Functional anatomy of Brain Flashcards
what does white matter contain?
contains myelinated nerve fibres
what part of the motor cortex is contained in the frontal lobe?
the part associated with voluntary movement, as well as areas associated with psychomotor skills
cerebellum - gray matter?
the gray matter forms an external layer, the cerebellar cortex with a lot of folds and the cerebellar nuclei
the white matter in the cerebellum is composed of?
it is composed of fibres that look like a tree, hence known as arbor vitae
what does the cerebellum do?
it is involved in maintenance of balance, coordination but doesn’t initiate them
control and adjusts body movements
maintaining proper position of body in space and coordination of movement
describe the brain stem?
it is continuous with the spinal cord and is the smallest and least changed region
pons?
fibres situated parallel - found in ventral metencephalon
are the gyri and sulci symmetrical in appearance/function on each hemisphere?
yes they are
are the corpora quadrigemina and the rostral/caudal colliculus the same thing?
yes they are, two rostral and two caudal colliculus
which cranial nerve leaves from the forebrain?
optic nerve
what structures are part of the diencephalon?
hypothalamus
thalamus
hypophysis
(PONS IS NOT PART OF IT - IT IS BRAIN STEM)
Deep to the cerebral cortex are aggregates of subcortical white matter called basal nuclei - true/false
false - it’s gray matter
fibre that connects two parts of your brain - left/right?
corpus callosum - connects two hemispheres
which part of the brain initiates voluntary skeletal muscle movements?
cerebrum
what region is characterised by four round swelling - corpora quadrigemina?
midbrain
meninges - outer layer?
Dura mater - thick outer later which is tough and fibrous
middle layer of meninges?
Arachnoid layer - thin middle layer-non-vascular connective tissue - many fine filaments that traverse the subarachnoid space connecting with pia matter
inner layer - meninges?
pia mater - innermost, vascular layer - firmly attached to the underlying nervous tissue
what makes the leptomeninges (lepto-thin)?
arachnoid and pia mater
in two places - dura mater folds inwardly to form?
to form double-layered folds (falx cerebri and tentorium cerebelli)
subarachnoid space?
space between arachnoid and pia mater - filled with CSF - contains fine network of connective tissue fibres that originate from arachnoid
what are the ventricles of the brain derived from?
from the fluid-filled centre of the embryonic neural tube
what are the ventricles of the brain?
the ventricles are a series of interconnected cavities in the core of the brain that have an ependymal cell lining and are filled with cerebrospinal fluid (CSF)
cavity forms?
four ventricles, connected to each other and to central canal in spinal cord
what produces cerebrospinal fluid?
small arteries and arterioles in the leptomeninges and choroid plexus in the ventricles produce the majority CSF
choroid plexus formed by?
by invagination of pia matter into ventricles
plexuses consist of?
tufts of capillaries covered by a layer of ependymal cells
how does CSF flow?
flows down a pressure gradient from ventricles to subarachnoid space where it bathes the surface of the central nervous system
what does CSF fill?
fills the subarachnoid space as well as the ventricular system
from the subarachnoid space - where does thw CSF eventually go to?
eventually passes into the venous system (arachnoid villi)
CSF drained from?
drained from the subarachnoid space via arachnoid villus
into venous sinuses of brain
venules of the subarachnoid space
Drained into lymphatic vessels
IN CONCLUSION - CSF is produced by blood and returned to the blood
microscopic arachnoid villi?
these project into the venous sinus and function as one-way valves for cerebrospinal fluid drainage into the blood stream
cranial nerves - reptiles, birds + mammals?
they all have 12 pairs of cranial nerves
numbered with roman numerals 1 to XII
serve only head and neck apart from vagus nerve
arterial blood supply of brain?
it is based around 5 pairs of arteries
four of these arise from the cerebral arterial circle
rostral, middle, caudal and rostral cerebellar a.
caudal cerebellar a. originate from basilar a. (II)
the arterial circle of the dog is supplied from how many sources?
3
what does the internal carotid and basilar artery both supply?
they both supply the cerebral arterial circle and most parts of brain
where does the carotid and vertebral blood reach to?
reaches to most of the cerebral hemipsheres except the caudal portion
vertebral artery also supplies rest of the brain
vertebral artery?
travels from vertebrae - still blood supply to forebrain so still conscious when slashing of neck
what does the maxillary blood supply - supply?
all the brain except the caudal part of the medulla oblongata (cat and sheep)
what happens to the lumen of the proximal 2/3 of the internal carotid in the first few weeks of life? (cat and sheep)
it becomes occluded - absent in the adult
only anastomosing branch of maxillary artery supply?
supply cerebral arterial circle (via rete mirabile)
what does the maxillary artery anastomose with? (cat and sheep)
with internal carotid artery
maxillary blood supplies? (cat and sheep)
all the brain except the caudal part of the medulla oblongata
vertebral artery supplies? (cat and sheep)
medulla oblongata
vertebral artery anastomoses with? (cat and sheep)
occipital artery
cow - two thirds of the internal carotid artery?
it is absent in the adult
what does the vertebral artery anastomose with in cow?
with occipital artery
what is the brain also known as?
encephalon
what is the cerebrum also known as?
telencephalon
what is the cerebellum also known as?
dorsal metencephalon
what is the brain stem composed of?
medulla oblongata (myelencephalon)
pons (ventral metencephalon)
midbrain (mesencephalon)
thalamus, epithalamus, hypothalamus (diencephalon)
what is the largest part of the brain and also carries higher functions?
the cerebrum - telencephalon
how is the cerebrum divided?
divided into two cerebral hemispheres by longitudinal cerebral fissure
describe the folds of each hemisphere for the cerebrum:
each hemisphere has outward and inward folds named gyri (ridges) and sulci (grooves)
what is each hemisphere of the cerebrum composed of?
each hemisphere composed of gray matter superficially (neuronal cell bodies) and central white matter process of (axons) neurons and basal nuclei
what is the outer layer of the cerebrum?
cerebral cortex
what is the cerebral cortex?
it is the thin, superficial layer of the gray matter
what does the cerebrum receive inputs from?
from sensory organs to interpret vision and audition, proprioception and general sensations
what does the cerebrum initiate?
it initiates voluntary skeletal muscle movements, stores memory, voluntary motor control, behaviour and mental status
what is grey matter made up of?
neuron cell bodies
what does most grey matter of the mammalian cerebrum form?
forms a cerebral cortex on the surface
where is grey matter also located?
deep within the hemispheres in the hippocampus, the basal nuclei and septal nuclei
what is the hippocampus?
complex brain structure deep to temporal lobe includes set of memory processes
what is the basal nuclei?
consist of number of subcortical nuclei-voluntary and involuntary musculoskeletal activity
what are association fibres?
cell bodies lie in the cerebral cortex-interconnect adjacent gyri-establish connection between different parts of cortex within the same hemisphere
what are commissural fibres?
cell bodies lie in the cerebral cortex-connects two hemispheres (corpus collosum)
what are projection fibres?
connects the cerebral cortex with other parts of the brain and spinal cord (connects more or less vertically)
what does the cerebral cortex play a key role in?
in the most sophisticated neural functions with three key regions
in general, where do the two hemispheres receive information from?
from the opposite side of the body that result in consciousness
what does the motor cortex do?
it initiates nonreflex movements; impulses from these areas in one hemisphere causes muscle movements on the opposite - contralateral
meaning of contralateral?
with the opposite side of the body
what does the sensory cortex deal with?
deals with sensory perception
what is the association cortex for?
the sites of complex memory, integration and planning as well as (some species) self-awareness, language and personality traits
what are the main sensory areas of the brain include?
include the primary auditory cortex, primary somatosensory cortex and primary visual cortex
the frontal lobe of the cerebrum contains part of the motor cortex, what is it associated with?
associated with voluntary movement and with psychomotor skills
what does the parietal lobe of the cerebrum function as part of?
as part of the somato-sensory cortex
what does the somato-sensory cortex of the cerebrum control?
it controls conscious perception and localisation of pain, touch and temperature
what does the occipital lobe of the cerebrum function as?
as the visual cortex
what does the temporal lobe of the cerebrum function as?
functions as the auditory function, behaviour and memory
what is the piriform lobe of the cerebrum associated with?
with conscious olfaction, it receives olfactory input from the olfactory bulb
where does the cerebellum lie in accordance to the cerebrum?
it lies caudal to cerebrum (dorsal to the fourth ventricle and the brainstem)
what separates the cerebellum from the cerebrum?
the transverse cerebral fissure
what connects the cerebellum to the brainstem?
three cerebellar peduncles on each side of the fourth ventricle connect it to the brainstem
what is the white matter of the cerebellum composed of?
composed of fibres that look like a tree hence known as arbor vitae
what does the grey matter of the cerebellum form?
it forms an external layer
the cerebellar cortex with a lot of folds and the cerebellar nuclei
what does the motor reflex help with?
with coordinating subconscious and conscious skeletal muscle movements
why do flying mammals and birds have comparatively large cerebellum?
due to the complexity of flying
what does the cerebellum help maintain?
maintenance of balance, coordination but it doesn’t initiate them
how does the cerebellum help with body movements?
control and adjust body movements
what does the motor reflex centre coordinate?
coordinates the subconscious and conscious skeletal muscle movements
meaning of ipsilateral?
belonging to or occurring on the same side of the body
on what side of the body does the motor effect operate on and how is this different to how the cerebral hemisphere works?
motor effect is exerted on the same side of the body (ipsilateral) whereas the cerebral hemisphere operates on opposite sides of the body
what part of the brainstem is the most rostral part?
the diencephalon
what does the diencephalon consist of?
paired groups of nuclei separated by the third ventricle
what is the thalamus composed of?
of a large number of individual nuclei (grey matter) communicating with cerebral cortex
what does the thalamus do?
it acts to relay sensory info (and contains some motor fibres) from cortex to other brain areas
which senses come to the thalamus?
all senses (except smell) come to the thalamus
what does the thalamus interpret awareness of?
of nonlocalised pain, touch and temp
what are the thalamus’s lateral and ventral walls formed by?
formed by the hypothalamus
on the ventral surface of the diencephalon - what is formed?
the optic nerves form the optic chiasm of the diencephalon
what makes up the diencephalon?
thalamus, hypothalamus, subthalamus, epithalamus
what is found rostral to the optic chiasm of the diencephalon?
the optic nerves (CN II) which runs to the eyeball
what is found caudal to the optic chiasm on the median plane of the diencephalon?
the hypophysis
what is the mesencephalon (midbrain) immediately caudal to?
the diencephalon
what does the mesencephalon (midbrain) connect?
it connects the lower brain centres and spinal cord with higher brain centres
what is the mesencephalon (midbrain) divided into?
divided into a dorsal portion/tectum and a ventral portion
what characterises the tectum region of the mesencephalon?
four round swellings characterise tectum region - corpora quadrigemina
what is the larger - rostral colliculus or caudal colliculus?
rostral colliculus
what is the rostral colliculus?
it is a visual reflex centre and is part of the midbrain (mesencephalon)
what is the caudal colliculus?
it is an auditory reflex centre that is part of the midbrain (mesencephalon)
what does the ventral portion of the midbrain (mesencephalon) include?
it includes cerebral peduncles
where does the oculomotor nerve (CNIII) arise from?
arises from cerebral peduncle caudal to mamillary body (midbrain/mesencephalon)
where does the trochlear nerve (CNIV) arise?
arises slightly caudal to the colliculi
What is the mesencephalic (cerebral) aqueduct?
it is a ventricular tube connecting the third and fourth ventricles
where is the pons situated?
between the medulla oblongata and the mesencephalon
in what part of the brain is the pons found?
ventral mesencephalon
what is the pons composed of?
composed of a dorsal portion or tegmentum and a ventral portion
what does the ventral surface of the pons include?
includes the transverse fibres of the pons
what do transverse pontine (of the pons) fibres produce?
a prominent bridge of the surface
what is the pons connected to the cerebellum by?
by cerebellar peduncles
what part of which ventricle does the pons contain?
contains the rostral end of the fourth ventricle
what nerve does the pons give rise to?
the trigeminal nerve
what is the medulla oblongata aka?
myelencephalon
what does the medulla oblongata extend from?
from transverse fibres of the pons to the level of the ventral rootlets of the first cervical spinal nerve
what presents along the ventral surface of the medulla oblongata?
bilateral pyramids
how many cranial nerves does the medulla oblongata give rise to?
SEVEN of the twelve cranial nerves
which cranial nerves does the medulla oblongata give rise to?
cranial nerves CNVI through CNXII
what is the abducens nerve?
carry motor neurons that control other muscles of the eye
what two nerves lie at the border between the pons and medulla oblongata?
the abducens nerve (CNIV) and the facial nerve (CNVII)
what part of the brain stem contains most of the fourth ventricle?
the medulla oblongata (myelencephalon)
the medulla oblongata and pons together contain many?
many ascending and descending pathways
what are associated with the regulation of visceral functions: heart rate, blood vessel muscle tone, respiration etc.?
several reflex centres
