T/F?
The notochord develops into the CNS
FALSE. Neural tube becomes CNS.
T/F?
The neural plate differentiates from the central part of the ectoderm and then forms the neural tube in week 4.
TRUE
Which of these refers to neural tube differentiation by BMP? Shh?
A. Highest conc. is on dorsal side
B. Associated with motor neural tissue development
C. Derived from ectoderm.
D. Derived from notochord
A. BMP (bone morphogenetic protein)
B. Shh (Sonic hedgehog)
C. BMP
D. Shh
Describe Primary Neurulation.
Columnarization of epithelium/ectoderm (= neural plate)
Rolling/folding of epithelium
Neural folds fuse to form neural tube
Describe Secondary Neurulation.
Condensation of mesenchyme to form a rod/cord
Separate structure from ectoderm
Cord hollows out to form neural tube
Where do primary and secondary neurulation occur?
Secondary - sacral region of spinal cord
Primary - rest of spinal cord
What is the sequence of neural tube closure?
When does it happen developmentally?
Five separate waves of closure during days 19-21
- brain stem and upper spinal cord
- top of skull
- face
- back of neck/occiput
- sacrum
What need to close for complete CNS formation?
Rostral and caudal neuropores
What results from failure of wave 2 closure?
Anencephaly
lack of cerebrum and skull formation with only brain stem intact
What results from incomplete closure of caudal neuropore, located at the junction of waves 1 and 5?
Spina bifida
Incomplete formation of both the spinal cord and the overlying vertebrae which remain unfused and open
What are the types of spina bifida? Which type is the most severe?
- Occulta - no SPs form, mild
- Meningocele (most severe) - spinal cord out of body, very vulnerable
- Myelomeningocele
Neural tube becomes…
Spinal canal and ventricles of brain stem and cerebral hemispheres
Another name for midbrain?
Mesencephalon
What structures are in the hindbrain? (common name/fancy name)
Pons = metencephalon Medulla = Myelencephalon
Telencephalon becomes
Cerebral hemispheres (inc. eyes)
Diencephalon becomes
thalamus, hypothalamus, epithalamus
Forebrain is comprised of
telencephalon and diencephalon
Describe the flexures by rostral/caudal folding during brain development
Pontine flexure = creates 4th ventricle; pons enlarges; cerebellum derived from edge of pons
Cephalic flexure = cranial base flexion to point eyes forward
Cephalic flexure is present at ___ wks
3
Enlargement of all brain areas and budding of CNs at ___ wks
7
Continued enlargement and folding at ___ wks. Forebrain takes on appearance of cerebral hemispheres.
11
Describe the function of three horns that make up gray matter
Dorsal - visceral and somatic sensory nuclei
Ventral - somatic motor nuclei
Lateral - autonomic efferent nuclei (preganglionic sympathetic)
These tracts within the spinal cord carry sensory information to the brain
Located in between dorsal horns and along the periphery of spinal cord
Ascending tracts
These tracts within the spinal cord carry commands to motor neurons
Located lateral to dorsal horns and in between ventral horns
Descending tracts
What are Rexed’s lamina?
Functionally specific areas of gray matter.
What is the function of the dorsal horns?
Dorsal horns - Sensory
Afferents carry tactile, proprioceptive, pain and temperature sensations to neurons for somatosensory processing/integration
What information is carried by 2nd order neurons and where does this info go?
2nd order neurons send information up dorsal column to local spinal areas as well as to brain stem and thalamus
What is the function of the intermediate area in between dorsal and ventral horns?
Intermediate - ANS symp and parasymp
Site of preganglionic autonomic neurons (visceral motor)
What is the function of the ventral horns?
Ventral horns - Motor
Efferent motor neurons project to skel. muscle groups
What are funiculi? What are fasciculi?
Funiculi = Bundles of axons located within white matter Fasciculi = Same but smaller
How are funiculi organized spatially in the spinal cord?
Separated into dorsal, ventral, and lateral funiculi
What forms spinal tracts?
Regions of axons of ascending and descending vertically-oriented neurons located within funiculi
What are the spinal tracts located in the dorsal funiculus and what do they do?
Cuneate and gracile fasciculi
Carry tactile info to brain stem and thalamus (ascending sensory)
What are the spinal tracts located in the lateral funiculus and what do they do?
Lateral corticospinal tract - major desc. motor tract from cortex
Spinocerebellar tracts (ventral and dorsal) - tactile and proprioceptive info to cerebellum
Anterolateral system - pain and temp info to thalamus
What are the spinal tracts located in the ventral funiculus and what do they do?
Anterior (ventral) corticospinal tract - desc. motor from cortex
Vestibular and reticulospinal tracts - desc. motor from brain stem
What is the propriospinal tract and where is it located?
Wraps around the periphery of gray matter
Interconnects various spinal levels
Structures and functions of brain stem
Pons, medulla, midbrain Regulatory (resp, cardio, GI) CNs Sensory and motor pathways reticular formation swallowing, vomiting, bladder
Structures and functions of cerebellum
Cerebellar peduncles - input/output tracts bet cerebellum and pons
Muscle coord., motor planning, procedural memory, balance, timing/coordination, eye movements, emotional/visceral
Structures and functions of midbrain
Substantia nigra - dopamine modulation of motor control
Colliculi
Superior - vision (eyes superior to ears)
Inferior - hearing
Red nucleus - part of descending pathway
Periaqueductal grey (PAG) - regulates pain/stress responses
Peduncle, cerebral - sensory and motor pathways to/from spinal cord, brain stem, and cortex
SCRPP - solitary confinement rots people’s personalities
The diencephalon is a part of the ______ brain and has these regions
Part of forebrain
Regions:
Thalamus - process & distribute sensory/motor info to/from cerebral cortex
Hypothalamus - paired structures flanking 3rd ventricle
Epithalamus - contains pineal gland
The thalamus contains many nuclei. Describe their organization and function.
Groups of areas containing many nuclei that each interact (“dialogue”) with different areas of the cerebral cortex.
Dorsal, ventral, lateral, medial, anterior, posterior, geniculate bodies, reticular nucleus etc.
Describe the nuclei of the hypothalamus.
Strong regions (blobs of nuclei) of control over visceral systems (water balance, thirst, body temp, b.p., satiety, GI, shivering)
Also controls behavior and communicates with motor system (put on sweater, get drink)
What hormones does the pituitary secrete?
FSH, LH, GH, ACTH, TSH, Oxytocin, ADH
How are the anterior and posterior pituitary different embryologically?
Ant. pit (adenohypophysis) from ectoderm roof of mouth, Rathke’s pouch
Post. pit - from neural tube; infundibulum
What connects the anterior and posterior pituitary?
blood vessels; communicate via blood
What is the connection between the hypothalamus and the anterior pituitary?
Hyp - Ant Pit = portal system of vessels extend from Hyp. to Ant. Pit.
Which of these is NOT a function of the frontal lobe?
a) Ideas, feelings, behaviors, associations
b) Primary motor cortex, premotor and supplementary motor cortex
c) Wernicke’s language area
d) Reasoning
C. Wernicke’s language area = parietal lobe, not frontal
Frontal lobe has Broca’s speech area
Which of these ARE functions of the parietal lobe?
a) Sense of self/ego
b) Receives sensory info from skin, musculoskeletal system, viscera, and taste buds, sensory association
c) Proprioception
d) Somatosensory cortex (primary, secondary)
ALL
T/F: The temporal lobe’s only functions are related to auditory processing
True. Contains auditory cortex and auditory association area
Which of these are NOT a function of the occipital lobe?
a) visual association
b) visual cortex (primary, secondary)
c) face recognition
d) associated with arousal/attention
C. face recognition is not a function of occipital lobe
D. arousal/attention function of reticular formation
What are insula? Describe location and function
Medial to frontal/temporal lobes along lateral sulcus
Gustatory cortex - taste
Olfactory cortex - smell
Visceral, emotional, gut feelings
Reticular formation, T or F?
A. Nuclei along lateral edge of brain stem.
B. Neurons receive general sensory input.
C. Project to cortex.
D. Assoc w/ arousal, attention, motivation, wakefulness
A. False. Medial axis of brain stem.
B. True
C. False. Project to cortex, limbic structures and spinal cord
D. True
What are the parts and what is the configuration of the limbic system?
C-shaped cluster of structures that extends into temporal lobe
H - Hippocampus
A - Amygdala
T - Thalamic nuclei (anterior and medial dorsal)
C - Cortex (Orbital and medial prefrontal cortex)
G - Gyri (Cingulate gyrus, Parahippocampal gyrus)
S - Ventral striatum
(Help a tired cranky girl smile)
What aspects are controlled by the limbic system?
Personality, values, mood, likes/dislikes, memory, emotions
____________ interconnect cortical regions of the brain.
Give examples.
White matter axon bundles
Sup longitudinal & occipitofrontal fasciculi - connect cortices along longitudinal axis
Arcuate fibers - connect local gyri
Corpus callosum - connects R & L hemispheres
What is the connection between the hypothalamus and the posterior pituitary?
Hyp - Post Pit = neurosecretory neuronal axons extend from Hyp. into post pit to release hormones into the blood
