---start anat 11.19.96----

large animal heads
no clin corr tomorrow.

horse and goat are being stressed equally for the exam, so you will have 
to look at the other species at someone else's table.

we will have skulls up there..we only have one or two goat skulls, we'll 
have some cow skulls. look at differences in the sinuses bet horse and 
ruminant.

[diagrams]
today we'll be skinning the heads. the horse has a facial crest for 
attachment of the masseter. ruminants have only a facial tuberosity.
note the infraorbital canal: can be palpated, and a maxillary nerve block 
done.

these animals are heavy, so superficial nerves are important also because 
there are certain nerves crossing the side of the face (dorsal and 
ventral buccal branches of VII). if those nerves are injured you lose 
motor function to the muscles innervated (lip droop, etc). another branch 
of VII is the auriculopalpebral which is motor to the eyelids and if it's 
hurt you lose blink reflex. this nerve can be palpated and blocked if you 
need to do a procedure on the eye and don't want it to blink. note also 
the facial artery ventrally, and the parotid duct (in the dog this ran 
across the masseter) which is ventral to the mandible as well.

goat has no facial artery, dont' try to take it's pulse below the 
mandible :)
the cow does have one similar to the horse.

paranasal sinuses in horse/goat more extensive than in dog. recall the 
dog had frontal sinus and maxillary recess. the horse has an airfilled 
maxillary sinus divided into a rostral and a caudal part. this is just a 
cavitation of the maxillary bone. it's divided by the oblique septum - a 
bony septum. the roots of the teeth go into this sinus. (last four cheek 
teeth). there's a thin wall of bone over the teeth. if one of these teeth 
abcesses, the sinus will fill up with pus.

recall the frontal sinus was big in the dog. in the horse it is also very 
large. it is a cavitation of the frontal bone. there IS communication bet 
frontal sinus and caudal maxillary sinus through the frontomaxillary 
opening.

the frontal also communicates with another more medial sinus.  the dorsal 
nasal concha itself has a sinus within it. the conchal sinus can 
communicate with the frontal sinus. there is also a nasomaxillary 
aperture opening the maxillary sinus into the nasal cavity. so the horse 
w/abcessed tooth can have pus dripping out of its nose.

the cow has unbelievable sinuses....one step beyond the horse in terms of 
complexity.

the goat however is simpler. there is a maxillary sinus which isn't 
divided. there is a large frontal sinus which also goes up into the bone 
of the horn. that's the cornule diverticulum of the frontal sinus.

if a cow or goat is dehorned in the winter you can see the frosty breath 
coming out the top of their head as they run away. that's not a big 
deal,though, it heals pretty nicely and quickly. BUT, so, now you have 
tht opening into the sinus - if you do it in the summer, the flies go in 
their and lay eggs in there and cause problems.
frontal sinus connects to the nasal cavity and maxillary sinus connects 
to the nasal cavity. these are separate openings in the goat unlike the 
single opening in the horse.






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