Lecture 2- Neuroanatomy, Anatomical Structure and Function Flashcards
What is the basic difference in the role of the central nervous system compared to the Peripheral Nervous System?
Central= Integrating/ command center Peripheral= System linking all parts of the the body to the CNS via nerves
What are the four basic subdivisions of the brain?
- Forebrain
- Midbrain
- Hind brain
- Cerebellum
What makes up the forebrain?
- Cerebral hemispheres (cerebrum)
- Diencephalon
What makes up the brain stem?
- Midbrain
- Pons
- Medulla
What two parts of the brain stem make up the hind brain?
- Pons
- Medulla
The two parts of the CNS are…
- Brain
- Spinal chord
How much volume of the brain does the cerebrum make up?
-Vast majority= 83%
What is the small part at the back of the brain called? What is interesting about the number of neurons it contains?
- Cerebellum
- Despite being a lot smaller than the cerebrum it has 50% of the neurons
How much does the brain weigh roughly?
1.5kgs
What is interesting about the coronal cross section through the brain stem?
Normally coronal is cutting up the brain from side on (draw picture). The brain stem however, is it at angle therefore the coronal section is at an angle.
What is a mid sagittal section of the brain? What is this also sometimes called? What arises from a section cut here?
- Mid sagittal: cut through midline from above (along where the left + right hemispheres divide)
- Sometimes known as parasagittal
- End up getting a medial view of the brain (what is happening inside)
What are the two types of cells in nerve tissue?
- Neurons
- Glia
What are the features of neurons?
- highly specialized, excitable cells
- have high metabolic rate
- provide rapid and specific communication between regions of the body highly specialized, excitable cells
What are the four types of glial (support) cells and what are their different functions?
- Astrocytes: metabolism
- Oligodendrocytes: insulation (produce myelin)
- Microglia: defense cells
- Ependymal cells: line ventricles/ cavities in the brain
Broadly what is the difference between grey and white matter?
- Grey matter= cell bodies (called nucleus in CNS, Ganglion in PNS)
- White matter= axons (lipid material in axon sheath gives the white apperance)
Broadly what is the difference between grey and white matter?
- Grey matter= cell bodies (called nucleus in CNS, Ganglion in PNS)
- White matter= axons (lipid material in axon sheath gives the white appearance)
What is the distribution of grey and white matter like in the brain?
- Grey on outside
- White on inside
What are the three words that describe the different hills and troughs of the brain?
- Gyri= hill tops (singular gyrus)
- Sulci= valleys (singular sulcus)
- Fissure= Separates large regions of the brain (deeper)
Draw a picture showing the basic lobes of the brain….
Check that its correct from slide slide 16
What is the insula?
- Is buried deep within the lateral sulcus & forms part of its floor
- Is covered by portions of the temporal, parietal & frontal lobes
What sulcus separates the frontal and parietal lobes?
-The central sulcus
What sulcus separates the frontal lobe from the temporal lobe?
Lateral sulcus
What separates the cerebrum from the cerebellum?
-The transverse fissure
On the medial surface what sulcus can be seen to separate the parietal and occipital lobes?
Parieto-Occipital sulcus
Draw where the diencephalon is located on the medial surface…
Refer to slide 20
What is associated with the brain stem and can be seen from the ventral surface of the brain?
Cranial nerves + blood vessels
Where does the spinal chord extend from? What is its vital function?
- From foramen magnum to first or second lumbar vertebra
- Two way street of information to and from the brain
How come the spinal chord is so delicate/ easy to damage?
Its only about the width of your thumb
How many pairs of spinal nerves are there? How many are there in each division of the spinal chord?
- 31 pairs of spinal nerves
- 8 cervical, 12 thoracic, 5 lumbar, 5 sacral spinal
Where are the two enlargements in the spinal chord?
- Where the nerves serving the upper & lower limbs arise.
- There is the cervical enlargement and lumbar enlargement.
What cone exists at the end of the spinal chord and what extends from it?
-Conus medullaris (Medullary cone)
-Filum Terminale (Terminal Filum): Extends from the conus
medullaris to the posterior surface of the coccyx
-The function of this is to anchor the spinal chord so it sits nicely within the spinal canal
What is the cauda equina/ Why does it exist?
- The collection of nerve roots at the inferior end of the vertebral canal
- The ‘horses tail’
- After birth the vertebral column grows faster than the spinal cord means the spinal nerves have to travel down and out their associated vertebrae instead of just going straight across
Draw a cross section of the spinal chord and describe the different features…
Refer to slide 25
How is the arrangement of white and grey matter different in the spinal chord as opposed to the brain? What does this mean?
- Brain= White matter on inside, grey matter on outside
- Spinal chord= grey matter on inside (butterfly), white matter on outside
- Means that Neurons are a lot more protected
What’s the difference between the dorsal root, ventral root and spinal nerve?
- Dorsal roots= afferent fibers, send sensory impulses to cord
- Ventral root= efferent fibers, axons go to effector organs (in charge of motor output)
- Spinal nerve= mixed: contains both the dorsal and ventral roots
What’s the two broad types of spinal chord injury?
- Paralysis - loss of motor function
- Paresthesias - sensory loss
What does the severity of a spinal chord injury depend on?
- C1-C4: high tetraplegia (Can’t move legs + arms at all, breathing apparatus as nerves that innervate diaphragm don’t work)
- C5-C8: low tetraplegia (No breathing machine but limited movement in arm + legs)
- Thoracic, lumbar or sacral injuries: paraplegia (No legs, arms can move though)
Spinal cord injuries can either be…
- Complete or incomplete
- Obviously complete is worse than incomplete
Do practice question on spinal chord damage on slide 29…
Answer on slide
What is the role of the meninges?
-Protection of the brain and spinal cord
-Three layers: dura mater (external): very tough, provides a lot of protection, thick connective tissue arachnoid mater (intermediate) pia mater (internal)
- Large subarachnoid space, within which is cerebrospinal fluid (CSF)
- Form the partitions within the skull (dura), these subdivide the cranial cavity and limit excess movement of the brain within the cranium
What are the two layers of the dura mater and what is in between?
- Periosteal
- Meningeal
Separate the and form large Dural venous sinuses e.g. superior sagittal sinuses
What are the three main folds of the meningeal layer and what do they form partitions between?
- two cerebral hemispheres: falx cerebri (sickle shaped, lies in medial sagittal plane/ in longitudinal fissure)
- cerebellum & cerebrum: tentorium cerebelli (tent shaped, more horizontal plane)
- two cerebellar hemispheres: falx cerebelli (smaller Dural folds along the vermis of the cerebellum)
Where does the falx cerebri attach?
- Attaches to crista galli, anteriorly
- Attaches to upper surface of tentorium cerebelli in the midline, posteriorly
What is the subdural space? What can happen sometimes?
- The space between meningeal dura mater & arachnoid mater
- Very narrow, contains a film of fluid, may be enlarged by bleeding (= subdural haemorrhage)
