Sem 2 - U - The brain - Lobes, cortex/basal ganglia, diencephalon, brainstem, circle of willis, meninges/ventricles/CSF, sinuses Flashcards
Name the lobes in the picture Start with black box and end with yellow
Black box - parietal lobe Red box - occipital lobe Green box - cerebellum Blue box - temporal lobe Yellow box - frontal lobe
Throughout the brain there are bumps and grooves (valleys) What is the proper name for these features?
The bumps of the brain are properly known as a gyrus (gyri=plural) The grooves of the brain are properly known as a sulcus (sulci=plural)
What is the large sulcus in the brain known as separating the frontal and parietal lobes? What gyri are found either side of this? and what is found in these gryi?
The central sulcus separates the frontal and parietal lobe The pre-central gyrus is found anterior to the central sulcus in the frontal lobe containing the primary motor cortex The post-central gyrus is found posterior to the central sulcus in the parietal lobe containing the primary sensory cortex
What is the deep groove in the brain that separates the right and left cerebral hemisphere?
- What arteries are found here?
What separates the frontal and parietal lobes from the temporal lobe and what artery is found here?
The longitudinal fissure separates the right and left cerebral hemispheres. The anterior cerebral arteries can be found here
The frontal and parietal lobes are separated from the temporal lobe by the lateral fissure. The middle cerebral artery can be found within this fissure
What are the areas for speech production and speech comprehension known as? What lobes are they found in?
Broca’s area is where speech production takes place and is found in the frontal lobe Wernicke’s area is where speech comprehension takes place and is found in the temporal lobe
Where is the primary motor cortex found? Where is the primary sensory cortex found? Where is the visual cortex found? Where is the auditory cortex found?
- Primary motor cortex - found in the pre-central gyrus in the posterior frontal lobe
- Primary sensory cortex - found in the post-central gyrus in the anterior parietal lobe
- Visual cortex - found in the occipital lobe
- Auditory cortex - found in the temporal lobe
State what is being labelled Begin with black box End with the brown box
- Black - Corpus callosum
- Red - Septum pellucidum
- Orange - Hypothalamus
- Dark green - Pons
- Light blue - Medulla oblongata
- Dark blue - cerebellum
- Lime green - midbrain
- Brown - thalamus
Where does the septum pellucidum sit?
The septum pellucidum is a sheet separating the anterior horns of the lateral ventricles running down from the corpus callosum to the fornix
What is the white matter tract connecting the cerebral hemispheres known as?
The corpus callosum is the white matter tract connecting the two cerebral hemispheres
- What are tracts between the gyri of the same hemisphere known as?
- What are tracts/fibres from one hemisphere to the same region of the other hemisphere known as?
- What are fibres from cerebrum to thalamus, brainstem etc known as?
Which one of the three above is the corpus callosum?
- * Tracts between gyri of the same hemisphere are known as association tracts
- * Tracts/fibres from one hemisphere to the same region of the other hemisphere are known as commissural tracts/fibres - corpus callsoum consists of a flat bundle of commissural fibres
- * Fibres form cerebrum to thalamus, brainstem etc are known as projection fibres
What structures make up the basal ganglia?
- Caudate nucleus
- Globus pallidus
- Putamen
- Substantia nigra
- Subthalamic nucleus
What is the function of the basal ganglia?
To facilitate purposeful movement
To inhibit unwanted movement
It is also thought to be involved in memory, planning and emotional response via the limbic system
What separates the caudate nucleus and the thalamus from the globus pallidus and putamen on a coronal section?
The internal capsule separates the caudate nucleus and thalamus from the globus pallidus and putamen ona coronal section
- What is the globus pallidus + putamen known as? Which is found closer to the thalamus?
- What is the globus pallidus + putamen + caudate nucleus known as?
- What is the putamen + caudate nucleus known as?
- Globus pallidus + putamen is known as the Lentiform nucleus (globus pallidus is closer to the thalamus)
- Globus pallidus + putamen + caudate nucleus is known as the Corpus striatum
- Putamen + caudate nucleus is known as the Striatum
Where is the substantia nigra found and what does it communicate with?
What does the subthalamic nucleus communicate with?
Substantia nigra is found in the midbrain and communicates with the caudate nucleus and putamen Subthalamic nucleus communicates with the globus pallidus
What artery do the branches to the basal ganglia mainly come from?
Branches to the basal ganglia mainly come from the middle cerebral artery which runs within the lateral fissure
What does the diencephalon give rise to?
The diencephalon gives rise to the thalamus + hypothalamus + epithalamus (contains pineal gland)
What is the major sensory relay station of the brain? How is sensation relayed from spinal cord to here?
The thalamus is the major sensory relay station
Sensory information travels from the spinal cord, to the brainstem to the thalamus and then to the cerebral hemispheres
The thalamus is the major sensory relay system It is also involved in the motor pathways What structure does the thalamus also have connections to?
The thalamus also has connections to the hypothalmus and limbic system
What connects the hypothalamus to the pituitary gland? What is the function of the hypothalamus?
The hypothalamus is connected to the pituitary gland by the infundibulum Hypothalamus is involved in the regulation of the ANS and homeostasis (body temperatures, thirst centres etc) and produces hormones
The pineal gland forms part of the epithalamus found (thalamus + hypothalamus + epithalamus make up diencephalon) What is the function of the pineal gland? What else is found in the epithalamus?
The pineal gland produces melatonin to regulate the body clock The epithalamus also contains the habenular nucleus which is involved in olfaction and the emotional resposne
Which cranial nerves arise in the midbrain and at the level of what?
Cranial nerves III (oculomotor) and IV (trochlear) arise in the midbrain
- CN III arises at the level of the superior colliculus
- CN IV arises at the level of the inferior colliculus
What does the midbrain connect?
The midbrain connects the pons and medulla to the diencphalon
Within the midbrain, we can find the
- * Cerebral aqueduct
- * Superior colliculi
- * Inferior colliculi
- * Substantia nigra
- * Red nucleus
State what each of these is involved in
- Cerebral aqueduct - communication between the 3rd and 4th ventricle
- Superior colliculi - visual tracking/scanning
- Inferior colliculi - involved in the auditory startle reflex (jump scare)
- Substantia nigra - controls sub-conscious muscle action
- Red nucleus - co-ordinate muscle movement
Which cranial nerves originate in the pons? Which cranial nerves originate in the medulla oblangata?
Pons - CN V, VI, VII and the vestibular part of CN VIII
Medulla - CN IX, X, XI, XII and the cochlear part of CN VIII
What is the function of the pontine nuclei? Name a tract which is found in the pons?
The pontine nuclei are involved in co-ordination and maximise motor output
There are also tracts in the pons such as the pneumotaxic tract which helps to control breathing (inhibits respiration) and the apneustic tract which helps (promotes respiration)
What are the vertical columns of the medulla known as and what tracts are found here? What are the little lumps on either side of the medulla known as and what are they involved in?
The vertical columns of the medulla are known as the medullary pyramids and make up part of the motor tracts
The little lumps on either side of the medulla are the medullary olives and they are involved in proprioception (joint and muscle position)
Already said how the medullary pyramids (motor tracts are found in the medulla) What centres are found in the medulla? What sensations are the medullary nuclei concerned with?
- The medulla contains both respiratory centres and cardiovascular centres (rate/force of heartbeat and diameter of vessels)
- The medullary nuclei are concerned with touch, pressure and vibration
- The olives are concerned with proprioception
What separates the cerebellum form the occipital lobe?
The cerebellum is separated from the occipital lobe by the tentorium cerebelli
What are the lobes of the cerebellum and what runs between this lobes?
Cerebellar lobes - anterior, posterior and flocculonodular lobe Between these lobes runs the vermis of the cerebellum
What is the cerebellar white matter known as? What are the cerebella folds known as?
Cerebellar white matter known as arbor vitae (tree of life)
Cerebellar folds known as folia
What does the cerebellum control? What does the cerebellum regulate?
The cerebellum controls sub conscious aspects of skeletal muscle movements and co-ordinates complex sequences
The cerebellum regulates posture and balance
The cerebellum communicates with the brainstem via little foot processes known as peduncles Where do these peduncles connect?
- Superior peduncle connects midbrain to cerebellum
- Middle peduncle connects pons to cerebellum (largest)
- Inferior peduncle connects medulla to cerebellum
Where does the pituitary gland sit? What is the layer of dura covering the pituitary gland known as?
The pituitary gland sits in a depression in the pituitary fossa which lies in a depression in the sphenoid bone known as the sella turcica The pituitary gland is covered by a pierce of dura known as the diaphragma sella
What hormones does the pituitary gland release?
- Anterior pituitary -
- Growth hormone,
- Follicle stimulating hormone,
- Lutenising hormone,
- Thyroid stimulating hormone,
- Adrenocorticotropic hormone,
- Prolactin
- Posterior pituitary
- Anti-diuretic hormone,
- Oxytocin
Sitting underneath the brain is the circle of willis What are the two major input arteries for the circle of willis? What arteries make up the circle of willis?
Two major input arteries are the internal carotid artery and the basilar artery
- Vertebral arteries join to form the basilar artery which gives off posterior cerebral artery which connects to the ICA via the posterior communicating artery
- ICA gives off the anterior cerebral arteries which are connected by the anterior communicating artery
Where do the vertebral arteries arise from?
Vertebral arteries arise form the 1st part of the subclavian artery
What branches does the basilar artery give before its bifurcation?
- What does the posterior cerebral artery supply?
- What does the middle cerebral artery supply?
- What do the anterior cerebral arteries supply?
Basilar artery gives branches to cerebellum (superior cerebellar/anterior inferior cerebellar), pontine and medullary branches
- Posterior cerebral artery supplies occipital lobe and base of brain
- Middle cerebral artery supplies temporal lobe
- Anterior cerebral artery supplies frontal and parietal lobes
What are the three layers of protective tissue around the brain collectively and individually known as?
The meninges * Dura mater * Arachnoid mater * Pia mater
Where does CSF flow?
CSF flows in the sub-arachnoid space between the pia and arachnoid mater
Which layer of the meninges lines the skull and forms venous sinuses? Which adheres to the surface of the brain going into the sulci and around the gyri? Which layer covers the surface of the brain and carries the blood vessels?
- The dura mater lines the skull and forms dural venous sinuses
- The pia mater will adhere to the brain going into the sulci and gyri
- The arachnoid mater will cover the surface of the brain and carry the blood vessels
What are the small sacs that carry CSF into the dural venous sinuses? What is the dural fold which separates the two cerebral hemispheres and is found in the longitudinal fissure?
Small arachnoid granulations carry CSF from subarachnoid space into the dural venous sinuses The falx cerebri separates the two cerebral hemispheres
The dura mater is supplied by the
- * Anterior meingeal artery
- * Middle meningeal artery
- * Posterior meingeal artery
Where does each artery arise and which is the main supplier?
- Anterior arises from the ethmoidal branches from the ophthalmic artery from the ICA - supplies dura of the anterior fossa
- Middle arises from the mandibular part of the maxillary artery - the main supplier of the meninges
- Posterior - arises from the occipital artery - supplies dura of the posterior fossa
- Anterior meningeal artery - ethmoidal branches from ophthalmic artery –> ICA
- Middle meningeal artery - mandibular part of maxillary artery –> ECA
- Posterior meningeal artery - occipital artery –.> ECA
Does the brain have any sensory nerve endings? What is different about the arachnoid and pia mater blood supply?
Brain does not have any sensory nerve endings but there is a sensory nerve supply to the dura Arachnoid mater is avascular Pia mater is also vascularised (dont need to learn the vascular supply)
The trigeminal nerve gives sensory branches back into the skull to supply the dura mater What is the specific sensory nerve innervation to the falx cerebri and the tentorium cerebelli?
Falx cerebri - anterior meningeal branches of ethmoidal nerve (CN V1) Tentorium cerebelli - Tentorial nerve - recurrent meningeal branch of CN V1
State what nerve branches each box is pointing to The nerves on the right are innervating the floor of the posterior cranial fossa
- Black - Anterior meingeal branches of ethmoidal nerve (CN V1)
- Red - Meningeal branch of maxillary nevre (CN V2)
- Blue - Meningeal branch of mandibular nerve (CN V3)
- Green - Tentorial nerve (recurrent meningeal branch of ophthalmic nerve (CN V1))
What are the nerve roots of the sensory innervation to the dura over the floor of the posterior cranial fossa?
Dura on the floor of the posterior cranial fossa is innervated by C2,3 cervical nerve fibres
Each sinus is formed either between the periosteum of the skull and the dura or between two layers of dura Give an example of each of the dural venous sinuses?
The sigmoid and superior saggital sinuses are formed between the perisoteum of the skull and the dura The inferior saggital sinus is between two layers of the dura mater
What sinuses drain into the confluence of sinuses and where is it located? Where does the confluence of sinsues drain?
The confluence of sinuses (deep to the external occipital protuberance) drains the superior saggital sinus, straight sinus and occipital sinus
- The confluence of sinuses drains into the transverse sinuses which continue as the sigmoid sinuses which exit the skull via the jugular foramen into the internal jugular vein
What are the possible routes of infection into the meninges from the sinuses? (ie from scalp to sinuses and from face to sinsues)
Communication between the emissary veins of the scalp (connecting superficial scalp veins from connective tissue layer to the dural venous sinuses) and superior saggital sinus
And the facial veins draining back into the cavernous dural venous sinsues represent possible routes of infection for bacteria to the meninges
What is the function of CSF? Where and how is it produced?
CSF provides a mechanical and physical protection to the brain and spinal cord It is produced in the choroid plexus of each ventricle (mainly the lateral ventricles)
The choroid plexuses contain ependymal cells which filter blood plasma to make CSF
Describe the flow of the CSF?
CSF is produced in the lateral ventricles (choroid plexuses), it travels via the interventricular foramina (of Monroe) to the 3rd ventricle in the thalamus
The cerebral aqueduct running in the midbrain connects 3rd ventricle -4th 4th ventricle connected to subarachnoid space by 2 lateral apertures and 1 medial aperture
Lateral ventricles connected to 3rd ventricle by interventricular foramina of Monroe 3rd ventricle found in the thalamus and is connected to the 4th ventricle by cerebral aqueduct (midbrain) 4th ventricle drains into medial and lateral apertures
- What is the other name for these apertures?
- Which connects to CSF in subarachnoid space?
- Which connects to CSF in central canal of spinal cord?
Lateral apertures drains from 4th ventricle to subarachnoid space - lateral aperture of Luschka
Medial aperture drains 4th ventricle to CSF in central canal of spinal cord - medial aperture of Magendie
