Nervous system II 14 Flashcards
What protects the spinal cord - x2?
Vertibral column and meninges
What protects the brain - x4?
Cranium, cranial meninges, cerebrospinal fluid, blood brain barrier
What is the meninges made from?
Connective tissue
What are the three layers of the meninges?
Dura mater
Arachnoid mater
Pia matter
What is the dura mater?
Tough outer layer of the meninges
Contains venous sinuses
What is the arachnoid mater?
Middle layer of the meniges
Collagen and elastic fibres
What is the pia mater?
Inner layer of the meninges.
Thin transparent layer than contains blood vessels that supply the spinal cord
What is the space between the dura mater and arachnoid mater?
Subdural space
What is the space between the arachnoid mater and pia mater?
Subarachnoid space
What is a subdural haematoma
Venous blow, slowly develops
What type of haemorrhage is a rapid arterial bleed?
Subarachnoid haemorrhage
What is cerebrospinal fluid
Clear liquid that protect the braind and spinal cord from trauma
What is cerebrospinal fluid made from?
Filtered blood - mostly water, ions and glucose
Where do you find cerebrospinal fluid
Subarachnoid space, ventricles and central canal of the spinal cord
What is cerebrospinal fluid made by?
Ependymal cells
What rate is cerebrospinal fluid produced at?
500ml per day
What are the functions of cerebrospinal fluid?
Supports and protects the brain and spinal cord - acting as a SHOCK ABSORBER
Maintains uniform pressure around the brain
Optimal chemical environment
Circulates nutrients and waste
What does the blood brain barrier do?
Protects the brain from: toxins, harmful substances and bacteria
Which cell type maintains the blood brain barrier?
astrocytes
What can be transported across the blood brain barrier?
Lipid soluable substances
Glucose
Gases
Ions
What does not pass the blood brain barrier
Proteins and some drugs
What are the four major parts of the brain?
Brainstem
Diencephalon ‘interbrain’
Cerebrum
Cerebellum ‘little brain’
Which part of the brain is known as the interbrain?
diencephalon
What are the three parts of the brainstem
medula oblongata
pons
midbrain
What are the three parts of the diencephalon?
thalamus
hypothalamus
epithalamus
What does the medulla oblongata do?
Respiratory and cardiac centres - regulates heartbeat and breathing
Reflexes such as vomiting, sneezing and hiccuping
4 cranial nerves - 9-12
Motor tracts - corticospinal tract
What does the pons do?
Controls breathing
4 cranial nerves - 5-8
Relayas motor tracs
What does the midbrain do?
Contains the substantia nigra - contains dopamine that helps control subconcious muscle activities
Eye reflexes and tracking
2 cranial nerves - 3 & 4
Movement of head and neck
Auditory tracts
What does the thalamus do?
Core of the brain - 80% of the diencephalon
Major relay centre - sensory info to the cerebrum
Integrates sensory and motor info
What does the epithalamus do?
Connects the limbic system (emotion, behaviour and long-term memory) to other parts of brain
PIneal gland secretes meletonin
What does the hypothalamus do?
Think emotional brain
Hormone regulation and homeostasis
Receives sensory info
Controls autonomic nervous system
Controls body temp
Regulations emotional and behaviour patterns (limbic)
Eating and drinking
Circadian rhythms
Facts about the cerebellum
of the 100 billion neurons in the brain - half are in the cerebellum but its only 1/10th of the brain mass
What are the functions of the cerebellum?
Maintain posture and balance
Co-ordinate skilled sequences of movement
Correction of errors during ongoing movement
Role in cognition, thought and language
Susceptible to injury from alcohol, Coeliac’s disease and B1 deficiency
What is the name of symptoms of cerebellar disease
ataxia
Key points about the structure of the cerebrum
It’s divided into two hemispheres - right and left
Outer cerebral cortex - grey matter
Deeper region - white matter
What is the corpus collosum
What contexts the two heispheres of the cerebrum
What are the functions of the cerebrum?
Sensory perception
Motor control of skeletal muscles
What is the corticospinal tract made from?
Motor neuron axons
Where does the corticospinal tract cross over?
Medulla oblongata
What does the corticospinal tract crossing over mean?
Left side of the brain coordinate the right side of the body and visa versa
What are the four lobes of the cerebrum (named after the four lobes that cover them)
Frontal lobe
Temporal lobe
Parietal lobe
Occipital lobe
What does the frontal lobe do?
Motor skills
What does the temporal lobe do?
Hearing
What does the parietal lobe do?
Sensory cortex
What does the occipital lobe do?
Vision
What does each region of the motor cortex do?
Controls voluntary movements of specific muscles
What does the limbic system do?
Activates different emotions
Which parts of the brain form the limbic system?
Cerebrum, diencephalon, midbrain
Which part of the brain is ke in dealing with emotions?
Amygdala
Which part of the brain plays a role in encoding and retrieving memories?
Hippocampus
Why does the brain need a constant supply of oxygen and glucose?
As it has a limited ability to supply and store oxygen and glucose
What percentage of cardiac output does the brain receive?
About 20% (despite only counting for 2% of the body mass).
Which two arterial system supply the brain?
Carotid and vertebral
Where the two arterial systems that supply the brain meet and form the circle of willis what type of aneurysms normally develop?
Berry aneurysms
What is the name and function of cranial nerve I
Olfactory - sense of smell
Name and function of cranial nerve II
OPtic - vision
Only nerve that spans through the majority of the cranium
NAme and function of cranial nerve II
Oculomotor - moves eyeball and elevates eyelid
Name and function of cranial nerve IV
Troclear - rotates eyes for reading
Name and function of cranial nerve VI
Abducens - abdusts the eyes
What can damage to cranial nerve III, IV and VI lead to
Strabismus (one eye crossed)
ptosis - drooping upper eyelid
diplopia - double vision
Name and function of cranial nerve V
Trigeminal - facial sensations, mastication and some tast
Name and function of cranial nerve VII
Facial nerve - taste, facial expression and salivary glands
What are the three branches of the trigeminal nerve?
Ophthalmic, maxillary and mandibular
Name and function of cranial nerve VIII
Vestibulocochlear - hearing and balance
Acronym for cranial nerves
On Occasion Our Trusty Truck Acts Funny, Very Good Vehicle Any How
Acronym for cranial nerve function
Some Say Money Matters, But My Brother Says Big Brains Matter Most
NAme and function of cranial nerve IX
Glossopharyngeal - taste and swallow
Name and function of cranial nerve X
Vagus nerve
Wandering nerve - long course
Largest nerve in autonomic nervous system
All sensory info from chest, and abdomen (heart, GI tract, lungs)
90% of its fibres are sensory
NAme and function of cranial nerve XI
Assessory spinal nerve
Shoulder elevation, neck side bending and rotation
Name and function of cranial nerve XII
Hypoglossal - tongue movement and speach
Where does the spinal cord start and end
Starts at the foramen magnum
Ends at L2
What is the cauda equina
‘horse’s tail) spinal nerves that continue beyond the conus
What does the spinal cord consist of
White matter around a grey matter core
Facts about white matter in the spinal cord
Bundles of mylenated axons
Tracts - motor decending
Sensory - ascending
Facts about the grey matter in the spinal cord
Cell bodies and dendrites
Divided into posterior dorsal horn - receives sensory info
Anterior ventral horn - sends motor impulses
Dorsal column receives?
Light touch, vibration, proprioception
Ascending
Spinothalamic tract recieves?
Pain and temperature
Ascending
What is a reflex
A fast, automatic, unplanned sequence of actions that occurs in response to a stimulus
5 steps of a reflex arc
- sensory receptor
- sensory neuron
- Integrating centre
- motor neuron
- effector organ
What is the name for the places where spinal nerves exit the vertebral column?
vertebral foramina (holes)
What does raised intracranial pressure mean?
An increase in pressure within the cranial cavity
3+ causes for raised cranial pressure
Tumours
Haemorrhage
Hydrocephalus - excess cerebrospinal fluid
Meningitis
Encephalitis - inflammation of brain tissue
