neuroanatomy

Question 1

Describe Neurulation in the embryo

Answer 1

Central part of ectoderm differentiates into the neural plate-forms neural tube in 4th week-differentiates along dorsal/ventral axis by growth signaling factors–>Shh (notochord) and BMP (ectoderm)

Question 2

Primary neurulation

Answer 2

involves invagination and columnarization of an existing epithelium. rest of the spinal cord (not sacral)

Question 3

Secondaty neurulation

Answer 3

characterized by condensation of mesenchyme (brown) to

form a rod, which then undergoes an epithelial transition to form the neural tube. Sacral part of column

Question 4

When and how does neural tube close?

Answer 4

during days 19-21. five separate waves of closure.
Begins in region of brain stem and upper spinal cord, followed by head & neck.
Final closure in caudal region where the sacral part of the spinal cord fuses with the rest of the
spinal cord

Question 5

What is Anencephaly

Answer 5

Lack of skull & cerebrum formation, with only a brain stem intact.
• Due failure of wave 2 closure

Question 6

Spina bifida

Answer 6

Incomplete formation of both the spinal cord and the overlying vertebrae which remain unfused and open:
spina bifida occulta, meningocele, myelomeningocele.
incomplete closure of caudal neuropore at junction of primary and secondary neurulation.

Question 7

CNS regions from dilation and flexure of neural tube

Answer 7

Hindbrain: medulla, pons( Myelencephalon, metencephalon)
Midbrain: Mesencephalon
Diencephalon: thalamus, hypothalamus, epithalamus
Telencephalon: cerebral hemispheres
Neural tube–> spina canal, ventricles

Question 8

Rostral

Caudal

Answer 8

Rostral – toward front of brain

Caudal – toward spinal cord

Question 9

Cephalic and Pontine Flexures

Answer 9

Cephalic flexure: Ensure that optical axes are at right angles to vertebral column. Related to cranial base flexion
Pontine flexure:Areas of 4th ventricle and pons enlarge. Cerebellum derived from edge of pons

Question 10

SPINAL CORD OVERVIEW

Answer 10

Grey matter area is divided into sensory, autonomic, and motor areas
White matter is divided into ascending (C) and descending (D) tracts

Question 11

GREY MATTER OF SPINAL CORD

Answer 11

Rexed’s lamina are functionally specific areas of 
gray matter
– Dorsal – sensory
– Intermediate – autonomic 
– Ventral - motor

Question 12

Dorsal horn

Answer 12

(sensory)
Afferents convey tactile, proprioceptive, pain and temperature sensations to neurons into lamina 2-5
Second order neurons send information to local spinal
areas as well as ascend to brain stem and thalamus

Question 13

Intermediate region

Answer 13

(autonomic) Site of preganglionic autonomic neurons (visceral motor, VM)

Question 14

Ventral horn

Answer 14

(motor) Efferent motor neurons project to skeletal muscle

groups

Question 15

WHITE MATTER OF SPINAL CORD

Answer 15

Separated into dorsal, ventral & lateral funiculi. Spinal tracts within white matter are formed by axons of ascending and descending neurons

Question 16

Funinculi: dorsal, lateral, ventral

Answer 16

Dorsal columns (cuneate & gracile fasciculi) carry tactile info to brain stem & thalamus
Lateral: corticospinal tract - major descending motor tract from cortex . Spinocerebellar tracts - tactile & proprioceptive information to cerebellum. Anterolateral system conveys pain and temperature to thalamus
Ventral: Anterior (ventral) corticospinal -descending motor pathways from cortex .vestibulospinal & reticulospinal - descending motor pathways from brain stem

Question 17

What does the Propriospinal tract do?

Answer 17

Surrounds grey matter and interconnects various spinal levels

Question 18

What does the brainstem contain?

Answer 18

regulatory centers for respiratory, cardiovascular, GI 
systems
• cranial nerves
• sensory and motor pathways 
• reticular formation

Question 19

Cerebellum

Answer 19

Cerebellar peduncles: input and output tracts between cerebellum & pons
Different regions regulate muscle coordination, motor planning & procedural memory, as well as balance
and eye movements

Question 20

MIDBRAIN contains?

Answer 20

Substantia nigra (dopamine), Periaqueductal grey (PAG)(Regulates pain / stress responses), Superior & Inferior Colliculi (Superior looks; inferior listens), Red nucleus
(descending motor pathway), Cerebral peduncle (sensory & motor pathways to and from spinal cord, brain stem and cortex)

Question 21

What is the DIENCEPHALON?

Answer 21

Nuclear regions
• Thalamus
• Hypothalamus (flanking third ventricle)
• Epithalamus contains pineal gland

Question 22

Thalamus?

Answer 22

Several nuclei that process & distribute

sensory & motor information to & from cerebral cortex

Question 23

Hypothalamus?

Answer 23

1. Nuclei
2. Pituitary
   – Anterior
   – Posterior

Question 24

Anterior pituitary

Answer 24

Derived from ectoderm primordia
Portal system of vessels extend from
hypothalamus into anterior pituitary

Question 25

Posterior Pituitary

Answer 25

Derived from neural tube | Neurosecretory neuronal axons extend into posterior pituitary to release hormones into blood

Question 26

Frontal lobe

Answer 26

Motor cortex: primary, premotor, supplementary, Broca’s speech area

Question 27

Parietal lobe

Answer 27

Somatosensory cortex: primary, secondary, association, Wernicke’s language area

Question 28

Temporal lobe

Answer 28

Auditory cortex: primary, | secondary, association

Question 29

Occipital lobe

Answer 29

Visual cortex: primary, | secondary, association

Question 30

insula

Answer 30

Gustatory, visceral, emotional cortex within lateral sulcus/fissure

Question 31

central sulcus and lateral fissue

Answer 31

Central sulcus separates frontal from parietal lobes. | Lateral fissure separates frontal from temporal lobes

Question 32

reticular formation

Answer 32

nuclei in brain stem. sensory input--> project to cortex, libic, spinal cord. Particular NT. Associated with wakefulness, arousal, attention, etc

Question 33

Basal ganglia

Answer 33

Caudate & putamen (striatum) Globus pallidus (GP)(embedded in white matter) Substantia nigra & Subthalamus (midbrain)

Question 34

LIMBIC SYSTEM

Answer 34

C-shaped cluster of structures that extends into temporal lobe cortex (Orbital & medial prefrontal cortex, Cingulate gyrus, Parahippocampal gyrus), thalamic nuclei, Hippocampus, Amygdala, Ventral striatum (nuc accumbens)

Question 35

What do white matter axon bundles do in the brain?

Answer 35

interconnect cortical regions sup. longitudinal & occipitofrontal fasciculi interconnect cortices along longitudinal axis Arcuate fibers interconnect local gyri Corpus callosum interconnects left and right hemispheres