2a and b. Embryology of the CNS and PNS Flashcards
Telecephalon
- Forms 1 Structure
Cerebral cortex
Diencephalon
- Forms 3 Structures
Hypothalamus
Thalamus
Optic cups (retina and optic nerve)
Mesencephalon
- Forms 2 Structures
Rostral colliculus
caudal colliculus
Metencephalon
- Forms 2 Structures
Pons
Medulla
Myelencephalon
- Forms 1 Structure
Medulla oblongata
Flexures
- 3
- Cephalic flexure
- Disappears in domestic species - Cervical flexure
- Not visible in the domestic species - Pontine flexure
- Forms between the metencephalon and myelencephalon
- Bends the rhombencephalon ventrally
Ventricles
- 4
- 2 lateral ventricles in the telencephalon
- 3rd ventricle in the diencephalon
- 4th ventricle in the rhombencephalon
Ventricle Connections
- 2
Lateral ventricles to the 3rd ventricle:
- Foramen of Monroe
- Interventricular foramen
3rd to 4th ventricle
- Aqueduct of sylvius
- Interventricular aqeuduct
- Mesencephalic aqueduct
Brainstem
- 3 Structures
Rhombencephalon
Mesencephalon
Diencephalon
Neurone Origins
- 2
If the cell body is in the CNS the neurone if formed from the ectoderm neural tube
If the cell body is outside the CNS the neurone if formd from either:
- Neural Crest
- Ectoderm palcode
CNS Neurones
- 3
- Motor neurones in the ventral horn of the spinal cord or any of the motor nuclei in the brainstem
- Pre-ganglionic autonomic neurones in the brain or spinal cord
- Retinal ganglion cells
PNS Neurones
- 3
- Neural crest derived
- Most sensory neurones in the dorsal root ganglion, paravertebral ganglion or middle cervical ganglion
- post-ganglionic autonomic neurones - Ectoderm placode
- Sensory neurones involved in the special senses form from the ectodermal places
Holoprosencephaly
Occurs when the bifurcation of the prosencephalon into 2 telecephali fails, causing failure of duplication of structures in the head
PNS
- Derivation Tissue
- Neural Crest
- Ectoderm placodes
PNS
- Neural Crest Origin
Neural crest cells emigrate from the dorsal neural tube into the embro
PNS
- Neural Crest Structures
- Most peripheral neurones
- All autonomic ganglia
- Almost all peripheral somatosensory neurones- All neurones in the dorsal root ganglia
- Most neurones in the trigeminal ganglia
- All neurones in the superior ganglia of cranial nerves VII, IX and X
- All peripheral glia
- Schwann cells
- Satellite glia
PNS
- Ectoderm Placodes
Olfactory placed = olfactory epithelium
Optic placed = lens
Otic placode = inner ear hair cells and afferent neurones which form cranial nerve VIII
Lateral line organs and afferent neurones in fish and amphibia
Some somatosensory neurones in the trigmeinal ganglia, which form cranial nerve V
All taste and viscerosensory afferent neurones in the inferior ganglia of cranial nerve VII, IX and X
