Neuroanatomy PDF

Positional/directional terms: Rostral = towards head end Caudal = towards tail end Dorsal = back Ventral = belly Z Jhetam (2020) Positional/directional terms: Rostral = towards head end Caudal = towards tail end Dorsal = back Ventral = belly Brain & cerebrum & Diencephalon...

Positional/directional terms: Rostral = towards head end Caudal = towards tail end Dorsal = back Ventral = belly Z Jhetam (2020) Positional/directional terms: Rostral = towards head end Caudal = towards tail end Dorsal = back Ventral = belly Brain & cerebrum & Diencephalon & Brainster > cerebellum Z Jhetam (2020)  Arachnoid & Pia Mater (collectively known as leptomeningeal layer): Membranous coverings of the brain and spinal cord Arachnoid mater (parietal layer of leptomeninx) Protection damage) (CNS from mechanical Thin avascular membrane Supporting framework for vessels + venous sinuses Attaches to dura by several layers of flattened cells Enclose the subarachnoid space Conforms to general shape of brain/doesn’t dip into -. · tough membrane limits movement of sulci > allow CSF to re-enter circulation Dura Mater (aka pachymeninx) brain Separated from pia by arachnoid trabeculae and outermost , V 2 layers: external periosteal layer & inner meningeal ↑ layer I & deep periosted continous with dura matter , subarachnoid space for circulation of cerebrospinal located underneath of cord spinal layer bones of skull + > inner surface of bones fluid (CSF) vertebral coloumn → Mostly adherent to each other except where Arachnoid trabeculae wick tough , + they enclose the dural venous sinuses inextensible V → strands of collagenous connective tissue from empty jugular of cranium , into internal drainage ~ responsible for the between arachnoid → External periosteal layer ain’t in the spinal cord · pid + Matter arachnoid to pia Dural infoldings (reflections) of meningeal layer → Maintain patency + · Has CSF. bV trabeculae cells form partitions in cranial cavity: Subarachnoid · Arachnoid villi/granulations 7 distinct feature of durc naemmaroge → Falx cerebri right hemisphere ~separates cerebral → evaginations (outgrowths) of arachnoid and left o Lies in longitudinal fissure; free border lies projecting through dura into sinuses pulls Canteriorly) above corpus callosum ethmoid → & attaches to crista with age become large & aggregated of bone o Continuous post.ly with tentorium cerebelli (granulations) → Tentorium cerebelli & encircles midbrain o Lies in transverse cerebral fissure Pia mater (visceral layer of leptomeninx) sub-arachnoid > underneath space. o Separates occipital lobe from cerebellum Highly vascular o Tentorial notch: free border A delicate membrane - 2 to 3 cells thick very thin (anteromedially) through which brainstem Attaches to end feet of arachnoid trabeculae extends from post. To middle cranial fossa Invests surfaces of brain and closely follows all → Falx cerebelli sulci/surfaces of brain < follows contour of brain o Vertical infolding inferior to falx cerebri, Arteries and veins penetrate the pia when they attaches to internal occipital crest enter/leave brain substance (perivascular space) o Separates cerebellar hemispheres → Diaphragma sellae sella opening for Spinal meninges - covers turica with an infundibulum o Circular sheet of dura suspended between Devoid of fibrous layer of dura which ends at margin clinoid processes, forming a roof over of foramen magnum sphenoid’s hypophysial fossa Not much difference in arachnoid mater o Covers pituitary gland; has aperture for Spinal pia mater forms 21 denticulate ligaments and hypophysial veins & infundibulum * thickened anteriorly to give a shining appearance in Vasculature: midline, called linea splendens (arteries of the dura supply calvaria more than dura) → Middle meningeal a. (branch of maxillary a.) o Frontal; & parietal branches MOOV → Meningeal branch of ophthalmic arteries → Branches of occipital arteries → Branches of vertebral arteries * Nerve supply ITHT (dura is pain sensitive) → Meningeal branches from CNV: Tripemil is S Ant. Meningeal branches of ethmoidal nerve (CNV1), Meningeal branches of maxillary (CNV2) and Mandibular (CNV3) – dura of ant. & middle cranial fossa → Tentorial nerve (branch of CNV1 ophthalmic n.) – post. Cranial fossa → Upper cervical nerves Clinical relevance : meningealveryas crevic bloocollectsbetween 3 Tearing (Extracural haematomas : of middle between durp + arachnoid matter. 1 Subdural :· collection of venous blood to cerebral veins · Due to damage & Meningitis : · part of brain is forced out ) cranial herniation Z Jhetam (2020) intracranial pressure ↓ cerebral systemic hypotension = · + perfusion  to middle - damage cerebral artery Meningeal Spaces Extradural Space/Epidural Space Subdural Space Subarachnoid/Leptomeningeal Space @ dura-cranial interface @dura-arachnoid interface @ between arachnoid and pia Potential/unnatural/pathological Potential/unnatural/pathological Real/naturally occurring May separate when blood from May develop as a result of Contains Cerebrospinal fluid meningeal vessels pushes trauma (CSF), blood vessels and periosteum away from cranium trabeculae cells NOT continuous with the natural > Haematora is the tearing Site for Subarachnoid of veins + blood seeping spinal epidural space (which is into space haemorrhage internal to periosteum lining the vertebrae, not external) * Subarachnoid cisterns dilations of subarachnoid space at significant reabsorption * site of CSF into circulation of ) Cindy Is Coming to Pretoria depressions in the brain, pooling with CSF Cisterna magna (aka cerebromedullary cistern) between cerebellum and dorsal surface of medulla gets CSF from 4th ventricle’s apertures Interpeduncular cistern Located at base of brain between temporal lobe Deepest between cerebral peduncles of midbrain Contains optic chiasm + circle of Willis Has subdivisions: o Pre- and post- chiasmatic o Cistern of lamina terminalis o Supracallosal cistern Cistern ambiens (aka superior cistern) OT's Practice And Study Basic Greeting & Between splenium (post. Part) of corpus callosum Contents: optic tract, trochlear nerve. Posterior cerebral and superior surface of cerebellum artery, anterior choroidal artery, superior cerebellar artery, contains great cerebral vein and pineal gland basal vein, great cerebral vein OT-PcAcSc-BGc Pontine cistern Basilar artery runs through it 3rd ventricle CSF filled interconnecting chambers derived from lumen Located between right & left halves of diencephalon V lined choroid plexus by ependymal cells Lateral walls formed by thalamus and hypothalamus > = choroid plexus produces (SF of embryonic neural tube responsible production & for the removal of CSF , transport + on either side vo r e i Roof formed by pia-epyndyma spanning between lim stria medullaris thalami nerve bundles mo Interventricular foramen (Monro) pramet → Aperture in rostral 3rd venricle but inc → Between column of fornix & ant. pole of thalamus Continuous posto-inferiorly with cerebral aqueduct, connecting it to 4th ventricle Lateral Ventricles (1st & 2nd) 1 supra-optic infundibular recess : above optic chiasm ⑮ Located within the cerebral hemispheres above optic stalk recess : Est 4th ventricle ↳ Parts: recieves , flis From4th Ventricle L Diamond shaped Anterior (Frontal) horn L Spinal a bathes spil V Central : > lies within · brainstem between Floor: dorsal surface of brainstem beneath → Ant. to IV foramen subarchoniod bathes & : + medulla pons I Have brain between p mater D. Mater oblangata cerebellum → Lateral wall: head of caudate nucleus +. Covid Son Roof: formed mostly by cerebellum except at caudal → Roof: corpus callosum part which consists of pia + epyndyma, and rostral → Medial wall: septum pellucidum part which is partly formed by superior cerebellar Body ABPI : FOT peduncles bridged by superior medullary velum → Floor: thalamus and tail of caudate nucleus CSF enters subarachnoid space via lateral & median Posterior (Occipital) apertures Inferior (Temporal) Lateral aperture (foramen of Lushka) → Lies in temporal lobe → Continuous with subarachnoid space of → Floor: hippocampus cerebellopontine angle → Roof: attenuated tail of caudate nucleus Median aperture (foramen of Magendie) Note: Names of parts relate to parts of the cerebrum → opening in caudal roof Opens through interventricular foramen into 3rd → communicates between lumen of ventricle and ventricle cisterna magna Z Jhetam (2020)  Fiona Is Hiding Very Low, Shrek Can Guess I produced by choroid plexus CSF circulation & reabsorption 1. Most CSF is produced by the choroid plexus of the faciallicaus ↓ lateral ventricle. [CP 2. From here it flows through the interventricular - fibers of facial new x - Lateral cureclus foramen into the third ventricle and then via the > - Hypoglossal Stra med cerebral aqueduct into the fourth ventricle. of medullyis - Cureate 3. CSF leaves the ventricular system through the three found ↳ gal - Geraci apertures of the fourth ventricle and enters the subarachnoid space. 4. Most CSF passes through the median aperture to enter the cisterna magna, located between the medulla and cerebellum. Cerebrospinal Fluid (CSF) 5. A lesser amount flows through the 2 lateral Colourless fluid in ventricles and subarachnoid spaces apertures to enter the subarachnoid space in the bathing bathing brain and spinal cord region of the cerebellopontine angle. Volume: 150 ml 6. From these sites, the majority of CSF flows superiorly, Manufactured at a rate of ~ 0.35 ml/ min (500 ml of round the cerebral hemispheres, to the sites of total CSF made per day and replaced every 4-6 reabsorption. hours). 7. CSF is reabsorbed into the venous system by passing Functions: into the dural venous sinuses – mainly the superior → Supports and cushions brain against trauma sagittal sinus. (counter-coup effect where the CSF is dispersed 8. Along the sinuses are located numerous arachnoid at site of impact and pain felt in the opposite villi – invaginations of arachnoid mater through the location). dural wall and into the lumen of the sinus. V CSF maintains low → Supports and cushions the spinal cord 9. Reabsorption occurs at these sites because the extracellular K + for synaptic transmission → Acts as a buoyant fluid: hydrostatic pressure in the subarachnoid space is higher than that in the lumen of the sinus and → Brain weighing 1500 g in air weighs 50 g in CSF because of the greater colloid osmotic pressure of → Maintains uniform pressure in cranial cavity venous blood compared to CSF. → Nutrition of neural tissue: CSF contains little 10. With age, the arachnoid villi become hypertrophic to protein & few cells form arachnoid granulations → Removes waste products of neuronal metabolism Hydrocephalus Formed by choroid plexus Excess accumulation of CSF which produces an → Spongy, convoluted invagination of vascular pia elevated intracranial pressure and in infants can mater into ventricular lumen cause swelling of the ventricles. → Located in the floor of the lateral ventricles (via Also known as ‘Water in the brain’ choroid fissure) and the roofs of 3rd & 4th It could be Congenital or Acquired ventricles. Possible causes of congenital Hydrocephalus: Overproduction of CSF CSF circulation E Obstruction at some point within ventricular system Problems with CSF absorption ciquaduct (4thV( choroid plexus ((V) < [V foramen (3rdV) > Cerebral Anatomy of Lumbar puncture (Spinal Tap) subarachnoid space< Three apertures of 4th Withdrawal of CSF from lumbar cistern. Jesse most , v Based on absence of spinal cord below L2 with large L median aperture lateral aperture space to S2 V V Preferred Site: Level of vertebra between L3 & L4 or cisterna magna subarachonoid space of Cerebellopulatine L L4 & L5 V Slight damage or injury to nerve roots of cauda cerebral hemisphere (reabsorption) equina present at this level dural s crachnoid villi Venous sincs Introduction of the troca between vertebral lamina is rather difficult except at lumbar levels C T I Cincy Takes N.B: The cerebellomedullary cistern may be used to Chances To S obtain a specimen of CSF when a lumbar puncture is not MC Secure Money LG C > D & A claiming Late possible or unsuccessful Cathy's Car Death as Accident Z Jhetam (2020)  → Cortical branches supply medial surface & marginal area of superolateral surfaces of cerebrum (includes the motor and sensory cortices for the lower limb + arise from anterior communicating narrow lateral band of frontal and parietal cortices arterly Arterial supply by 2 main pairs: Internal Carotid arteries via fine terminal branches also extending out of the (carotid system) and Vertebral arteries (vertebrobasilar great longitudinal fissure) system) → Central branches supply deep structures in cerebral prisefromthenecktsceintocranium circle of Willis hemispheres (rostrum of corpus callosum, septum Internal carotid artery pellucidum, putamen, head of nucleus) - Origin: bifurcation of common carotid artery of 4 Course: Middle cerebral artery 1. It enters the middle fossa of the cranial cavity Largest cerebral artery, with most extensive cortical through the carotid canal (in petrous temporal b.) territory 2. It then bends as the carotid syphon passes laterally from its origin to enter the lateral 3. Then it passes forwards through the cavernous sinus fissure within which it subdivides - > to supply lateral cortical surfaces along insula with CNVI, CNIII & CIV. cortical branches supply virtually the whole of the 4. Then passes upwards on the medial aspect of the · frontal a "perfuse : lateral surface of the frontal, parietal and temporal inferior anterior clinoid process, and runs in carotid groove of frontal , precentral gyri lobes (incl. primary motor and sensory cortices for middle+ sphenoid bone’s body · lateral orbital : the whole of the body, excluding the lower limb) parts of frontal lobe , frontal gyrus 5. Eventually reach the surface of the brain lateral to · inferior parietal : part of inf 2 sets of Central branches: the optic chiasm. parietal superior lobe + → Medial striate supplies caudate nucleus, internal postcentral gyrus capsule, lentiform nucleus Extracerebral Branches of Internal Carotid Artery → Lateral striate supplies caudate nucleus Petrous part in petrous part of temporal bone Charcot’s artery of cerebral haemorrhage – → Caroticotympanic branch to tympanic cavity largest & most frequently ruptured in → Pterygoid artery to pterygoid canal apoplexy Cavernous part* in lateral wall of cavernous sinus MCA also serves the auditory cortex and the insula → Cavernous brs within the depths of the lateral fissure → Meningeal brs → Hypophysial brs After cavernous course → Ophthalmic to contents of orbital cavity Pre-terminal branches: Hypophyseal arteries – supply neurohypophysis Ophthalmic artery – supplies the structures of the orbit, the frontal and ethmoidal sinuses, the frontal part of the scalp and dorsum of the nose. Anterior choroidal artery supplies the optic tract, the choroid plexus of the lateral ventricle, the hippocampus and some of the deep structures of the hemisphere, including the internal capsule and globus pallidus. The posterior communicating artery passes backwards to join the posterior cerebral artery, thus forming part of the circle of Willis. Terminal branches (dividing lateral to optic chiasm): the anterior and middle cerebral arteries - begins & terminal portion of ICA Anterior cerebral artery: > smaller branch courses medially above the optic nerve and then passes into the great longitudinal fissure, between the frontal lobes of the cerebral hemispheres joined to the corresponding vessel of the opposite side by the short anterior communicating artery. 2. short thin, artery that runs horizontally Within the great longitudinal fissure, the anterior between anterior cerebral arteries anterior to optic chiasm posteromedial cerebral artery follows the dorsal curvature of the · , to olfactory tracts corpus callosum, branches ramifying over the medial · completes and part of circle of Willis surface of the frontal and parietal lobes, which it supplies. Z Jhetam (2020)  Vertebral Arteries < posterior blood supply (brainstem, cerebellum, occipital lobe) Origin: subclavian artery (1st part) Course: 1. ascends through the foramina transversaria of the cervical vertebrae and enters the cranial cavity Arterial Circle of Willis: & inferior surface of brain , within interpeducular cistern of subarachnoid through the foramen magnum, alongside the Arterial anastomosis connecting vertebrobasilar & ventrolateral aspect of the medulla. internal carotid systems (via post communicating arteries between internal carotid and posterior Along its course, the vertebral artery gives rise to: cerebral arteries + anterior communicating artery posterior spinal arteries – supply dorsal 1/3rd of between anterior cerebral arteries) spinal cord & dorsal root ganglions Location: Base of interpeduncular fossa, encircling anterior spinal artery: Ventral 2/3rd spinal cord < converge anterior to in midline MO the optic chiasm and the floor of the hypothalamus Medullary artery – supplies medulla oblongata and midbrain posterior inferior cerebellar artery (PICA) – supplies Branches Involved the inferior aspect of the cerebellum → Anterior communicating S → Anterior cerebral arteries connecting 2. As they pass rostrally, the two vertebral arteries → Internal carotid converge, uniting at the junction of the medulla and → Posterior communicating L pons to form the midline basilar artery. → Posterior cerebral 3. The Basilar artery runs the length of the pons Importance: 1. Serves to equalise blood flow to various parts of brain Branches of basilar artery: < found O pontine cistern & posterior to clivus , anterior to pons maintaining a constant supply of oxygen & glucose even when a contributing artery is narrowed or in head Pontine branches – supply pons movements anterior inferior cerebellar artery (AICA) – supplies 2. Furnishes collateral circulation in cases of occlusion of the anterior and inferior portion of the cerebellum one or more of the arteries contributing to circle labyrinthine artery – passes into the internal acoustic meatus to supply the inner ear. Small perforating arteries arise from the circle of Willis to supply the hypothalamic area, the basal ganglia and the 4. At the junction of the pons and midbrain, the basilar internal capsule. Two groups: anterior and posterior artery divides into two pairs of vessels, the superior perforating arteries. cerebellar arteries & the posterior cerebral arteries. & separated by Oculomotor nerve The superior cerebellar artery (SC) supplies the superior aspect of the cerebellum and anastomoses with AICA The posterior cerebral artery curves around the midbrain and divides into terminal branches: > division occurs o dorsum sellae Cortical – supply inferior surface of cerebrum, occipital pole (visual cortex) and inferomedial aspect of temporal lobe Central supply thalamus, 3rd ventricle, globus pallidus Posterior choroidal – supply choroid plexus of lateral ventricle, thalamus, fornix & tectum of midbrain Perforating arteries Anterior perforating arteries from anterior cerebral a. and AComm: 1) enter the brain between optic chiasm + terminating branches of olfactory tract & anterior perforated substance 2) supply basal ganglia, optic chasm, internal capsule, hypothalamus Posterior perforating a from posterior cerebral a and Pcomm: 1) enter the brain between two crura cerebri of midbrain posterior perforated & substance 2) supplies ventral portion of midbrain, subthalamus, hypothalamus Z Jhetam (2020) Internal carotid artery Preterminal branches *(EC = extracerebral) Hypophysial arteries (EC*) neurohypophysis Opthalmic artery (EC) structures of the orbit, the frontal and ethmoidal sinuses, the frontal part of the scalp and dorsum of the nose Anterior choroidal artery optic tract, the choroid plexus of the lateral ventricle, the hippocampus and some of the deep structures of the hemisphere, including the internal capsule and globus pallidus Posterior communicating artery passes backwards to join the posterior cerebral artery, thus forming part of the circle of Willis. Terminal branches Anterior cerebral artery Basically, medial surface of frontal & parietal lobes Cortical branches supply medial surface & marginal area of superolateral surfaces of cerebrum (includes the motor and sensory cortices for the lower limb + narrow lateral band of frontal and parietal cortices via fine terminal branches also extending out of the great longitudinal fissure) cingulate gyrus + Central branches supply deep structures in cerebral hemispheres (rostrum of corpus callosum, septum pellucidum, putamen, head of nucleus) Middle cerebral artery In addition to structures below, MCA serves the auditory I precentral postcentral , superior + midle frontal , and temporal pyri parts , of parietal gyrus cortex and the insula within the depths of the lateral fissure Cortical branches virtually the whole of the lateral surface of the frontal, parietal and temporal lobes (incl. primary motor and sensory cortices for the whole of the body, excluding the lower limb) Central branch: Medial striate supplies caudate nucleus, internal capsule, lentiform nucleus Central branch: lateral striate caudate nucleus Charcot’s artery of cerebral haemorrhage – largest & most frequently ruptured in apoplexy Vertebral Artery Brainstem, cerebellum, occipital lobe posterior spinal arteries supply dorsal 1/3rd of spinal cord & dorsal root ganglions anterior spinal artery Ventral 2/3rd spinal cord Medullary artery Medulla oblongata posterior inferior cerebellar artery (PICA) Inferior aspect of cerebellum Basilar artery Runs length of pons Pontine branches pons anterior inferior cerebellar artery (AICA) anterior and inferior portion of the cerebellum Labyrinthine artery passes into the internal acoustic meatus, supplying inner ear Superior Cerebellar artery superior aspect of the cerebellum and anastomoses with AICA Posterior Cerebral artery curves around the midbrain and divides into terminal branches Cortical inferior surface of cerebrum, occipital pole (visual cortex) and inferomedial aspect of temporal lobe Central thalamus, 3rd ventricle, globus pallidus Posterior choroidal choroid plexus of lateral ventricle, thalamus, fornix & tectum of midbrain Blood supply of spinal cord: Disorder of blood supply to spinal cord The arteries supplying the spinal cord are branches of the The blood supply of the spinal cord is most vertebral, ascending cervical, deep cervical, intercostal, vulnerable in the thoracic region and in the anterior lumbar, and lateral sacral arteries. & arise from thoracicc orta & ventral branch portion of the cord. Occlusion of the anterior spinal artery leads to an lateral cutaneous > dorsal branch medial cutaneous At medulla, vertebral arteries give off anterior spinal Spinal branch acute thoracic cord syndrome with paraplegia and artery (ASA) incontinence (because sympathetic nerves emerge 10 to 12 segmental (medullary) arteries (brs of aorta) from the lateral horns of the thoracic segment of SC) join anterior spinal artery The spinothalamic modalities of pain and Vertebral arteries (or PICA) give rise to paired temperature are preferentially lost, whereas the posterior spinal arteries (PSA) that run along dorsal proprioceptive functions of the dorsal columns are surface. relatively preserved. Z Jhetam (2020)  Inferior sagittal sinus → Enclosed by free border of the falx → veins on the medial aspect of the hemisphere flow into it Straight sinus > continuation of ISS great vetebral vein + → Within the tentorium cerebelli, along the line of its attachment to the falx → great cerebral vein, which drains the deep structures of the forebrain, and the inferior sagittal sinus drain into it Occipital sinus (OS) → lies in the attached border of the falx cerebelli and ends superiorly in the confluence of sinuses Superior petrosal sinus (SpS) Inferior petrosal sinus (IpS) Venous Drainage of brain 1 The superior sagittal sinus and the straight sinus Characteristic Features of the veins that drain the brain converge at the confluence of the sinuses, which lies No valves adjacent to the internal occipital protuberance. Extremely thin walls 2 From here, blood flows laterally on either side in the Lack muscular tissue in tunica media transverse sinus, which lies along the line of Pierce arachnoid mater & inner layer of dura mater attachment of the tentorium to the occipital bone. End in dural venous sinuses 3 The transverse sinus is continuous with the sigmoid