Spinal Cord

Question 1

Where do the CNS and PNS derive from?

Answer 1

CNS- process of neurulation

PNS- neural crest cells also from neurulation

Question 2

Functional division of the nervous system

Answer 2

Somatic

autonomic

Question 3

What does the somatic nervous system do?

Answer 3

The sensory system receives pain, temp, touch, position to conscious level.
Motor system innervates skeletal only causing voluntary and reflexive movement.

Question 4

What does the autonomic NS do?

Answer 4

consist of visceral efferent and afferent fibers which are organized into sympathetic and parasympathetic groups.

Question 5

What are the differences between sympathetic and parasympathetic?

Answer 5

1) location of presynaptic cell bodies.

2) the nerves that conduct presynaptic fibers from CNS

Question 6

explain the role of efferent and afferent divisions of the NS.

Answer 6

• efferent conducts the signals to gernerate movement and leave the anterior horn.
• afferent conducts signals based on sensations and enter the posterior horn.

Question 7

What are the types of somatic fibers and functions?

Answer 7

• general somatic afferent: send sensation from body to CNS. extero and proprioceptive.
• general somatic efferent:send impulse to skeletal muscle.

Question 8

What are the Visceral fibers?

Answer 8

• afferent: pain or reflex signal from hollow organ or blood vessels.
• efferent: postsynaptic and presynaptic fibers send signal to smooth muscle and glandular tissue.

Question 9

What are the meninge layers of spinal cord?

Answer 9

Dura mater: the outermost covering. Covers the post/ant nerve roots.
Pia mater:innermost layer, covering spinal root nerves and blood vessels. Forms the filum terminale. Contain denticulate ligaments to suspend spinal cord.
Arachnoid mater: middler layer which maintains the CSF. connect to pia mater via arachnoid trabeculae.

Question 10

What are the major components of a spinal nerve?

Answer 10

• ventral nerve root: efferent fibers pass ant. horn of grey matter to peripherally located effector organs.
• dorsal nerve root: afferent fibers in dorsal root ganglion extending peripherally and centrally to the posterior horn of grey matter.

Question 11

What are the two structural divisions of the nervous system?

Answer 11

Central nervous system( consisting of brain and spinal cord.)
Peripheral nervous system (consisting of parts outside CNS)

Question 12

What are multipolar neurons?

Answer 12

-motor neurons with 2+ dendrites and 1 axon in a collateral branch. Most common in CNS/PNS

Question 13

A pseudounipolar sensory neuron

Answer 13

• double process to conduct impulse from receptor to cell body, and then from cell body to CNS.
• part of PNS; cell body located in sensory neurons.

Question 14

Neuroglia (glial cells)

Answer 14

• non excitable
• CNS: oligodendroglia, astrocytes,ependymal, microglia
• PNS: satellite cell, autonomic ganglia, schwann cell.

Question 15

Differentiation of spinal cord levels

Answer 15

• prosencephalon: telencephalon, diencephalon
• mesencephalon: midbrain
• rhombencephalon: myelencephalon, metencephalon

Question 16

Somatic Fibers

Answer 16

-transmit sensation from body to CNS, extero/proprioceptive.

Question 17

Visceral Fibers

Answer 17

• sensory:pain or visceral reflex sensations from blood vessels, organs
• motor: impulse to smooth muscle and glandular tissues.

Question 18

What are the different horns in the spinal cord?

Answer 18

• lateral: visceral innervations.
• dorsal: sensory
• Ventral: motor

Question 19

Anterior Rami

Answer 19

Branches that are located AFTER the root ganglion.

-generally thicker and contain sensory and motor

Question 20

Posterior Rami

Answer 20

Smaller region, mostly with the back (epaxial)

-contain sensory and motor. Located after root ganglion.

Question 21

Dermatomes

Answer 21

-areas on the skin that can be tracked back to a spinal nerve root.

Question 22

Myotome and its features

Answer 22

-large area of muscles that can be traced back to nerve root. have large overlap with dermatomes.

Question 23

Monosynaptic Reflex

Answer 23

• 1 synapse occurs, no interneurons are used.

ex. patellar reflex

Question 24

Polysynaptic Reflex

Answer 24

• 2 or more synapses with one occurring with interneuron in the lateral horn.
• longer response due to more synapse signals.
• ex. withdrawal reflex.

Question 25

Golgi Tendon reflex

Answer 25

prevents excessive skeletal muscle tensing.

nerve ending located in tendons. Allow muscle to relax, and prevents hyperactivity.