Skull & Head Musculature

Question 1

Skull is divided into 2 parts

Answer 1

Neurocranium: surrounds the brain
Viscerocranium: bones of the face around oral & nasal cavities

Question 2

Neurocranium forms from

Answer 2

paraxial mesoderm sclerotomes (somitomeres + occipital somites)

Question 3

Cartilaginous neurocranium

Answer 3

forms base of skull (where brain sits)

Question 4

Membranous neurocranium

Answer 4

Forms flat bones of the calvaria (bones that surround the brain)

Question 5

Which type of ossification forms the cartilaginous neurocranium

Answer 5

endochondral ossification

Question 6

How does the cartilaginous neurocranium form?

Answer 6

7 somitomeres form from the sclerotome & migrate ventrally and medially to surround neural tube

Question 7

Cartilaginous bodies fuse to form

Answer 7

prechordal cartilage, hypophyseal cartilage, ala orbitalis & ala temporalis, otic capsule

Question 8

Prechordal cartilage

Answer 8

forms ethmoid bones

Question 9

Hypophyseal cartilage

Answer 9

forms body of sphenoid bone

Question 10

ala orbitalis and ala temporalis

Answer 10

forms wings of sphenoid

Question 11

otic capsule

Answer 11

forms petrous portion of temporal bone

Question 12

4 occipital somites form the

Answer 12

parachordal cartilage

Question 13

How is the occipital bone formed?

Answer 13

comes from parachordal cartilage

Question 14

Membranous neurocranium is divided into

Answer 14

parietal and frontal bones

Question 15

How are frontal bones of the membranous neurocranium formed?

Answer 15

From neural crest cells

Question 16

How are parietal bones formed in the membranous neurocranium?

Answer 16

7 somitomeres that form sclerotome

Question 17

Which type of ossification forms the membranous neurocranium?

Answer 17

Intramembranous ossification

Question 18

What is the origin of the viscerocranium?

Answer 18

Neural crest cells associated with branchial apparatus (branchiomeric mesenchyme)

Question 19

Which type of ossification forms the membranous viscerocranium?

Answer 19

intramembranous ossification

Question 20

Which bones make up the membranous viscerocranium?

Answer 20

Maxillary prominence - maxilla, zygoma, squamous portion of temporal bone
Mandibular prominence - mandible

Question 21

Which type of ossification forms the cartilaginous viscerocranium?

Answer 21

endochondral ossification

Question 22

Bones that make up cartilaginous viscerocranium from the 1st branchial arch

Answer 22

malleus and incus

Question 23

Bones that make up cartilaginous viscerocranium from the 2nd branchial arch

Answer 23

stapes, styloid process, lesser horn of hyoid, superior portion of hyoid

Question 24

Bones that make up cartilaginous viscerocranium from the 3rd branchial arch

Answer 24

greater horn of the hyoid, inferior portion of hyoid

Question 25

Bones that make up cartilaginous viscerocranium from the 4th branchial arch

Answer 25

thyroid cartilage and cricoid cartilage

Question 26

sutures

Answer 26

fibrous joints between the bones in fetal skull

Question 27

fontanelles

Answer 27

large fibrous areas where several sutures meet in fetal skull

Question 28

craniosynostosis

Answer 28

deformities in skull resulting from premature closure of sutures