Topography of the Brain Flashcards
When do the ectoderm, mesoderm and endoderm become established during embryonic development?
By the beginning of the second week
What germ layer gives rise to the nervous system in the adult?
Ectoderm
The process of formation of the embryonic nervous system is known as
neurulation
The dorsal midline ectoderm undergoes thickening to form the neural plate during which week of embryonic development?
Third week
The lateral margins of the neural plate become elevated to form
neural folds on either side of the neural groove
The neural folds become apposed and
fuse together, sealing the neural groove and forming neural tube
What processes occur during transformation of the neural tube into the adult CNS?
Growth
Distortion
Cellular differentiation
What part of the neural tube develops into the brain?
The rostral part
What part of the neural tube develops into the spinal cord?
The caudal part
The central cavity within the neural tube becomes the
central canal of the spinal cord and the ventricles of the brain
The neural crests form the
sensory ganglia of spinal and cranial nerves and autonomic ganglia
What three primary vesicles can be identified around the fifth week of embryonic development?
Prosencephalon
Mesencephalon
Rhomboencephalon
The prosencephalon becomes the
cerebrum
The telencephalon becomes the
two cerebral hemispheres
The diencephalon becomes the
thalamus
The mesencephalon becomes the
pons and cerebellum
The myencephalon becomes the
medulla oblongata
The brainstem consists of the
medulla, pons and midbrain
The brainstem acts as a pathway for
fibre tracts running between higher and lower centres
Brainstem centres produce
the rigidly programmed automatic behaviours essential for survival
Where does the diencephalon lie?
Deep within the cerebral hemispheres, around the III ventricle
What are the paired structures of the diencephalon?
Thalamus
Hypothalamus
Pituitary
Epithalamus
What is the thalamus responsible for?
Processing sensory information, acts as a sensory relay
What is the hypothalamus responsible for?
Visceral control centre, essential for overall homeostasis
Give the homeostatic functions of the hypothalamus
Autonomic control centre Body temp. regulation Regulation of food intake Regulation of water balance and thirst Regulation of sleep-wake cycle Control of endocrine system functioning
How do the common carotid arteries enter the skull to supply the brain?
Through the carotid canal (foramen lacerum)
What branches does the ICA give off in the brain?
Anterior and middle cerebral and posterior communicating arteries
What branches of the ICA supply a large part of the cerebral hemispheres?
Anterior and middle cerebral arteries
How do the vertebral arteries enter the skull?
Through the foramen magnum
The vertebral arteries join together to form
the basilar artery (on ventral surface of brainstem)
The basilar artery ends at the level of the
midbrain, by dividing into two posterior cerebral arteries
The two posterior cerebral arteries supply
the posterior part of the cerebral hemispheres
What is the Circle of Willis?
Continous circle of arteries at the base of the brain
What does the Circle of Willis protect against?
Vaso-occlusion of large arteries
The superficial and deep veins of the brain drain into
venous sinuses between the two layers of dura mater
The dural venous sinuses join together to drain into the
internal jugular veins
The vertebrobasilar arteries supply
the posterior two-fifths of the cerebrum, part of cerebellum and brainstem
The external carotid arteries supply
the face and scalp
The internal carotid arteries supply
most of the anterior portion of cerebrum
Any decrease in the flow of blood through one of the ICAs brings about
some impairment in the function of the frontal lobes which may result in numbness/weakness/paralysis of opposite side of body
Because the carotid and vertebrobasilar arteries form a circle, if one of the main arteries is occluded then
the distal smaller arteries that it supplies can receive blood from the other arteries
Stroke in the anterior cerebral artery results in
opposite leg weakness
Stroke in the middle cerebral artery can result in
paralysis, sensory loss in opposite side, aphasia
Weber’s syndrome results from occlusion of what arteries?
Posterior cerebral
