Central Nervous System Flashcards
How does the position of the orbit vary in carnivores and herbivores?
Carnivores- positioned rostrally
Herbivores- laterally
How does orbit construction vary between carnivores and herbivores and why?
Herbivores orbit is enclosed
Domestic carnivores it is open to allow wider jaw opening
What bones make up a dogs orbit?
Frontal Lacrimal Zygomatic Sphenoid Palatine bones Completed by orbital ligament
How does enclosed orbits structure vary?
The frontal process of the zygomatic bone and zygomatic process of the frontal bone meet and complete orbit
What are the foramina in a dogs eye for?
Ophthalmic artery/vein
Cranial nerves- II, III, IV, VI
What lines the orbit?
Orbital fascia, three layers
What are the three layers of orbital fascia?
Outer periorbita (encloses eyeball and associated muscles, nerves and vessels) Fascia bulbi (surrounds globe itself) Fascial sheaths (continuous bulbi)
What are all the extra ocular muscles?
Dorsal rectus Dorsal oblique Ventral rectus Ventral oblique Lateral rectus Medial rectus Retractor bulbi
What is the innervation and action of the dorsal rectus?
Rotate eye upwards
Innervated by III
What is the innervation and action of the dorsal oblique?
Rotate dorsal globe medially and ventrally
Innervated by IV Trochlear
What is the innervation and action of the ventral rectus?
Rotate eye downwards
Innervated by III
What is the innervation and action of the ventral oblique?
Rotate globe medially and ventrally
Innervated by III- oculomotor
What is the innervation and action of the medial rectus?
Rotate globe medially
Innervated by III
What is the innervation and action of the lateral rectus?
Rotates globe laterally
Innervated by VI abducens
What is the innervation and action of the retractor bulbi?
Retracts globe into orbit
Innervated by VI- abducens
What species do not possess a retractor bulbi?
Birds and snakes
What is the name for the dysfunction of one or more extra ocular muscle?
Strabismus
What is the name for a strabismus when eyes are pointing to the side, rotated, cross eyed?
Ventrolateral strabisimus- pointing to side
Extorsional strabismus- rotated
Medial strabismus- cross eyes
What are the functions of the eyelids?
Protect the eyeball
Spread the tear film
Help to remove foreign material
Close to exclude light
What is the name for when they eyelid opens after being born?
Palpebral fissure
What are the eyelids made up of?
Thin folded skin
Haired skin on the outside and mucous membrane on the inside
What is the lid margin of the eyelid?
Transition between skin and conjunctiva
Hairless, upper part posses cilia
What support the lid margins?
Tarsal plate
Where do the upper and lower eyelids meet?
Medial and lateral canthus