Anatomy of Spinal Cord

Question 1

What does PNS vs CNS consists of?

Answer 1

CNS = brain, brainstem, spinal cord
PNS = peripheral and cranial nerves

Question 2

What’s structure of neuron?

Answer 2

soma(cell body), dendrites, myelinated axons, and terminal

Question 3

What are the three types of neurons?

Answer 3

1. Multipolar - many dendrites are off one soma (motor)
2. Pseudo unipolar - one process out of the soma that has an axon that splits into two branches; one branch travels to the PNS and the other CNS. (sensory)
   Bipolar - not located in the spinal cord, and has one axon and one dendrite; retina, cochlea, vestibular

Question 4

White matter vs grey matter

Answer 4

White matter are the groups of axon tracts on the edges of the spinal cord. grey matter is the groups of cell bodies (more medial in cross section); in CNS = nuclei, and PNS = ganglia

Question 5

Where are the two enlargements of the spine?

Answer 5

They’re in the cervical and lumbosacral region because of all the nerves for our extremities

Question 6

What’s the conus medullaris and cauda equina?

Answer 6

The conus medullaris is where the cord ends at L1, however those nerves still continue to come out past the cord. This is called the cauda equina (think of horse tail) which is the PNS.

Question 7

Of the white matter, what do each of the horns control?

Answer 7

Dorsal horn (sensory), lateral horn (organs/autonomic), and ventral horn motor (motor)

Question 8

How do we process touch?

Answer 8

sensation > peripheral nerve (pseudo unipolar)> dorsal root ganglia >spinal cord > cortex

Question 9

How does the body send out motor signals?

Answer 9

motor is ventral, so comes right out ventral horn and synapses on the muscle

Question 10

Where does C8 nerve project?

Answer 10

C1-C7 project up the vertebrae, but since there’s no C8 vertebrae, nerves C8-S5 project down.

Question 11

Why is injury to lower thoracic/ lumbar region worse than cervical?

Answer 11

Spinal nerves angle down as you go down the spinal cord because spine is shorter than how far vertebrae project. So if you injure your lower regions, because more nerves pass through.

Question 12

What are characteristics of parasympathetic and sympathetic autonomic systems?

Answer 12

Sympathetic: Fight or flight, vasoconstriction, pupil dilation, bronchial dilation, inhibit glands, decrease bowl peristalsis, urinary/fecal retention, and ejaculation. Parasympathetic: vasodilation, pupil constriction, glands secrete, activate peristalsis, initiate defecation/urination, and erection.

Question 13

How does the sympathetic autonomic nervous system project to target organ?

Answer 13

Brain (hypothalamus)> lateral horn > exits T1-L2> ascends/descends to synapse with preganglionic in ganglia >synapses on postganglionic nerve > target organ. These neurons and regular motor neurons take the ventral root, while sensory neurons take the dorsal root.

Question 14

Which 3 cranial nerves exit the parasympathetic autonomic nervous system?

Answer 14

Oculomotor(III), Facial (VII), Glossopharyngeal (IX), Vagus (X). These nerves. These nerves, unlike the sympathetic, will exit the brainstem, then synapse with preganglion, then synapse with the post ganglion.

Question 15

What are the 3 horns?

Answer 15

1. Autonomic = lateral
2. motor = ventral
3. sensory = dorsal

Question 16

Describe the covering around the spinal cord.

Answer 16

The most outer layer is the dura mater, in that is the arachnoid layer, and these two are stuck together. Cerebral spinal fluid flows in subarachnoid space (lumbar cistern) between arachnoid layer and pia mater. There are denticulate ligaments that come out the lateral sides of the cord to help anchor it.

Question 17

Describe the bottom meningeal covering of the spinal cord.

Answer 17

The pia continues past the spinal cord, this is called the filum terminale (internus only pia). This filum terminale joins with arachnoid and dura layers to form filum terminale externus (goes to coccyx). The cauda equina that projects from the conus medullaris is protected and anchored by the filum terminale.

Question 18

Where do you want to do spine tap/epidural?

Answer 18

Since spinal cord stops at L1, you want to go between L3-L4. When you put needle through, it goes through ligamentum flavum, and through the interspinous process space. MAKE SURE, you pull needle directly back incase you’re in artery.

Question 19

Where do most herniations appear?

Answer 19

In the lumbar region, and project between the anterior/posterior longitudinal ligaments.