Comparative Anatomy of the Head and Forelimb Flashcards
what organ does the palatine fissure lead to?
leads to vomeronasal organ
What parts of the skull (dog/cat) are you able to palpate?
Zygomatic arches, zygomatic processes, external occipital protuberance, nuchal crests, median sagittal crest, infraorbital foramen. Sometimes temporal bulla in cat.
What is the coronoid process?
The site of insertion of the temporal muscle - found at the top of the mandible
What is the condylar process?
The temporomandibular joint (TMJ) is the articulation between the condylar process and the mandible and the mandibular process of the skull. It is a synovial joint
What is the Masseteric fossa?
This is a depression (‘fossa’) where the masseter muscle sits
In what species is the angular process found?
found in carnivores
How can you tell if the view of the mandible is lateral or medial?
if it is a lateral view you WILL NOT be able to see the mandibular foramen - this is found on the medial side
What is the mandibular foramen for?
for the passage of the mandibular alveolar nerve (V3)
What bones are involved in the orbit of a horse’s skull?
The orbit in horses is composed of the lacrimal, zygomatic, frontal, and temporal bones. You can see that in horses, the zygomatic arch continues rostrally as the facial crest
Difference between species - orbit?
In horses (and ruminants) the orbit is complete, whereas in the carnivores it is incomplete (but closed by the orbital ligament, which can sometimes ossify in cats)
Where is the vascular notch?
it is on the ventral-most part of the ramus of the mandible
Which structures pass over the vascular notch?
The facial artery and vein pass here
What is the cornual process?
this is the bone core of the horn in ruminants
what does the frontal bone of horned ruminants form?
the cornual process
what sinus extends into the cornual process in horned ruminants?
the frontal sinus
Describe the location of the temporal fossa in ruminants?
it has been pushed to the lateral side of the skull due to the expansive frontal bone
Describe the frontal bone of ruminants and pigs?
The frontal bone forms the entire roof the cranium.
which species have anapsid skulls?
ancestral reptile species
which species have diapsid skulls?
tuatara and crocodiles
which species have modified diapsid skulls?
lizards and snakes
which species have modified anapsid skulls?
chelonia
What is an anapsid skull?
it describes skulls that have no openings in the temporal region (no temporal fenestrae) - turtles have a modified anapsid skull
What is a diapsid skull?
it describes skulls where there are two temporal fenestrae behind the orbit - one is inferior (smaller) and one is superior. e.g. dinosaurs, birds, crocs
modified diapsid - lizards and snakes
What is a synapsid skull?
they have a single temporal fenestrae situated below the postorbital bone
mammals are a type of synapsid
Describe the skull bones of a bird?
they have pneumatised skull bones which connect to airways in the head (rather than air sacs in the body, like their other pneumatised bones)
What (in the skull) allows for more rotation of the head - for a bird?
a single occipital condyle articulates with the atlas allowing for more rotation of the head
In which bird species is the skull adapted in order to allow for greater jaw opening?
most notably parrots, but also chickens
What allows the skull to have a greater jaw opening for chickens and parrots?
the nasal bone and frontal bone are joined by a flexible cartilage structure allowing greater jaw opening - this is called the craniofacial hinge, it allows kinesis to occur
What is the thin jugal arches (in a bird) equivalent to in other species?
the zygomatic arches
describe the orbits of a bird’s skull?
large
describe how the skull plates of a bird’s skull are separated?
by spongy bone
What is a bird’s beak made up of?
bone, vascular dermis and a modified highly keratinised germinal layer of epidermis
Cere of a bird?
visible externally
base of the dorsal maxillary beak, which can be naked/feathered and soft/firm depending on species
helps sexing budgies
cere - colour for sexing budgies
blue - male
brownish/pink - hen
when can male budgies develop a brownish cere?
under the feminising influences of testicular Sertoli cell tumours
