Lect. 23 - Skeletal system Development II

Question 1

Viscerocranium

Answer 1

(Refers to pharyngeal arches); surrounds oral cavity and pharynx; cartilagenous portion - forms pharyngeal arch I and II; membranous portion forms - temporal, zygomatic, maxillary, nasal, lacrimal, alanine, vomer, pterygoid plates, mandible, tympanic ring

Question 2

Components of the pharyngeal arches

Answer 2

Pharyngeal arch I: mechel’s cartilage, malleus, incus

Pharyngeal Arch II: Reichert’s cartilage, stapes, styloid

Question 3

What is the origin of the mesenchyme that forms the Viscerocranium?

Answer 3

Mostly from neural crest

Question 4

4 components of each pharyngeal arch?

Answer 4

Skeletal element, muscles, branch of specific cranial nerve, artery

Question 5

Basiooccipital portion of chondrocranium is derived from?

Answer 5

Parachordal cartilages and occipital sclerotomes

Question 6

What is the cause of the elongation of primary ossification centers?

Answer 6

Shh

Question 7

Fontanelle

Answer 7

Intersection of more than 2 bones

Question 8

Fusion of suture pathway

Answer 8

Noggin is expressed in all sutures; FGF-2 blocks Noggin; Noggin blocks BMP which leads to closure of sutures

Question 9

What results in the neurocranium arising?

Answer 9

Inductive interactions of surrounding mesenchyme - characterized by transient appearance of type II collagen and cartilage-specific proteoglycan

Question 10

Neurocranium

Answer 10

Part of the skull that surrounds the brain; has cartilaginous portion and membranous portion; base formed from chondrocranium - origin of occipital, sphenoid, ethmoid, and parts of temporal; membranous part - origin of occipital, parietal so, frontals, part of temporals

Question 11

Membranous portion of the viscerocranium forms what?

Answer 11

Part of temporal, zygomatic, maxillary, nasal, lacrimal, alanine, vomer, pterygoid plates, mandible, tympanic ring