Topography of the Brain Flashcards
What can the brain be divided into?
Cerebral hemispheres
Diencephalon
Cerebellum
Brainstem (midbrain, pons, medulla oblongata)
What is the brainstem composed of?
Midbrain
Pons
Medulla oblongata
What is white matter?
Myelinated axons
What is grey matter?
Neuronal cell bodies
What is a tract?
Fibre pathway passing through the CNS carrying a specific modality (such as motor fibres or pain sensation or touch sensation)
What is a nucleus?
Neuronal cell body collection (grey) within CNS
What is a ganglion?
Neuronal cell bodies outside of CNS (such as dorsal root ganglion)
What are ventricles?
Spaces in the brain
What are the different ventricles?
Lateral ventricles (x2)
III ventricle
Cerebral aquaduct
IV ventricle
Where are the lateral ventricles located?
Within cerebral hemispheres
Where is III ventricle located?
Within diencephalon
Where is cerebral aquaduct located?
Within midbrain
Where is IV ventricle located?
Between pons and medulla (in front) and cerebellum (at the back)
Where is CSF found?
Inside ventricles and in the subarachnoid space
What is CSF formed by?
Choroid plexus in each ventricle
Where is CSF absorbed to?
Arachnoid villi into saggital sinus
What do the internal carotid arteries enter the skull through?
Carotid canal (foramen lacerum)
What vessels provide the main blood supply to the brain?
Internal carotid arteries
Vertebral arteries
What are the internal carotid arteries branches off?
Common carotid arteries
What are the two vertebral arteries branches off?
Subclavian artery
How do the vertebral arteries enter the skull?
Throught the foramen magnum
What is the circle of Willis a protective feature against?
Vaso-occlusion of large arteries
What forms the circle of Willis?
Branches of the ICA join with those of the opposite side and with the PCA (branch of the basilar artery) to form a continous circle at the base of the brain
What is A?
Anterior cerebral artery
What is B?
Anterior communicating artery
What is C?
Internal carotid artery
What is D?
Posterior communicating artery
What is E?
Posterior cerebral artery
What is F?
Basilar artery
What is G?
Anterior spinal artery
What is H?
Vertebral artery
What branches come of the ICA?
Anterior communicating artery (ACA)
Middle communicating artery (MCA)
Posterior communicating artery (PComA)
What do the anterior and middle communicating arteries supply a large part of?
Cerebral hemispheres
What do the two vertebral arteries join together to form and where does this occur?
Basilar artery, happens on the ventral surface of the brainstem
What does the vertebral-basilar system give off branches to supply?
Brainstem and cerebellum
Where does the basiliar artery end and what does it divide into?
Level of the midbrain dividing into two posterior cerebral arteries (PCA) which supply the posterior part of the cerebral hemispheres
What does ACA stand for?
Anterior communicating artery
What does MCA stand for?
Middle communicating artery
What does PComA stand for?
Posterior communicating artery
What does PCA stand for?
Posterior cerebral arteries
What does the anterior cerebral artery supply?
Medial aspect of cerebral hemispheres exclding occipital lobe
What does the medial cerebral artery supply?
What does the posterior cerebral artery supply?
Inferior aspect of cerebral hemipheres and occipital lobe
What do superficial and deep veins of the brain drain into?
Venous sinuses that lie between 2 layers of dura mater
Where do venous sinuses lie between?
2 layers of dura mater
Where do the dural venous sinuses drain into?
Join together to ultimately drain into the internal jugular veins
What is A?
Transverse sinuses
What is B?
Superior sagittal sinus
What is C?
Great cerebral vein
What is D?
Cavernous sinus
What is E?
Petrosal sinus (superior and inferior)
What is F?
Internal jugular veins
What is A?
Diencephalon
What is B?
Brainstem
What is C?
Cerebellum
What is D?
Cerebrum
What is found in the brainstem?
Vital centres such as cardiorespiratory
Pathway for fibres
What is the cerebellum responsible for?
Balance and coordination
What is the cerebrum?
Seat of consciousness
In embryology, what does the neural tube develop from?
Dorsal surface ectoderm
In embryology, what happens to the cranial end of the neural tube?
Forms vesicles each of which develop into different parts of the brain
In embryology, how many vesicles does the neural tube divide into
3 primary vesicles (week 4) and then into 5 secondary vesicles (week 5)
What are the 3 primary vesicles that the cranial end of the neural tube forms?
Prosencephalon (forebrain)
Mesencephalon (midbrain)
Rhomboencephalon (hindbrain)
What vesicle goes on to form the forebrain?
Prosencephalon
What vesicle goes on to form the midbrain?
Mesencephalon
What vesicle goes onto form the hind brain?
Rhomboencephlon
Which of the 3 primary vesicles go on to allow the development of the 5 secondary vesicles?
Prosencephlon
Rhomboencephalon
What are the 3 parts of the brainstem?
Midbrain
Pons
Medulla
What is found in the brainstem?
Cranial nerves III-XII
Tracts from spinal cord
Vital centres such as cardiorespiratory centre
What cranial nerves are found in the brainstem?
Cranial nerves III-XII
What are some functions of the brainstem?
Pathway for fibre tracts running between higher and lower centres
Brainstem nuclei involved with 10 of the 12 cranial nerves, so innvervation of the head and neck
Brainstem centres produce the rigidly programmed autonomic behaviours essential for survival
What cavity is found in the medulla?
IV ventricle
What does the medulla continue as?
Spinal cord at foramen magnum of cranium
What does the lower part of the medulla resemble in structure?
Spinal cord
What are some surface features of the medulla?
Pyramids and their decussatoin (crossing over)
Olives laterally
Connected to cerebellum by inferior cerebrllar peduncle
Cranial nerves Ix, X, XI and XII from its surface
What white matter is found in the medulla?
Pyramidal tract
Medial lemniscus
Inferior cerebellar peduncle
Other tracts
What grey matter is found in the medulla?
Cranial nerve nucleii and inferior olivary nucleus
Nucleii of the reticular formation (vital centres)
Sensory nucleii (gracile and cuneate)
What ventricle is posterior to the pons?
IV ventricle
What are surface features of the pons?
Middle cerebellar peduncle
Cranial nerves V, VI, VII and VIII originate from its surface
What cranial nerves originate from the surface of the medulla?
IX, X, XI and XII
What cranial nerves originate from the surface of the pons?
V, VI, VII and VIII
What white matter is found inside the pons?
Middle cerebellar peduncle
Medial lemniscus (sensory)
Pyramidal tract (motor)
What grey matter is found inside the pons?
Cranial nerve nucleii
Pontine nucleii
Nucleii of reticular formation
What is the central cavity in the midbrain?
Cerebral aquaduct
What are the surface features of the midbrain?
Cerebral penuncle
SUperior cerebellar peduncle
Corpora quadrigemina (superior and inferior colliculus)
Origin of oculomotor (CN III) and trochlear (CN IV)
What cranial nerves originate in the midbrain?
III and IV
What is the only cranial nerve to originate posteriorly?
CN IV
What does the cerebral aquaduct connect?
III ventricle and IV ventricle
What are the right and left hemispheres of the cerebellum seperated by?
Vermis
What lobes are found on each hemispheres of the cerebellum?
Anterior, posterior and floculonodular lobe
What connects the cerebellar to each part of the brainstem?
3 cerebellar peduncles
What is found on the surface of the cerebellum?
Sulci and folia
What is sulci?
A groove on the surface of the brain
What is folia?
Folds on the outer surface of the brain
What white matter is found in the cerebellum?
Arbor vitae
Cerebellar peduncles
What grey matter is found in the cerebellum?
Cortex on surface
Deep nucleii
What are the functions of the cerebellum?
Posture maintanence
Fine tuning motor activity
Explain the process of the cerebellum achieving its functions?
1) Recieves information from pyramidal tracts (motor intention of brain), ipsilateral proprioceptors from periphery and vestibular nucleii regarding balance and posture
2) Calculates best way to coordinate force, direction, extent of muscle contraction to maintain posture and prevent overshoot and ensure smooth coordinated muscle contraction
3) Sends ‘blueprint’ back to cerebral cortex via superior cerebellar peduncle
What is an abnormality of the cerebellum?
Ataxia
What is ataxia?
Group of disorders that affect coordination, balance and speech
Where is the diencephalon found?
Within cerebral hemispheres around III ventricle
What does the diencephalon develop from?
Diencephalic vesicle (part of forebrain vesicle)
What are paired structures found in the diencephalon?
Thalamus
Hypothalamus (and pituitary)
Epithalamus (pineal gland)
What are the thalamus, hypothalamus and epithalamus mainly composed of?
Grey matter
What is A?
Lateral ventricles
What is B?
Pineal gland (epithalamus)
What is C?
Thalamus
What is D?
Hypothalamus
What is E?
Infundibulum (stalk of pituitary)
What is F?
Subthalamus
What groups of nuclei does the thalamus contain?
Anterior, middle and lateral group
What group of nucleii of the thalamus is involved in processing sensory information?
Lateral group
What is the thalamus?
Sensory relay station
Where is the thalamus found?
Egg shaped body on either side of III ventricle amking up 80% of diencephalon
Where is the hypothalamus found?
Lies below the thalamus separated from it by the hypothalamic sulcus
What is the hypothalamus seperated from the thalamus by?
Hypothalamic sulcus
What is the hypothalamus?
Main visceral control centre and is essential for overall homeostasis
What are some of the homeostatic roles of the hypothalamus?
Autonomic control centre
Body temperature regulation
Regulation of food intake
Regulation of water balance and thirst
Regulation of sleep-wake cycle
Control of endocrine system functioning
