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What is the CNS?
Central nervous system
What is the PNS?
Peripheral nervous system
What does the CNS consist of?
Brain and spinal cord
What does the PNS consist of?
Spinal nerves and cranial nerves (12 pairs)
What is the cerebrum made up of?
Frontal lobes Parietal lobes Temporal lobes Occipital lobes
What is a cerebral hemisphere?
A side of the cerebrum
What is a gyrus?
A ridge in the cerebrum
What is a sulcus?
A groove in the cerebrum
What is the function of the corpus callosum?
It conveys messages between cerebral hemispheres
What is the function of the cerebellum?
Fine control of movement, balance and coordination
What is the brainstem made up of?
Midbrain, pons and medulla oblongata
What is the function of the brainstem?
It contains centres vital for life
Which cranial nerves arise from the brainstem?
III to XII
What is CSF?
Cerebrospinal fluid
What is the function of CSF?
It circulates through the CNS to remove metabolic waste from the interstitial fluids of nervous tissues and return them to the bloodstream
Where does CSF circulate?
In the ventricles
Where is CSF produced?
In specialized ependymal cells by the choroid plexus
What is the function of the choroid plexus?
To produce CSF
What are ventricles?
Open spaces where CSF circulates and where it is produced by choroid plexi
What does CSF do after circulating through the ventricles?
It emerges through arachnoid granulations into the subarachnoid space
What is the name of the first two ventricles?
Lateral ventricles
Where are the lateral ventricles?
Deep within the cerebrum
How are the lateral ventricles connected to the 3rd ventricle?
By the interventricular foramen
What is another name for the interventricular foramen?
Foramen of Monro
How are the 3rd and 4th ventricles connected?
By the cerebral aqueduct that passes through the midbrain
What does the cerebral aqueduct pass through?
The midbrain
What is another name for the cerebral aqueduct?
Aqueduct of Sylvius
What is the 4th ventricle?
The space between the cerebellum and the pons/upper medulla
What is the outer surface of the CNS covered by?
Meninges
What are the meninges from superficial to deep?
Dura mater Arachnoid mater Pia mater
Describe dura mater:
Thick fibrous layer and strong protective sheath over the entire brain and spinal cord Anchored to the inner surface of the cranium and vertebral cavity 2 layers in the brain (endosteal and meningeal) 1 layer in the spinal cord
What is the dura mater?
A thick fibrous layer and strong protective sheath over the entire brain and spinal cord
What is the dura mater anchored to?
The inner surface of the cranium and vertebral cavity
How many layers of dura mater are there in the cranium?
2
How many layers of dura mater are there in the spinal cord?
1
What is the difference between dura mater in the cranium and in the spinal cord?
Consists of 2 layers in the brain and only one in the spinal cord
What are the names of the dura mater layers in the brain?
Endosteal and meningeal layers
Describe arachnoid mater:
Membrane of thin fibrous tissue that forms a loose sac around the CNS between the dura and pia mater In the spinal cord it is held to the dura by CSF (in life)
What is the arachnoid mater?
A membrane of thin fibrous tissue that forms a loose sac around the CNS between the dura and pia mater
How is arachnoid held to the dura in the spinal cord in life?
By CSF
Describe pia mater:
Directly adjacent to the CNS Thin fibrous membrane that follows the convolutions of gyri/sulci in the cerebral cortex and fits into other grooves and indentations
What is pia mater directly adjacent to?
The CNS
What are the spaces in the cranium?
Extra/epidural space Subdural space Subarachnoid space
What are the spaces in the spinal cord?
Extra/epidural space Subdural space Subarachnoid space
Describe the epidural space in the cranium:
Potential space as the dura is adhered to the skull
Describe the subdural space in the cranium:
Potential space between the dura and arachnoid that contains nothing
Describe the subarachnoid space in the cranium:
Space between the arachnoid and pia that contains CSF
What kind of space is the epidural space in the cranium?
Potential space
What kind of space is the subdural space in the cranium?
Potential space
What kind of space is the subarachnoid space in the cranium?
Anatomical space
What does the subdural space in the cranium contain?
Nothing
Why is the epidural space in the cranium and potential space?
Because it is adhered to the skull
What does the subarachnoid space in the cranium contain?
CSF
What is the subdural space between?
Dura and arachnoid
What is the subarachnoid space between?
Arachnoid and pia
Describe the epidural space in the spinal cord:
Anatomical space between dura and ligamentum flavum Contains lymphatics, spinal nerve roots, loose connective tissue, fatty tissue, small arteries and networks of venous plexi Needle inserted here to reduce inflammation/pain from nerve root compressionn
Describe the subdural space in the spinal cord:
Potential space between dura and arachnoid Becomes an anatomical space in death
Describe the subarachnoid space in the spinal cord:
Anatomical space containing CSF between the arachnoid and pia Insert needle here to examine CSF
What kind of space is the epidural space in the spinal cord?
Anatomical space
What kind of space is the subdural space in the spinal cord?
Potential space
What kind of space is the subarachnoid space in the spinal cord?
Anatomical space
What is the epidural space in the spinal cord between?
Dura and ligamentum flavum
What does the epidural space in the spinal cord contain?
Lymphatics Spinal nerve roots Loose connective tissue Fatty tissue Small arteries Network of venous plexi
Why would you insert a needle into the epidural space in the spinal cord?
To reduce inflammation and pain from nerve root compression
What is the difference between the subdural space in life and in death?
It is a potential space in life and an anatomical space in death
What does the subarachnoid space contain?
CSF
Why would you insert a needle into the subarachnoid space in the spinal cord?
To examine CSF
What space would you insert a needle into to examine CSF?
Subarachnoid space in the spinal cord
What space would you insert a needle into to reduce inflammation and pain from nerve root compression?
Epidural space in the spinal cord
What is the difference between the epidural space in the cranium and in the spinal cord?
It is a potential space in the cranium and an anatomical space in the spinal cord
Why is the epidural space a potential space in the cranium but an anatomical space in the spinal cord?
In the cranium the dura is adhered to the skull so there can be no space but in the spinal cord there is no bone to adhere to
Where does the spinal cord start?
At the foramen magnum, after the medulla oblongata
What does the spinal cord pass through?
The vertebral canal
What is the spinal cord a continuation of?
The medulla oblongata/brainstem
Where does the spinal cord end in adults?
L1/L2
What forms because the vertebral column continues to grow after L1/L2?
The cauda equina
What is the cauda equina?
A set of hanging fibres outside the spinal cord
Why does the cauda equina form?
Because the spinal cord ends at L1/L2 but the vertebral column keeps growing
What kind of joints are intervertebral discs?
Secondary cartilaginous (symphysis)
Describe the structure of intervertebral discs:
Nucleus pulposus in the centre, surrounded by the annulus fibrosus
What is more central, nucleus pulposus or annulus fibrosus?
Nucleus pulposus
What do erector spinae muscles lie posterior to?
Transverse processes
What do erector spinae muscles extend?
The spinal column
What do spinal nerves exit via?
Intervertebral foramina
What passes through intervertebral foramina?
Spinal nerves
What is the nervous system divided into?
Autonomic and somatic
What is the ANS?
Autonomic nervous system
What is the SNS?
Somatic nervous system
What is the ANS made up of?
Motor/visceral efferents (sympathetic and parasympathetic) Sensory/visceral afferents
What is the SNS made up of?
Motor/somatic efferents Sensory/somatic afferents
What is the difference between sympathetic and parasympathetic neurone pathways?
The sympathetic pathway has a much longer postganglionic fibre
What is a myotome?
A group of muscles innervated by a single spinal nerve root
What is a dermatome?
A strip of skin innervated by a single spinal nerve root
What is the name for a strip of skin innervated by a single spinal nerve root?
Dermatome
What is the name for a group of muscles innervated by a single spinal nerve root?
Myotome
What is the dermatome for the nipples?
T4
What is the dermatome for the umbilicus?
T10
What is the dermatome for the thumb?
C6
What is the dermatome for the front of the knee?
L3
What is the dermatome for referred diaphragmatic pain?
C3/C4
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