THE NERVOUS SYSTEM Flashcards
White matter of the brain
- myelinated axons of neurons
- comprises the inner part of the brain
myelinated axons organised as tracts connect
- different regions (and lobes) of the hemispheres - association fibres
- left and right hemispheres (commissural fibres) - corpus callosum
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grey matter of the brain
- made up by clusters of neuronal cell bodies
- majority of grey matter found superficially, comprising the cerebral cortex with small clusters found deep, comprising the sub-cortical structures, the basal ganglia and the diencephalon
frontal lobe (function and location)
- “executive functioning”
- located anterior to the central sulcus
- involved in personality, behaviour, emotions (pre-frontal cortex)
- involved in body movement (primary motor cortex)
parietal lobe (function and location)
- located posterior to the central sulcus and superior to the lateral sulcus
- involved in the sense of touch, pain, and temperature
- primary somatosensory cortex
- association cortex (aspects of language processing)
occipital lobe (function and location)
- located in the posterior region of each hemisphere (found behind the parietal and temporal lobes)
- lies just underneath the occipital bone
- involved in vision (colour, light, movement) (contains the visual cortex)
temporal lobe
- inferior to the lateral sulcus (sylvian fissure)
- involved in auditory/auditory-visual processing (primary auditory area)
insula cortex (function and location)
- deep to the frontal, temporal and parietal lobes - parts that overlay are referred to as opercula
- involved in taste, vestibular, visceral sensation
diencephalon (function and location)
- rostral (front), central grey matter
- found medial to the cerebrum
- relays sensory information between brain regions and controls many autonomic functions of the peripheral nervous system
- composed of the thalamus, hypothalamus, and epithalamus
thalamus (diencephalon) function
relay for sensory input into the cortex
hypothalamus (diencephalon) function
homeostatic control, endrocrine regulation
epithalamus (diencephalon) function
contains the pineal gland (sleep/wake cycle)
mesencephalon (midbrain) (function and location)
- connects forebrain and the hindbrain (pons and cerebellum)
- processing of visual and auditory information
- generation of reflexive somatic motor responses
- maintainence of consciousness
tectum (mesencephalon) funtion and location
- lies dorsal to the tegmentum and cerebral aqueduct
- contains the nuclei of the superior and inferior colliculi
- control visual and auditory reflexes
tegmentum (mesencephalon) function and location
- posterior to the substantia nigra
- forms the floor of the midbrain
- involved in the integration of information for involuntary motor commands (eye movements, sleep/wake cycle) and the modulation of somatic motor responses
cerebral peduncles (mesencephalon) function and location
- white matter tracts to brainstem and spinal cord
metencephalon (hindbrain) function and location
- rostral part of the hindbrain
- ventral part of the metencephalon develops into the pons while the dorsal portion expands into the cerebellum
pons (metencephalon) function and location
- largest part of the brainstem, located above the medulla and below the midbrain (mesencephalon)
- ventral side
- connection to the cerebellum (dorsal)
- pathway for fibre tracts from the brain to the spinal cord
- controls respiration (with medulla)
cerebellum (metencephalon) function and location
- located at the back of the brain, inferior the occipital and temporal lobes
- posterior to the pons - seperated by the fourth ventricle
- involved in the coordination of muscle movement (fine tuning)
- involved in the storing of memories of previously learned movements (muscle memory)
myelencephalon (medulla) (hindbrain) function and location
- cadual part of the hindbrain
- continous with the spinal cord inferiorly
- controls respiration and cardiovascular function
- control of vomiting, sneezing and coughing
spinal cord (location and function)
- continous with the brainstem (medulla to foramen magnum)
- extends to level L1/L2
- peripheral nerves extend through intervertebral foramen
- grey matter - neuronal cell bodies and processing
- white matter - axon tracts ascending/descending to the brain
- shape and size of grey matter varies along length of the spine
- central canal runs through the centre of the spinal cord (grey matter)
dura mater (meninges)
- “tough”
- cranial (outmost layer)
- consists of two fibrous layers
- outer layer (endosteal) is fused to the periostinum lining of the cranial bones whilst the inner layer (meningeal) lies superficial to the arachnoid mater
arachnoid mater (meninges)
- “spider”
- adheres to dura mater
- inner surface shows thin fibrous projections known as arachnoid trabeculae which extend into the pia mater
- deep to the arachnoid mater is the subarachnoid space which contains a delicate, web-like meshwork of collagen and elastic fibres - contains cerebrospinal fluid and cerebral arteries and veins
pia mater
- tightly attached to the surface contours of the brain (sulci)
- highly vascular
- physically separates the neural tissue from the blood vessels within the subarachnoid space (adding to the blood-brain barrier)
epidural space (meninges)
- between periosteum and dura mater in spinal cord
- site of applying local epidural anaesthesia
subarachnoid space
- space between the arachnoid and pia mater
- contains cerebrospinal fluid and major blood vessels
subdural space
- between the dura mater and the arachnoid mater
denticulate ligaments (connections and anatomy of the spinal cord)
- lateral extensions of the pia mater attaching to the dura
lumbar cistern (spinal cord anatomy and connections)
- subarachnoid space below L1/2 which does not contain the spinal cord
filum terminale (spinal cord anatomy and connections)
- extensions of pia mater from the spinal cord that attach to the coccyx
cauda equina (spinal cord anatomy and connections)
- dorsal and ventral rootlets (that form spinal cords)
what two vessels are responsible for the blood supply of the brain?
- vertebral arteries
- internal carotid arteries
- arise in the neck (common carotid artery and basilar artery) and ascend into the cranium
role of the circle of Willis?
- provides an alternative blood supply
- the terminal branches of the arteries form an anatomotic circle
- ring-like arterial connections located at the base of the brain
- key purpose is to collect arterial blood from two vertebral arteries and two internal carotid arteries
ophthalmic artery
supplies structures of the orbit (eye)
posterior communicating artery
acts as a connecting vessel
anterior choroidal artery
supplies structures in the brain important for motor control and vision
anterior cerebral artery
supplies part of the cerebrum
middle cerebral artery
supplies the lateral portions of the cerebrum
meningeal arch
supplies a sheet of the dura mater
anterior and posterior spinal arteries
supplies the spinal cord, spanning its entire length
posterior inferior cerebellar artery
supplies the cerebellum
blood drainage from the brain
- located in the subarachnoid space
- empty into the dural venous sinuses (in the dura mater)
- ultimately empty into the internal jugular vein
- CSF returns to the bloodstream via arachnoid granulations projecting into the dural venous sinuses
role of olfactory nerve (CNI)
conveys sensory information related to smell
- sensory nerve
role of optic nerve (CNII)
transfers visual information from the retina to the visual centres of the brain
- sensory nerve
oculomotor nerve (CNIII)
innervates extrinsic and intrinsic eye muscles
- motor nerve
role of trochlear nerve (CNIV)
innervates the superior oblique muscle of the eye
- motor nerve
role of the trigeminal nerve (CNV)
sensory information from the face and anterior tongue and is involved in the innervation of the muscles of mastication
- motor and sensory nerve
role of abducens nerve (CNVI)
innervates the lateral rectus muscle of the eye
- motor nerve
role of the facial nerve (CNVII)
involved in the innervation of muscles of facial expression and taste
- motor and sensory nerve
vestibulocochlear nerve (CNVIII)
consists of processing sensory information for hearing and balance
- sensory nerve
role of glossopharyngeal nerve (CNIX)
provides motor, parasympathetic and sensory information to your mouth and throat (enables swallowing)
- motor and sensory nerve
role of the vagus nerve (X)
responsible for the regulation of internal organs
- motor and sensory nerve
role of the accessory nerve (CNXI)
innervates the sternocleidomastoid and trapezius muscle
- motor nerve
role of the hypoglossal nerve (CNXII)
innervates the muscles of the tongue
- motor nerve
where does sensory information travel into?
Dorsal root
Dorsal/posterior horn
some of ascending sensory neurons/interneurons
ventral/anterior horn
soma of somatic motor neurons
lateral horn
soma of ANS
where does motor information leave from the spinal cord?
ventral root
Differences between the anatomy of the sympathetic and parasympathetic nervous system
sympathetic:
- ganglia a greater distance from the target organs
- preganglionic neurons in thoracic/lumbar region
- cell bodies located in the lateral horn of the thoracic spinal cord
parasympathetic:
- ganglia close to organs
- preganglionic neurons in brainstem/sacrum region
