case 1

Question 1

dura matter of head

Answer 1

outer periosteal and inner meningeal layer. P attached to skull M close to arachnoid. seperate in dural partitions, falx cerebri tentorium cerebelli, falx cerebelli and diaphragm sellae. Diaphragma sellae is a small horizontal shelf that covers the hypophysial fossa in the sella turcica of the sphenoid bone. There is an opening in the centre of the diaphragma sellae through which passes the infundibulum, connecting the pituitary gland with the base of the brain, and any accompanying blood vessels.

Question 2

arachnoid

Answer 2

Unlike the pia, the arachnoid does not enter the grooves or fissures of the brain, except for the longitudinal fissure between the two cerebral hemispheres.

Question 3

what do the germ layers form

Answer 3

Endoderm = epithelial lining of many of the internal organs
Mesoderm = muscles, bones and other connective tissues
Ectoderm = nervous system and skin

Question 4

neurulation

Answer 4

day 22. notochord sends signals to ectoderm. thicken neuroectodermal cells. differentiate to neural plate. neural groove. neural fold. fuse cephalically and caudally to neural tube. anterior closes before post neuropore. ample folic acid needed. failure close ant neuropore anencephaly. failure post is spina bifida. neural crest cells migrate underneath. somites grow. start cranial end. new pair every 90 mins. form muscle vertebra ribs dermis cartilage tendons. notochord becoms nucleus pulosus.

Question 5

primary vesicles in ant neuropore

Answer 5

primary vesicles: prosen, mesen, rhombencephalon. cervical and cephalic flexure.

Question 6

secondary vesicles

Answer 6

prosencephalon: telencephalon gives rise to cerebrum and hippocampus basal ganglia. Diencephalon thalamus hypo epi subtrhalamus and eye.
Mesencephalon just stays and makes midbrain.
Rhimbencephalon: Metencephalon forms cerebellum and pons. Myelencephalon forms medulla. controlled Hox genes.

Question 7

alar and basal plates

Answer 7

neuroepithelial cells give rise to neuroblasts, form mantle layer which forms gray matter. proliferate posterolatterally form alar dorsal horn. anterolateral form basal motor ventral horn. sulcus limitans seperates them. outermost layer marginal layer contains nerve fibres from mantle layer myelinated so white matter. cells white matter begin disolve ant median fissure, post median sulcus.

Question 8

neuronal migration

Answer 8

info about point of origin and expression Hox genes. undergo transition to migrate. begin as neuroepithelial cells, need to downregulate undergo epithelial to mesenchymal transition. transciption factors bHLH members Snail1 and 2 which repress expression of intercellular junctional proteins and epithelial adhesion molecules. when in final destination cease to express snail 1 and 2.

Question 9

dorsoventral axis of neural tube development

Answer 9

morphagens essential for patterning. DV set up by TGFb BMP and Shh. AP by retinoic acid and FGF and Hox genes. TGFb in dorsal SHH in notochord. BMP 4 &7 secreted ectoderm then roof plate. cause cascade of TGFb including BMP5,7 activin and dorsalin. SHH from notochord binds receptors encoded by PTCH1 gene.• BMP receptors are serine/threonine kinases that phosphorylate a group of cytoplasmic proteins called SMADS (SMAD4 and R-SMAD).
• Upon phosphorylation, SMAD multimers translocate to the nucleus and interact with other DNA-binding proteins, thus modulating gene expression in response to the BMP signal.

Question 10

anterior posterior axis

Answer 10

retinoic acid and FGF and Hox genes. FGF psot axis retanoic acid ant.

Question 11

differentiation of neurons and glia

Answer 11

neuroectodermal symetrical division slow and renew indefinitely. neuroblasts assymetrical divide quicker limited capacity divisions.

Question 12

neural tube defects

Answer 12

aeteologically related so if one in fam affected higher risk others being. Dysraphism incomplete closure of raphe defective fusion particulaly in neural tube. more common females. interaction genes and environment like lack folic acid, diabetes. better to take naturally occuring folates like folinic acid and THF.

Question 13

folic acid

Answer 13

take 400ug daily for first 12 weeks or to prevent reccurunce 4-5mg per day.

Question 14

prenatal diagnosis

Answer 14

AFP in liver leaks through open neural tube into amniotic fluid. inc in maternal serum AFP detected 16 weeks. doesnt detect when closed by skin or when taking antiepiliptic drugs like sodium valproate. look for lemon sign. from scalloping of frontal bones, dec intraspinal pressure brain shift down so dec intracranial pressure so frontal bones go in, disapears after 24 weeks as inc intercranial pres. or banana sign from shape cerebellum due caudal displacement.

Question 15

chiari malformation

Answer 15

usually headaches and hydrocephalus. Type 1 only type can be aquired characteristic headaches. extension of cerebellar tonsils into foramen magnum w/o brainstem.
type II: cerebellar and BS into FM. usually in SB.
Type III: most serious BS and cerebellum protrude into SC.
type IV: incomplete cerebellum, cerebellar hypoplasia.
treated decompression surgery. Lumbar puncture can measure CSF pressure which shouild be less than 20cm H20. posterior iliac crest is landmark for L4/5

Question 16

cephalocele

Answer 16

herniation of cranial contents through a skull defect. There are several subtypes:  A cranial meningocele contains only meninges  An encephalocele contains brain tissue  A ventriculocele contains part of the ventricle within the herniated portion of the brain
Cephaloceles are less common that anencephaly or spina bifida

Question 17

holoprosencephaly

Answer 17

• This occurs when the embryonic Prosencephalon does not undergo segmentation and cleavage (into telencephalon and diencephalon).
• The anterior midline brain, cranium, and face are abnormal.
• This malformation may be caused by defects of the sonic hedgehog gene.
• Severely affected foetuses may die before birth.
• Treatment is supportive.

Question 18

spina bifida occulta

Answer 18

defect post arch of one or more lumbar or sacral vertebrae normal skin covering hairy patch. motor weakness deminished reflexes gait disturbances bladder control

Question 19

myelomeningocele

Answer 19

most serious spinal cord and nerve roots exposed. leak CSF constant risk infection paralysis of legs urinary incontinence. hydrocephalus and ACM II present. usualy lumbosacral. usually try and repair whilst in uterus as amniotic fluid toxic. or surgery in first 48h life antibiotics given. higher the defect the worse paralysis. allergy latex. BMD dec obesity prevalent.
often in breech position as cant wriggle legs to move to correct. usually C section.

Question 20

hydrocephalus

Answer 20

excess CSF production, dec reabsorption by arachnoid granulations, or obstruction flow. 1. Communicating Hydrocephalus:
 This is caused by impaired CSF reabsorption in the arachnoid granulations, obstruction of flow in the subarachnoid space, or (rarely) by excess CSF production.
2. Obstructive (Non-communicating) Hydrocephalus:
 This is caused by obstruction of flow within the ventricular system
symptoms headache nausea cog impairment dec conciousness dec vision. bulging anterior fontanelle is sign in babies. 6th nerve palsy can see in eyes.
external ventricular drain/ventriculostomy or ventriculoperitoneal shunt. Normal Pressure Hydrocephalus
• This is a condition that is sometimes seen in the elderly.
• It is characterised by chronically dilated ventricles.
• Patients with this condition normally present with a clinical triad of:
1. Gait difficulties (walking difficulties)
2. Urinary incontinence
3. Mental decline.

Question 21

rachischisis

Answer 21

Rachischisis – most severe defect, which is a widely patent dorsal opening of the spin, often associated with anencephaly.

Question 22

Bipolar disorder

Answer 22

mania and depression. hypomania is a mild form where no psychotic symptoms. Bipolar I one or more mania episodes, severe bipolar. Bipolar II: depressive episode with at least one hypomania. age onset 21. genetic aetiology. Depression monoamine hypothesis. Diathesis stress hypothesis, hyperactivity HPA. Psychological-previous life events play minor role.

Question 23

treatment of bipolar

Answer 23

mania-stop antidepressents. antipsychotic sodium valproate or lithium. atypical antipsychotics like olanzapine quetiapine and risperidone. Lithium rapidly absorbed in GI excreted kidneys mood stabalising drug.
Semisodium valproate-shouldnt be taken in pregnancy or given to people under 18. inc GABA in brain alter Na channels. Dissociates valproate ion in GI binds and inhibits GABA transaminase. block reuptake in glia and nerve. folate antagonist as inhibit DHFR which usually activates folic acid.