L21 - Embryological dev of spinal cord - WIP

Question 1

What are the different germ layers of the embryo?

Answer 1

1. Ectoderm
2. Mesoderm
3. Endoderm

Question 2

What does the ectoderm form?

Answer 2

• Skin

- Neural tissue

Question 3

What does the mesoderm form?

Answer 3

• Skeleton

- Cardiac

Question 4

What does the endoderm form?

Answer 4

• Digestion

- Respiratory

Question 5

What is the tripartite brain?

Answer 5

1. Prosencephalon
2. Mesencephalon
3. Rhombencephalon

Question 6

What is the pentapartite brain?

Answer 6

1. Prosencephalon –> telencephalon AND diencephalon
2. Mesencephalon –> Mesencephalon
3. Rhombencephalon –> Metencephalon AND myelencephalon

Question 7

What does the telencephalon become?

Answer 7

Cerebrum

Question 8

What does the diencephalon become?

Answer 8

• Eye cup
• Thalamus
• Hypothalamus
• Epithalamus

Question 9

What does the mesencephalon become?

Answer 9

Midbrain

Question 10

What does the metencephalon become?

Answer 10

• Pons

- Cerebellum

Question 11

What does the myelencephalon become?

Answer 11

Medulla oblongata

Question 12

How many plates is the developing neural tube divided into and what are they?

Answer 12

1. Roof plate - signalling centre
2. Alar plate - sensory
3. Basal plate - motor
4. Floor plate

Question 13

What is anencephaly?

Answer 13

• 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)

Question 14

How does anencephaly arise?

Answer 14

Most result from a failure of the rostral neuropore to close (failure of cranial end of neural tube to close)

Question 15

What are the 4 variants to spina bifida?

Answer 15

1. Spina bifida occulta
2. Spina bifida cystica (myelomeningocele)
3. Spina bifida meningocele
4. Spina bifida lipomeningocele

Question 16

What happens in spina bifida cystica?

Answer 16

• Characterised by a sac-like cyst at the caudal end of the spine
• Spinal cord and/ or meninges may be found in the cyst

Question 17

What happens in spina bifida cystica?

Answer 17

• 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

Question 18

What happens in spina bifida occulta?

Answer 18

• 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

Question 19

What happens in spina bifida meningocele?

Answer 19

• 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

Question 20

What happens in spina bifida myelomeningocele?

Answer 20

-

Question 21

What happens in hydrocephalus?

Answer 21

• 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

Question 22

How can hydrocephalus be corrected?

Answer 22

Normally, a drain is inserted - a shunt - which shifts CSF into the jugular vein or peritoneum