CNS Anatomy Flashcards
What is the basal ganglia?
A region of the base of the brain consisting of 3 clusters of neurons
What is the more accurate name for the basal ganglia?
Basal nuclei
Collection of subcortical cell bodies inside the nervous system
What are the input nuclei of the basal ganglia?
Caudate nucleus
Putamen
What are the intrinsic nuclei of the basal ganglia?
External globus pallidus
Subthalamic nucleus
Pars compacta of substantia nigra
What are the output nuclei of the basal ganglia?
Internal globus pallidus
Pars reticulata of the substantia nigra
Where is the caudate nucleus located?
Collection of grey matter on the wall of the lateral ventricles
What is the lentiform nucleus comprised of?
Globus Pallidus
Putamen
What is the function of the basal ganglia?
Provide a feedback mechanism to the cerebral cortex
What is the arterial supply of the basal ganglia?
Middle cerebral artery
What is the embryological origin of the cerebrum?
Prosencephalon
What separates the 2 cerebral hemispheres?
Falx cerebri (dura mater)
What is the cerebrum located above inferoposteriorly?
Tentorium cerebelli
What is the internal structure of the cerebrum?
Grey matter- forms cerebral cortex
White matter- consists of glial cells and myelinated axons
What is the external structure of the cerebrum?
Sulci (grooves)
Gyri (elevations)
What divides the two hemispheres anatomically?
Median longitudinal fissure
Falx cerebri fills this fissure
What white matter structure connects the two hemispheres?
Corpus callosum
What are the main sulci?
Central sulcus- separates frontal and parietal
Lateral sulcus- separates frontal and parietal from temporal
Lunate sulcus- located in occipital cortex
What are the main gyri?
Precentral gyrus- primary motor cortex
Post central gyrus- primary somatosensory cortex
Superior temporal gyrus- inferior to lateral sulcus, responsible for reception and processing of sound
What are cortical association areas?
Where information from different modalities are collated for processing
What are the association areas of the frontal lobe responsible for?
Higher intellect
Personality
Mood
Social conduct
Language
What are the association areas of the parietal lobe responsible for?
Language- dominant hemisphere
Calculation- dominant hemisphere
Visual spatial functions- non dominant hemisphere
What are the association areas of the temporal lobe responsible for?
Memory
Language
Hearing- primary auditory cortex
What are the association areas of the occipital lobe responsible for?
Vision- primary visual cortex
What is the arterial supply to the cerebrum?
Anterior cerebral arteries- branches of ICAs
Middle cerebral arteries- continuation of ICAs
Posterior cerebral arteries- branches of basilar arteries
What is the venous drainage of the cerebrum?
Network of small cerebral veins
Empty into the Dural venous sinuses
What functions is the cerebellum involved in?
Motor control:
- Coordination
- Precision and timing of movements
- Motor learning
What is the embryological origin of the cerebellum?
Hindbrain divides into metencephalon and myelencephalon
Cerebellum develops from metencephalon division
What separates the cerebellum from the occipital and temporal lobes?
Tentorium cerebelli (tough layer of dura mater)
What separates the cerebellum from the pons?
4th ventricle
What connects the 2 cerebellar hemispheres?
Vermis
What does the cerebellum consist of?
Grey matter- cerebellar cortex
White matter- embedded in the white matter are the 4 cerebellar nuclei
What are the 4 cerebellar nuclei?
Dentate
Emboliform
Globose
Fastigi
What are the anatomical lobes of the cerebellum?
Anterior lobe
Posterior lobe
Flocculonodular lobe
What are the functional divisions of the cerebellum?
Cerebrocerebellum
Spinocerebellum
Vestibulocerebellum
What is the arterial supply of the cerebellum?
Superior cerebellar artery (branch of basilar)
Anterior inferior cerebellar artery (branch of basilar)
Posterior inferior cerebellar artery (branch of vertebral)
What is the venous drainage of the cerebellum?
Superior and inferior cerebellar veins
Drain into superior petrosal, transverse and straight dural venous sinuses
What are the characteristics of the dura mater?
Thick
Tough
Inextensible
What are the 2 connective tissue layers of the Dura Mater?
Periosteal layer
Meningeal layer
Where are the dural venous sinuses located?
Between the 2 layers of the dura mater
What is the vascular supply of the dura mater?
Middle meningeal artery and vein
What is the innervation of the dura mater?
Trigeminal nerve
What are dural reflections?
Meningeal layer folds in on itself
Reflections project into cranial cavity dividing it into several compartments
What are the 4 dural reflections?
Falx cerebri
Tentorium cerebelli
Falx cerbelli
Diaphagma sellae
What are the characteristics of the arachnoid mater?
Thin
Avascular
No innervation
What are the characteristics of the pia mater?
Thin
Tightly adhered to the surface of the brain and spinal cord
Only covering to follow the gyri and fissures of the brain
Highly vascularised
What is the main secretion of the pineal gland?
Melatonin- regulates circadian rhythm of the body
What cells are present in the pineal gland?
Pinealocytes- hormone secreting cells
Glial cells- suppoting cells
What is the anatomical position of the pineal gland?
Located between the 2 cerebral hemispheres
Attached by a stalk to the posterior wall of the 3rd ventricle
In close proximity to the superior colliculi of the midbrain
What is the arterial supply of the pineal gland?
Posterior choroidal arteries (branches of posterior cerebral artery)
What is the venous drainage of the pineal gland?
Internal cerebral veins
What does the pituitary gland secrete?
Hormones that control the action of other endocrine organs and various tissues
What is the anatomical position of the pituitary gland?
Suspended from underside of brain by pituitary stalk (infundibulum)
Sists within sella turcica of the sphenoid bone
What covers the superior surface of the pituitary gland?
Diaphragma sellae
What are the anatomical relations of the pituitary gland?
Anterior- sphenoid sinus
Posterior- posterior intercavernous sinus, dorsum sellae, basilar artery, pons
Superior- diaphragm sellae, optic chiasm
Inferior- sphenoid sinus
Lateral- cavernous sinus
What is the structure of the pituitary gland?
Anterior lobe
Posterior lobe
What is the arterial supply of the pituitary gland?
Anterior lobe- superior hypophyseal artery (branch of ICA)
Posterior lobe- superior hypophyseal artery, infundibular artery, inferior hypophyseal artery
What is the venous drainage of the pituitary gland?
Hypophyseal portal system
What are the 4 main columns of the spinal cord grey matter?
Dorsal horn- sensory information
Ventral horn- motor information
Intermediate column/ Lateral horn- visceral and pelvic organs
What are the main spinal cord nuclei?
Marginal zone (MZ)
Substantia gelatinosa (SG)
Nucleus proprius (NP)
Dorsal nucleus of Clarke (DNC)
Interomediolateral nucleus (IMN)
Lateral motor neurons and medial motor neurons (MNs)
What are the MZ nuclei?
Marginal zone
Tip of dorsal horn
Pain, temperature
What is SG nuclei?
Substantia gelatinosa
Top of dorsal horn
Pain, temperature, light touch sensation
What are the SG nuclei?
Substantia gelatinosa
Top of dorsal horn
Pain, temperature, light touch sensation
What are the NP nuclei?
Nucleus proprius
Neck of dorsal horn
Mechanical, temperature sensation
What are DNC nuclei?
Dorsal nucleus of Clarke
Most dorso-medial nuclei
Unconscious proprioceptive information
C8-L3
What are IMN nuclei?
Intermediate column and lateral horn
Sensory information from viscera to brain
Autonomic information from brain to viscera
What are Rexed laminae?
Layers (laminae) within spinal cord where cells are grouped according to structure and function rather than solely on location
Lamina I- X
What is another name for the midbrain?
Mesencephalon
What does the midbrain travel through as it ascends?
Tentorium cerebelli
What are the 2 divisions of the midbrain?
Tectum- posterior to cerebral aqueduct
Paired cerebral peduncles
Tegmentum- anterior to cerebral aqueduct
What does the tectum of the midbrain house?
Superior colliculi
Inferior colliculi
Collectively known as the corpus quadrigemina
What separates the colliculi?
Cruciform sulcus
What separates the cerebral peduncles anteriorly?
Interpeduncular fossa
What is the arterial supply of the midbrain?
Posterior cerebral a. and its peduncular branch
Interpeduncular branches of basilar a.
Superior cerebella a.
Posterior choroidal a.
What is the embryological origin of the pons?
Metencephalon (part of hindbrain)
What fibres form the anterior surface of the pons?
Transverse pontocerebellar fibres
What demarcates the midline of the anterior surface of the pons?
Basilar groove
Where the basilar artery located
What cranial nerves originate from the ventral surface of the pons?
V- trigeminal
VI- abducens
VII- facial
VIII- vestibulocochlear
What connects the pons and the cerebellum?
Middle cerebellar peduncles
What composes the floor of the 4th ventricle?
Dorsal surface of pons and medulla
What is the cerebellopontine angle?
Angle formed at junction of the pons, medulla and cerebellum
What are the 2 components of the pons?
Ventral pons- coordinating movement
Tegmentum- forms part of reticular formation
What is the arterial supply of the pons?
Pontine arteries (branches of basilar a,
Anterior inferior cerebellar a.
Superior cerebellar a.
What is the venous drainage of the pons?
Anterior Ponto mesencephalic vein
Drains into basal vein -> drains into cerebral veins
Where does the medulla exit the skull?
Foramen magnum
What structures are on the anterior surface of the medulla?
3 fissures/sulci
Pyramids
Olives
5 Cranial nerves
What fissures/sulci are present on the anterior surface of the medulla?
Anterior median fissure
Ventrolateral sulcus
Posterolateral sulcus
What cranial nerves are present on the anterior surface of the medulla?
VI- abducens: (junction between pons and medulla)
IX- glossopharyngeal (posterolateral sulcus)
X- vagus (posterolateral sulcus)
X- accessory (posterolateral sulcus)
XII- hypoglossal (ventrolateral sulcus)
What is the midline structure on the posterior aspect of the medulla?
Posterior median sulcus
What is the closed medulla?
CSF containing cavities are surrounded by the medulla
What is the open medulla?
CSF containing cavities are not surrounded by the medulla
Becomes open with central canal opens into 4th ventricle
What are the 3 levels of the medulla?
Level of decussation of the pyramids
Level of decussation the medial lemnisci
Level of the olives
What is the arterial supply of the medulla?
Anterior spinal a.
Posterior spinal a.
Posterior inferior cerebellar a.
Anterior inferior cerebellar a.
Vertebral arteries
What are the ascending tracts?
Neural pathways by which sensory information from the peripheral nerves is transmitted to the cerebral cortex
Also known as somatosensory pathways
What are 2 examples of ascending tracts?
Dorsal column- medial leminiscus pathway (DCML)
Lateral spinothalamic tract
What does the DCML carry?
Sensory modality of fine touch, vibration and proprioception
What neurones are part of the DCML pathway?
First order
Second order
Third order
Where do the first order neurons of the DCML travel?
From peripheral nerve up the dorsal column to the medulla oblongata
Where do the second order neurons of the DCML travel?
Decussate in the medulla
Travel in the contralateral medial lemniscus to the VPL of the thalamus
Where do the third order neurons of the DCML travel?
Ascend from the VPL of the thalamus
Travel through internal capsule
Terminate at ipsilateral sensory cortex of brain
What is the VPL of the thalamus?
Ventral posterolateral nucleus
What information does the lateral spinothalamic tract carry?
Sensory modalities of pain and temperature
Where do the first order neurons in the lateral spinothalamic tract travel?
Arise from periphery
Enter spinal cord and synapse at same level at the tip of the dorsal horn: area known as the substantia gelatinosa
Where do the second order neurons in the lateral spinothalamic tract travel?
Synapse with first neuron in substantia gelatonisa then decussate within spinal cord
Carry information to the thalamus
Where do the third order neurons in the lateral spinothalamic tract travel?
Ascend from VPL of thalamus
Travel through internal capsule
Terminate at sensory cortex
What are descending tracts?
Pathways by which motor signals are sent from the brain to the lower motor neurones
LMNs innervate skeletal muscle
What are the neurons in descending tracts classified as?
Upper motor neurons (UMNs)
No synapses within descending pathways until their termination
What are the 2 pyramidal descending tracts?
Corticospinal tracts- body musculature
Corticobulbar tracts- head and neck musculature
What is the pathway of the corticospinal tract?
Originate from cortex
Neurons converge and descend through internal capsule
Neurons pass through brain stem
Fibres within lateral corticospinal tract decussate, descend spinal cord and terminate in ventral horn
Fibres within anterior corticospinal tract remain ipsilateral, descend into spinal cord then decussate and terminate in ventral horn
What is the pathway of the corticobulbar tract?
Originates from lateral aspect of primary motor cortex
Neurons converge and descend through internal capsule to brainstem
Neurons terminate on motor nuclei of cranial nerves and synapse with lower motor neurons
What does the auditory pathway convey?
Special sense of hearing
Where is the primary auditory cortex located?
In the superior temporal gyrus right under the lateral fissure
What are the 2 paired arteries that supply the brain?
vertebral arteries
Internal carotid arteries
What are the terminal branches of the vertebral and internal carotid arteries?
Circle of Willis
Anastomotic circle
What are the branches of the ICAs?
Ophthalmic artery
Posterior communicating artery
Anterior choroidal artery
Anterior cerebral artery
What is the continuation of the ICAs?
Middle cerebral artery
What do the vertebral arteires arise from?
Subclavian arteries
What are the branches of the vertebral arteries?
Meningeal branch
Anterior and posterior spinal arteries
Posterior inferior cerebellar artery
What do the vertebral arteries converge to form?
Basilar artery
Where do the dural venous sinuses lie?
Between the periosteal and meningeal layers of the dura mater
What vein do the dural venous sinuses drain into?
Internal jugular vein
What are some examples of dural venous sinuses?
Superior sagittal
Inferior sagittal
Straight
Transverse
Sigmoid
What do the superficial veins drain?
Cerebral cortex
What are some examples of superficial veins?
Superior cerebral
Superficial middle cerebral
Inferior cerebral
Superior anastomotic
Inferior anastomotic
What are some examples of deep veins?
Subependymal veins
Medullary veins
What is the venous drainage of the cerebellum?
Superior and inferior cerebellar veins
What is the venous drainage of the spinal cord?
3 anterior spinal veins
3 posterior spinal veins
What is the cavernous sinus?
Paired dural venous sinus located in the cranial cavity
Where is the cavernous sinus located?
Middle cranial fossa
Either side of the sella turcica of the sphenoid bone
What is the anterior border of the cavernous sinus?
Superior orbital fissure
What is the posterior border of the cavernous sinus?
Petrous part of temporal bone
What is the medial border of the cavernous sinus?
Body of sphenoid bone
What is the lateral border of the cavernous sinus?
Meningeal layer of dura mater running from the roof to the floor of the middle cranial fossa.
What is the roof of the cavernous sinus?
Meningeal layer of the dura mater that attaches to the anterior and middle clinoid processes of the sphenoid bone.
What is the floor of the cavernous sinus?
Endosteal layer of dura mater that overlies the base of the greater wing of the sphenoid bone
What are the contents of the cavernous sinus?
III- oculomotor
IV- trochlear
V1- ophthalmic
V2- maxillary
VI- abducens
Carotid plexus
ICA
Where does the cavernous sinus receive venous drainage from?
Ophthalmic veins
Central vein of retina
Sphenoparietal sinus
Superficial middle cerebral vein
Pterygoid plexus
What is the ventricular system?
Set of communicating cavities within the brain
Responsible for production, transport and removal of CSF
What are the 3 main functions of CSF?
Protection
Buoyancy
Chemical stability
What is the function of the choroid plexus?
Produce CSF
What are the 4 ventricles?
Right lateral
Left lateral
Third ventricle
Fourth ventricle
What connects the lateral ventricles and third ventricle?
Foramen of monro
What connects the third ventricle and fourth ventrcile?
Cerebral aqueduct
Where does drainage of CSF occur?
In the subarachnoid cisterns
Drain into dural venous sinsues
