Axons

Question 1

The component axons of the dorsal root

Answer 1

All roots transmit GSA and GVA

*note: C1 has very few afferent and a very small DRG

Question 2

The component axons of the sympathetic chain

Answer 2

The sympathetic chain transmits preganglionic sympathetic axons from the white rami of T1-L2/3 to all levels of the chain; the chain ganglion itself consists of postganglionic sympathetic cell bodies, thus the axons will be present as well. Also, from the thoracic and abdominopelvic viscera, GVAs will return to the dorsal root via the sympathetic chain. Therefore: pre- and postganglionic sympathetic axons and GVA axons are transmitted by the sympathetic chain.

Question 3

The component axons of the gray ramus

Answer 3

The gray rami transmit postganglionic GVE sympathetic axons to all spinal nerve levels. Therefore, there are gray rami for all spinal nerves. No other axons are transmitted by these nerves.

Question 4

The component axons of the T5 ventral root

Answer 4

The ventral roots from T1-L2/3 will transmit both GSE axons and preganglionic GVE sympathetic axons because the preganglionic axons arise from those segments

Question 5

Ventral root

Answer 5

All roots transmit GSE; T1-L2/3 also transmit Preganglionic GVE Somatic; S2-4 also transmit Preganglionic GVE Parasympathetic

Question 6

The white Rami

Answer 6

Only exist between T1-L2/3

Transmits Preganglionic GVE Somatic and GVA (only high threshold)

Question 7

The gray rami

Answer 7

Exists for all levels

Transmits postganglionic GVE Somatic ONLY. Moreover these axons are bound for the body wall and limbs only.

Question 8

What is in the sympathetic chain?

Answer 8

The sympathetic chain ganglia exhibit the following axons: GVA, pre-and post ganglionic GVE somatic; the house the cell bodies of the postganglionic GVE somatic

Question 9

What is in CNX?

Answer 9

(Vagus nerve)

Transmits GVA (low threshold) axons and Preganglionic GVE parasympathetic axons.

Question 10

What is in the ventral primary rami?

Answer 10

Transmits: GVA, GSA, GSE, and postganglionic GVE sympathetic.

The ventral ramus projects to the lateral and anterior body walls and skin as well as the entire upper and lower extremity. The GVAs in these nerve branches are both HT and LT

Question 11

What is in the dorsal primary rami?

Answer 11

Transmits: GVA, GSA, GSE, and postganglionic GVE sympathetic.

The dorsal ramus projects to the posterior body wall and skin of the intrinsic back muscles

Question 12

What is in the prevertebral ganglia?

Answer 12

The prevertebral ganglia house the postganglionic GVE sympathetic cell bodies for the abdominopelvic viscera. They transmit the GVA, pre-and post ganglionic sympathetic axons as well as the preganglionic GVE parasympathetic. (both the high and low threshold GVAs are present)

Question 13

What is in the splanchnic nerve?

Answer 13

The splanchnic nerves transmit preganglionic sympathetic axons and high threshold GVA axons.

Question 14

What is in the cardiopulmonary nerves?

Answer 14

The seven cardiopulmonary nerves transmit postganglionic sympathetic axons and high threshold GVA axons.

Question 15

What is in the cardiopulmonary ganglia?

Answer 15

The cardiopulmonary ganglion is a parasympathetic ganglion housing postganglionic parasympathetic cell bodies, pre-and post ganglionic parasympathetic axons, Post ganglionic sympathetic axons, and both high threshold and low threshold GVA axons.

Question 16

What generally enters the lateral division of the dorsal root?

Answer 16

The A-delta and C-fibers enter the lateral division of dorsal root

Question 17

Generally, what fibers enter the medial division of the dorsal root?

Answer 17

The larger Ia, Ib, and A-bets divers enter the medial division of the dorsal root

Question 18

What two spinal nerves represent exceptions to the general schema of spinal nerves?

Answer 18

The first cervical and first coccygeal spinal nerve.

C1 nerve transmits almost no sensory component

The coccygeal nerve usually does not exhibit any somatic motor component, it is mainly a sensory nerve supplying the perineum

Question 19

Is the ventral root composed of primarily myelinated or unmyelinated axons?

Answer 19

Ventral root is composed of primarily myelinated axons. Any unmyelinated axons May be sensory axons that enter and “turn around” returning to the dorsal root.

Question 20

Where do most of the myelinated axons arise from?

Answer 20

Large anterior horn cells (GSE) in Rexed Laminae IX. These axons are also known as Alpha motor neurons or final common pathway axons.

Question 21

Where do the sympathetic Preganglionics exit the spinal chord?

Answer 21

Through the ventral root, and then become part of the white communicating ramus

Question 22

White rami

Answer 22

Myelinated, sympathetic Preganglionic fibers (GVE- Preganglionic) and visceral Afferent axons, returning information from the organ systems and internal cavity vessels to the CNS

Only associated with spinal nerves T1-L2/3

Question 23

Gray rami

Answer 23

Contain only unmyelinated postganglionic fibers (GVE- postganglionics) arising from the sympathetic chain and destined for the body wall and limbs. These postganglionics will innervates only 3 different types of structure: sweat glands, vascular smooth muscle and erector pili muscles. Gray rami are branches of all spinal nerves.

Question 24

Dermatome

Answer 24

The sensory innervation of a dorsal root

Question 25

Spinal nerves

Answer 25

31 pairs of spinal nerves

8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal

They each transmit GSA and GSE axons as well as GVA and GVE sympathetic components