NSB 2. Structure of the Central Nervous System Flashcards
What is the frontal lobe associated with?
personality
What is the temporal lobe associated with and important for?
hearing
What is the occipital lobe associated with and important for?
visual cortex
What is the cerebellum important for? What is transient cerebellar disease?
- important for movement + coordination
Transient Cerebellar Disease:
- when cerebellum not working, it’s like you are drunk
- motor activity is impaired
What are the 3 main parts of the brain?
[1] Cerebrum
[2] Brainstem
[3] Cerebellum
What are the cortexes present in the frontal lobe?
[1] Motor Cortex
- somatic motor association area
[2] Gustatory Cortex
[3] Olfactory Cortex
What are the cortexes present in the temporal lobe?
[1] Auditory Cortex
(a) Primary Auditory Cortex
(b) Auditory Association Area
What is the cortex present in the parietal lobe?
Somatic Sensory Association Area
What are the cortexes present in the occipital lobe?
[1] Primary Visual Cortex
[2] Visual Association Area
What does the Central Sulcus separate?
it separates the motor cortex and somatosensory cortex
Where do the sensory neurons going to the somatosensory cortex end?
they end in the POST-central gyrus
Where do the motor neurons going to the motor cortex end?
they end in the PRE-central gyrus
What are the 2 neurons involved in the motor neurons going to the motor cortex?
[1] Upper Neuron
- from brain down to spinal cord
[2] Lower Neuron
- from spinal cord down to muscle/tissue
Where do the Upper Motor Neurons start and go through? Where do they end?
- starts in the cerebral motor cortex (pre-central gyrus)
- they pass through the pyramids of the medulla
- goes to the brainstem/spinal cord
Where do the Lower Motor Neurons start and go through? Where do they end?
- comes from the brainstem cranial nerve motor nucleus
- goes from spinal cord to muscle
What is the pyramidal motor system?
- it consists of the upper and lower motor neurons
- it is responsible for PLANNED MOVEMENT
- needs fine tuning though
What is the pyramidal motor system responsible for?
responsible for planned movement
- needs fine tuning though
Outline the steps/mechanism behind the Pyramidal System?
- the upper motor neuron starts in the cerebral cortex (pre-central gyrus)
- they pass through the pyramids of the medulla
- conscious movement
Outline the steps/mechanism behind the Extrapyramidal System?
- the upper motor neurons starts in other brain center nuclei (e.g. basal ganglia)
- do NOT pass through the pyramids of the medulla
- it fine tunes movement
- involuntary actions
What is the medulla? What does it consist of?
- the lower part of the brain stem
Consists of:
[1] Olives
[2] Pyramids
What is the putamen?
a round structure located at the base of the forebrain
What structures are part of the extrapyramidal system?
[1] Cerebellum
[2] Basal Ganglia
What is the cerebellum? What is its function in relation to the extrapyramidal system? What impairs this system?
- cerebellum is responsible for balance, tone + posture and coordination + planning movement
- impaired by alcohol intoxication
- this leads to intention tremor
What is the basal ganglia? What is its function in relation to the extrapyramidal system? What impairs this system?
- a diffuse set of nuclei (nucleus accumbens, caudate, putamen, globus pallidus, subthalamic nucleus, substantia nigra)
- responsible for allowing/stopping movements to happen as well as other functions
- impaired in cases of Parkinson’s Disease
- this leads to resting tremor
What type of tremor may arise if the cerebellum is impaired?
- intention tremor
- from alcohol intoxication
What type of tremor may arise if the basal ganglia is impaired?
- resting tremor
- e.g. Parkinson’s Disease
What is the function of the thalamus?
- all general sensory info goes through the thalamus
- known as the sensory relay station in the brain
- located on either side of the 3rd ventricle
Where is the Internal Capsule located?
- white matter structure
- separates caudate nucleus, + thalamus from putamen and globus pallidus
- carries info past the basal ganglia
What are the 2 sensation types (neurons) and their sensory pathways? [mentioned in lecture]
[1] Touch/Proprioception
- signals transferred up through Dorsal Columns
- decussates in the medulla (crosses over)
[2] Pain + Temperature
- signals transferred up through the Spinothalamic Tract
- decussates immediately
What neurons do signals from touch/proprioception go up from?
Dorsal Columns
- decussates in medulla
What neurons do signals from pain + temperature go up from?
Spinothalamic Tract
- decussates immediately
What is the body representation on the motor and sensory cortices -homunculus?
- the brain is associated with with different parts of the body
- not a lot of the brain is associated with the back
- a lot of the brain is associated with the hands and face
- LOOK AT IMAGES
What is the main part of the brain that allows for homeostasis based on internal inputs?
hypothalamus
What is the limbic system made up of?
DEEP IN TEMPORAL LOBE
- amygdala
- hippocampus
- thalamus
- hypothalamus
- basal ganglia
- cingulate gyrus
What is the function of the limbic system/limbic lobe?
“societal homeostasis”
- based on external inputs at a basic/survival level
- involved in emotional aspects of behaviour and memory
Explain the ventricular system of the brain.
- there are Lateral Ventricles (1st and 2nd) filled with CSF
- CSF flows from the lateral ventricle through the Interventricular Foramen of Monro to third ventricle
- 3rd ventricle is in the cavity of Diencephalon
- the 4th ventricle is located in the pons
What does the Interventricular Foramen of Monro do?
it connects the 1st and 2nd ventricle to the 3rd ventricle
What does the Aqueduct of Midbrain do?
it connects the 3rd ventricle to the 4th ventricle
Explain the flow of the cerebral spinal fluid (CSF) in the brain.
[1] CSF from lateral ventricles enter 3rd ventricle through Foramen of Munro
[2] CSF flows from Foramen of Munro to 3rd ventricle
[3] CSF flows from 3rd ventricle to 4th ventricle through the Cerebal Aqueduct (of Sylvius)
[4] CSF from 4th ventricle enters subarachnoid space through:
(a) Foramina of Magendie (posteriorly)
(b) Foramina of Lushka (laterally)
What is the main difference between an adult and a child’s brain?
- a child’s brain has multiple parts (e.g. anterior and posterior fontanelle)
- there are sutures between the parts of the child’s skull
- in adults, the parts of the skull are all fused together
What is hydrocephalus?
- usually occurs in children
- due to an increase in CSF in the skull
- since the skul hasn’t been merged together, the skull expands
- in adults, if there is an icnrease in CSF, this leads to an increase in pressure
- the skull cannot expand because everything is already fused
What is cranial nerve 1 related with?
smell
- olfactory bulb (I)
What is cranial nerve 2 related with?
vision
- optic nerve (II)
What is cranial nerve 3, 4 and 6 related with?
eye movement
- oculomotor nerve (III)
- trochlear nerve (IV)
- abducens nerve (VI)
What is cranial nerve 5 related with?
facial and scalp sensation, mandibular movements
- trigeminal nerve (V)
What is cranial nerve 7 related with?
facial expression
- facial nerve (VII)
What is cranial nerve 8 related with?
hearing + balance
- vestibulocochlear nerve (VIII)
What is cranial nerve 9 and 10 related with?
swallowing + phonation
- glossopharyngeal nerve (IX)
- vagus nerve (X)
What is cranial nerve 11 related with?
neck and head movement
- accessory nerve (XI)
What is tongue cranial nerve 12 related with?
tongue movement
- hypoglossal nerve (XII)
How can you test the XI cranial nerve?
- related with neck and head movements
- test it by shrugging shoulders (it supplies the trapezius)
Where does the spinal cord end?
L1 (sometimes L2)
How many cranial nerves are there?
8
How many thoracic nerves are there?
12
How many lumbar nerves are there?
5
How many sacral nerves are there?
8
What is Cauda Equina?
- means “horse tail”
- after the end of the spinal cord, the nerves start flowing downwards (looks like a pony tail)
What is the anterior horn?
the motor neurons come off of the anterior horn
What is the posterior horn?
the sensory neurons enter the posterior horn
Does the spinal cord have a subdural space?
NO
- it only has dura mater and arachnoid mater
- the dura and arachnoid are stuck together
What does the Cauda Equina activate/supply?
- bladder
- bowel
- sexual organs
- legs
What is Cauda Equina Syndrome?
- a condition that occurs when the cauda equina is compressed/damaged
- can lead to lower back pain, pain that radiates down leg, loss of bowel + bladder control
What are causes of Cauda Equina Syndrome?
- back/spine problems such as a slipped disc
- tumours near the spine
- injuries/trauma
What are the 5 red flags of Cauda Equina Syndrome?
[1] Saddle Anaesthesia
- weakness/tingling/numbness in “saddle” region (parts of body that would touch the saddle if you were sitting on a horse
- upper inner thighs, groin, buttocks and genitals
[2] Pain
- pain, weakness, tingling or numbness in your lower back, backs of thighs, lower legs + feet
[3] Incontinence
- loss of control, urgency or finding it hard to urinate/defecate (or any strange sensation or numbness along with it)
[4] Numbness
- numbness in lower back, backs of thighs, lower legs and feet
- loss of feeling around your groin during sex
[5] Emergency
- any of these can be a warning sign of CES
- go to emergency department!
Why is it important to treat Cauda Equina Syndrome quickly?
because delay can equal disability