Development of the Brain Flashcards
3 Steps of Neurulation
(1) Notochord forms from mesoderm cells after gastrulation is complete
(2) Signals from notochord cause inward folding of ectoderm at the neural plate
(3) Ends of neural plate fuse and disconnect to form an autonomous neural tube
When does brain development occur?
During the 3rd week from the NT (cranial to 4th pair of somites)
Fusion of neural folds in cranial region and closure of rostral neuropore form:
Primary Vesicles (n=3)
When do secondary vesicles form? How many are there?
- 5th week
- 5
What are the 3 primary vesicles?
(1) Forebrain (Prosencephalon)
(2) Midbrain (Mesencephalon)
(3) Hindbrain (Rhombencephalon)
What are the 5 secondary vesicles?
(1) Telencephalon
(2) Diencephalon
(3) Mesencephalon
(4) Metencephalon
(5) Myelencephalon
What secondary vesicles form from the Forebrain primary vesicle?
- Telencephalon
- Diencephalon
What secondary vesicle forms from the Midbrain?
Mesencephalon
What secondary vesicles form from the Hindbrain?
- Metencephalon
- Myelencephalon
Adult Derivatives of the Telencephalon:
(1) Wall
(2) Cavities
(1) Wall: cerebral hemispheres
(2) Cavities: lateral ventricles
Adult Derivatives of the Diencephalon:
(1) Wall
(2) Cavities
(1) Walls: thalami, etc
(2) Cavities: third ventricle
Adult Derivatives of the Mesencephalon:
(1) Wall
(2) Cavities
(1) Walls: midbrain
(2) Cavities: aqueduct
Adult Derivatives of the Metencephalon:
(1) Wall
(2) Cavities
(1) Walls: pons and cerebellum
(2) Cavities: upper (rostral) part of 4th ventricle
Adult Derivatives of the Myelencephalon:
(1) Wall
(2) Cavities
(1) Walls: medulla
(2) Cavities: lower part of 4th ventricle
Space of ___ cavity is limited by growth of the ___ is extensive
- Cranial cavity
- Brain
Brain Flexures
- Form as primary vesicles –> secondary vesicles (5th week)
- Specific locations in the NT where the brain folds to fit in the skull
How many brain flexures are there?
- 2 ventral flexures
- 1 dorsal flexure
What are the two Ventral Flexures?
- Mesencephalic Flexure
- Cervical Flexure
Pontine Flexure
- Dorsal Flexure
- Divides metencephalon (rostral) from myelencephalon (caudal)
Cervical Flexure
Demarcates (forms the boundary) hindbrain from spinal cord (superior rootlet of C1/foramen magnum)
Cervical Flexure
Demarcates (forms the boundary) hindbrain from spinal cord (superior rootlet of C1/foramen magnum)
Mesencephalic Flexure
- Located between the Prosencephalon and Mesencephalon
- It is the midbrain flexure
Neuroblasts in the Ventral Zone divide to form:
Neurons
Neuroblasts in the Alar Plates form the ___ columns
Lateral
Alar Plate gives rise to:
- Sensory Nuclei
- Develops into the dorsal horns
4 Lateral Columns (M –> L)
(1) General Visceral Afferent
(2) Special Visceral Afferent
(3) General Somatic Afferent
(4) Special Somatic Afferent
Neuroblasts in the Basal Plates form the ___ columns
Medial
3 Medial Columns (M –> L)
(1) General Somatic Efferent
(2) Special Visceral Efferent
(3) General Visceral Efferent
In the caudal region of the Myelencephalon, Alar neuroblasts migrate into the ___ zone to form ___ ___ and ___ ____
- Marginal Zone
- Nucleus Gracilis
- Nucleus Cuneatus
In the Myelencephalon, dorsal sensory nuclei associate with afferent tracts of the:
Dorsal Column - Medial Lemniscus Pathway (DCML)
In the Myelencephalon, Pyramids (ventral) consist of:
Corticospinal Tract Fibers
Rostral region of the Myelencephalon is wide and flat due to the:
Pontine Flexure
- causes walls to move laterally
- roof plate is greatly thinned
- cavity is part of 4th ventricle
Pontine Flexures force walls of the ___ laterally
Pons
Cerebellum develops from:
Dorsal parts of Alar Plates form the Cerebellar Swelling (primordium of cerebellum)
Cerebellar swellings project into the ___ ventricle and fuse in the median plane, causing them to overgrow the ___ ___ ___, ___ and ___.
- 4th Ventricle
- Rostral 4th Ventricle, Pons, Medulla
What nuclei form from Alar Plates?
- Cerebellar Nuclei
- Pontine Nuclei
- Cochlear Nuclei
Another name for Anterior Lobe of Cerebellum
Paleocerebellum
Another name for Posterior Lobe of Cerebellum
Neocerebellum
Structures of Pons/Cerebellum that also form from Metencephalon
- Cerebellar hemisphere
- Vermis
- Posterolateral Fissure
- Flocculus
Structures of Medulla that also form from Myelencephalon
- Gracile Tubercle
- Cuneate Tubercle
- Obex
Ependymal roof of 4th ventricle is covered with:
Pia Mater from Hindbrain Mesenchyme
___ + ___ = Tela Choroidea
Pia + Ependymal Roof