CNS Dev

Question 1

Development of the neural tube

Answer 1

Simple cubodial eptheliel cells that are the etcoderm form columnar epithelium that is the neural plate

Anterior and posteriar axis fold forming the neural folds

They fuse making the neural tube pulling future skin over it as it fuses

Division into pentapartite brain

Question 2

What are the parts of the tripartite and pentapartite brain?

Answer 2

Tripartite brain:

• prosencephalon
• mesencephalon
• rhombencephalon

Pentapartite:

• Telencephalon
• diencephalon
• mesencephalon
• metencephalon
• myelencephalon

Question 3

What is anecephaly?

Answer 3

Failure of the cranial end of the neural tube to close

Question 4

What is holoprosencephaly?

Answer 4

The failure of the prosencephalon to divide into two cerebral hemisphres

Causes facial deformities

• single orbit with two eyes. One eye or no eye
• proboscis-type nose located above eye
• cleft lip and palate

Question 5

What is spina bifida?

Answer 5

Failure of the caudal end pore to close

Type main types: cystica and occulta

Question 6

Occulta

Answer 6

Type of spina bifida

Failure of inferior neuropore to close

Vertebral arch fails to develop in caudal area

Spinal cord function is usually normal

Question 7

Cyctica

Answer 7

Type of spina bifida
-sac like cyst at caudal end of spine, spinal cord or meninges may be found in the cyst

Meningocele
-meninges in sac, some spinal cord misfunc.
Meningomyelocele
-meninges and spinal cord in cyst, paralysis and bowel/bladder dysfunction
Myeloschisis
-failule of the neural folds to close

Question 8

Arnold chiari deformity

Answer 8

The inferior cerebellum and medulla are elongated and protrude into the vertebral canal

Medulla and pons are small and deformed

Hydrocephalus

Malformation of the lower cranial nerves

• deafness
• tongue, facial muscle, lateral eyemovements

Question 9

The lumina, floor and roof of the telencephalon form what brain structures?

Answer 9

Lumina: lateral ventricles

Floor: Basal nuclei (ganglia) and alfactory lobes and nerves

Roof: cerbral cortex

Question 10

Diencephalon lumen, roof, walls, and floor form what?

Answer 10

Lumen: third ventricle

Roof: epithalamus

Walls: thalamus

Floor: hypothalamus and infundibulum

Question 11

Mesencephalon’s lumen, roof anf floor form which brain structures?

Answer 11

Lumen- cerebral aqueduct

Roof forms the tectum

• superior colliculi: visual reflexes
• inferior colliculi: auditory and olfactory reflexes

floor: tegmentum
- red nucleus
- substantia nigra
- various tracts

Question 12

The lumen, roof and floor of the Metencephalon form what structures?

Answer 12

Lumen: part of the fourth ventricle

Roof: cerebellum

Floor: pons

• nuclei (relay between cerebrum and cerebellum)
• centers (respiratory and sleep)

Question 13

What portions of the brain are formed from the myelencephalon?

Answer 13

Lumen: rest of the fourth ventricle

Roof: posterior chordius plexus

Majority: medulla oblongata

Question 14

What are the major components of the medulla?

Answer 14

Nuclei: vestibular nuclear complex (equillibrium and balance), sensory nuclei, portions of reticular formation

Pyramids: lateral corticospinal tracts

Vital relfex centers

• cardiac center
• vasomotor center
• centers related to respiration

Question 15

Where in the nervous system is the site of most reflex arcs? What else is found in this structure, general

Answer 15

The spinal cord

Incoming sensory information processing and relay station for motor nerves

Question 16

Peripheral nervous sytem.

Answer 16

Composed of Afferent and Efferent pathways

Cranial nerves, spinal nerves , sensory receptors and motor end plates are all part of the PNS

Question 17

The ANS

Answer 17

Entirely motor
Supplies smooth muscle, visera

Sympathetic system and parasympathetic system

Question 18

What part of a neuron conducts local potentials?

Answer 18

The dedrites

Axons conduct action potentials

Question 19

Are gray rami myelinated or unmyelinated? Pre or post ganglionic?

Answer 19

Unmyelinated postganglionic fibers

Question 20

A spinal nerve breaks into two rami, what are they?

Answer 20

White ramus and gray ramus

White is myelinated and preganglionic

Question 21

Paravertebral ganglia

Answer 21

Form a chain on either side of the vertebral column

Cell bodies of postganglionic sympathetic nerves and synaplse with preganglionic nerves

Question 22

Prevertebral ganglion

Answer 22

In abdominal aorta, site of synapse between preganglionic myelinated sympatheric neurons and postgangl non-myelination neurons

Question 23

What is a reflex arc?

Answer 23

A pathwat that leaves from and returns to the CNS, miminum of a sensory neuron and a motor neuron

Afferent - can be non-viseral or viseral

Efferent - somatic or viseral

Some pathways have interviening neurons that can modulate the reaction , called association neurons

Question 24

What are the physiological states of a neuron?

Answer 24

Resting
-cell body potential about (-65 mv)
Excited
-cell body potential in more positive, about (-45 mv)
Inhibited
-cell body potential is more negative than at rest, (-70 mv)
-typically due to influx of chloride ion or efflux of potassium ion

Question 25

What are the components of the somatosensory axis?

Answer 25

The somatosensory axis is a sequence of structures that transmit a sensory signal from peripheral receptors to higher brain centers

Peripheral receptors 
Afferent neurons
Spinal cord/brainstem
Reticular substance: medulla, pons, mesencephalon
Cerebellum 
Thalamus 
Somesthetic areas of cerebral cortex

Question 26

What is the arrangemnt of afferent neurons in the somatosensory axis?

Answer 26

Primary afferent neuron: synapse in the posterior horns of spinal cord or sensory nuclei in the brain

Ssecondaary afferent neurons: synapse in thalamus

Tetiary afferent neurons: synapse in the somethetic areas of cerbral cortes

Question 27

Skeletal motor nerve axis

Answer 27

Structures involves with the transmission of an action potential from higher brain centers to skeletal muscles

Motor cortex of cerebrum
Efferent pathways
-upper motor neurons - from cortical areas to anterior horns of spinal cord
-alpha motor neurons (lower motor neruons) to skeletal muscles

Effectors: skeletal muscles