VAGUS (X) NERVE
| A | Phrenic nerve anterior, vagus nerve posterior | |
| B |
Phrenic nerve posterior, vagus nerve anterior |
|
| C |
Both in same plane anteroposteriorly |
|
| D |
Variable in relationship |
At the level of Arch of aorta, the relationship of left vagus nerve and left phrenic nerve‑
| A |
Phrenic nerve anterior, vagus nerve posterior |
|
| B |
Phrenic nerve posterior, vagus nerve anterior |
|
| C |
Both in same plane anteroposteriorly |
|
| D |
Variable in relationship |
Phrenic nerve anterior, vagus nerve posterior
Bilateral cutting of vagus nerve causes ‑
| A |
Decrease heart rate |
|
| B |
Decrease respiratory rate |
|
| C |
Increase heart rate |
|
| D |
Decreased BP |
Ans. is ‘c’ i.e., Increase heart rate
Aortic nerve (a branch of vagus nerve) carries :‑
i) Baroreceptor afferent from Aortic sinus.
ii) Chemoreceptor afferent from Aortic bodies.
Bilateral sectioning of vagus nerve causes increase in heart rate and BP due to two reasons :‑
i) Abolition of baroreceptor discharge of aortic sinus on RVLM → causing increasing in sympathetic output.
ii) Inhibition of nucleus ambiguous → causing decreased parasympathetic tone.
Effect on chemoreceptors afferent is minimal as chemoreceptors are stimulate by low PO, and normally they have no dischange.
