The Central Nervous System Flashcards
What joint are all the bones in the skull, besides the mandible, joined by?
Sutures
What are meninges? And name them (3)
Are three layers that surround the brain.
1. Dura Mater
2. Arachnoid Mater
3. Pia Mater (inner most layer)
What does the cerebral spinal fluid do? and where is it produced?
It suspends the brain in fluid to protect it.
It continuously circulates around the brain and spinal cord in the subarachnoid space.
Produced in the choroid plexus- a network of blood vessels in each ventricle of the brain
What are the sulcus and gyrus on the brain? What do these help to do?
Sulcus are the grooves
Gyrus are the bumps
The brain is uneven and this helps to increase the surface area
Types of matter in the brain (2)
White matter
Grey matter
White matter in brain- What does it do?found? myelinated? What info does it interpret?
- Deals with communication
- Found in the deeper tissues of the brain
- Surrounded by myelin, which gives the white colour
- Interprets sensory information from various parts of the body
Grey matter of the brain- What does it do?found? myelinated? What info does it interpret/
- Deals with processing
- Found in more superficial tissues of the brain
- Not surrounded by myelin
- Conducts, processes and sends information to various parts of the body
Cerebellum - Function? (3)
- Coordination- of complex skeletal contractions
- Motor learning
- Error corrects
Occipital lobe (2 areas) what is the main function?
Main function- to control vision
1. Primary visual area- receives visual info
2. Visual association area- Evaluates what is seen
Pons (1 part of brain stem) - Function? What does it contain?
-Contains sensory and motor pathways
-Helps control breathing along with the medulla
-Pontine nuclei relay information from motor areas to cerebellum
Temporal lobe- Main function? What are the 5 areas?
Processing auditory information and the encoding of memory
1. Primary auditory- receives auditory info
2. Auditory association- recognises particular sounds as speech, noise or music
3. Primary olfactory- receives info about smells
4. Facial recognition- Recognition of faces. More dominant on right
5. Wernicke’s- recognises and interprets speech
Frontal lobe- Main function? What are the 5 areas?
Main function- Motor output
1. Primary motor- in pre-central gyrus: each region in this area controls specific muscles/movements
2. Broca’s speech- production of speech
3. Pre-frontal cortex- personality, intellect, mood
4. Pre- motor- Learns and stores movement patterns
5. Orbito-frontal cortex- Identify and differentia odours
Parietal lobe- Main function? 3 areas?
Main function- sensory perception and integration
1. Primary somatosensory- in post central gyrus: Receives and perceives sensory info
2. Somatosensory association- Object recognition via touch alone
3. Common integrative- received info from other parts of the brain
Medulla oblongata (1 part of brain stem) Functions? (4)
- Contains sensory and motor nerve pathways
- Cardiovascular centre regulates heart rate and blood pressure
- Respiratory centre regulates breathing
- Coordinates vomiting, swallowing, sneezing etc..
Mid brain- (1 part of brain stem)- Functions? (3)
-Contains sensory and motor tracts
-Coordinates head, eye and trunk movements in response to visual or auditory stimuli
-Contain substantia nigra which extend to basal nuclei and control
subconscious movements
What are the two types of nervous tissue?
- Neurons
- Neuroglia
Neurons- what do they do? What 3 parts do neurons contain?
-Electrically excitable
-Respond to stimuli and converts that into an action potential
-Cell body, dendrites and axon
What is a collection of cell bodies outside the CNS called?
Ganglion or nuclei
Neurons can be classified by the number of projections extending from the body. What are the 3 structurally different cells?
Multipolar- Single axon, many dendrites
Bipolar- have an axon and one dendrite extending from the cell body toward opposite poles.
Unipolar- have one axon, with the cell body located to the side
Neurons can be classified by function- according to the direction in which the nerve impulses travel. What are the three differently functioned neurons?
Sensory- receptors at dendrites. most unipolar
Motor neurons- convey impulses away from the CNS to effectors. Most multipolar
Interneurons- Located in CNS mainly between sensory and motor neurons. Process and create a motor response. Multipolar
Neuroglia- What are they? What do they do? What are the 6 types?
- They are supporting cells and create and maintain the environment for neurons
- They do not create action potentials
4 in the CNS- astrocytes, oliodendrocytes, microglia and ependymal
2 in PNS- Schwann cells, satellite cells
Astrocytes- Neuroglia of CNS
-Most numerous
-They maintain appropriate chemical environment for nerve impulses
Oligodendroctyes- neuroglia of CNS
-Form and maintain myelin sheath around CNS axons
Microglia- neuroglia of CNS
-Function as phagocytes
-Remove cellular debris
Ependymal- neuroglia of CNS
-Have cilia and microvilli
-Assist in circulation of cerebrospinal fluid
Schwann cells- neuroglia of PNS
-Form myelin sheaths around axons
-Assist with axon regeneration
Satellite cells- neuroglia of PNS
-flat cells which surround ganglia in PNS
-Provide structure for support
The Autonomic NS (4)
-Division of PNS
-Divides into sympathetic, parasympathetic, enteric
-Responsible for involuntary control of our systems e.g digestion, urination, heart rate
-Innervates smooth muscle, cardiac muscle and glands
Parasympathetic NS- fibres, long/short fibres, ganglia location, funcitons, neurotransmitter?
-Fibres arise from brain and sacral spinal cord
-Long pre-ganglionic and short post ganglionic fibres
-Located in the visceral effector organ
-Maintenance functions and storage of energy
-Acetylcholine
Sympathetic- fibres, long/short fibres, ganglia location, functions, neurotransmitter?
-Fibres arise in preganglionic neurons in the spinal cord segments T1-L2
-Short pre-ganglionic and long post ganglionic fibres
-Located close to the spinal cord
-Prepares body for emergency situations and high levels of muscle acitvity
-Acetylcholine, noradrenaline, adrenaline
Enteric NS- what does it control? Can it control this independently?
-Gastrointestinal tract activity
-Communicates with the brain via the Gut brain axis and vagus nerve
What is cerebral blood flow?
The movement of blood through a network of arteries and veins supplying the brain
Anterior circulation of the brain- which arteries, what is supplied?
-Interior carotid artery supplies the anterior cerebral artery and middle cerebral artery.
-Supplied the frontal lobe, parietal lobe, temporal lobe
Posterior circulation- which arteries, what is supplied?
-Vertebral arteries divide into the basilar artery and posterior circulation artery
-Supplied the occipital lobe, cerebellum and brain stem
Venous drainage of the brain- what is the superficial system? what is the deep system?
Superficial- venous sinuses (at the bottom of the brain) which drain into the jugular veins then into the superior vena cava
Deep- join behind the mid brain into the sagittal sinus to join the superficial venous drainage system- then into the jugular vein and into superior vena cava
What is the blood brain barrier? (3)
- A selectively permeable membrane regulated the passage of a multitude of large and small molecules into the microenvironment of the neurons- achieved by cellular transport channels
-There are tight junctions between epithelial cells that line the blood vessels
-Prevents toxins and pathogens from entering the brain
What are the 12 cranial nerves?
- Olfactory nerve
- Optic nerve
(both originate from cerebrum) - Oculomotor
- Trochlear
- Trigeminal
- Abducens
- Facial
- Vestibulocochlear
- Glossopharyngeal
- Hypoglossal
- Vagus
- Accessory
What protects the spinal cord? (4)
Vertebral column, vertebral ligaments, meninges, cerebrospinal fluid
Where does the cord extend from and to?
From the medulla in the brain stem to L1 conus then forms the cauda equina
What is the function of the spinal cord?
Relays electrical impulses from the CNS to the spinal nerves via the cord.
These messages then travel to the peripheral nerves
Ventral root (motor route)- the route
Brain- white matter (in those tracts) - grey matter- PNS - muscles/glands/organs
Afferent information- route
relayed back through sensory nerves through the dorsal spinal nerves in grey matter and jumps into white matter (contain tracts)
What is the Cauda Equina?
Part of the cord where the cord termintes at the conus medullaris at L1
How many spinal nerve roots are there from the conus?
10 pairs- which start from conus and go down
Function of the Cauda Equina?
Send and receive messages between the lower limbs and the pelvic organs, which consist of the bladder, the rectum, and the internal genital organs.
What are meninges? What are the 3 layers?
Are 3 protective, connective tissue coverings that encircle the spinal cord and brain
1. Dura Mater
2. Arachnoid Mater
3. Pia Mater
Facts about the meninges
- Dura Mater= most superficial
-thick, strong layer of dense irregular connective tissue - Arachnoid Mater= middle
-thin, avascular covering comprised of cells and thin, loosely arranged collagen and elastic fibres - Pia Mater= most deep
- thin transparent connective tissue layer
- Adheres to the surface of the spinal cord and brain
What does the subarachnoid space contain?
Cerebrospinal fluid
Circle of Willis- what is it? what does it supply? What is the circle of willis fed by? Draw it
-A circle of arteries
-Supplies the brain
-Fed in by the vertebral arteries and the carotid arteries
Where does the circle of willis sit?
Subarachnoid space
Function of Circle of Willis? (2)
-Provide collateral blood flow between the anterior and posterior circulations of the brain
-Prevents ischemia- condition in whihc the blood flow is restricted or reduced
Cerebrospinal fluid- what is it? where is it made? function?
-A clear fluid that around the subrachnoid space of the brain and spinal cord
-Made in the choroid process in the ventricles of the brain
- Support and shock absorbs
What are tracts? Two types of tracts? What are they made up of? What happens when tracts cross over?
-Pathways that carry information up and down the cord
1. Descending tracts carry motor information to the skeletal muscles
2. Ascending tracts carry sensory information back to the brain
-Made up of neuronal axons that gather together in long columns
-Tracts crossing over is the reason why the right side of the brain controls the left and vice versa
Ascending tracts (5)
- Gracile fasciculus= proprioception, fine touch, vibration of upper limbs
- Cuneate fasciculus= proprioception, fine touch, vibration of lower limbs
- Spinocerebellar= proprioception in joints and muscles
- Spinothalamic= lateral- pain and temp
anterior-pressure and crude touch - Spino-olivary= voluntary, skilled motor activities
Descending tracts (5)
- Rubrospinal= fine motor control of upper limbs
- Reticular spinal= postural control (trunk and lower limbs), preparing movements
- Vestibulospinal= inhibition of flexor and promotion of extensor muscles activity
- Corticospinal tract= primary motor activity
- Tectospinal tract= reflex activity of head, eyes and trunk in response to stimuli
Spinothalamic tract - ascending pathway. Rresponsible for? What 4 tracts is it composed of?
-responsible for transmission of pain, temp and crude touch to the somatosensory region of the thalamus
-Composed of 4 tracts
1. Anterior spinothalamic tract
2. Lateral spinothalamic tract
3. Spinoreticular tract
4. Spinotectal tract
Posterior (dorsal) column- what does it convey? What is the pathway?
-Conveys sensation of fine touch, vibration and pressure
-Receptors for touch, proprioception, prressure etc head into spinal cord towars medulla
- Cell bodies of these first-order nerurons are in the DRG.
- In the spinal cord their axons form dorsal columns either cuneate fasciculus (upper body) or gracile fasciculus (lower body).
- First order neurons synapse with second order neurons whose cell bodies are in cuneate nucleus or gracile nucleus of the medulla
- Axons of second-order neurons cross to opposite side of medulla entering medial lemniscus
- They enter ventral posterior nucleus of thalamus and third order neurons project axons to primary somatosensory area
Nerve roots. how many pairs? what do they do? what do they become? what do they communicate with?
-31 pairs arise from the cord at each vertebral level
-Carry info from the cord to the PNS
-they pass through the dura to become a spinal nerve- considered a mixed nerve
-mixed nerve communicated with either anterior or posterior structures and then branches into a plexus
Anterior (ventral) root
Carries motor info to the periphery and comes out of the front of the spinal cord
Posterior (dorsal) root
Carries sensory info to the brain and comes out of the back of the cord
DRG’s- Dorsal route ganglion- what are they? where are they found? Structure?
-They are a cluster of peripheral nerve cells which gather sensory input from thermoreceptors, nociceptors, proprioceptors and chemoreceptors and relay it to neurons in the spinal column
-Found on the dorsal sensory spinal nerve
-They have an axon that has two branches
What are myotomes?
A group of muscles innervated by a single spinal nerve
What are dermatomes?
An area of skin innervated by a single spinal nerve
What movement occurs at L2 myotome level?
Hip flexion, illio-psoas
What movement occurs at L3 myotome level?
Knee extension, Quadriceps
What movement occurs at L4 myotome level?
Ankle dorsiflexion, Tibilalis anterior
What movement occurs at L5 myotome level?
Big toe extension/hip extension, Extensor hallucis
longus/ Gluteus
maximus
What movement occurs at S1 myotome level?
Ankle eversion
What movement occurs at S2 myotome level?
Knee flexion, Peroneus longus
and brevis
What movement occurs at C5 myotome level?
Shoulder abduction, Deltoid
What movement occurs at C6 myotome level?
Elbow flexion, Biceps brachii, brachialis
What movement occurs at C7 myotome level?
Elbow extension, Triceps brachii
What movement occurs at C8 myotome level?
Thumb extension, Extensor pollicis longus
What movement occurs at T1 myotome level?
Finger abduction/adduction, Interossei/Lumbricals
What movement occurs at C1 myotome level?
Neck flexion
What movement occurs at C2 myotome level?
Neck extension
What movement occurs at C3 myotome level?
Neck side flexion
What movement occurs at C4 myotome level?
Shoulder elevation, Upper trapezius
Levator scapulae
What is the spinothalamic pathway route?
- Nerve impulses for pain, temperature, pressure and crude touch from limbs, trunk, neck and head ascend to the thalamus
- First- order neurons connect receptors with spinal cord
- Cell bodies of these first order neurons are in DRG
- These neurons synapse with second order neurons, whose cell bodies are located in the dorsal grey horn of spinal cord
- Axons of second order neurons cross over to opposite side of cord
- They pass up spinothalamic tract to brain stem
- Second order neurons end in ventral posterior nucleus of thalamus, synapsing with third order neurons
- These project axons into primary somatosensory area on the same side of the cerebral cortex as the thalamus
What dermatome does C2 cover?
Temple, forehead, occiput
What dermatome does C3 cover?
Entire neck
What dermatome does C4 cover?
Shoulder area, clavicle area
What dermatome does C5 cover?
Deltoid area, anterior aspect of entire arm to base of thumb
What dermatome does C6 cover?
Anterior arm, radial side of hand to thumb and index finger
What dermatome does C7 cover?
Lateral arm, forearm to index, long and ring fingers
What dermatome does C8 cover?
Medial arm, forearm to long, ring and little fingers
What dermatome does T1 cover?
Medial side of forearm to base of little finger
What dermatome does T2 cover?
Medial side of upper arm to medial elbow, pectoral area
What dermatome does T3-6 cover?
Upper thorax
What dermatome does T5-7 cover?
Costal margin
What dermatome does T8-12 cover?
Abdomen and lumbar region
What dermatome does L1 cover?
Back, over trochanter and groin
What dermatome does L2 cover?
Back, front of thigh to knee
What dermatome does L3 cover?
Back, upper buttock, anterior thigh and knee, and medial lower leg
What dermatome does L4 cover?
Medial buttock, lateral thigh, medial leg, dorsum of foot, big toe
What dermatome does L5 cover?
Buttock, posterior and lateral thigh, lateral aspect of leg, dorsal foot, medial half of sole, 1st 2nd 3rd toes
What dermatome does S1 cover?
Buttock, posterior leg
What dermatome does S2 cover?
Same as S1
What dermatome does S3 cover?
Groin, medial thigh to knee
What dermatome does S4 cover?
Perineum, genitals, lower sacrum
