PNS And Spinal Cord

Question 1

What functional nerves are in the posterior horn?

Answer 1

Somatic afferent and visceral afferent

Question 2

What functional nerves are in the anterior horn?

Answer 2

Visceral efferent and somatic efferent

Question 3

What are the three meninge layers of peripheral nerves?

Answer 3

1. Epineurium: most prominent around whole trunk; gives tensile strength
2. Perineurium: continuous with arachnoid; blood-nerve barrier
3. Endoneurium: surrounds individual fibers

Question 4

What is the function of myelin?

Answer 4

Insulates axon membrane to increase conductivity velocity

Question 5

What produces myelin in the CNS? PNS?

Answer 5

CNS: oligondedroglia cells
PNS: Schwann cells

Question 6

What is the term for the areas between the myelin and what do these areas do?

Answer 6

Nodes of Ranvier; conduct the signal as it jumps from node to node

Question 7

Which fibers are thicker: preganglionic autonomic or postganglionic autonomic?

Answer 7

Preganglionic autonomic

Question 8

Which fibers are thicker: sharp pain or slow pain?

Answer 8

Sharp pain

Question 9

Chemoreceptors are typically responsible for what?

Answer 9

Taste, smell, pH, metabolite concentrations

Question 10

Photoreceptors are responsible for what?

Answer 10

Rentinal visual receptors

Question 11

Thermoreceptors?

Answer 11

Temperature

Question 12

Mechanoreceptors?

Answer 12

Respond to physical deformation: touch, muscle length and tension, auditory, vestibular receptors

Question 13

Nociceptors?

Answer 13

Pain

Question 14

T/F: Joints have one type of receptor that responds to position and movement.

Answer 14

False

Many types of receptors

Question 15

What are the two components of all receptors?

Answer 15

1. Receptive area

2. Synaptic area: where message is sent toward CNS

Question 16

What is the main function of a receptor?

Answer 16

Turn a physical stimulus into an electrical signal the nervous system can understand

Question 17

What is a receptor potential?

Answer 17

Describes the intensity and duration of a stimuli

Question 18

What is a receptive field?

Answer 18

This allows the CNS to perceive the location of the stimulus.

Question 19

What is the likely function of free nerve endings in muscles?

Answer 19

Detect muscle pain

Question 20

What are the two types of encapsulated receptors in the muscles?

Answer 20

Muscle spindles: detect muscle length

Golgi tendon organs: detect muscle tension

Question 21

What is the conus medullaris?

Answer 21

It is the caudal end of the cord before it narrows into the nonfunctional filum terminale

Question 22

Where are the spinal cord enlargements and what are they for?

Answer 22

Cervical enlargement: C5-T1

Lumbar enlargement: L2-S3

More motor neurons to supply upper and lower extremities

Question 23

The dorsal rootlets _______ the cord in the _____________.

Answer 23

Enter; posterolateral sulcus

Question 24

The ventral rootlets _______ the cord from the ____________.

Answer 24

Leave; anterolateral sulcus

Question 25

Which root has a ganglion at the coalescence of the dorsal and ventral roots?

Answer 25

Dorsal root ganglion: contains cell bodies of sensory neurons

Question 26

How do you deduce the level of a cord lesion?

Answer 26

Each spinal nerve innervates one dermatome level

Question 27

What is the pathway of a sensory signal?

Answer 27

Receptor -> afferent fibers enter dorsal root -> terminate in posterior horn or ascend to medulla

Question 28

What is the pathway of a motor signal?

Answer 28

Signal from brain -> Anterior horn -> leave thru ventral roots

Question 29

What is a reflex?

Answer 29

Stereotyped motor outputs, involve neural circuits only in cord NO BRAIN

Question 30

What structure do the two sides of the cord communicate through?

Answer 30

Anterior white commissure

Question 31

What structure divides the posterior funiculi at the C and T levels?

Answer 31

posterior intermediate sulcus

Question 32

What is the common configuration of the spinal cord?

Answer 32

H-shaped gray matter surrounded by white matter funiculi

Question 33

What structure is only found above T6 in the spinal cord?

Answer 33

The posterior intermediate sulcus

Question 34

What happens to the spinal cord shape as it goes from cervical to sacral?

Answer 34

Gets narrower from C->T Gray matter gets larger from T->L

Question 35

What is the substantia gelatinousa related with?

Answer 35

Pain and temperature

Question 36

Which horn contains motor neurons that control skeletal muscle?

Answer 36

Anterior horn

Question 37

What are alpha neurons and where are they found?

Answer 37

Muscle moving motor nuerons; found in the anterior horn

Question 38

Why do the alpha neurons cluster into small groups?

Answer 38

Each group is indicative of innervating an individual muscle

Question 39

What are the two specialized columns in the cervical anterior horns?

Answer 39

Spinal accessory nucleus: forms accessory nerve (caudal medulla to C5) Phrenic nucleus: innervates diaphragm (C3,4,5... keeps the body alive)

Question 40

What types of neurons are found in the intermediate gray matter (between the horns)?

Answer 40

Preganglionic sympathetic neurons (T1-L3) ANTERIOR Clarke's nucleus (T1-L2): relays proprioception of legs to cerebellum; POSTERIOR Sacral parasympathetic nucleus (S2-S4): supply pelvic viscera; ANTERIOR

Question 41

Where would you do a spinal tap?

Answer 41

Lumbar since spinal cord is degenerated to filum terminale

Question 42

What suspends the spinal cord in the column?

Answer 42

denticulate ligaments

Question 43

How many neurons are involved in the stretch reflex?

Answer 43

2 neurons and one synapse between them

Question 44

What is an interneuron?

Answer 44

Interneurons are in all reflexes except the stretch reflex. They are in between the receptor and effector neurons

Question 45

Which artery is responsible for the anterior horn? Posterior horn?

Answer 45

Anterior spinal artery; posterior spinal arteries