Lecture 18 3/20/24 Flashcards
What is the nuchal crest?
transverse ridge at the highest point of the occipital bone
When is the nuchal crest most prone to fracture?
when horses rear up in confined areas
Where is the rostral process of the nasal bone?
caudal to dorsal part of the nose
When is the rostral process of the nasal bone susceptible to fracture?
when a lead rope/halter is pulled on while it sits over the bone
What is the nasoincisive notch?
angle formed between the nasal bone and incisive bone
What is the facial crest?
ridge of bone that projects laterally from the zygomatic bone and maxilla
Which vein runs ventral to the facial crest?
transverse facial v.
What is the infraorbital foramen?
rostral opening of infraorbital canal
What is the role of the zygomatic process of the frontal bone?
protects the eye by completing the lateral aspect of the bony orbit
How does the zygomatic process of the frontal bone differ between canine and equine/bovine?
-canine has a ligament
-equine/bovine has bone
Where is the supraorbital foramen located?
over the orbit in the base of the zygomatic process
Which nerve runs through the mandibular foramen?
inferior alveolar n.
Which lines are used to approximate the mandibular foramen?
-line from lateral commissure to angle of the mandible
-occlusal level of the cheek teeth caudally
Which vessel in the notch for facial vessels can be used to evaluate the equine pulse?
facial a.
What is the mental foramen?
opening on the rostral, lateral side of the mandibular body halfway between the corner incisor and the first cheek tooth
What are the paranasal sinuses?
embryologic expansions from the nasal cavity into the diploë
What is the diploë?
spongy, cancellous bony tissue between the internal and external layers of the skull
Which type of epithelium lines the sinuses?
resp. epithelium
What is the function of the maxillary sinus?
used to repel cheek teeth
What is the function of the frontal sinus?
used with maxillary sinus to repel M3
How do the frontal and maxillary sinuses communicate?
frontomaxillary opening
How do the sinuses change as the animal ages?
-more filled with teeth roots at a younger age
-teeth roots move down as horse ages
What are the branches of CN5/trigeminal nerve?
-ophthalmic
-maxillary
-mandibular
Which nerve blocks follow the trigeminal nerve?
-infraorbital nerve block
-supraorbital nerve block
-mental nerve block
What are the characteristics of the infraorbital nerve block?
-blocked at infraorbital foramen
-anesthetizes nose, upper lip, upper incisors
What are the characteristics of the supraorbital nerve block?
-blocked at supraorbital foramen
-anesthetizes upper eyelid
What are the characteristics of the mental nerve block?
-blocked at mental foramen
-anesthetizes lower lip
What are the auriculopalpebral nerve block?
-blocked as it crosses highest point of zygomatic arch caudal to eye
-immobilizes eyelid but does not block sensation
-blocks branch of facial nerve/CN7
What are the branches of the facial n.?
-dorsal buccal
-ventral buccal
When can unintentional damage to the facial n. occur?
during surgical procedures where the horse is down while still wearing a halter
What are the characteristics of the guttural pouch?
-caudoventral expansion of auditory tube
-located between base of skull, atlas, and pharynx
-distends when its opening is blocked; enlarges caudally
Which bone divides the guttural pouch into medial and lateral compartments?
stylohyoid bone
Which structures are associated with the caudal aspect of the medial guttural pouch compartment?
-CN9
-CN10
-CN11
-CN12
-internal carotid artery
Which structure provides surgical access to the guttural pouch?
Viborg’s triangle
What are the boundaries of Viborg’s triangle?
cranial: ramus of mandible
ventral: linguofacial vein
dorsocaudal: tendon of sternocephalicus m.
Why is it important that the internal carotid a. passes through the guttural pouch?
helps to cool down the blood before it goes to the brain
How do the parotid duct, facial artery, and facial vein orient?
rostral to caudal order:
-facial a.
-facial v.
-parotid duct
What are the characteristics of the bovine frontal bone?
-large
-parietal bone further back
-occipital bone further down
What are the characteristics of the bovine frontal sinus?
-expands along top/back of head
-grows over time
-not present in neonate
What is the bovine cornual diverticulum?
extension of frontal sinus into the horn
