Central nervous system Flashcards
What is the gross anatomy of the brain (forgetting about lobes)?
Cerebrum (forebrain).
- Cerebral cortex – outer layer of neural tissue of the cerebrum. [PHOTO].
- Sulcus – groove of the cerebral cortex.
- Gyrus – ridge of the cerebral cortex.
- Corpus collosum – thick band of nerve fibres that join the two hemispheres of the brain.
Cerebellum (hind brain).
Pituitary gland.
Brainstem.
What is the function of the brainstem?
Oldest part so has most important functions. Involved in cardiovascular system control, respiratory control, pain sensitivity control, alertness, awareness, and consciousness.
Why are the folds important in the cerebrum?
Increases surface area so more surface to pack in neurones. Means we don’t have huge heads.
How is dorsal and ventral interpreted in the CNS?
In the brain, dorsal means superior. In the spinal cord, dorsal means posterior.
What are the names and locations of the cranial nerves?
Olfactory nerve (I) Optic nerve (II) Oculomotor nerve (III) Trochlear nerve (IV Trigeminal nerve (V) Abducens nerve (VI) Facial nerve (VII) Vestibulocochlear nerve (VIII) Glossopharyngeal nerve (IX) Vagus nerve (X) Accessory nerve (XI) Hypoglossal nerve (XII).
Ooh, Ooh, Ooh, to touch and feel very good velvet. Such heaven.
What is the structure of the cross-section of the spinal cord? (x2 points of focus)
Grey matter (cell bodies of the neurones) is surrounded by white matter (myelinated nerve fibres). Grey matter is where the processing happens. Two nerves emerge from each side – posterior (dorsal) root and anterior (ventral) root (each exist as horns in the spinal cord as seen in the diagram). Dorsal is the afferent root (sensory info enters and it either processes or sent to the brain). Ventral root is the efferent root (motor neurones that go out to the periphery).
What is the structure of the white matter in the spinal cord?
There are bundles called ascending tracts that carry sensory information UP to the brain, and descending tracts which bring motor information down from the brain.
What anatomical differences differentiate the dorsal and ventral horn?
Dorsal route has a dorsal root ganglion (loads of cell bodies). This is because in sensory neurones, the dendrites extend into the periphery, and the cell bodies sit somewhere in the middle.
What is the purpose of the vertebral column?
Spinal cord is protected and enclosed within the vertebral column.
What is the structure of the vertebral column in relation to how the CNS fits in? (x2 points)
Vertebral foramen is the large hole in the middle of each vertebra where the spinal cord sits. The vertebral column is arranged such that there are intervertebral foramen where nerves emerge from the CNS.
How many segments are there in the spinal cord?
31 segments in the spinal cord. Each correspond to the 31 pairs of spinal nerve.
What are the names of each of the spinal nerves and spinal segments?
8 cervical – named C1-C8. 12 thoracic – named T1-T12. 5 lumbar – named L1-L5. 5 sacral – named S1-S5. 1 coccygeal nerve – named Co.
How many vertebrae does the body have?
30 vertebras.
How are the spinal nerves arranged when there is one less vertebra than there are spinal nerve pairs?
This is because the C1 spinal nerves emerge from ABOVE the first vertebra, and the C8 spinal nerves emerge BELOW the C7 vertebra.
How are each spinal nerve pairs named (with exception to the cervical curvature)?
The nerves emerge lower than the corresponding vertebral segment.
What is length of the spinal cord relative to the vertebral column? What is the anatomy – therefore, of the remaining vertebral column?
Spinal cord is shorter than the vertebral column. (REMEMBER, the spinal cord is still made up of C, T, L, S and Co segments; it’s just the L, S and Co segments are found relative to the thoracic curvature of the vertebral column, and spinal roots and nerves emerge from here down the cistern)
Spinal cord finishes at the beginning of the lumbar curvature. Where the spinal cord ends, a bundle of spinal nerves and roots (the first part of the emerging nerves from the CNS) emerge from the lumbar enlargement of the spinal cord. This bundle is called the Cauda equina. There is an enlargement of the subarachnoid space in the lumbar region of the vertebral column called the lumbar cistern.
Where is a lumbar puncture done and why this location?
Lumbar puncture done between L3,L4 or L4,L5 because there’s no nervous tissue, so the risk of harming the spinal cord is avoided.
What is a dermatome?
An area of the skin supplied by A spinal nerve. It maps all the nerves, with exception to C1 and the coccygeal nerve.
What is a myotome?
A group of muscles that a single spinal nerve innervates.
What is the nature of the diameter of each segment of the spinal cord?
Cervical and lumbar regions of the SPINAL CORD are enlarged – called the cervical and lumbar enlargements. Because these regions innervate the arms and legs.
What are the functions of the spinal cord? (x4)
Connects brain to the PNS (peripheral) and ANS (autonomic). Carries sensory signals to the brain. Carries motor signals to the muscles. Coordinates reflexes.
What are the two methods that the brain can be classified?
Embryonic origin. Functionality.
How is the brain classified embryogenically? (x3) Alternative names for each.
FOREBRAIN: aka prosencephalon.
MIDBRAIN: aka mesencephalon.
HINDBRAIN: aka rhombencephalon.
Embryogenically, the forebrain, midbrain and hindbrain develop first, and each develop into their own constituent parts. The midbrain however, stays pretty much the same.
What does the hindbrain consist of? (x3)
Hindbrain includes the cerebellum, pons and the medulla.
What does the forebrain consist of? (x2) Alternative name for each.
Telencephalon (or cerebral hemisphere). Diencephalon (the thalamus and hypothalamus).
How is the brain classified functionally?
BRIAN STEM: Midbrain, pons, medulla oblongata. CEREBRUM: includes the cerebral hemisphere and diencephalon. CEREBELLUM.
What does the brain stem comprise of? (x3)
Midbrain, pons, medulla oblongata.
What are the functions of the brain stem? (x3)
Responsible for the control of many vital functions such as: breathing, heart rate, blood pressure, swallowing, balance etc. Responsible for defensive reflexes (cough, gag, sneeze…) Involved in sleep-wake cycles, alertness and consciousness.
What is the nature of the brainstem in relation to the cranial nerves?
Contains the nuclei (meaning a group of cell bodies of a neurone – all with similar function) of 10 of the 12 cranial nerves which control vital functions.
What does the diencephalon consist of?
Thalamus and hypothalamus. REMEMBER, this is in the cerebrum and the forebrain.
What is the structure of the thalamus?
Made up of two thalami connected together in the centre.
What does the thalamus and hypothalamus look like in your brain?
The two photos are from a lateral and coronal (ventral/dorsal) view respectively. Thalamus is above the hypothalamus.
What are the functions of the hypothalamus and thalamus?
Thalamus: Relay station and integration centre for somatic and special senses information and projection to cortex. Involved in emotional status, consciousness, appropriate motor response. Hypothalamus: integration hub. Regulates temperature, hunger, thirst, hormone (connected with pituitary) and autonomic function i.e. it is important in coordinating haemostasis.
What are the main basal ganglia? Where does each component lie when you look at the brain horizontally AND laterally?
Caudate nucleus (highlighted in purple – has a head and tail). Putamen (highlighted in pink – it is the ball-like structure below the head of caudate). The caudate and putamen together is called the corpus striatum.
Globus pallidus (highlighted in dark blue). The globus pallidus and putamen together forms the Lentiform nucleus.
Subthalamic nucleus and Substantia Nigra (which is part of the MIDBRAIN; not the forebrain).
What fissures are there in the cerebral cortex? (x3)
Longitudinal – divides the two hemispheres of the brain. Central – divides the frontal and parietal lobe. Lateral fissure – separating temporal from frontal and parietal.
What are the different lobes of the cerebral cortex, their location and basic function? (x4)
FRONTAL: house the primary motor cortex = voluntary movement. PARIETAL: somatosensory cortex = sensory information from the somatic area of your body is processed here. TEMPORAL: auditory perception, primary auditory cortex, and also part of your personality. OCCIPTIAL: visual cortex.
What are the main primary cortical areas of the brain? (x4)
PRIMARY MOTOR CORTEX: stimulate motor neurones for movement – contralateral. PRIMARY SOMATOSENSORY CORTEX: adjacent to the primary motor cortex and somatotopic. Receives general sensory information coming from the body e.g. temperature, pain, touch. PRIMARY AUDITORY CORTEX: first to receive information from the ears. PRIMARY VISUAL CORTEX: first to receive information from the retina.
What are the main association cortical areas? Where are they found?
Wernicke’s area – understanding language. Broca’s area – for speech. Can be located on the photo, but main point is that they are found in the LEFT region of the brain!
What are the bones of the anterior cranial fossa? (x2)
Frontal and ethmoid (at the base next to the nose) bones. Calvarium means the upper part of the neurocranium.
What are the bones of the middle cranial fossa? (x3)
Sphenoid and temporal bones in the base. Parietal bone across the top. Calvarium means the upper part of the neurocranium.
What is the bone anatomy of the posterior cranial fossa? (x2)
Occipital bone. And the foramen magnum. Calvarium means the upper part of the neurocranium.
List the ventricles of the CNS. (x3) What is the structure of the biggest one?
Lateral ventricles – biggest. Have anterior, inferior and posterior horns. Found in both hemispheres. The third ventricle – in yellow. Has characteristic shape with hole. Fourth ventricle is lower down (purple). Has characteristic diamond shape.
What are the ‘links’ in the ventricular system? (x3)
The lateral ventricles are joined by two interventricular foramina (bright blue), which joins onto the third ventricle and allow passage of CSF between the two ventricles. Aqueduct – in red – carries out the same role as the interventricular foramina, but links CSF between the third and the fourth ventricle. Central canal – green – extends down.
How does each ventricle look like histologically in the brain?
REALLY REVISE THIS. This is crucial. DON’T JUST LOOK AT THESE PHOTOS, LOOK AT OTHERS ONLINE TOO!
What is the pathway of CSF flow?
It circulates from the lateral ventricles, down to the third and fourth ventricle. CSF then, through lateral and median apertures, enters the subarachnoid space of the meninges and circulates round the meninges of the brain. CSF is then filtered out via arachnoid villi into the Dural venous sinuses (in the dura mater space) where it enters the system circulation.
What is the optic chiasm and where is it found?
The optic chiasm or optic chiasma is the part of the brain where the optic nerves partially cross. The optic chiasm is located at the bottom of the brain immediately inferior to the hypothalamus.
