Lab 5 Flashcards
(29 cards)
What cranial nervces emerge from the midbrain?
Oculomotor and Trochlear
What cranial nerves emerge from the pons?
Trigeminal nerve
What cranial nerves emerge from the medulla?
Abducent
Facial
Vestibulocochlear
Glossopharyngeal
Accessory
Hypoglossal
What cranial nuclei contribute to CN III?
Approximately where in the brainstem is it located?
Motor nucleus of the oculomotor nerve, parasympathetic nucleus of the oculomotor nerve
These nuclei are located in the rostral colliculi
see pg 154
What cranial nuclei contribute to CN IV?
Where are they located?
motor nucleus of the trochlear nerve (motor function only!)
located in the caudal colliculi
see figure 10-2B
The trochlear nerve is an exception to the rule of non-crossing over! It innervates the contralateral dorsal oblique
What nuclei contribute to CN V?
Where are they located?
Motor nucleus of the trigeminal nerve - in the dorsolateral area of the pons
3 sensory nuclei: mesencephalic nucleus of the trigeminal nerve (in the midbrain), the pontine sensory nucleus of the trigeminal nerve (in the pons), the ncleus of the spinal tract of the trigeminal nerve (in the medulla oblongata)
What nuclei contribute to CN VI?
Where are they located?
Motor nucleus of the abducent nerve - motor only
located immediately ventral to the genu of the facial nerve, in the medulla
see page 180
Which nuclei contribute to CN VII?
Where are they located?
Motor nucleus of the facial nerve - #2
parasympathetic nucleus of the facial nerve - #3
nucleus of the solitary tract (sensory nucleus of the facial nerve) - #4
Which nuclei contribute to CN VIII?
Where are they located?
Vestibular nuclei - lateral floor of the fourth venticle on either side of the medulla oblongata - 4 nuclei (rostral, lateral, medial, caudal) see fig 12-16A
Cochlear nuclei - (dorsal and ventral)
The trapezoid body is made up of fibers that carry auditory signals from the ventral cochlear nuclei and the dorsal nucleus of the trapezoid body
Which nuclei contribute to CN IX?
Where are they located?
Sensory - nucleus of the solitary tract in the medulla (remember that these fibers are carrying signals from the taste buds, etc., to this nucleus)
Motor - nucleus ambiguus in medulla - innervates muscles of pharynx
Paraympathetic nucleus of the glossopharyngeal nerve - in the medulla - innervates parotid and zygomatic salivary glands
Which nuclei contribute to CN X?
Where are they located?
Sensory - nucleus of the solitary tract - in the medulla
motor - nucleus ambiguus - muscles of pharynx, larynx, esophagus - in the medulla
parasympathetic nucleus of X - cardiac muscle, smooth muscle in esophagus and gut - in the medulla
Another pic with nuclei
don’t panic, you don’t have to memorize all of this, it’s just to give you an idea of which nerves might be affected if different parts of the brain are lesioned
Which nuclei contribute to CN XI
Cranial root: Nucleus ambiguus
Spinal root: motor nucleus of the accessory nerve
Identify the foramina - also be able to ID the cribitform plate, canal for the trigeminal nerve, internal acoustic meatus, jugular foramen, hypoglossal foramen and tympano-occiptal
See pages 144-145 for things not labeled here
- ethmoid foramen
- optic canal
- orbital fissure
- rostral alar foramen
- caudal alar foramen
- oval foramen
Be able to identify the facial canal - remember they had a red string going through it - see back of notecard
string is inserted into the stylomastoid foramen to reach the area where the facial canal is separated from the middle ear by thin connective tissue
see Fig 12-9 and 19-1
Run the neuro-dog program to check for palpebral and 3rd eyelid relfexes if these nerves are lesioned:
CN V, CN VI, CN VII - do them one at a time
If CN V is lesioned - no palpebral reflex, corneal relfex or 3rd eyelid response - on same side as lesion
If VI is lesiond - no 3rd eyelid reflex, medial strabismus - same side as lesion
If VII is lesioned - no blink, no palbebral reflex, no corneal reflex - same side as lesion
See page 187 and review the reflex circuits involved for palpebral, corneal, and tearing reflexes
Identify the nuclei
A. pontine sensory nucleus of the trigeminal nerve in the pons
B. Motor nucleus of the trigeminal nerve
C. Motor nucleus of the facial nerve in the rostral medulla
Remember that they lie within the brain stem, not on the surface as illustrated in these pics
Structure - cerebellum
space - fourth ventricle
ID these structures
- trigeminal nerve
- motor nucleus of the trigeminal nerve
- pontine sensory nucleus of the trigeminal nerve
Explain clinical problems associated with lesion a or lesion b
Lesion a - ophthalmic innervates (sensory) the upper eyelid, eyeball, lacrimal gland, nasal mucosa - important in sneezing response to irritation of mucosa
lesion b - mandibular nerve affected - muscles of mastication paresis or paralysis, no contraction of tensor tympani in response to loud sounds. Loss of sensory innervation to oral cavity, lower lip. lower teeth, nasal passage, rostral 2/3 of the lingual mucosa
see page 165 for dermatome
The right eye does not blink. Furthermore, when the right medial canthus is touched, the right eye fails to close. What is wrong with this dog?
The right facial nerve is damaged (or the motor nucleus of the facial nerve)
Negative palpebral relfex could point to a trigeminal nerve (ophthalmic) injury, since they would not feel you toching their medial canthus.
Both eyes blink, but touching the right medial canthus fails to induce blinking. Where is the lesion?
Pointine sensory nucleus of CN V or on the ophthalmic nerve (on the right side)
Since the dog can blink, we know it is not the facial nerve that is damged. Lack of palpebral reflex points to lack of sensory innervation to the medial canthus in this instance.
