Nervous System Flashcards
What constitutes the Brain Stem?
Mid brain, pons and medulla
What constitutes the Hindbrain?
Pons, Medulla and cerebellum
What is gray matter?
Dendrites and cell bodies
Its faster enlargement causes the cortical region to roll and fold upon itself
Receives and integrates incoming/outgoing information
What is white matter?
Bundle of Myelinated Axons of neurons
What is a gyrus?
Fold
Convolution
Gray matter (5-7mm variable thickness)
White matter underneath
What is a sulcus?
Shallow gap/groove between folds
What is the role of the cerebellum?
co-ordinates muscles/movement
What is the Transverse gyrus of Heschl?
Heschl’s gyrus
Located transverse on the temporal gyrus
Within the 1 Primary Auditory area
therefore Processes sound
What is the Primary Motor Cortex?
Voluntary movement - Each region controls voluntary contractions of specific muscles/groups of muscles on the opposite side of the body
down –>up (fingers eyes, vocalisation/head&neck (face=1/3))–> (fingers, head, arms) –> (thorax, abdomen, nipple) –> (leg thigh) –> foot
Muscles involved in skilled, complex or delicate movements required a greater number of brain cells to control that movement therefore they have more cortical area devoted to it.
Dominated by face, hands, forearms
Electrical stimulation at any point in the primary motor area cases the contraction of specific muscle fibres on the opposite side of the body
What is the Primary Somatosensory Cortex?
Conscious appreciation/perception of sensation -“touch, pressure, pain & temperature”
Located posterior to the central sulcus, in the post central gyrus of the parietal lobe
Each region receives nerve impulses from a specific part of the body (input from skin), and projects sensation out to the skin
Somatotopically organised according to the distorted body map of the sensory homunculus
Size devoted in cortical area which receives impulses depends on the number of receptors present (not the size of the body part)
Larger regions-lips, tongue, face, fingertips/hands - very discriminative and very precise
Highly discriminative - can pinpoint somatic sensations
What is the Primary Somatosensory cortex dominated by?
Lips, Tongue, Face, Fingertip/hands
highly discriminative and very precise
What is the Primary Visual Cortex?
Visuotopically organised (according to the map of the visual field) and Retinotopically organised (according to the map of the retina)
Highly acute
Central part of the visual field is: Discriminative, Upside down, Tip of the cortex
Peripheral=Deep part of the Cortex
Very discriminative sensation in the middle
Visual field on the right side goes to the opposite side of the brain
Brain flips the image
Right and Left side’s combine to give 3D panoramic vision
There is communication with the visual field on the opposite side, is a continuous representation in the brain
Supplementary visual field is involved with movement and colour, and adds quality
What is the overall functional role of the Forebrain?
CONSCIOUS appreciation
end points of different functions
What is the Primary Auditory Cortex?
Located superior part of the temporal lobe, near the Lateral Fissure
Receives information from sound, from the opposite ear
Involved in auditory perception
Transverse gyrus of heschl located 2.5cm deep into the lateral fissure, receives input from ear on opposite side
Tonotopically organised- according to frequency/pitch = Front=Low freq. and Back=High freq.
What is a stroke?
Characterised by an abrupt onset or persisting neurological symptoms such as :Paralysis or Loss of sensation
a. Intra-cerebral haemorrhage from blood vessels
b.blood clots
c. atherosclerosis –> formation of cholesterol-contianing plaques that block blood flow
Stroke on right side affected by opposite side of the brain
Risk factors: - High BP blood pressure, High blood Cholesterol, Diabetes, Smoking
How does a stroke affect the Primary Motor cortex?
Lesion would Paralyse muscle movement on the Opposite side of the body
the Particular muscle(s) paralysed would depend on Where on the 1 Primary motor cortex/motor homunculus the lesion occurs
How does a stroke affect the Primary Somatosensory cortex?
Lesion would result in Loss of Sensation on the opposite side if the body
The particular area with loss of sensation depends on Where on the mapping of the 1 Primary somatosensory cortex/according to the sensory homunculus
How does a stroke affect the Primary Auditory cortex?
A lesion would lead to a Loss of Hearing in the opposite ear
How does a stroke affect the Primary Visual cortex?
A lesion would result in a Loss of vision in the opposite eye
What are features of the Left Hemisphere?
Dominant side
Verbal language area/centres used to Talk
80-90% of people are Right handed
Hearing, Speaking, Reading, Writing
-to accumulate knowledge and expand societies
What are features of the Right Hemisphere?
Non Dominant side
Non-verbal language
LH= Some still have a dominant Left Hemisphere, Few other’s have it divided between the two hemispheres
1. Non-verbal language area (body language) (90% of communication)
2. Emotional expression (language) - modulation of speech
3. Spatial skills (3D) - shape of the object
4. Conceptual understanding
5. Artistic and Musical Skills - someone who can’t talk could sing
Large extent on right hemisphere but not entirely
What 5 things would a lesion on the Right hemisphere result in?
Injury to non-verbal language areas
Loss of Non-verbal (body) language
Speech lacks emotion
Spatial disorientation
Inability to recognise familiar objects
Lack of musical appreciation
What is the Frontal association cortex involved in
Intelligence, personality, mood, behaviour and cognitive function
What is the parietal association cortex involved in
Spatial skills, 3D recognition of shapes, faces, concepts and abstract perception
What is the temporal association cortex involved in
Memory, Mood, Aggression, intelligence
What is Broca’s area vs Wernickes area and which lobe are they located in. Left hemi vs right corresponding regions
Left hemisphere: Broca’s area in the pre motor area in the frontal lobe. This coordinates vocal muscles and breathing to speak. Wernickes area is in the superior temporal gyrus in the temporal lobe. It interprets the meaning of speech and recognises spoken word.
Right: Add emotional content to spoken word
What happens when Brocas vs Wernickes area is damaged
Brocas- non fluent aphasia: has clear thoughts but can’t coordinate muscles to speak.
Wernickes: fluent aphasia: can still speak but cannot arrange words in a coherent fashion.
What is the homunculus. The two types and the regions of the brain they are in
A homunculus is a “map” of the body with different amounts of cortical area on the gyrus corresponding to different parts of the body, with adjacent areas being adjacent parts on the body. Some areas are bigger than others based on the amount of receptors/ neurons in that area in the body- not the size of the part.
There is a homunculus in post central gyrus- somatosensory and in pre central gyrus for motor.
What is the structure and function of the visual sensory cortical area
Primary visual sensory area is right at the end of the occipital lobe at the bottom next to the longitudinal fissure. It receives visual information and orders it based on where it is in the field of vision
Visual association area: anterior of 1’, it uses info from thalamus and 1’ area to relate past and present visual experiences to recognise and evaluate what is seen, large area because more cells
What is the difference between primary and secondary (association areas)
Primary receives the information but Secondary interprets it- involved with recognising. Blind vs not recognising objects
What is the structure and function of the auditory sensory cortical area
1’ Auditory area is close to the lateral fissure in the superior temporal lobe and receives information for sound.
Auditory association area just beneath this helps you recognise sound as music, speech or noise.
What is the main difference between the dominant and non dominant hemisphere of the brains
Left has most of the functions. Both have a primary auditory cortex, and primary visual cortex
What is the purpose of the spinal cord
Send motor information from the CNS (brain) to the PNS (skin) and sensory information from the PNS to the CNS
How the 31 nerves in the spinal cord divided up top to bottom
8 pairs of cervical nerves, 12 pairs thoracic nerves matching the ribs, 5 pairs of lumbar nerves, 5 pairs of sacral nerves and 1 pair of coccygeal nerves.
What are the two enlargements on the spinal cord and why
Cervical enlargement- where all the sensory/ motor info for arms and hands are
Lumbar enlargement- where all the sensory/motor info for legs is.
Enlargement because they need more SA for more neurons
What is the cauda equina
The horses tail, roots of the lumbar, sacral and coccygeal nerves that spread out laterally
What is the conus medullaris
Cone shaped end of the spinal cord
What are dermatomes
They are segments of the body that provides sensory input to the CNS through one pair of spinal nerves. As these areas are mapped, and although there can be some overlap between areas, they can be used to determine if there is damage to specific parts of the spinal cord
What is the organisation of white matter and grey matter in the spinal cord and the orientation regarding anterior and posterior
White matter on the outside and grey matter butterfly in the middle The small wings of the butterfly are closest to the posterior
What are ‘nuclei’ in grey matter and the two types
clusters of neuronal cell bodies that form functional groups. Sensory nuclei receive input from sensory neurons and motor nuclei provide output to effector tissues via motor neurons.
Where do the cell bodies of incoming sensory neurons located in
the posterior (dorsal) root ganglion of the spinal nerve
Where does sensory information sent to the CNS (general afferent pathway) first enter at what root
Nerve impulses from the sensory receptor go along the axon which enters the spinal cord at the posterior (dorsal) root. The cell bodies are in the dorsal root ganglia. They can then go 3 possible pathways
What are the 3 possible pathways for sensory information to go from once it enters the spinal cord
- Axons can extend into the white matter of the spinal cord and ascend into the brain as part of the sensory tract.
- Axons of neurons may enter the posterior grey horn and synapse with interneurons whose axons extend into the white matter of the spinal cord.
- Axons of neurons may enter the posterior grey horn and synapse with interneurons that in turn synapse with somatic motor neurons involved in spinal reflex pathways
What is the difference between the first order neurons that carry touch/pressure and pain/temperature sensation
Pain and temperature is carried by unmyelinated neurons with free nerve endings.
Touch and pressure are carried by myelinated pseudounipolar neurons with encapsulated nerve endings
The capsule of the nerve ending determines what type of information a nerve will respond to. What are the names of the different capsules for touch and pressure
touch: Meisners corpuscles, Pressure is pacinian corpuscle.
Define sensation vs perception
The conscious or subconscious awareness of changes in the external or internal environments. Perception of sensation only happens when impulses reach the cerebral cortex.
What are the four kind steps that lead to sensation being felt
Stimulation of the sensory receptor
Energy of Stimulus converted to graded potential (transduction)
Generation of nerve impulse that go to CNS
Integration of sensory input in the cerebral cortex which leads to perception.
What are three main layers of the protective structures for the spinal cord and brain (CNS)
The outer skull/ vetebral column made of bone
The three connective tissue layers of the meninges
The cerebrospinal fluid/ fat and connective tissue in the space between two of the meningeal membranes
What is the order of the 3 spinal meningeal membranes from outside to inside
Dura mater, Arachnoid mater and Pia mater.
Describe the dura mater. What is it continuous with
Thick strong layer of dense irregular connective tissue. It forms a sac form the foramen magnum in brain to sacral vertebra 2. It is continuous with the meningeal dura mater of the brain and epineurium
