Brainstem II

Question 1

Brainstem

Answer 1

-UMNs and proprioceptive tracts travel through the brainstem

Question 2

Brainstem lesions

Answer 2

-result in UMN signs caudal to the level of the lesion
-proprioceptive deficits if there is a lesion in the brainstem (signs appear caudal to the level of the lesion)

Question 3

Reticular formation

Answer 3

-receive information from periphery, stimulate the cortex; keep animal awake

Question 4

Neurons of the reticular formation

Answer 4

-known as Ascending Reticular Activating System (ARAS)
-they receive sensory input from the periphery

Question 5

Cortex consciousness

Answer 5

-can only be maintained with activation from reticular formation
Ex. painful stimulus

Question 6

Animals lacking consciousness

Answer 6

-obtunded
-depressed
-sterberos
-comatosed

Question 7

Maintenance of respiration

Answer 7

-mostly subconscious pattern regulated by locomotion and physiological conditions (CO2)
>CN IX, X supply information to the pacemakers of the resp system
-Pacemakers of respiratory system: Dorsal respiratory group, ventral respiratory groups, Prebotscellar (PBC) group
>when these fire, causing diaphragm to contract pulling it caudally, increasing lung volume
>when these relax, diaphragm relaxes

Question 8

Maintenance of cardiac respiration

Answer 8

-sensory input from CN IX, X into the medulla, impacting cardiac cycle
>Parasympathetic neurons go to the heart

Question 9

Emetic center

Answer 9

-involuntary reflex of emptying the stomach
-Located mostly in medulla:
>Chemoreceptor trigger zone (outside the blood-brain barrier) detects unwanted materials inside the body, sends signals to emetic center and causes GIT to contract and vomiting occurs
>Vestibulocochlear nuclei and CN VIII: receives information from periphery about motion of head and body, and will trigger emetic center and stimulate the GIT
>Higher brain regions: animals that are anxious, seizure animals, gross smells/sight… will stimulate emetic center and then descending stimulus to GIT
>GIT has receptors that detect irritation and toxins, and can send ascending information to emetic center which sends information back to the GIT for vomiting

Question 10

Lesions to the brainstem

Answer 10

1.UMN signs to all 4 limbs
>If right sided lesion, then right side signs OR signs to all 4 limbs
2. LMN signs to cranial nerves
>Ipsilateral signs
3. Proprioceptive deficits to all 4 limbs
>can be ipsilateral or bilateral
4. Altered mentation
>depressed, unconcious
5. Changes to the respiration or cardiac function
>gasping/irregular rhythms
>severe lesions may result in death (apnea, inability to maintain blood pressure)
6.Vomiting
>emetic center
>CN VIII (vertigo)

Question 11

C1-C5 deficits

Answer 11

1.UMN signs (same side, or all 4 limbs)
2. proprioceptive deficits to all 4 limbs
3.changes in respiration and cardiac function