divisions which merge into cords which divide into nerves
• axillary, radial, ulnar, musculocutaneous, median, long thoracic
• Injuries cause issues with arm

Question 9

Lumbar Plexus

Answer 9

L1-L4

• anterolateral abdominal wall, external genitals, and part of lower limb
• femoral nerve and obturator nerve

Question 10

Sacral Plexus

Answer 10

L4-S4

• Butt, perineum, and lower limb
• Sciatic nerve

Question 11

Coccygeal Plexus

Answer 11

S4-CO1

-small area of skin in coccygeal region

Question 12

Dermatome

Answer 12

area of skin that provides sensory input to CNS via one pair of spinal nerves or the trigeminal nerve

Question 13

4 types of somatic sensations

Answer 13

tactile, thermal, pain, and proprioceptive

Question 14

Tactile sensations

Answer 14

touch, pressure, vibration, itch, tickle
-In skin: Meissner’s corpuscle, hair root plexus, Merkel Disc, Ruffini corpuscles, Pacinian corpuscles, and free nerve endings

Question 15

mechanoreceptor
thermoreceptor
photoreceptor
chemoreceptor
nociceptor

Answer 15

• touch, pressure, vibration, and stretch
• temp
• light (retina)
• smell, taste, change in blood chem
• pain

Question 16

Exteroreceptor

Answer 16

• stimuli outside body

- skin and most special sense organs

Question 17

Interoreceptor

Answer 17

• visceroceptors
• internal stimuli from blood and viscera
• tissue stretch, temp, chem changes
• often unnoticed by person

Question 18

prprioceptors

Answer 18

inform brain of one’s movements and body part location

Question 19

Speed of sensory receptor adaptation

Answer 19

• Fast ones (phasic)= pressure, touch, smell, and temp –> send signals only at beginning and end of stimulus
• Slow (tonic) = pain, body position, of chem composition of blood

Question 20

Pain

Answer 20

• warns of actual or impending tissue damage
• stimuli includes potassium, ATP, acids and bradykinin
• impulses travel up fibers that release glutamate and substance P
• Some pain is blocked by endogenous opiods (endorphis)

Question 21

Visceral and Referred pain

Answer 21

Visceral = stimulation of visceral organ receptors –> vage aching, gnawing, burrowing –> activated by stretchig, ischemia, chems, muscle spasms

Referred = perceived as coming from somewhere else –> impulse travels along same nerve, so brain assumes stimulus is coming from common somatic region

Question 22

Somatic Sensory Pathways

Answer 22

• First order neuron = somatic receptor to brain stem/ spinal cord
• Second order neuron = brain stem/ spinal cord to thalamus (decussate)
• Third order neuron = thalamus to primary somatosensory area of cortex

Question 23

Posterior Column Medial Lemniscus Pathway

Answer 23

• senses touch, pressure, vibration, and proprioception from everything except face
• 1st neuron cell body in dorsal root ganglion –> travels up and synapses at either gracile or cuneate nucleus in medulla
• 2nd neuron decussates and synapses at thalamus
• 3rd neuron goes to primary somatosensory area

Question 24

Anterolateral (spinothalamic) pathway

Answer 24

• senses pain, temp, itch, and tickle from everywhere except face
• 1st cell body in dorsal root ganglion –> snapses immediately in posterior grey horn
• 2nd neuron immediately decussates and travels up opposite column to thalamus
• 3rd neuron goes to primary somatosensory area

Question 25

Trigeminothalamic Pathway

Answer 25

-somati sensation of face, oral cavity, nasal cavity, and teeth -1st neuron body in trigeminal ganglion --> synapses in pons or medulla -2nd neuron decussates and synapses in thalamus 03rd neuron goes to primary somatosensory region

Question 26

Somatic Motor Pathways

Answer 26

- upper motor neurons to lower motor neurons to skeletal muscles - neural circuits involving basal ganglia and cerebellum regulate upper motor neurons

Question 27

Direct vs indirect motor neuron pathways

Answer 27

Direct - originates in cerebral cortex - corticospinal = to lmbs and trunk - corticobulbar = to head Indirect = originates in brainstem

Question 28

Lateral Corticospinal pathway

Answer 28

- most of the motor stuff - upper neuron in cerebral cortex --> crosses in pyramids --> lateral corticospinal tract --> anterior gray horn - lower motor neuron goes out anterior root to innervate skeletal muscle - distal limbs (forearms and hands)

Question 29

Anterior Corticospinal Pathway

Answer 29

- upper motor neuron in cerebral cortex --> doesn't cross at pyramids --> anterior corticospinal tract --> crosses and synapses at anterior gray horn - lower neuron exits and innervates muscle - trun kand posterior limbs

Question 30

Corticobulbar pathway

Answer 30

- facial and hypoglossal nerves - partially decussates --> upper right cranial nerve splits and innervates right and left facial nerve/hypoglossal nerve - stroke/ bell's palsy