Head and Neck Lecture

Question 1

Chondrocranium aka neurocranium

Answer 1

Begins as cartilage then ossifies to bone -Forms base and back of skull and capsules -All cranial nerves pass through foramina in or between chondrocranial elements

Question 2

Splanchnocranium aka visceral skeleton

Answer 2

cartilage or bone within the gill arches-aka branchial or pharyngeal arches -Supported gills and respiratory muscles in early fish -Primitively 7, we have six -First two have names 1) Mandibular arch 2) Hyoid arch -Most posterior arches supported the gills in fish form hyoid complex, larynx, and tracheal cartilages

Question 3

Dermatocranium

Answer 3

Dermal bones that make up cranial skeleton -Derived from the dermal armor of ancient fish -Gave rise to fish scales, turtle shells, and dentin in our teeth -Form lateral and superior parts of skull -Ossify from sheets of connective tissue (intramembranous ossification)

Question 4

The only bone that is totally chondrocranial

Answer 4

ethmoid

Question 5

Cranial elements of sphenoid bone

Answer 5

Chondrocranial: body, lesser wing and base of greater wing

Splanchocranial: greater wing (arch #1) spine of sphenoid

Dermatocranial: pterygoid process

Question 6

Cranial elements of temporal bone

Answer 6

Chondrocranial: Petrous portion and mastoid process

Splanchnocranial: malleus and incus (arch #1), stapes and styloid process(arch #2)

Dermatocranial: squamous portion

Question 7

Cranial elements of occipital bone

Answer 7

chondrocranial: portion around foramen magnum and the basioccipital (connects to body of sphenoid)

Dermatocranial: rest of occipial

Question 8

Cranial elements of maxilla

Answer 8

During early ontogeny maxilla made of splanchnocranial and dermatocranial elements, but by birth splanchnocranial elements have been replaced

Splanchnocranial: palatoquadrate cartilage (arch 1)

dermatocranial: maxilla

Question 9

Cranial elements of mandible

Answer 9

During early ontogeny maxilla made of splanchnocranial and dermatocranial elements, but by birth splanchnocranial elements have been replaced

Splanchnocranial: Mandibular or Meckel’s cartilage (arch 1)

Dermatocranial: mandible

Question 10

Rest of skeleton from splanchnocranium

Answer 10

hyoid bone

laryngeal cartilages (maybe a few tracheal cartilages)

what is left of gill arches 2-6 in us

Question 11

Rest of skeleton from dermatocranium

Answer 11

All else that has not been mentioned