Neuroanatomy Flashcards
What does the CNS comprise of?
The brain (Encephalon) and the spinal cord
What does the Rhombencephalon (Hind brain) become?
Myelencephalon and the Metencephalon
What does the myelencephalon become?
Medulla oblongata and the lower part of the 4th ventricle
What does the metencephalon become?
Pons, Cerebellum and the upper part of the 4th ventricle
What does the Mesencephalon (Mid Brain) become?
2 regions separated by the cerebral aqueduct
Dorsally becomes the Tectum (Containing inferior and superior colliculi)
Ventrally becomes cerebral peduncle divided into the tegmentum and the crus cerebri which are separated by the substantial nigra
What does the prosencephalon become?
Diencephalon and the telencephalon
What does the diencephalon become?
Thalamus and Hypothalamus and the third ventricle
What does the telencephalon become?
Cerebral cortex and basal ganglia and the lateral ventricles
What are the sagittal and parasaggital planes of the brain
Vertical line through the midline of the brain along the saggital suture. Planes parallel to this but away from the midline are parasagittal
Describe the anatomical directions of the brain
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Describe the structure of white matter
Collection of nerve fibres (Axons and dendrites) with few or no neuronal bodies
Describe the structure of grey matter
Formed by aggregations of neural cell bodies and there local processes
Define nuclei or ganglia
Collections of nerve cells within the brain
Define the cortex of the brain
Outer surface of the brain ie. cerebral hemispheres and cerebellum formed by flatter sheets of neurones
What are the three meningeal layers
Dura mater
Arachnoid Mater
Pia Mater
Describe the properties of the dura mater
Outermost layer
Fibrous sheet
Consists of white collagen fibres with few elastic fibres arranged in laminae
Adjacent laminae have opposing fibre directions forming a lattice
2 layers –> Outer endosteal layer and inner meningeal layer
Describe the properties of the arachnoid mater
Poorly vascularised membrane of loose connective tissue (elastin, collagen and reticulin)
cells joined together by tight junctions (Zonula occludent)
Describe the properties of the pia mater
Covers the entire surface of the CNS to which it adheres
Innermost layer lies on CSF surface
Separated from arachnoid mater by subarachnoid space that’s filled with CSF
Connective tissue elements are continuous between arachnoid and pia forming trabeculae
What are the functions of the frontal Lobe?
Primary motor cortex and prefrontal cortex
Functions of the temporal lobe
Primary auditory cortex, auditory association cortex (Wenicke’s area), hippocampus and amygdala
Constituents of Parietal lobe
Primary somatosensory cortex and association cortex
Constituents of the occipital lobe
Primary visual and visual association cortex
Constituents of the cerebellum
motor control of equilibrium, posture and muscle tone - movement and coordination
What does the brainstem contain
Ascending and descending tracts, cranial nerve nuclei and reticular formation
What is a gyri
Rolls of the cerebral cortex
What are sulci
Grooves between gyrus
What is the central sulcus
Large fissure separating the frontal from the parietal lobe
What is the lateral sulcus
Large fissure that separates the temporal lobe from the parietal and frontal lobe
What is found in the lateral sulcus
Insula - forms the floor of the lateral sulcus
Opercula - the parts of the temporal, parietal and frontal lobes that overlie the insula
What is the corpus callosum
Large bundle of white matter than connects the two hemispheres together
What is the only part of the diencephalon visible on the outside of the brain?
hypothalamus
Draw a labelled diagram of the inferior surface of the brain
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What are the functions of the parietal lobe?
Primary sensory rea
Dominant (Normally left) lobe is important for perception, interpretation of sensory information and the formation of the idea of a complex, meaningful motor response.
Supramarginal and angular gyrus are concerned with language and mathematical operations
Non dominant lobe (Right) is important for visuospatial functions
What are the functions of the frontal lobe?
Motor function, problem solving, spontaneity, memory, language, judgement, personality, impulse control and social/sexual behaviour
What are he functions of the prefrontal cortex?
Higher cognitive functions and determination of personality
What are the functions of the posterior frontal lobe?
Contain motor and premotor areas
Where is brocas area found and what is its function?
Found at the inferior frontal gyrus and is important for language production and comprehension
Where is Wernickes area located and what is its function?
Found in the superior temporal gyrus of the left hemisphere and is concerned with understanding a spoken word.
What are the components of the limbic system and what is its function?
Hippocampus, fornix, amygdala
Function in emotion, memory, behaviour and olfaction
What is the function of the hippocampus
Establishing Long term memory
What is the function of the amygdala
Motivationally important stimuli such as reward and fear
How does the limbic system operate
Interacts with the endocrine and the autonomic NS and is highly interconnected with the brains pleasure centre the nucleus accumbens which has a role in sexual arousal
What are the two layers of the dura mater
Outer endosteal layer
Inner meningeal layer
Describe the outer endosteal layer of the dura mater
Lines and adheres to the interior of the skull sending blood vessels and fibrous processes into the cranial bones
How are the dural venous sinuses formed?
Where the inner meningeal layer of the dura mater separates from the outer endosteal layer, dural folds are formed which help outline the left and right hemispheres and the posterior cranial fossa, where these folds attach to the skull the dural venous sinuses form
What are subarachnoid cisterns?
Spaces between the arachnoid and the pia mater that are filled with CSF
What is the foramen of magendie?
A midline communication between the 4th ventricle and the subarachnoid space
What is the foramen of luschka
A lateral communication between the 4th ventricle and subarachnoid space
Where is the cerebellomedullary cistern?
Lies in the angle formed by the dorsal surface of medulla and the inferior surface of the cerebellum
What is the clinical significance of the foramen of magendie?
This where CSF flows from the ventricular system into the subarachnoid space
Where is the pontine cistern
on ventral surface of the pons
Describe the 4 protective features of the BBB
- Endothelial cells that line blood vessels are bonded by tight junctions that prevents molecules passing through
- Basement membrane of CNS blood vessels lack fenestrations
- Pericytes are embedded in basement membrane and wrap around endothelial cells to regulate blood flow, immunity and vascular permeability
- Astrocytes extend end feet that envelope CNS capillaries and restrict flow of molecules into the CNS parenchyma
Where do the arteries and the veins on the surface of the brain lie?
Within the subarachnoid space
Which arteries bring arterial blood to the brain
Internal carotid and the vertebral arteries
Which parts of the brain do the vertebral arteries supply?
Supply 20% of the brain
Posterior Cerebrum
Contents of the posterior cranial fossa
Which parts of the brain does the internal carotid artery supply?
80% of brain
Anterior and middle parts of the cerebrum and diencephalon
Draw the circle of willis
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Where does the internal carotid artery arise from?
Arises from the bifurcation of the common carotid at the level of the upper border of the thyroid cartilage
What does the anterior cerebral artery supply?
Corpus callous and medial aspects of the hemispheres
What does the middle cerebral artery supply?
Majority of the lateral surface of the hemisphere and deep structures of the anterior part of the cerebral hemisphere due to its anterior perforating branches
Draw a diagram of the major arteries on the surface of the brain
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Where does the vertebral arteries arise from
Subclavian arteries
Where do the vertebral arteries enter the skull?
At the foramen magnum
Where does the basilar artery lie?
Anterior median fissure on the pons
Where do the cerebral veins drain before they drain to the heart?
Dural venous sinuses which are channels between two layers of the dura mater
What are the two divisions of the cerebral veins?
Internal cerebral veins and external cerebral veins
Where do internal cerebral veins run?
Within the brain tissue and end when the reach the surface of the brain and become external cerebral veins
Where do the external cerebral veins run?
Run on the surface of the brain crossing the subarachnoid space to drain into the dural venous sinuses
What is the clinical significance of the cavernous sinus
Houses 5 cranial nerves and the internal carotid artery
Which cranial nerves are housed in the cavernous sinus
Maxillary nerve Ophthalmic nerve abducens nerve trochlear nerve oculomotor nerve
How do the intracranial venous sinuses and the veins outside the skull communicate?
Via emissary veins
What is the clinical significance of emissary veins
Allow infection and inflammation to spread from outside the skull into the cranial cavity
Where is the majority of the CSF produced?
Choroid plexus in the lateral ventricles
Describe the movement of CSF through the ventricles
CSF passes from the choroid plexus in the lateral ventricles via the inter ventricular foramen into the 3rd ventricle, then backwards through the cerebral aqueduct into the 4th ventricle. This then communicates with the subarachnoid space via the median foramen of magendie and the lateral foramina of luschka
Describe the formation of the choroid plexus
Vessel invagination into the ventricles produce vascular fold in the Pia mater covered by an epithelium derived from the ependymal lining of the ventricle
How Is the volume and composition of the CSF controlled?
Tight junctions prevent passage of fluid from the extracellular space of the choroid plexus into the ventricle except via the choroidal cells themselves
What are the two routes of CSF resorption into the venous drainage of the brain?
Arachnoid granulations (Tufts) allow CSF to reabsorbed into venous structures Drains along nerves to the lymphatics mainly the nasal mucosa lymphatics
What are the two routes of CSF resorption into the venous drainage of the brain?
Arachnoid granulations (Tufts) allow CSF to reabsorbed into venous structures Drains along nerves to the lymphatics mainly the nasal mucosa lymphatics
What are the branches of the internal carotid artery?
(i) Opthalmic artery
(ii) Posterior communicating artery
(iii) Anterior Choroidal artery
(iv) Anterior cerebral artery
What are the branches of the vertebral artery?
(i) Meningeal branch
(ii) Anterior and posterior spinal arteries
(iii) Posterior inferior cerebellar artery
What lies in the anterior cranial fossa?
Frontal lobe
What lies in the middle cranial fossa?
Temporal, Parietal and occipital lobes of the brain
Is much deeper than the anterior cranial fossa
What lies in the posterior cranial cavity?
Cerebellum, pons and medulla oblongata
Deepest of the three fossa
Which cranial nerves pass through the internal acoustic meatus?
Facial (7)
Vestibulocochlear (8)
Which cranial nerves pass through the jugular foramen?
Glossopharyngeal (9)
Vagus (10)
Accessory (11)
Which cranial nerves pass through the ethmoidal foramen?
Olfactory (1)
Which cranial nerves pass through the optic canal?
Optic (2)
Which cranial nerves pass through the superior orbital fissure?
Oculomotor (3)
Trochlea (4)
Trigeminal (5) - opthalmic branch
Abducens (6)
Which cranial nerves pass through the foramen rotundum?
Trigeminal (5) - maxillary branch
Which cranial nerve passes through the foramen ovale
Trigeminal (5) - mandibular branch
Which cranial nerve passes through the hypoglossal canal?
Hypoglossal (12)
What are the causes of raised intracranial pressure?
Space occupying lesions (Tumour, haemotoma and access)
Idiopathic intracranial hypertension
The frontal nerve is a branch of which cranial nerve?
Centrally placed branch of cranial nerve 6 (Abducens)
What are 2 branches of the frontal nerve?
Supra-orbital nerve
Supratrochlear nerve
What is the origin and insertion of levatator palpebral superioris?
Origin - posterior orbit at common tendinous ring
Insertion - Upper eyelid
Where does the lacrimal gland lie?
Inside the lateral margin of the orbit, adjacent to the lateral margin of levator palpebral superioris
What is the nerve supply of levator palpebral superioris?
branch of the oculomotor nerve
What is the origin and insertion of the superior rectus muscle?
Origin - deep part of the orbit at the common tendinous ring
Insertion - runs over top of eyeball and inserts anterior to the equator to the eyeball behind the conjunctival sac
What is the origin and insertion of the superior oblique muscle?
Origin - posterior orbit
Inserts - runs forward to pass the trochlear and inserts onto the posterior part of the eyeball
Describe parasympathetic outflow from the CNS and spinal cord
CN 3, 7, 9 and 10
Sacral spinal segments 2, 3 and 4
Which cranial nerves have branches to the orbit?
3 and 7
Describe the pathway of the parasympathetic fibres of the third cranial nerve in the orbit
parasympathetic fibres of CN 3 originates in the dinger-westphal nucleus in the midbrain and travel into the branch of the inferior oblique muscle, they leave the nerve and enter the ciliary ganglion which gives fibres that innervate the ciliary muscle and the sphincter papillae
Describe the pathway of the parasympathetic fibres of the 7th cranial nerve in the orbit
leave middle ear nerve and synapse in a ganglion in the pterygopalantine fossa and supply the lacrimal gland
Describe the sympathetic outflow from the CNS
From spinal segments thoracic 1 to lumbar 2 passing into sympathetic trunks which run from the base of the skull to the bottom of the sacrum
Describe sympathetic outflow from the CNS to the orbit
Sympathetic fibres to the orbit arise from segment T1 and pass up through the sympathetic trunk through the stellate ganglion to the base of the skull
They leave the superior cervical ganglion of the sympathetic trunk to supply the dilator pupillae muscle and blood vessels
What is the greater petrosal nerve a branch of?
parasympathetic branch of CN VII which emerges from petrous temporal bone and passes anteromedially
What is the order of the ear ossicles?
Maleus –> Incus –> Stapes
What is the chorda tympani nerve a branch of?
branch of CN 7 crossing the tympanic membrane
Which cranial nerves does the internal acoustic meatus transmit?
CN 7 and CN 8
What are the 3 cranial fossa
Anterior
Middle
posterior
What is the space between the cerebral peduncles called?
interpeduncular fossa
What does the inferior brachium carry and where does it travel between?
Between the lateral geniculate ganglion and the the superior colliculi
Visual information
What information does the superior brachium carry and where does it travel between?
Auditory information
Between the medial geniculate body and the inferior colliculi
Impairment of the cranial nerves that arise from the medulla (9, 10, 11 and 12) causes what disease?
Bulbar palsy
What are the symptoms of bulbar palsy?
Dysphagia Slurring of speech Dysphonia Excessive saliva Wasting and fasciculation tongue Absent gag reflex
What are the 2 main causes of bulbar palsy
Guillain Barre syndrome
Motor neurone disease
Gracile afferents carry information from where
Lower limbs
Cuneate afferents carry information from where
Upper limbs
Cuneate afferents carry information from where
Upper limbs
What is the medullary striae
Ponto-cerebellar fibres passing from the pons to the cerebrum that divide the flor of the 4th ventricle into rostral and caudal
What is the function of locus coeruleus
Stress response and arousal
What is the function of the area postraema?
Nausea control - chemoreceptive trigger zone for emetic response
What is the function of the lamina terminalis?
Prevents the third ventricle draining into the subarachnoid space
What are the 4 parts of the corpus callosum
Rostrum (Anterior)
Genu
Body
Splenion (End)
What are the 3 main types of white matter fibres
Association fibres
Commissural fibres
Projection fibres
What are association fibres
Link Cortical regions within one hemisphere
What are commissural fibres
Link functionally similar areas across hemispheres
What are the projectional fibres
vertically projecting fibres
