L21 - Embryological dev of spinal cord - WIP Flashcards
What are the different germ layers of the embryo?
- Ectoderm
- Mesoderm
- Endoderm
What does the ectoderm form?
- Skin
- Neural tissue
What does the mesoderm form?
- Skeleton
- Cardiac
What does the endoderm form?
- Digestion
- Respiratory
What is the tripartite brain?
- Prosencephalon
- Mesencephalon
- Rhombencephalon
What is the pentapartite brain?
- Prosencephalon –> telencephalon AND diencephalon
- Mesencephalon –> Mesencephalon
- Rhombencephalon –> Metencephalon AND myelencephalon
What does the telencephalon become?
Cerebrum
What does the diencephalon become?
- Eye cup
- Thalamus
- Hypothalamus
- Epithalamus
What does the mesencephalon become?
Midbrain
What does the metencephalon become?
- Pons
- Cerebellum
What does the myelencephalon become?
Medulla oblongata
How many plates is the developing neural tube divided into and what are they?
- Roof plate - signalling centre
- Alar plate - sensory
- Basal plate - motor
- Floor plate
What is anencephaly?
- Absence of the major portion of the brain, skull and scalp following embryological development
- In the more severe cases, there is a more or less complete absence of the brain
- Common (3 in 1000)
How does anencephaly arise?
Most result from a failure of the rostral neuropore to close (failure of cranial end of neural tube to close)
What are the 4 variants to spina bifida?
- Spina bifida occulta
- Spina bifida cystica (myelomeningocele)
- Spina bifida meningocele
- Spina bifida lipomeningocele
What happens in spina bifida cystica?
- Characterised by a sac-like cyst at the caudal end of the spine
- Spinal cord and/ or meninges may be found in the cyst
What happens in spina bifida cystica?
- Characterised by a sac-like cyst at the caudal end of the spine
- Spinal cord and/ or meninges may be found in the cyst
- Spinal cord function may be impaired
- May be lower extremity dysfunction
- Bladder and bowel function may be impaired
What happens in spina bifida occulta?
- Results from failure of L5/ S1 vertebral arches to fuse (failure of the inferior neuropore to close)
- It is the ‘hidden spina bifida’
- Found in 25% of normal population
- Most carriers are not aware of it
- Not associated with any nerve dmg (no presenting signs)
- Site of split spine is attended by a tuft of hair on the overlying skin in some cases
What happens in spina bifida meningocele?
- Only the meninges of the spinal cord herniate through the unfused region of the lumbar (or sacral) spine
- Within the herniating meningeal tissue can be found cerebrospinal fluid in the subarachnoid compartment
What happens in spina bifida myelomeningocele?
-
What happens in hydrocephalus?
- An imbalance between the production and absorption of the CSF leads to an accumulation of fluid in the ventricles of the brain
- This acc of fluid may cause significant expansion of the head
How can hydrocephalus be corrected?
Normally, a drain is inserted - a shunt - which shifts CSF into the jugular vein or peritoneum
