Week 3

Question 1

What is the vertebral formula for the dog? the cat? the horse?

Answer 1

* the dog: cervical- 7, thoracic- 13, lumbar- 7, sacral-3, caudal-20

* the cat: same as dog

* the horse: C7 T18 L6 S3 Cd~20

Question 2

How can you recognize C6?

Answer 2

Question 3

How do you recognize anticlincal vertebrae?

Answer 3

T11 (T10 pointing caudally)

Question 4

How do we count lumbar vertebrae in a large dog in a radiograph?

Answer 4

Include T13 or the diaphragm attaches to the ventral border of L3 and L4 (they have a scalloped appearance)

Question 5

What should the intervertebral disc space look like?

Answer 5

A hobby horse’s head (should be a nice dark grey)

Question 6

What is important to remember about the size of the intervertebral disc space relative to each other in a radiograph?

Answer 6

They should be the same, however there will be distortion and they will look smaller than they are moving away from the central radiograph beam

Question 7

What is radiograph used for with neurologic disease?

Answer 7

* Trauma, neoplasia of skull and vertebrae, intervertebral disc degeneration, +/- intervertebral disc herniation, discospondylitis, (hydrocephalus)

Question 8

What is ultrasound used for with neurologic disease?

Answer 8

* high density of bone prevents ultrasound from penetrating through so can only image through a hole in the calvarium- natural hoels (fontanelle or foramen magnum) or surgical holes (craniotomy or pediculectomy)

* ultrasound allows you to see the internal structure of the brain or spinal cord

Question 9

What is a myelogram?

Answer 9

Myleography- inject the positive contrast agent in the subarachnoid space to highlight the margins of the spinal cord

* using radiograph or CT

* allows you to identify spianl cord compression or enlargement

* indications:

• clinically: myleopathy (paresis, paralysis, neck pain, neurologic deficits of the limbs)
• find a lesion when radiographs are normal
• better define lesions suspected on radiographs (confirm or define extent)
• surgical planning and prognosis

Question 10

Where is the cisternal puncture performed? The lumbar puncture?

Answer 10

* Cerebromedullary cistern

* Lumbar interarcurate space

Question 11

What is the ideal method of imagine for neurological disease?

Answer 11

* MRI

*pictures are meningiomas (one in brain, on in the spinal cord in two different dogs)

Question 12

What can happen with neoplasia in the brain with contrast?

Answer 12

BBB junctions are no longer as tight, so the contrast can leak out– normal neural tissue does not take up contrast due to the BBB

Question 13

What is the constrast medium used in MRI?

Answer 13

Gadolinium

Question 14

What anatomic structures make up the auditory system?

Answer 14

External ear, middle ear, cochlear part of inner ear

Question 15

What is another name for the pinna?

Answer 15

Auricle

Question 16

Answer 16

Question 17

Answer 17

Question 18

What is the tympanic cavity?

Answer 18

* Air-filled cavity in the temporal bone separated from external acoustic meatus by the tympanic membrane

* Changes air vibrations (sound waves) into mechanical movement through auditory ossicles

Question 19

Answer 19

Question 20

What moves the ossicles? What happens when they contract?

Answer 20

Stapedius muscle (attached to the stapes)

and

Tensor tympani muscle (attached to the malleus)

* When they contract, they dampen the vibrations of the auditory ossicles (protective mechanism)

Question 21

What anatomically is the inner ear?

Answer 21

Membranous labyrinth sitting within a bony labyrinth within the temporal bone

*membranous labyrinth is surrounded by perilymph (the fluid, perilymph, suspends it inside the bony labyrinth)

*the membranous labyrinth contains endolymph

Question 22

What does the vestibule contain?

Answer 22

It is one of three parts of the bony labyrinth

* utricle and saccule (part of the vestibular system)

Question 23

What does the semicircular canals contain?

Answer 23

It is one of three parts of the bony labyrinth

* semicircular ducts (part of the vestibular system)- there are three semicircular canals.

Question 24

What does the cochlea contain?

Answer 24

It is one of three parts of the bony labyrinth

* cochlear duct

Question 25

What is the vestibular system?

Answer 25

Organ responsible for sensing body position

* static and kinetic sensations perceived by hair cells in specialized sensory regions

• 40-80 cilia and one kinocilium on apical surface of hair cells
• movement of cilia towards or away from kinocilium results in depolarization or hyperpolarization or inhibition of firing of neuron at base of hair cell

Question 26

What is the function of the cilia and kinocilium?

Answer 26

Mechanotransduction- Vibrations (either by movement or sound waves) cause displacement of the hair bundle, resulting in depolarization or hyperpolarization of the hair cell. The depolarization of the hair cells in both instances causes signal transduction via neurotransmitter release.

Question 27

What are the two membranous enlargements of the inner ear?

Answer 27

Utricle (at the base of the semicircular canals) and saccule (connected to the endolymphatic duct)

Question 28

What is a maculae?

Answer 28

In the utricle and saccule

* Monitor position of head with respect to gravity

* kinocilium and cilia of hair cells project into the otolithic membrane (gelatinous matrix containing calcium carbonate/ protein crystals e.g. otoliths)

* pull of gravity on otolithic membrane causes shearing force on cilia

* macula in saccule oriented in vertical plane

* macula in utricle oriented in horizontal plane

** the two maculae are always at right angles to each other

Question 29

What is the function of the semicircular ducts?

Answer 29

* sense dynamic positon due to movement of endolymph (accelteration too)

Question 30

What are the anatomic regions of the semicircular ducts?

Answer 30

* each duct contains enlargement at one end- ampulla: contains sensory regin (crista)

* Crista is a thickened region of the epithelial lining + connective tissue underneath which projects as a ridge into the ampulla- arranged at right angles to the length of the semicircular duct. HAIR CELLS are located on the CRISTA.

When there is movement within the semicircular duct- the CRISTA is moved around

* Cupula- cilia of hair cells project into gelationous material- cupula.. Cupula is readily deflected by movement of endolymph created by rotation or deceleration of the head.

Question 31

How does vibration result in impulses to the brain?

Answer 31

Question 32

Answer 32

Cochlea

Question 33

Answer 33

Cochlear duct

Question 34

Answer 34

Question 35

Answer 35

Answer 36

Question 37

Answer 37

Question 38

What innervation does the vestibulocochlear nerve (CN VIII) supply to the ear? What are the two branches, where are the ganglion, and how does it run to the brain?

Answer 38

** the signal that has been created from the sound waves that were picked up by the ear, is carried to the brain by the vestibulocochlear nerve (CN VIII) which synapses in the cochlear nucleus

* nerve endings in maculae of the utricle and saccule, and in ampullae of semicircular ducts have cell bodies in the vestibular ganglion in vestibular branch of CN VIII

* also in the basilar membrane of cochlear ducts– cell bodies in the spiral ganglion in cochlear branch of CN VIII

* the vestibular and cochlear branches unit and travel to the brainstem through internal acoustic meatus of temporal bone

Question 39

What innervation does the facial nerve supply to the ear?

Answer 39

Moves the muscles of the ear to move the ear (preauricular, ventroauricular, and postauricular mm.)

Question 40

What innervation does the trigeminal nerve provide to the ear?

Answer 40

Branch of mandibular division supplies m. tensor tympani

Sensory innervation to the outer ear- auriculopalpebral branch of trigeminal nerve to most of the lateral pinna

(also the second cervical spinal nerve to medial pinna, and the facial and vagus nerves via small aurical branches to the pinna)