CNS Flashcards
what is the PNS composed of ?
Nerves (cranial and spinal) and ganglia outside brain and spinal cord
What are the 3 components you can split the brain into?
Forebrain, midbrain, hindbrain
What can you split the forebrain into?
Cerebral Hemispheres and Diencephalon
what does the hindbrain consist of?
Pons, medulla, cerebellum
what does the diencepholon consist of?
Thalamus, hyperthalamus,
what are the different lobes associated with?
Frontal- motor function, language, cognitive e.g.planning , attention and memory
Parietal-Sensation, sensory aspects of language, spatial orientation and self perception
Occipital- vision
Temporal-auditory
What does the limbic lobe consist of? What is it associated with?
Amygdala, hippocampus, mamillary body, cingulate gyrus Learning, memory, emotion, motivation and reward
what cortex is deep within the lateral fissure? What is it concerned with?
Insular cortex visceral sensations, autonomic control, interoception (awareness about if inside of your body is working properly), auditory processing, visual vestibular integration(concerned with balance and coordination)
what are the 3 layers of the meninges?
Dura- peristeal - meningeal
Arachnoid (fibrous and thin)
Pia (meshlike and thin) (cerebral cortex underneath the pia)mater)
what is a vertical cross section of the brain called?
Mid sagital view
Where in the brain does the cerebrospinal fluid occupy?
Ventricular system and then sub arachnoid space
Where is the cerebro-spinal fluid produced in the brain?
produced in modified epithelial cells called the choroid plexus of lateral 3rd and 4th ventricles of the brain
where is the cerebro-spinal fluid reabsorbed?
via arachnoid villi(granulations) into the superior sagittal sinus
what is the difference between the makeup of the CSF vs Plasma?
CSF = lower pH. less glucose, less protein, less potassium, same sodium conc
What does blood and high protein in the CSF indicate?
blood= internal bleeding Protein= some sort of disease or disorder as there is a barely any protein in the CSF usually
what extends from the spinal cord grey matter?
dorsal rootlets which form doral root at the back of the spinal cord Ventral rootlets which form ventral roots at the front of the spinal cord
what is grey matter of the spinal cord split into
2 main parts- dorsal horn and ventral horn
what information is conveyed by the ventral root and dorsal root?
Dorsal- sensory and afferent Ventral- motor and efferent
what is the mixed spinal nerve?
has afferent an efferent signals, as the dorsal and ventral root are still joined together
what is the dorsal root ganglian?
swelling of dorsal root as it contains cell bodies for sensory nerves
what is the posterior ramus?
comes off of the mixed spinal nerve
consists of a mixture of afferent and efferent nerves.
Communicates with muscle and skin at the BACK of spine
mixed spinal nerve communicates with the rest of the body as it is a bigger branch
what is the spinal cord made of?
What comes out of the spinal cord?
segments which all give rise to corresponding PAIRS of spinal nerves
there are also corresponding bones to the nerves but these can be in different places to the segments and nerves
what are the segments of the spinal cord and how many pairs of each corresponding nerves are there?
Cervical-8 Thoracic-12 Lumbar-5 Sacral-5 Coccygeal-1 (31 total)
What would we mean if we said there was a lesion at T11?
It would depend on the discipline you are e.g. spinal surgeon or neurologist. If a spoonal surgeon said it they would be referring to the bones(vertebrates) of the spinal cord, implying that nothing below T11 (Thoracic vertebrate 11) is working. Whereas the neurologist would be referring to the spinal segment implying that nothing below Thoracic segment 11 is working
How does the relationship between nerve and its vertebrae change as you go down the spinal cord?
Nerves C1-C7 emerge ABOVE the vertebrae. Nerves Below that the nerves come out below there corresponding vertebrae
Where do nerves emerge from in the spinal cord?
Intervertebral foramina (between 2 verebrates i.e. bones)
What vertebrae does the nerve pair C3 and T12 emerge from?
C3 from inbeetween vertebrae C2 and C3. T12 from inbetween the vertebrae T12 and T13
Where are enlargements on the spinal cord?
Cervical enlargement (c5)- at the top of cord - due too huge amounts of nerve innervation in the limbs Lumbar enlargement (L2) - due to large amounts of innervation in lower limbs
What is the major pathway for voluntary movement?
corticospinal tract
What is the corticospinal tract composed of?
2 neurones: upper motor neuron in the primary motor cortex and lower motor neuron in the brain stem/spinal cord
What are the main sensory pathways ?
Dorsal column pathway- fine touch, vibration and proprioception
Spinothalamic pathway- for pain, temeperture (and crude touch) from the skin
Name the tracts of the spinal cord?
2 descending tracts(motor) of each type- Lateral corticospinal tract, ventral corticospinal tract 2 ascending tracts of each type (Sensory)- Dorsal columns(fine touch, proprioception, vibration),lateral spinothalamic tract (Pain temperature), ventral spinothalamic tract (crude touch)
What is the central sulcus? What is on either side of it
longitudinal fissure along brain with Pre central gyrus and Post central gyrus on either side
What occupies the pre central gyrus?
Primary motor cortex
What is somatotopy?
Ponit for point correspondence of an area of the body to a specific point on the brain. Typically corresponds with the primary somatosensory cortex(post central gyrus)
where do fibres from the motor cortex go in the corticospinal tract?
85% cross to the other side of the body (DECUSSATES) in the medulla to innervate limbs. Fibres that stay on the same side innervate mostly trunk muscles
what is the corticobulbar tract?
2 neurone MOTOR pathway that unites the MOTOR CORTEX in the cerebral cortex with the cranial nerve nuclei in the brainstem
where does the corticospinal cord travel?
travels through the posterior limb of the internal capsule
How else can somatotopy be applied?
as fibres descend, viewed as horizontal cross section of the brain.
What are the names of 4 involuntary motor tracts?
Vestibulospinal - provides information about head movement and position and mediates postural adjustments Tectospinal - orientation of the head and neck during eye movements Reticulospinal - control of breathing and emotional motor function Rubrospinal - innervate lower motor neurons of the upper limb
What are the 2 principal ascending pathways?
Dorsal(posterior) column pathway: Mechanical- fine touch, pressure, vibration, proprioception Spinothalamic pathway: mecanical, chemical and thermal-crude touch, pain, temperature
What are the 2 corticospinal tracts and what do they innervate?
Lateral (where neuron from motor cortex crosses)-innervates limbs Anterior (where neuron from the motor cortex does not cross)-innervates the Axial muscles e.g. trunk
What are the Major descending pathways?
Corticospinal tract - goes from motor cortex ->brainstem-> limbs/trunk Corticobulbar tract- goes from motor cortex->brainstem ->Muscles in face/ muscles of mastication Both are motor pathways
How many neurons are involved in the corticobulbar tract?
2- one from the cortex to the brainstem - one from the brainstem to face
Where can the 2nd fibre in the corticobulbar tract emerge from and which muscles do these innervate?
Oculomotor nucleus-extraocular muscles
Trochlear nucleus -extraocular muscles
Trigeminal nucleus- Muscles of mastication
Abduchens nucleus-Extraocular muscles
Facial Nucleus -muscles of facial expression
Hypoglossal Nucleus -Muscles of the tongue
What are the 2 principal ascending pathways?
Dorsal(posterior column)- occupies the back of the spinal cord and convey info about: touch pressure, vibration, proprioception Spinothalamic pathway- conveys info about pain, temperature and crude touch
What are the 2 spinothalamic tracts and what information do they convey?
Lateral -pain and temperature Anterior-Crude touch
What are the 2 dorsal tracts?
Gracile tract Cuneate tract
How many neurons make up both dorsal column pathways?
3
Describe the Dorsal column Gracile pathway?
1- 1st neuron cell body is in the DORSAL ROOT as this is a sensory pathway- it ascend IPSILATERALLY to the medulla along the gracile tract carrying info from the lower limbs and body (below T6)
2- First synapse is in the Gracile nucleus which is in the MEDULLA
3-The second neuron crosses to the other side of the body at this point and goes up to the THALUMUS
4- 3rd neuron goes from the thalamus to the SOMATOSENSORY cortex
Describe the Dorsal column Cuneate patrhway?
1- 1st neuron cell body is in the DORSAL ROOT as this is a sensory pathway- it ascend IPSILATERALLY to the medulla along the cuneate tract carrying info from the upper limbs and body (above T6)
2- First synapse is in the Cuneate nucleus which is in the close part of the MEDULLA, (lateral to the gracile nucleus and medial to the spinal trigeminal nucleus in the medulla)
3-The second neuron crosses to the other side of the body at this point and goes up to the THALUMUS
4- 3rd neuron goes from the thalamus to the SOMATOSENSORY
What is the size of the somnatosensory areas in the brain proportional to?
The density of sensory neurons in that region of the body
Describe the Spinothalamic Pathway?
1- Primary cell body In the Dorsal root Ganglian 2-Secondary cell body in the SPINAL CORD and crosses here to the other side of the body to enter either the lateral or anterior tract and then terminates in the Thalamus 3- 3rd neuron cell body is in the thalamus
