Neuroscience 7 - CNS Flashcards
Describe the meaning of the term rostral, in relation to anatomy.
Rostral means towards the front of the brain, ie. the nose and mouth.
Define the meaning of the term caudal in anatomy.
Near the posterior part of the body, away from the brain. Indicated the direction that points towards the feet.
What is the spinal cord?
The spinal cord is the nervous tissue that extends from the medulla oblongata down to the lumbar region of the vertebral column. It consists of nervous tissue.
What is the vertebral column?
The bone which surrounds the spinal cord and provides protection.
What is the intervertebral foramen?
These are the gaps between vertebrae where the nerves can exit and enter.
What are the segments of the spinal cord, in descending order?
- Cervical vertebra are dorsal
- Thoracic vertebra
- Lumbar vertebra
- Sacral vertebra
- Coccygeal vertebra are ventral
How many vertebra and nerves are in the cervical spinal cord segment?
7 vertebra
8 nerves
How many vertebra and nerves are in the thoracic spinal cord segment?
12 vertebra
12 nerves
How many vertebra and nerves are in the lumbar spinal cord segment?
5 vertebra
5 nerves
How many vertebrae and nerves are in the coccygeal spinal cord segment?
4 vertebra
1 nerve
How many vertebrae are in the vertebral column?
33
How many nerves are in the spinal cord?
31 pairs of nerves
Why can a lumbar puncture be performed?
The spinal chord terminates at the lumbar vertebrae, and so CSF can be taken without damage to the spinal cord.
Between which vertebrae is a lumbar puncture performed?
- In adults, a sample is taken from between L3 and L4.
- In children, the sample is taken from between L4 and L5
What is the function of the ventral root of the spinal cord?
It is an efferent root, meaning it has motor functions.
What is the function of the dorsal root of the spinal cord?
It is an afferent root, meaning it has sensory functions.
Where do the axons in the ventral root of the spinal cord arise from?
They arise from the cell bodies in the ventral horn.
Where do the axons in the dorsal root of the spinal cord arise from?
They arise from cell bodies in the dorsal horn.
List the functions of the spinal cord.
- Connects the PNS and ANS to the brain
- Carries sensory signals to the brain
- Carries motor signals to the muscles
- Coordinates reflexes (eg. patellar reflex)
List the components of the brain stem.
- Midbrain
- Pons
- Medulla oblongata
List the major components of the forebrain/cerebrum
- Diencephalon (thalamus + hypothalamus)
- Cerebral hemisphere
Describe the contents of the brain stem.
- All sensory and motor fibres that connect the cerebrum, cerebellum and spinal cord run through
- Contains nuclei of 10 of the 12 cranial nerves
List the functions of the brain stem.
- Controls many vital functions (breathing, heart rate, blood pressure, swallowing, balance)
- Defensive reflexes (cough, gag, sneeze)
- Involved in sleep cycles, alertness and consciousness
What area of the brain degenerates in parkinsons disease?
The substantia nigra, from the midbrain
List the functions of the diencephalon.
- Hypothalamus regulates temperature, hunger, thirst, hormone and autonomic function
- Thalamus integrates somatic and special senses and projects this to the cortex. Involved in emotional status, consciousness and motor response.
List the components of the basal ganglia and their location.
- Cordate, putamen, globus pallidus (cerebrum)
- Substancia nigra (midbrain)
- Subthalamic nucleus (diencephalon).
What is the corpus striatum?
- Caudate + putamen
- Connected to the cortex, thalamus and nigra
What is the lentiform nucleus?
Putamen + globus pallidus
List the functions of the basal ganglia.
- Control of movement
- Facilitating voluntary movement, and inhibiting unwanted/inappropriate movements (fine tuning)
List the main functional areas of the cerebral cortex.
- Prefrontal cortex determines personality and appropriate behaviour
- Auditory association area recognises sounds as words/music
- Primary visual/auditory cortexes recieve signals
- Primary somesthetic cortex deals with touch, pain and temperature
- Motor association area is were neurones plan the contraction of muscles
- Primary motor cortex determines finely coordinated limb movement.
- Visual association area recognises faces/familiar objects
What is the broca area and where is it found?
- Generates a motor program for all the muscles of speech
- LHS of the frontal lobe (or RHS if left-handed)
What is the Wernicke area and where is it found?
- Recognises spoken and written language
- LHS of temporal lobe
Which part of the brain is laminar?
- The meninges have 3 layers
- The neurones of the cerebral cortex are arranged in 6 layers
Why can the cortex be described as somatotopic?
- There is an orderly relationship between the part of the body innervated and its location in the corresponding motor areas of the brain.
- Relates to both sensory and motor neurones.
List the components of the limbic system.
- Corpus callosum
- Fornix
- Pineal gland
- Hippocampus
- Hypothalamus
List the functions of the limbic system.
- Motivation
- Instinctive behaviour
- Emotion
- Memory
How is the cerebellum connected to the brain?
- Attached to the brainstem by 3 pairs of penduncles
Describe the structure of the cerebellum.
- Grey matter on the surface, tightly folded to form the cortex
- White matter on the inside with nuclei
- Two hemispheres divided into lobes.
- Hemispheres connected by central vermis
Which parts of the CNS is the cerebellum connected to and why?
- Vestibular system for balance
- Spinal cord and muscles for posture and muscle tone
- Motor cortex and thalamus for learned movements
What are the three parts of the brain, as formed in embryonic development?
- Forebrain
- Midbrain
- Hindbrain
What is another name for the forebrain?
Prosencephalon
What is another name for the midbrain?
Mesencephalon
What is another name for the hindbrain?
Rhombencephalon
What is contained within the forebrain?
Cerebral hemisphere and diencephalon
What is contained within the hindbrain?
- Pons
- Medulla oblongata
What are the three types of fibres in the brain?
- Commissural (connect the hemispheres)
- Association (connect cortical areas in the same hemisphere)
- Projection (couple the brain and the spinal cord)
List the layers of the meninges
- Dura mater
- Arachnoid mater
- Pia mater
What is the function of the dura mater?
- To separate the cranial cavity into compartments.
- Protect the brain from displacement
What is the function of the arachnoid mater?
Transfer cerebrospinal fluid from the ventricles to the bloodstream.
What is the function of the pia mater?
- Protects the brain, CSF contained between pia mater and dura mater
- Encloses and protects the vessels supplying the brain
List the components of the ventricular system.
- Lateral ventricles (right and left)
- Third ventricle
- Fourth ventricle
How much CSF is produced in one day?
500ml
What is the total amount of CSF in the brain at any one time?
150ml
What is the composition of CSF compared to plasma?
- Lower glucose
- Lower protein
- Lower Ca2+ and K+
- Higher Cl- and Mg
- Slightly lower pH
List the functions of CSF
- Cushioning
- Nutrition
- Removal of waste
- Immune cells
Describe the pathway of CSF flow.
- Produced in the choroid plexus, at the lateral, 3rd and 4th ventricles
- Lateral ventricles via interventricular foramina to the third ventricle
- From the third ventricle to the fourth ventricle via te cerebral aquaduct
- Passes into the subarachnoid space via midline foramen or two lateral foramina
- Passess down the spinal cord inferiorly, envelops the brain superiorly
- Absorbed through arachnoid granulations in the walls of dural venous sinuses
What is the location of the lateral ventricles?
Connect to the frontal, occipital and temporal lobes
What is the location of the third ventricle?
- Situated between the right and left thalamus
- Surpa-optic recess is above the optic chiasm
- Infundibular recess is above the optic stalk
What is the location of the fourth ventricle?
Lies within the brainstem, between the pons and medulla oblongata
Where does fluid enter and drain the 4th ventricle?
- Enters via the verebral aqueduct
- Drains via the central spinal canal and subarachnoid cisterns
Define hydrocephalus
An abnormal collection of CSF within the ventricles of the brain
What are the two types of hydrocephalus?
- Communicating hydrocephalus (no flow obstruction)
- Non-communicating hydrocephalus (obstruction)
How is hydrocephalus treated?
- With stunt surgery (shunt in the brain drains CSF)
- Endoscopic third ventriculostomy (makes a hole in the bottom of one of the ventricles so CSF can drain out the brain)
How can you distinguish between an epidural and subdural haemorrhage?
- On a CT scan, epidural haematomas show a convex (lemon) shaped bleed, while subdural shows a crescent (banana) shaped, concave bleed.
What are the contents of the anterior cranial fossa?
Frontal lobes and olfactor nerves
What are the contents of the middle cranial fossa?
Temportal lobes and pituitary gland
What bone does the pituitary gland lie in?
Sphenoid bone
What are the contents of the posterior cranial fossa?
The brainstem and cerebellum
Describe the distribution of grey and white matter in the spinal cord.
White matter surrounds the grey matter.
Which lobes are separated by the central fissure sulci?
The frontal lobe and the parietal lobe.
What separates the temporal lobe from the parietal and the frontal lobe?
Lateral sulcus
Where are the precentral gyrus and postcentral gyrus?
- Either side of the central sulcus.
- Precentral in the frontal lobe
- Postcentral in the parietal lobe
Where is the extradural space?
- Potential space between the dura mater and bone
- Normally the outer layer is firmly attached to the bone
Where is the subdural space?
- Anatomically does not exist
- Blood entering this region creates a subdural hematoma
- The space between the two layers of dura mater
Where is the subarachnoid space?
- The arachnoid mater clings to the inner layer of the dura mater, while the pia mater clings to the contours of the brain. As a result, this space forms between the two layers
- It enlarges into expanded areas, subarachnoid cisterns which contains CSF and blood vessels