Embryology of the Skull (finished)

Question 1

neurocranium

Answer 1

1. The neurocranium or brain case develops around the rostral end of the neural tube, giving rise to bones that surround the brain and special sense organs.

Question 2

viscerocranium

Answer 2

2. The viscerocranium includes the lower face, jaws, palate, larynx, hyoid and epiglottis. It develops around the gut tube.

Question 3

Craniosynostosis

Answer 3

general term for premature closure of sutures; may not impact neural function

1. Scaphocephaly: sagittal sutures; long narrow
2. Oxycephaly (turricephaly): coronal and lambdoidal sutures; tower skull
3. Brachycephaly: coronal suture; wide skull
4. Plagiocephaly: one side of coronal or lambdoidal suture; assymetric or twisted
5. Trigonocephaly: frontal (metopic) suture;

Question 4

Apert Syndrome

Answer 4

autosomal dominant trait; mutation in fibroblast growth factor receptor 2 gene.
 		Symptoms may include some or all of:
•	Under-developed mid-face
•	Symmetric syndactyly
•	Hearing loss; frequent ear infections
•	Short stature
•	Possible slow intellectual development

Question 5

Crouzon syndrome (craniofacial dysostosis)

Answer 5

similar appearance to Apert syndrome, but only craniofacial abnormalities are present.

Question 6

Microcephaly

Answer 6

small head, usually due to underdeveloped brain. Individuals are mentally deficient. May be genetic or due to exposure to radiation, infectious agents, drugs or alcohol, rubella or chicken pox during the fetal period.

Question 7

Acrania

Answer 7

partial or complete absence of cranial vault; often occurs with vertebral column defects. Meroencephaly (partial absence of brain) with acrania is not viable.

Question 8

Cranioschisis

Answer 8

cranial vault fails to close due to failure of cranial neuropore to close (anterior NTD); usually in the occipital region.
1. The fissure may be limited to a smaller area where the brain and/or meninges can protrude.
2. Exposure of neural tissue to amniotic fluid causes brain degeneration—
anencephaly

Question 9

Hydrocephalus

Answer 9

a build up of CSF in the brain.

1. Increased fluid pressure can cause enlargement of ventricles, pressure on cortical tissue →brain damage.
2. Since sutures have not ossified, brain case can enlarge. 1/1000 live births