Glossary of 6. Gross Anatomy of the Brain and Spinal Cord

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How much cortex does the human brain have?
2.5 ft, but most of it is hidden in depths of sulci.
What is the relation of wt. and size of brain and a persons intelligence?
No relation. Intelligence is due to the complexity of conections in grey matter.
What part of the brain makes up most of the human brain?
Are all persons sulci and gyri the same?
No, there is individual variablity in the sulci and gyri
What are deep sulci called?
What is the size of the brain at birth?
Approx. 400grams, but the weight triples in the first 3 years.
What does a rat's brain look like, other than size, compared to a human brain?
Very smooth surface. Called lissencephalic
What is the size of the brain at age 18?
1400 grams, from ages 11-50, but can range any where from 1100 to 1700 grams.
What happens to the weight of the brain as we age?
After age 50, the weight of the brain begins to decrease.
What is the increase in size of the brain due to?
Myelination and growth of neuronal processes, also called dendritic arborization. There are not a lot of new neurons generated after birth.
1. Brain convolutions are called what?

2. What are these convolutions seperated by?
1. Gyri
2. Sulci
What do the convolutions in the brain increase?
Surface Area
How do convolutions vary from one brain to the next?
Many gyri and sulci are constant from brain to brain, but the PATTERN of convolutions can differ from brain to brain AND from hemisphere to hemisphere
What seperates the lobes of the brain?
Prominent SULCI
What does our text book author believe as far as how many lobes the brain has?
Nolte describes 5 lobes, and 1 cortical area that is not a true lobe.
What is the largest lobe in the brain? and just HOW large is it?
Frontal lobe, 1/3 of cortical surface area is here. (gray matter)
What are the boundaries for the frontal lobe?
Everything in front of the central sulcus.
What functions of the brain does the cortical surface have?
Consciousness, memory, creativity, higher level thinking skills, etc.
What are the four functional areas of the frontal lobe?
1. Primary motor cortex
2. Premotor cortex
3. Broca's Area
4. Prefrontal cortex
What is found in the primary motor cortex of the frontal lobe?
Descending motor pathways/tracts start here. Axons go thru the prosencephalon. Involved in the initiation of voluntary movements, motor activity.
Where is the primary motor cortex located specifically?
In the pre-central gyrus
Where is the premotor cortex located?
In the superior and middle frontal gyrus'.
What is the premotor cortex responsible for?
Also responsible for initiating voluntary movement.
Where is the Broca's Area located? (general) Name it's two specific areas.
In a triangular area within the frontal lobe. Has two parts: 1. Pars Opercular and 2. Pars Triangular
What is the Broca's area responsible for?
Production and expression of written and spoken language.
Where is the prefrontal cortex located?
In the area comprising the remainder of the frontal lobe. (all areas that are not taken)
What is the prefrontal cortex responsible for?
Complex thinking, personality, creativity, delayed gratification, imagination, ability to do good things for others, insight
What are the 3 functional areas of the parietal lobes?
1. Primary somatosensory cortex (sensory map of body)
2. Much of the inferior parietal lobule
3. The rest of the parietal lobe (superior parietal lobule and part of the inferior parietal lobule)
What is the primary somatosensory cortex responsible for?
"body sensation", proprioception, touch, pain, temperature, "feel"
What is "much of the inferior parietal lobule" responsible for?
Comprehension of language
What is a Homonculous Map?
When parts of the body surround the part of the brain that their function originates from.
What is the "rest of the parietal lobe (sup. parietal lobule and part of the inf. parietal lobule)" responsible for?
Spatial orientation and perception. (Identifying where you are on a map, getting from point A to B)
What are the three general functional areas of the temporal lobe?
1. Primary auditory cortex
2. Comprehension of Language (Wernicke's area is in both temporal and parietal lobes)
3. Hippocampus and parahippocampal gyrus
What is the primary auditory cortex responsible for?
Being able to discriminate sounds and put them together as words, music, etc. Understanding what words mean.
What are the hippocampus and parahippocampal gyrus responsible for?
Learning and memory
What is the occipital lobe associated with? and where is it located?
The visual system, visual assoication area. Located in the back of the brain.
Where is the limbic lobe located?
Part of it is in the frontal, parietal and temporal lobes.
What is the limic lobe responsible for?
Mediates emotions, drive-related behavior, memory, eating, fighting, processes emotions (anger, humor, satisfaction). Very difficult to measure and study
Where is the insula located?
An AREA (not a lobe) that is deep in the lateral fissure
What is the insula responsible for?
Not sure what it does, function unknown. Visual processing?
What ventricle is the diencephalon associated with?
The third ventricle
What are four structures that are a part of the diencephalon?
1. Thalamus
2. Hypothalamus
3. Epithalamus
4. Subthalamus
Where is the thalamus located and what is it responsible for?
Located on either side of the 3rd ventricle. Responsible for All sensory information, except olfaction (smell). Info. has to synapse in thalamus before it gets to the cortex, so this area is VERY important!! Senses are located here: see, touch, hear, etc.
What is the hypothalamus responsible for?
Vissceral/Endocrine control center, autonomic nervous system, mediates emotions and drives.
Where is the hypothalamus located?
Hypo = below, the thalamus
What structure is found in the epithalamus? What does this structure do?
A pine cone shaped Pineal gland, which produces and releases mela?
Where is the epithalamus?
"epi" means upon. Upon the thalamus
What is found in the subthalamus?
Part of the basal ganglia, which has motor functions
What passes through the brainstem?
Ascending and descending axons that go to and from the spinal cord and cerebral cortex. Basically, lots of axons pass thru here to get to somewhere else!
What three structures make up the brian stem?
Midbrain, pons and medulla
Most (blank) are found in the brainstem.
Cranial Nerves
What structure covers most of the posterior surface of the brainstem?
The cerebellum
What is another name (nickname) for the cerebellum
"Little brain"
How is the cerebellum attached to the brainstem?
Via cerebellar peduncles
What is the primary function of the cerebellum?
Motor function, helps with coordination and balance
What form spinal nerves?
Dorsal and ventral spinal roots
The spinal cord is the location of what kind of output?
What is located in the ventral horn of the spinal cord?
Cell bodies that innervate skeletal muscles throughout body. Autonomic preganglionic neurons
What test is related to the spinal cord?
Stretch reflex-spinal cord reflex
Describe the segmental organization of the spinal cord.
Segment is indiciated by spinal nerves
Why does the spinal cord not go all the way down to the sacrum? How does this relate to the segmental orgainization?
The vertebral bodies grow faster than the spinal cord, so the spinal cord ends about L2. The spinal nerves still exit out the appropriate vertebrae, because the dorsal and ventral spinal roots just get longer and longer in order to obliquely exit at the approriate site.
Where are there enlargements on the spinal column? Why are there enlargements here?
At the cervical and lumbar areas. These areas supply the upper and lower extremities and therefore contain increased numbers of motor neurons and interneurons, which require a larger area.
Where is it ok to do a spinal tap?
Below L2 and up to S2. No spinal cord there.
What is the conus medullaris?
The pointed, caudal end of the spinal cord.
What is the cauda equina?
"horse's tail" Collection of dorsal and ventral roots
What is the filum terminale?
An extension of the pial covering of the conus medullaris anchoring the caudal end of the cord to the end of the dural tube/sac.
Gray matter is divided into (blank) and white matter is divided into (blank)
Gray = horns
White = funiculi
Where is the ventral (anterior) median fissure located on the spinal cord? Describe.
On the anterior aspect of the spinal cord. Its a deep groove that extends almost to the center of the cord.
Describe where the dorsal median sulus is on the spinal cord.
Midline of the posterior aspect of the spinal cord. Lies between the fasciculus gracilis. Barely present, very shallow
Where is the ventrolateral (anterolateral) sulcus on the spinal cord?
It's where the ventral (anterior) rootlets LEAVE, on either side of the ventral median fissure. Poorly defined.
Where is the dorsolateral (posterolateral) sulcus on the spinal cord?
It's where the dorsal (posterior) rootlets ENTER. Just lateral to the fasciculus cuneatus. Shallow
Where is the dorsal (posterior) intermediate sulcus on the spinal cord?
Just lateral to the dorsal median sulcus, but only present in the cervical and upper thoracic levels. Seperates fasciculus cuneatus and fasciculs gracilis
What are denticulate ligaments?
Come off of pia mater, tooth-shaped. Btwn spinal nerves that anchor the spinal cord within the dural sac.
Is the epidural space in the spine real or potential?
What is attached to the inner surface of the dura?
Arachnoid mater
How many layers does the dura mater of the spine have? It is suspended in what structure in the spine?
Single layer, suspended in vertebral canal
Within a cross section of the spinal cord there are three funiculus (white matter). Name them.
Posterior, lateral and anterior funiculus.
The anterior/ventral horn of the spinal cord contains what?
Motor neurons
The posterior/dorsal horn of the spinal cord contains what?
Sensory neurons
What is the substantia gelatinosa?
A distinctive region of gray matter that caps the posterior horn. Sensory fibers carry pain and temperature info.
What is the body of the posterior horn contain?
Interneurons and projection neurons that transmit somatic and visceral sensory info.
What is in the intermediate gray matter of the spinal cord?
preganglionic autonomic neurons
What does the lateral horn contain and where is it located?
Contains preganglionic sympathetic neurons for the entire body which lie btwn segments T1 and L2. It is a pointy lateral extension to the intermediate gray area.
Where will these preganglionic sympathetic neurons synapse?
In the sympathetic chain
Where is the sacral parasympathetic preganglionic nucleus located?
Same general location as the lateral horn, except in segments S2 - S4
Where is Clarke's nucleus (nucleus dorsalis) located? and what does it do?
T1 - L2, right above the central canal. Relays information to the cerebellum for proprioception of skeletal muscles, especially legs
What is Rexed's Laminae?
A roman numeral system used to figure out where spinal cord lesion/injury is.
How many layers of neurons are in the Rexed's Laminae? and where do you begin to number?
10, begin from the dorsal horn of the spinal cord.
What numbers are located in the posterior horn? and what kinds of neurons are they?
I-VI (1-6) are sensory neurons
What are VII, VII, IX and X?
VII: Intermediate gray matter
VIII: Interneurons in anterior horn (don't leave spinal cord)
IX: motor neurons in anterior horn, form spinal nerves that innervate skeletal muscles
X: surrounds central canal, grey matter
What are the two sub divisions of the posterior funiculs?
Fasciculus gracilis and fasciculs cuneatus
What is the fasciculus proprius? What is in it and what is it's function?
It is the white matter closest to the gray matter. Has axons that project a few spinal levels. Only travel a short distance in spinal cord. Axons interconnect spinal cord segments, as motor activity requies a linkage of several spinal levels. Basically they allow for coordination within the spinal cord for motor movements.
What is the function of the anterior white commissure? and where is it located?
A thin zone of white matter below area X. It's where sensory information crosses from one side of the spinal cord to the other. Can cut here to block pain impulses.

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