Blaire is studying for her anatomy test. She went back into her notes to review everything she learned.

While she was studying, she was struggling with a certain topic, meninges. After lots of review, Blair remembered that meninges are specialized membranes that isolate the spinal cord from surroundings. Their functions include protecting the spinal cord and carrying blood supply.

After Blair studied on her own she ran into Serena. They both were stressing out about their anatomy test. Serena struggled to remember the difference between the Central and Peripheral nervous system. Blair told her the central nervous system consists of the brain and spinal cord while the peripheral nervous system consists of nerves. 

The spinal cord is about 18 inches, from base the of the cranium where it connects through the foramen magnum down to the L1 vertebrae.

What do you know about Spinal Cord anatomy?

Then Serena helped Blair remember main ideas of the spinal cord anatomy

Isn't there also white and gray matter? White matter is made of myelinated neurons and gray matter is made up of unmyelinated neurons, but what do they do?

Yes! White matter has ascending tracts that carry sensory information to the brain, and it's descending tracts carry motor commands to the effectors. Gray matter processes spinal reflexes, which we will get to later. 

Each spinal nerve is mixed so that means that each nerve carries both sensory and motor information.

Blaire, what are mixed spinal nerves?

Back and Forth Serena and Blair took time to study together before their test.  Reviewing major topics such as mixed spinal nerves 

Blair decided she needed to study independently. She got in her limo and went back home. She remembered that spinal reflexes work with rapid, automatic nerve responses that are triggered by specific stimuli. A stimulus arrives, activating a sensory neuron, information is processed in the CNS, a motor neuron is activated, and finally there is a response by the effector. From studying with Serena, she also remembered that the spinal reflexes are controlled by the spinal cord's gray matter.

Nate was at home studying for the big anatomy test. He first started off by looking at Spinal Reflexes, remembering that they are triggered by a certain stimuli. Then he also knew it is controlled by spinal chord grey matter, not the brain. 

When Blaire finally got home, she thought to herself, "Don't we also have to learn about each major spinal plexus? What are they?

She looked in her textbook, she read a nerve plexus is a complex, interwoven web made from the blended roots of adjacent nerves. There are 4 major plexuses! The cervical, brachial, lumbar, and sacral plexuses.

The Cervical Plexus provides skeletal muscle control of the neck and upper torso. The Brachial Plexus is a major network of nerves transmitting signals responsible for motor and sensory innervation. The Lumbar Plexus supplies motor and sensory innervation to the anterior compartment of the thigh. And finally, the Sacral Plexus provides motor and sensory nerves for the pelvis, buttocks, thighs, and calves.

As Blaire studied on her own, she read from the textbook:

After lots of studying, it was finally time for Blair to take her test. The first part of her exam was asking about the brain. She recalled that the CSF is the cerebrospinal fluid which cushions and protects from physical injury and helps the control of the chemical environment of the brain. Along with this, Blair remembered that the brain stem processes information between the spinal cord and the cerebrum/cerebellum. She felt pretty confident on this section of the test. 

There were also questions about the cerebrum, which is the largest part of the brain, controls all conscious thoughts and intellectual functions, and processes somatic and motor information. Along with the cerebrum, there were questions about the cerebellum. Blair remembered that the cerebellum is like the cerebrum, and is divided into two halves called hemispheres. The functions are to adjust postural muscles and fine-tune conscious and subconscious movements by processing sensory information. 

When it got to the second portion of the exam, Blair blanked out. She couldn't remember the specifics about the cerebrum. Since this was a major test, Blair decided to cheat... 

She laid her notes out in front of her;

Names and Location of Lobes:

frontal, parietal, temporal, occipital: bounded by sulci (ridges on brain)

insula: between frontal and temporal lobes

Corpus Callosum: 

found beneath the cerebral cortex, connects the left and right cerebral hemispheres

cerebral cortex:

the surface of each hemisphere, composed of a layer of gray matter. 

contralateral: 

when each cerebral hemisphere receives sensory information from, and sends motor commands to the opposite side of the body