L6: Functions of parasympathetic supply to head and neck, thorax, abdomen and pelvis

Question 1

What is the origin and relay of the oculomotor nerve?

Answer 1

• Edinger Westphal nucleus in the midbrain

- Ciliary ganglion

Question 2

What is the origin and relay of the facial nerve?

Answer 2

-Superior salivary nucleus in the pons

• 1. Greater superficial petrosal branch→ Sphenopalatine(petrosal) ganglion.
     
     2. Chorda tympani branch →Submandibular ganglion

Question 3

What is the origin and relay of the glossopharyngeal nerve?

Answer 3

• Inferior salivary nucleus in the medulla oblongata.

- Otic ganglion

Question 4

What is the origin and relay of the vagus nerve?

Answer 4

• Dorsal motor nucleus of vagus in the medulla oblongata

- Terminal ganglion

Question 5

What is the origin and relay of the pelvic nerve?

Answer 5

• Sacral segments (S2,3,4) and preganglionic nerve fibers unit together to form pelvic nerve or nervous erogenous.
• Terminal ganglia

Question 6

What is the function of the parasympathetic supply by the oculomotor nerve?

Answer 6

a. Contraction of constrictor pupillae ms → narrowing of the pupil (miosis)
b. Contraction of ciliary ms → ↑ed convexity of the lens → helps eyes to see near objects→ accommodation to near vision

Question 7

Why is parasympathetic stimulation important in near vision like reading?

Answer 7

to decrease the size of the pupil to decrease the amount of light entering the eye and increase the lens power to focus the image of the object on the retina of the eye

Question 8

What is the function of the parasympathetic supply by the facial nerve?

Answer 8

a- Greater superficial petrosal nerve: (GSP)

1. Lacrimal glands:
   i) Vasodilatation.
   ii) Secretion of tears from lacrimal glands
2. Mucus membrane of the nose, soft palate, and pharynx: i)Vasodilatation.
   ii) Secretion of mucus. (nasal secretion with crying)

b- Chorda tympani nerve:

1. Submandibular and sublingual salivary glands:
   i) Vasodilatation.
   ii) True salivary secretion (large in volume, watery, rich in electrolytes, and poor in enzymes).
2. Mucus membrane of anterior 2/3 of tongue and floor of mouth→ vasodilatation and mucous secretion.

Question 9

What is the function of the parasympathetic supply by the glossopharyngeal nerve?

Answer 9

1. Parotid salivary gland
   i) Vasodilatation.
   ii) True salivary secretion.
2. Mucus membrane of posterior 1/3 of tongue and floor of mouth→ Vasodilatation

Question 10

What are the nerves responsible for parasympathetic supply to the head and neck?

Answer 10

i) Oculomotor nerve
ii) Facial nerve
iii) Glossopharyngeal nerve

Question 11

What are the organs affected by the parasympathetic supply of the vagus nerve?

Answer 11

• Thorax (heart and lungs)

- Abdomen (GIT, Glands, Liver, Gall bladder, and blood vessels)

Question 12

What is the function of the parasympathetic supply of the vagus nerve at the heart?

Answer 12

a. It ↓es the heart rate, the force of contraction, conductivity, and excitability →↓es the effectiveness of the heart as a pump.

b. Coronary vessels
 Direct effect → vasodilatation
 Indirect effect → vasoconstriction because it inhibits cardiac work with less production of metabolites

“ Vagus nerve supplies the atria only and does not supply the ventricles

Question 13

What is the function of the parasympathetic supply of the vagus nerve at the Lungs?

Answer 13

a. Contraction of smooth ms of the bronchi → bronchoconstriction.
b. Stimulate the mucus secretion of the air passages.
c. Vasodilatation of the pulmonary blood vessels.

“That’s why asthma happens casually at night”

Question 14

What is the function of the parasympathetic supply of the vagus nerve at the GIT ( esophagus, stomach, small intestine, and proximal part of the large intestine)?

Answer 14

Contraction of their walls and relaxation of their sphincters → help both digestion and evacuation of GIT contents i.e. helps deglutition, gastric motility, and peristaltic movement.

Question 15

What is the function of the parasympathetic supply of the vagus nerve at the glands?

Answer 15

 Gastric glands→ ↑es gastric juice secretion (rich in HCL).
 Bruner’s glands in the duodenum→↑es alkaline mucus secretion.
 Pancreas: stimulates both endocrine and exocrine components pancreatic secretions

Question 16

What is the function of the parasympathetic supply of the vagus nerve at the Liver?

Answer 16

It ↑es hepatic bile flow.

Question 17

What is the function of the parasympathetic supply of the vagus nerve at the gall bladder?

Answer 17

Contraction of its wall and relaxation of the sphincter of Oddi → help its evacuation.

Question 18

What is the function of the parasympathetic supply of the vagus nerve at the blood vessels?

Answer 18

Vasodilatation

Question 19

What is the function of the parasympathetic supply by the pelvic nerve at the urinary bladder?

Answer 19

Contraction of its wall and relaxation of internal urethral sphincter → micturition.

Question 20

What are the organs affected by the parasympathetic supply of the pelvic nerve?

Answer 20

Urinary bladder, rectum, and sex organs

Question 21

What is the function of the parasympathetic supply by the pelvic nerve at the Rectum?

Answer 21

Contraction of its wall and relaxation of internal anal sphincter → defecation.

Question 22

What is the function of the parasympathetic supply by the pelvic nerve at the Sex organs?

Answer 22

1. Vasodilatation of the blood vessels of the pelvic viscera including that of sex organs → erection of the penis, clitoris, and congestion of the labia.
   - So, the pelvic nerve is named the nervous erogenous.
2. It ↑es the secretions from the seminal vesicles, prostate

Question 23

Are the external anal and urethral sphincters voluntary or involuntary?

Answer 23

They are voluntary ms supplied by the somatic spinal pudendal nerve.

Question 24

What are the organs that have sympathetic supply only?

Answer 24

1) Dilator pupillae muscle
2) Muller’s muscle.
3) Cutaneous effectors
4) Ventricles of the heart.
5) Spleen
6) Adrenal medulla

Question 25

What are the organs that are affected by the parasympathetic supply only?

Answer 25

1) Constrictor pupillae muscle
2) Upper esophagus.
3) Glands of stomach

Question 26

What are the types of relations between sympathetic and parasympathetic nervous systems?

Answer 26

• Antagonistic: one system increases the function and the 2nd decreases the functions e.g. heart rate, sympathetic NS increases HR, and parasympathetic N.S. decreases HR
• Synergistic: during salivary secretion (sympathetic secretes enzymes and parasympathetic secretes water and electrolytes)
• Cooperative: during sexual intercourse (parasympathetic NS causes erection and sympathetic NS causes ejaculation)