Lecture 2 DA

Question 1

What is the main nerve of the parasympathetic pathway concerning viscera?

Answer 1

Vagus nerve.

Question 2

Describe the lengths of pre and post ganglionic neurons in sympathetic and parasympathetic nerves.

Answer 2

Sympathetic: Short pre-ganglionic neurons, long post-ganglionic neurons.Parasympathetic: Long pre-ganglionic neurons, short post-ganglionic neurons.(Yes, it’s spelt neurons and not neurones. It’s ok, I know it’s hard for yankees to understand. They are a pretty dumb population after all).

Question 3

What are splachnic nerves, and how do they function?

Answer 3

They are nerves that run through the sympathetic trunk, but do not synapse there. Instead they do so further on, to get to the viscera in the abdomen and pelvis.

Question 4

What are grey communicantes?

Answer 4

Non-myelinated, post-ganglionic neurons.They are more proximal than white communicantes.

Question 5

What are white communicantes?

Answer 5

Mylinated, pre-ganglionic neurons to the sympathetic trunk.They are more distal than grey communicantes.

Question 6

What are visceral afferent neurons?

Answer 6

They act as sensory neurons to the viscera when they are damaged or distended.They follow the same pathway as the sympathetic pathway to the viscera. It can also follow the parasympathetic pathway (ie. vagus nerve).Plays a key role in referred pain.

Question 7

What is referred pain, and why is it believed to occur?

Answer 7

When pain in one area is felt elsewhere, such as damaged appendix felt on overlying skin.Due to convergence of two inputs to the same neuron at a given spinal segment (likely by visceral afferents).The brain cannot differentiate between the two signals, and assumes pain at the associated dermatome.

Question 8

Which ribs are true ribs? What is characteristic of them?

Answer 8

Ribs 1-7.They attach directly to the sternum via costal cartilage.

Question 9

Which ribs are false ribs? What is characteristic of them?

Answer 9

Ribs 8-10.They attach only to the costal cartilage, but not to the sternum.

Question 10

Which ribs are floating ribs? What is characteristic of them?

Answer 10

Ribs 11 & 12.They have no anterior attachment (neither to the sternum nor to other ribs).

Question 11

Which ribs are atypical?

Answer 11

Ribs 1, 2, 10, 11 & 12.Each have different markings.

Question 12

What is characteristic of typical ribs?

Answer 12

They are curved and flat.

Question 13

Describe the articulation of ribs with vertebra.

Answer 13

Rib x will articulate with vertebra x inferiorly, and vertebra x-1 superiorly, via demifacets. Called the costovertebral joint.Rib x also articulates with vertebra x transverse process.Called costotransverse joint.

Question 14

What direction does the external intercostal muscle orient?

Answer 14

Anteroinferiorly, also known as the hands in pockets muscle.

Question 15

What happens to the external intercostal muscle medioanteriorly?

Answer 15

It becomes fibrous, continuing as a membrane.

Question 16

What is the action of external intercostal muscles?

Answer 16

It acts to elevate the ribs.

Question 17

What direction does the internal intercostal muscle orient?

Answer 17

Perpendicular to the external intercostal muscles.

Question 18

What is the action of internal intercostal muscles? Why is their action atypical?

Answer 18

Posteriorly, they depress the ribs. Anteriorly, they elevate the ribs.This is due to the curvature of the ribs, and how they orient.

Question 19

What is the positioning of the neurovascular bundle within the costal groove inside ribs?

Answer 19

Most superior-Intercostal veinIntercostal arteryIntercostal nerve-Most inferior

Question 20

How does the intercostal nerve relate to the ventral ramus? How does this relate to dermatomes?

Answer 20

A given intercostal nerve is an extension of the ventral ramus of its spinal segment. In this way, it lays the foundation for dermatomes.

Question 21

Name the associated dermatome landmarks of T4 and T10, as well as a way to remember them.

Answer 21

Landmarks:T4-nipple levelT10-umbilicus levelRemembering them:T4 - T4 titsT10 - draw a dot in the 0 of T10, representing a stomach with a belly button

Question 22

Describe the pathway of the Intercostal artery beginning with its branch off the descending aorta. Include branches/anastamoses.

Answer 22

Begins as the Intercostal artery when it branches off the descending aorta. Travels posteriorly, branching into the dorsal branch of the intercostal artery (supplies dorsal vertebra), and the posterior intercostal artery, which enters the costal groove. The internal thoracic (also internal mammary) artery runs through the sternum and gives off anterior intercostal arteries, which anastamose with posterior intercostal arteries.
The internal thoracic/mammary artery has a perforating cutaneous branch that supplies much of the subcutaneous thoracic wall.
Clinical relevance. The internal thoracic/mammary artery can be harvested for a coronary bypass surgery as the perforating cutaneous branch supplies most of the area provided by the anterior intercostal artery.

Question 23

Name the three intercostal muscle layers.

Answer 23

Innermost internal intercostal muscleInternal intercostal muscleExternal intercostal muscle