Topography of the Brain Flashcards
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
Where does the 2 internal carotid arteries enter the skull to supply the brain?
Carotid canal
foramen lacerum
Where does the 2 vertebral arteries enter the skull to supply the brain?
Foramen magnum
What is the Circle of Willis?
Branches of the internal carotid artery join together from both sides and with the posterior cerebral artery to form a continuous circle at the base of the brain
What is the importance of the Circle of Willis?
Protective feature against vaso-occlusion of large arteries
What branches does the internal carotid artery give?
Anterior cerebral artery
Middle cerebral artery
Posterior communicating arteries
What artery is formed by the joining of the 2 vertebral arteries on the ventral surface of the brainstem?
Basilar artery
What does the vertebro-basilar system supply?
Gives branches that supply the brainstem and cerebellum
Where does the basilar artery end?
Level of the midbrain - divides into 2 posterior cerebral arteries
What do the posterior cerebral arteries supply?
Posterior part of the cerebral hemispheres
What does the anterior cerebral artery supply?
Medial aspect of cerebral hemispheres excluding occipital lobe
What does the middle cerebral artery supply?
Lateral aspect of cerebral hemispheres
What does the posterior cerebral artery supply?
Inferior aspect of cerebral hemispheres and occipital lobe
Where do superficial and deep veins of the brain drain into?
Venous sinuses which lie between 2 layers of dura mater
Where do the dural venous sinuses drain into?
Internal jugular veins
When does the neural tube divide into 3 primary vesicles?
As soon as it is formed
Week 4
When does the neural tube divide into secondary vesicles?
Week 5
What is in the brainstem?
Midbrain, pons, medulla
What are the functions of the brainstem?
Pathway for fibre tracts between higher and lower centres
Nucleii involved with 10/12 cranial nerves
Brainstem centres produce the rigidly programmed automatic behaviours that are essential for survival
What is the cavity in the medulla called?
IV ventricle
What does the medulla become?
Continues as spinal cord and foramen magnum of cranium
What are the surface features of the medulla?
Pyramids and their decussation
Olives laterally
Connected to cerebellum by inferior cerebellar peduncle
CN IX, X, XI, XII from its surface
Where is the IV ventricle in relations to the pons?
Posterior
What are the surface features of the pons?
Middle cerebellar peduncle
CN V, VI, VII, VIII originate from its surface
What does the midbrain develop from?
Mesencephalon
What is the central cavity in the midbrain called?
Cerebral aqueduct
What are the surface features of the midbrain?
Cerebral peduncle
Superior cerebellar peduncle
Corpora quadrigemina (superior and inferior collicolus)
Origin of oculomotor and trochlear nerves
What cranial nerve is the only nerve to originate posteriorly?
Trochlear (IV)
What connects the 3rd and 4th ventricles in the brainstem?
Cerebral aqueduct
What separates the right and left cerebellar hemispheres?
Vermis
What are the 3 lobes of each cerebellar hemisphere?
Anterior
Posterior
Flocculonodular
What does the surface of the cerebellum consist of?
Sulci
Folia
How many cerebellar peduncles connect the cerebellum to the brainstem?
3
What are the 2 main functions of the cerebellum?
Posture maintenance
Fine tuning motor activity
What tests identify ataxia?
Finger - nose test
Knee - heel test
Walking in a straight line
Where is the diencephalon?
Deep within cerebral hemispheres, around the III ventricle
Which vesicle does the diencephalon develop from?
Diencephalic vesicle (part of forebrain vesicle)
What are the paired structures within the diencephalon?
Thalamus
Hypothalamus (+ pituitary)
Epithalamus (pineal gland)
What is the thalamus?
Egg shaped body on either side of the III ventricle
Makes up 80% of the diencephalon
What groups of nucleii lie within the thalamus?
Anterior
Medial
Lateral
What is the lateral group of nucleii in the thalamus involved in?
Processing sensory information
What is the function of the thalamus?
Sensory relay station
Where is the hypothalamus?
Below the thalamus separated from it by the hypothalamic sulcus
What is the hypothalamus’ function?
Main visceral control centre
Essential for overall homeostasis
What is the homeostatic role 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
