CT Flashcards
What are the dental formulas for dogs & cats?
Dog 42 (I 4/4, C 1/1, P 4/4, M 2/3)
Cat 30 (I 4/4, C1/1, P 3/2, M 1/1)
Which neoplasia of the mandible/maxilla tends to be more osteoproliferative than others?
Chondrosarcoma
What is the most common tumor of the soft palate?
Lymphoma
What is the most common tonsillar and lingual neoplasia in dogs?
Squamous cell carcinoma
Where are dentigerous cysts most commonly seen?
Near 1st premolar in brachycephalic dogs
What is the difference in origin between an epulide and an odontogenic tumor?
- Epulides arise from periodontal ligament (benign gingivial proliferation)
- Odontogenic tumors arise from dental lamina (rare)
What is the hallmark feature of an odontoma?
Dental structures within the mass
What foramen is at the level of the TMJ joints? What structure(a) pass through it?
Oval foramen
- mandibular branch of trigeminal nerve
What are the 5 muscles of mastication?
1) Temporal (innervation: mandibular n)
2) Masseter (mandibular nerve)
3) Medial pterygoid (mandibular N)
4) Lateral pterygoid (mandibular N)
5) Dogastricus ( mandibular & facial nerves)
What is the pathophys of jaw drop? And what conditions cause it?
Jaw drop requires bilateral flaccid mandibular nerve paralysis.
-Etiologic conditions = idiopathic trigeminal neuropathy, lymphoma, juvenile masticatory myositis; rare differentials = rabies, botulism, Meningiomas
Why is the digastricus muscle unaffected by masticatory myositis?
Made of type 2A fibers. Masticatory myositis affects 2M fibers
What dog breed is predisposed to juvenile masticatory myositis?
Cavies
What 6 bones form the orbit?
1) Frontal
2) Lacrimal
3) Zygomatic
4) Palatine
5) Maxillary
6) Sphenoid
What structures pass through the orbital fissure?
Oculomotor, trochlear, abducens, and ophthalmic branch of trigeminal nerve, anastomotic branch of external ophthalmic artery, & orbital venous plexus
What is different about the feline osseous orbit?
Bony floor consists of only a small part of maxillary bone holding the last molar teeth
What 3 dog breeds are predisposed to extraocular polymyositis?
Goldens
Springer Spaniels
Dobermans
What are 3 common optic nerve tumors?
Neurofibrosarcoma
Glioma
Meningioma
What breed(s) are typically affected by craniomandibular osteopathy & calvarial hyperostosis respectively? And how can you differentiate the two conditions?
Craniomandibular osteopathy - Westies, Dobies, Labs, Bullmastiffs ; affects mandible, tympanic bulls, calvarium, & petrous temporal bone
Calvarial hyperostosis- bullmastiffs; affects calvarium (frontal, parietal, occipital) WITHOUT mandible abnormalities
MLO of the skull has a predilection site where?
Calvarium & zygomatic arch
What are the first and second most common primary bone tumors of the skull?
1) Osteosarcoma
2) Chondrosarcoma
Where is the lateral retropharyngeal lymph node located and in what percentage of dogs & cats is it present in?
Between the ear base & wing of C1
-Present in ~ 30% of dogs & almost always in cats
Where are the superficial cervical lymph nodes located?
Usually paired & located cranial to supraspinatus in between neck musculature
Where are the deep cervical nodes located & in what percentage of dogs & cats are they present in?
Located cranial to the thyroid gland
- present in ~ 30% of dogs & ABSENT in cats
Where does the auditory tube enter the nasopharynx?
Dorsolaterally just caudal to the pterygoid hamulus process
What is displaced with caudal transtentorial herniation?
Displacement of portions of cerebral cortex/cortices VENTRAL to tentorium cerebelli
What 2 areas of the brain are particularly affected by necrosis secondary to seizures?
Hippocampus & piriform loves
What are the two key components of Dandy-Walker syndrome?
Partial or complete absence of cerebellar vermis &cystic dilation of the 4th ventricle
Dry form of FIP results in what lesions?
Pyogranulomatous inflammation of the Leptomeninges, choroid plexus, ependyma & brain parenchyma
What dog breed is predisposed to necrotizing leukocephalitis & what location(s) does it affect?
Adult Yorkshire Terrier
- cerebrum & brainstem
What pituitary lesion has a stalk-like appearance?
Craniopharyngioma
Where does the maxillary branch of the trigeminal nerve exit in cats?
Round foramen (there is no alar canal in cats)
Where does the maxillary branch of the trigeminal nerve exit in dogs?
Round foramen —> alar canal —> rostral alar foramen
What congenital abnormality can result in reduced tracheal diameter with thickened misshapen cartilages?
Mucopolysaccardosis 7
What are the 3 reflections of the mediastinum?
1) Cranioventral
2) Caudoventral
3) Plicae vena cava
Describe the course of the mediastinum and what obliques it cranially & caudally, respectively?
Runs obliquely craniocaudally from right to left.
- Ventral cranial mediastinum slightly to RIGHT due to left cranial lung extension across midline
- Caudal mediastinum is to LEFT of midline due to extension of accessory lung lobe
Where is the Cisterna chyli located and what originates from it?
Cisterna chyli originates ventral to L4.
-thoracic duct originates from the Cisterna chyli
What is the course of the thoracic duct in the thorax?
Runs dorsal to aorta & ventral to azygous vein.
Describe a possible appearance of the cisterna chyli….
Sometimes seen as a “ hat-shaped” structure draping dorsally over aorta
Mean density levels for lung CT in dogs during expiration and inspiration are what?
-713 Hu = expiration
-846 Hu = inflated inspiration
What lung lobes are most likely to torse in deep-chested and barrel-chested breeds respectively?
Deep-chested: right middle
Barrel-chested: left cranial
Lower attenuation values have reported in the liver and spleen with what conditions, respectively?
Liver: hepatic lipidosis (cats/tortoises)
Spleen: hemangiosarcoma (in relation to benign etiologies such as hematomas & focal nodular hyperplasia)
What cat breed commonly develops pancreatic cysts?
Persians
What are the CT features of acute pancreatitis?
-Enlargement or mass effect
- Hypodense central or peripheral areas
- LACK of contrast enhancement
- Ascites
- Regional thrombosis possible
Where is the Cisterna chyli located?
Ventral to the first 4 lumbar vertebrae.
- Bordered ventrally by aorta & dorsally by azygous vein
-Becomes thoracic duct as it passes through aortic hiatus
What are the CT characteristics of an ameloblastoma?
-Mandibula > maxilla
- locally destructive
- spherical or multilocular cystic
- expansile
What are the CT characteristics of an odontoma?
-lobulated enamel foci within a well-defined cyst like structure
- at root of maxillary tooth
In horses, the dorsal and ventral nasal conchae divide the nasal cavity into what?
Longitudinally into the dorsal, middle, and large ventral nasal meatus
What are the communications and separations between the frontal and maxillary sinuses?
- sinuses communicate with eachother via large oval opening
- direct communication with nasal cavity
- separated into rostral and caudal parts by thin bony septum
-separated into medial & lateral compartments by infra orbital canal
The rostral and caudal maxillary sinuses overlie the apices of which teeth , respectively?
Rostral maxillary sinus - Triadan 8 & 9
Caudal maxillary sinus - Triadan 10 & 11
The dorsal and ventral conchal sinuses communicate with what structures respectively?
Dorsal conchae - caudal maxillary sinus
Ventral conchae - rostral maxillary sinus
What is the etiology of a dentigerous cyst?
Incomplete closure of the 1st branchial cleft —> cyst like structure surrounding tooth crown (often adjacent to temporal bone)
Describe the CT features of cholesterinic granulomas in horses?
- Benign outgrowths of choroid plexus
- common & often bilateral
- occur in lateral and 4th ventricles
- can cause neuro signs due to obstructive hydrocephalus or direct brain compression
What structures are collectively termed the distal sesamoidean ligaments?
- short sesamoidean ligament
-oblique sesamoidean ligament - cruciate sesamoidean ligament
-straight sesamoidean ligament
