Topography of the Brain Flashcards
Where is the seat of consciousness located?
Cerebrum
What part of the brain is responsible for balance and coordination?
Cerebelum
What does the brainstem contain?
- Vital centres
- Pathway for fibre tracts
- Location of cranial nerve nuclei
What are the 3 components of the brainstem?
- Midbrain
- Pons
- medulla
What ventricles are found in the brain?
- Lateral ventricles
- III ventricle
- Cerebral aqueduct
- IV ventricle
Where are the lateral ventricles found?
Within the cerebral hemispheres
Where is the III ventricle found?
Within the diencephalon
Where is the cerebral aqueduct found?
Within the midbrain
Where is the IV ventricle found?
Between pons and medulla (in front) ad cerebellum (at the back)
Where is the CSF found?
- Inside the ventricles
- Between pia and arachnoid mater
What forms the CSF?
Choroid plexus in each lateral ventricle
Where is the CSF absorbed?
Absorbed into the superior sagittal sinus (venous channel in the brain) by the arachnoid villi
What are the functions of the brainstem?
- Pathway for fibre tracts running between higher and lower centres
- Brainstem nuclei are involved with 10 of the 12 cranial nerves, so innervation of head and neck
- Brainstem centres produce the rigidly programmed automatic behaviours essential for survival
What cavity is located in the medulla (oblongata)?
IV ventricle
What does the medulla continue as inferiorly?
Spinal cord at foramen magnum of cranium
What does the lower part of the medulla resemble in structure?
Spinal cord
What are the surface features of the medulla?
- Pyramids and their decussation (crossing over)
- Olives laterally
- Connected to cerebellum by inferior cerebellar peduncle
- Cranial nerves IX, X, XI and XII from its surface
What is the caudal part of the medulla closed around?
IV ventricle
What is the cranial part of the medulla open with?
IV ventricle posteriorly
What does the white matter of the medulla contain?
- Pyramidal tract
- Medial lemniscus
- Inferior cerebellar peduncle
- Other tracts
What does the grey matter of the medulla contain?
- Cranial nerve nuclei and inferior olivary nucleus
- Nucleii of the reticular formation (vital centres)
- Sensory nuclei (gracile and cuneate)
What is posterior to the pons?
IV ventricle
What are the surface features of the pons?
- Middle cerebellar peduncle
- Cranial nerves V, VI, VII and VIII originate from its surface
What does the white matter of the pons contain?
- Middle cerebellar peduncle
- Medial lemniscus (sensory)
- Pyramidal tract (motor)
What does the grey matter of the pons contain?
- Cranial nerve nuclei
- Pontine nuclei
- Nucleii of reticular formation
What does the midbrain develop from?
Mesencephalon
What is the central cavity of the midbrain?
Cerebral aqueduct
What are the surface features of the midbrain?
- Cerebral peduncle
- Superior cerebellar peduncle
- Corpora quadrigemina (superior and inferior colliculus)
- Origin of the oculomotor and trochlear nerves
What is the only nerve to originate posteriorly?
Trochlear
What will you always see in section of the midbrain?
Substantia nigra
What components will be seen on horizontal section of the midbrain?
- Central cavity (cerebral aqueduct)
- Periaqueductal grey matter with nucleus for III and IV cranial nerves
- White matter with embedded nuclei surrounds the periaqueductal grey mater
What does the cerebral aqueduct connect?
Connect III and IV ventricles
What separates the right and left hemispheres of the cerebellum?
Vermis
What lobes are present on each hemisphere of the cerebellum?
- Anterior
- Posterior
- Fluccoluonodular
What does the surface of the cerebellum have?
Sulci and folia
How is the cerebellum connected to the brainstem?
Via three cerebellar peduncles
What is found in the grey matter of the cerebellum?
- Cortex on surface
- Deep nuclei
What is found in the white matter of the cerebellum?
- Arbor vitae
- Cerebellar peduncles
What is the function of the cerebellum?
- Posture maintenance
- Fine tuning motor activity
What is abnormality of the cerebellum known as?
Ataxia
What tests are there for ataxia?
- Finger-nose test
- Knee heel test
- Walking in a straight line
Where does the cerebellum receive information from?
- Pyramidal tracts (motor intention of brain)
- Ipsilateral proprioceptors from periphery
- Vestibular nuclei re. balance and posture
What does the cerebellum calculate upon receiving information?
Calculates best way to coordinate force, direction, extent of muscle contraction to maintain posture prevent overshoot and ensure smooth coordinated muscle contraction
What does the cerebellum ‘send’ once it has received information?
Sends ‘blueprint# back to cerebral cortex via superior cerebellar peduncle
Where is the diencephalon found?
Deep within cerebral hemispheres around III ventricle
What does the diencephalon develop from?
Diencephalic vesicle (part of forebrain vesicle)
What are the paired structures of the diencephalon?
All are mainly grey matter
- Thalamus
- Hypothalamus (and pituitary)
- Epithalamus (pineal gland)
What does the thalamus mainly contain?
Groups of nuclei
What groups of nuclei does the thalamus contain?
- Anterior
- Medial
- Lateral
What is the lateral group of nuclei of the thalamus involved in?
Processing sensory information
What is the thalamus?
A sensory relay station
Where is the hypothalamus?
Lies below the thalamus separate from it by the hypothalamic sulcus
What is the hypothalamus?
The main visceral control centre
What is the hypothalamus 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 an thirst
- Regulation of sleep-wake cycle
- Control of endocrine system functioning
What is the blood supply to the brain?
- Internal carotid arteries
- Vertebral arteries
How do the internal carotid arteries enter the brain?
Through the carotid canal of the skull (Foramen lacerum) t
How do the vertebral arteries enter the brain?
Through the foramen magnum
What branches of the ICA supply the brain?
- Anterior cerebral artery
- Middle cerebral artery
- Posterior communicating arteries
What do the ACA and MCA supply?
A large part of the cerebral hemispheres
What do the 2 vertebral arteries join together to form?
Basilar artery
Where is the basilar artery?
Ventral surface of the brainstem
What do the branches of the vertebra-basilar system supply?
Brainstem and cerebellum
Where does the basilar artery end?
Level of the midbrain
How does the basilar artery end?
Divides into the posterior cerebral arteries
What do the posterior cerebral arteries supply?
The posterior part of the cerebral hemispheres
How is the Circle of Willis formed?
Branches of the ICA join with those of the opposite side and with the PCA
What is the protective feature of the Circle of Willis?
Protective against vaso-occlusion of large arteries
What are effectively end arteries?
The branches of the ICA supplying the cerebral hemispheres distal to the circle of willis
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 doe the veins of the brain drain into?
Superficial and deep veins of the brain drain into venous sinuses
Where are the venous sinuses found?
Between the 2 layers of dura mater
What do the dural venous sinuse drain into?
The dural venous sinuses join together to ultimately drain into the internal jugular veins
