Chapter 7 Part 2: Cranial Skeleton

Question 1

How many middle ear bones are found in mammals?

Answer 1

3!

Question 2

From what bones of the splanchnocranium are the middle ear bones derived?

Answer 2

Incus, stapes, and malleus

Incus evolved from quadrate; Malleus evolved from articular

Question 3

How does the 3 middle ear bones compare to the other tetrapod vertebrates?

Answer 3

Birds only have 1 of those for ear (columella)

Question 4

Be able to name some tetrapod derivatives of the First branchial arch

Answer 4

becomes upper and lower jaws

Question 5

Be able to name some tetrapod derivatives of the Second branchial arch

Answer 5

leads to parts of the hyoid apparatus

Question 6

Be able to name some tetrapod derivatives of the 3rd and 4th BRanchial arches

Answer 6

formation of larynx and various cartilages in throat region(breathing and vocalization)

Question 7

Dermatocranium

Answer 7

Superficial to chondrocranium – derived from membrane bone

Roof and lateral walls of the skull
Upper and lower jaws
Palate
Operculum(in bony fish)

Question 7

Structures in Facial

Answer 7

premaxilla, maxilla, nasal

Question 8

Structures in Orbital

Answer 8

lacrimal, prefrontal, postfrontal, postorbital, jugalS

Question 9

Structures in Vault

Answer 9

frontal, parietal, postparietal

Question 10

Structures in temporal

Answer 10

Quadratojugal, Intertemporal, Supratemporal, Temporal, Squamosal

Question 11

Palatal: What is a secondary palate and which vertebrates have one?

Answer 11

o Vomer
o Palatine
o Ectopterygoid
o Pterygoid
o Parasphenoid

Seen in mammals, air flows in more than one cavity (oronasalcavity only has single cavity for air flow)

Question 12

Lower jaw structures

Answer 12

o Lateral: Dnetary, surangular, angular, splenials
o Medial: coronoid prearticular(further inside view)

Question 13

Opercular bones

Answer 13

cover gill cavity with rhythm of breathing

Question 14

Anapsid skull fenestration

Answer 14

Skulls have no temporal openings (fenestrae) near the temples.

Example: Found in early amniotes and turtles. These animals have solid skulls with no extra holes beyond the eye sockets.

Question 15

Diapsid skull fenestration

Answer 15

Skulls have two temporal fenestrae on each side. These openings lighten the skull and provide attachment points for muscles.

Example: Most modern reptiles, including lizards, snakes, crocodiles, and birds. This design allows for greater muscle attachment and jaw strength.

Question 16

Synapsid skull fenestration

Answer 16

Skulls have a single temporal opening on each side.

Example: Mammals and their extinct relatives (like the mammal-like reptiles). This single opening provides a surface for jaw muscle attachment, aiding in powerful chewing.

Question 17

What is the importance of neural crest cells?

Answer 17

o During early embryonic development, neural crest cells contribute to the head mesenchyme (ectomesoderm)
o Also contributing to the head mesenchyme are cells of mesodermal origin (mesodermal mesenchyme/aka embryonic connective tissue)
o The position of the mesodermal (stippled) and the neural crest (shaded) mesenchyme, and the approximate interface between them