Development of Skull (Embryology)

Question 1

bones of face and skull come from

Answer 1

neuroectoderm –> neural crest in head –> mesenchyme in pharyngeal arches

Question 2

base of skull comes from

Answer 2

intraembryonic mesoderm –> paraxial mesoderm –> somitomeres/somites –> sclerotome

Question 3

= brain case (cranial vault), base of skull

Answer 3

neurocranium

Question 4

= face; contains taste, sight and smell organs

Answer 4

viscerocranium

Question 5

The neurocranium forms around the rostral end of the _______

Answer 5

neural tube

Question 6

The viscerocranium forms around the rostral end of the developing _________

Answer 6

gut tube

Question 7

Cartilaginous contributions to neurocranium

Answer 7

Cartilaginous (contributes to skull base) → ethmoid, sphenoid, occipital base, petrous temporal, temporal-mastoid

Endochondral ossification (from cartilage)

Question 8

Membranous contributions to neurocranium

Answer 8

Membranous (contributes to cranial vault) → flat bones of vault = parietal, frontal, squamous occipital
Intramembranous ossification
From ossification center, ossify in radial pattern

Question 9

cartilaginous viscerocranium

Answer 9

Malleus, incus, stapes, hyoid, temporal-styloid

Endochondral ossification

Question 10

membranous viscerocranium

Answer 10

premaxilla, maxilla, zygomatic, temporal-squamous, mandible (both)
Intramembranous ossification

Question 11

fusion of the sagittal suture produces a long front-to-back diameter skull

Answer 11

scaphocephaly

Question 12

= fusion of coronal & lambdoidal sutures bilaterally produces a “tower skull”

Answer 12

Turricephaly (oxycephaly, acrocephaly)

Question 13

fusion of coronal suture bilaterally produces a shortened front-to-back diameter of skull (“flat-head”)

Answer 13

brachycephaly

Question 14

fusion of frontal (metopic) suture producing a median frontal ridge

Answer 14

Trigonocephaly

Question 15

fusion of coronal &/or lambdoidal sutures unilaterally produces an asymmetrical skull

Answer 15

plagiocephaly

Question 16

small head due to a brain that fails to grow

Answer 16

microcephaly

Question 17

skull defect the through which the meninges and/or brain herniate.

Answer 17

cranioschisis

Question 18

Autosomal dominant genetic disorder characterized by craniosynostosis and other congenital abnormalities e.g., syndactyly of hands and feet, mental retardation.

Answer 18

aperty syndrome

Question 19

no skull

Answer 19

acrania

Question 20

no brain

Answer 20

anencephaly

Question 21

some poorly formed brain stem tissue present

Answer 21

meroanencephaly

Question 22

Enlarged ventricles due to too much CSF. If this occurs prior to closure of the sutures, the head enlarges.

Answer 22

hydrocephalus