Brain Study Notes

The orbit : Roof= frontal bone Major floor= spenoid =zygomatic arch Medial floor = maxillary The zygomatic spenoid and frontal are not Join There's fissures between these bones Superior orbital fissure(SOF) = between two sides of sphenoide Inferior orbital fissure(IOF) =between the spenoid and the maxilla The frontal bone Join with the parietal bones by a coronal suture We have the Coronal Suture between the frontal bone and the two parietal bones. The two parietal bones are joint in the middle by the Sagittal Suture. The junction between the coronal suture and the sagittal suture is called Bregma. The Bregma isn’t the highest point in the skull, it is the Vertex. So the Vertex is around the middle of the sagittal suture. The parietal bones and the occipital bone join by the Lambdoid suture, because it forms a lambda sign. Here we see the occipital bone. On each side, we will continue with the Temporal bone. The Temporal Bone joins with the sphenoidal bone. We have up there a confluence. This area looks like an “H”. This junction of the 4 bones is called Pterion. We see that the frontal and parietal bones have a “ridge” or “temporal lines”. These temporal lines are important because they are the insertion of lateral skull muscles like Temporalis muscle, which is an important muscle of mastication. Here we removed the occipital bone, we see the frontal, sphenoidal, temporal, and part of the (anterior) occipital bone. In fact, the occipital bone covers the base of the skull. The majority of the base of the skull is covered by the temporal and occipital bones. The anterior part of the skull base is made by the maxilla, part of the zygomatic arch and the under surface of the sphenoidal bone. The Sphenoidal bone is the most complex bone. Choufo enno l Sphenoid mtl l 3asfour. Hel 3asfour 3endo Body bl nos. It has 2 lesser wings on the up, and 2 greater wings on the bottom. w 3endo 4 ejreyn mn ta7t. We have a fissure between the greater and lesser wing called “SOF” (superior orbital fissure). And between the greater wing and the zygomatic arch is called “IOS” (inferior orbital fissure). At the bottom we have the Pterygoid plates, 2 lateral and 2 medial. They are important la2an b 3alle2 3layon l Pterygoid muscle. So the mastication muscles b 3all2o 3a these 4 . We see that we have a lot of holes here. These holes are what we see from the outside. And if you follow the skull, metl ma shefna hon, men eddem la wara, menshouf enno ma3moule metl ljlele, awwal jal, tene jal, telit jal, w hol ljlele metl l “fossa”, metl ljouwar. And these fossa are where the parts of the brain reside. Bima enno hene 3 jlejle ya3ne the brain has to have 3 levels and in fact the brain has 3 levels, so fi 3ena sha2fe men eddem yali hiye frontal lobe yali hiye 3alye, li bel nos yali hiye temporal lobe, ta7t 3ena cerebellum yali hiye l inferior part of the brain (stem), awta shi. So bi hal 3 jlejle, we have the frontal anterior fossa byeje b2alba l frontal lobe, l middle fossa li b2alba ltemporal lobe wl posterior fossa li b2alba l cerebellum wl stem of the brain. Hon 3am nettala3 3layhon men fo2, the frontal fossa, medial fossa w hon fina nshouf l sphenoide wel greater and lesser wing , w hon mnshuf l temporal bone and the occipital bone. W shufo eno fi juwar, openings w 3al temporal fina nshuf juwar zghar, small openings w 3al sphenoid fina nshuf opening ben l lesser wel greater wings, ba3den ta7ta fi “borrayme mdawwara” (walla huwe hek 3am y2oul), w hon mnshuf ta7ta barme tenye yale hiye ovale (Foramen spinosum). W hon fina nshuf ka2eno fi jere7 ben l sphenoid wing and the temporal (foramen lacerum). Hon mneje mnshuf another opening (internal acoustic meatus) w hon a bigger opening (jugular foramen) w then then the biggest opening (foramen magnum), belnos yamin w shmel ( l foramen magnum) fi other openings (hypoglossal canal). Kel we7de of these openings, will let pass threw, MAINLY cranial nerves, nerves from 1 to 12. 1 to 12 logically lezem ybalsho men eddem la wara. The brain doesn’t like eno shi yja3lik fo2 shi. So number 1 is the olfactory nerve… few minutes of awkward silence… Olfactory nerve is here (au niveau de cribriform foramina de cribriform plate) elle est appelée comme ça car mtl l monkhol aashen ktir rfe3 and these are where olfactory nerves come in (byejtem3o hone). Hone l nerve byejo mn barra la jouwwa, lesh? La2enno l olfactory nerve is a pure sensory nerve manno motor nerve. Donc c’est pour le cranial nerve number 1 (olfactory nerve) Pour le cranial nerve number 2 qui est l’optic nerve li byo2ta3 bl optic canal w bifut aala l globe. Le 3eme c’est l’orbital fissure : logically li 7a yfut bl orbital fissure henne l nerve li 7a yrou7o aal 3en wl nerves li biru7o aal 3en henne CN3 CN4 CN6 and these are the motor nerves of the eye li bikhalluna nottala3 la fo2 aw ta7et aw la barra. Bidal fi sensation: for the sensation of the eye we have cranial nerve number 5 which has 3 branches (CN5(1), CN5(2) AND CN5(3)) and CN5(1): Olphactory nerve w huwwe the sensory nerve of the eye li bikhalline 7ess bl 3en. Therefore for the eye we have CN3 CN4 CN6 (motor nerves) and CN5(1) (sensory nerve) w maaon byo2ta3 veins the olphactory veins. In the optic canal byo2ta3 the optic nerve and the ophthalmic artery. For this hole li shklo mdawwar aashen hk esmo foramen rotundum (round yaane), hyda byo2ta3 fi CN5(2) which is called maxillary nerve and which bya3te sensation for the maxillary part of the face.Hyda l hole shklo ovale,, foramen ovale,byo2ta3 fi CN5(3) which is called mandibular nerve msh axillary (sal7uwa) and accessory meningeal artery. This small is called "foramen spinosum" ,it is very important because the middle meningeal artery pass through it. The middle meningeal artery will continue on the internal surface of the temporal bone and it will give an anterior branch and a posterior branch. -->the anterior branch will pass on the top of the dura behind an important anatomical spot which is the "pterion" . If we had an injury on the lateral side of the skull( on the pterion) the middle meningeal artery -anterior branch will be affected and we will get an extra-dural bleeding(or extra-dural hematoma). ( If the bleeding is inside the dura+ above the brain: we call it sub-dural bleeding) So to recap, the extra dural bleeding occur between the dura and the skull, the most common is the case of the anterior branch of the meningeal artery by a fracture of the pterion. The bleeding that occur above the brain and under the dura is called sub-dural bleeding and most commonly it is due to venous injuries. The foramen lacerum: it is not a true hole, it is just an emptiness ( because no structure pass through it) THE POSTERIOR FOSSA. 7- Facial Nerve 8- Cochlear nerve These two go to the ear, by passing through the internal acoustic meatus. • The hypoglossal canal o Is from either side of the foramen magnum. o The Hypoglossal nerve (nerve 12) passes through it à innervates the tongue (bi khalli yetharrak la eddem w yamin chmel). • The foramen magnum: o The biggest one. o The spinal cord, the meninges (pie- mere, arachnoide, dure-mere), the vertebral arteries, the dural veins, the spinal arteries and the cranial nerve 11 (spinal nerve) pass through it. • The jugular foramen: Nerves 9-10- the accessory 11- the jugular vein, the sigmoid sinuses, they all pass through it but we mainly focus on the nerves 9- 10 and 11. • The Mastoid foramen: small veins and small branches of the occipital arteries pass through it. On a 4 clinoid car anciennement les lits possedent des colonnes on a le clinoid procees et posterieurement on a le clinoid posterior ces 4 colonnes sont importants car comme depuis long temps il ya des roof où s'attache une chiffon ( ‫ )ﻗﻣﺎﺷﺔ‬qui couvre un espace comme ici nomme sellae turcica *actually this is the house for a very important gland * c'est le pineal gland and that it is why these fossa also called the hypophysial fossa so the sellae torcica dorsum sallae , clinoid anterior and posterior and these sallea also called the hypophysial fossa because that is where the hypophosis is found These fossa is called the cerebellum fossa these is where the cerebellum hemisphere reside . So these table and this image we look at the inside the skull where they come from and the other we look on the inferior side maybe I ask you what this feromen and what going through it we have to memorise this as well as these slide Now we come to the different parts of the brain so the first part of the brain of course it is the dura the dura mater the arachnoid and the pia mater this are the 3 meninges that separate the parenchymal of the brain from the skull inside the dura you have sinuses they collect the veins and drain the veins toward the jugular foramen where the CSF that produce .the CSF is produced in the choroid plexus it goes into the ventricular system so this CSF is continuing moving fluid (non stop) so it produced in choroid plexus enter into ventricle to wards the epedymal canal and it actually surounded the brain everything is in purple is CSF it is produced in the choroid plexus of the ventricles but it is absorbed by the arachnoid granulation towards this big vein ...msh mfhum .so this superior sagittal sinus the arachnoid granulation actually absorb the CSF towards the vein and this allows the circulation of the CSF .So the arachnoid granulations they are blood supply vessels that absorb the CSF and pushed toward the veins blood and you get something like this you have the lateral ventricles they have anterior and posterior horn And the lateral ventricles they have inferior horns this 3 every one of them is found in hemisphere and they are separated from the third ventricul so all the CSF is produced and goes than to the third ventricle the third ventricle is in the middle and this ventricle goes down an aqueduct names cerebral aqueduct each lateral ventricle is found in a hemisphere and they are separated from the 3rd ventricle all the csf is produced and goes to 3rd ventricle that is found in the middle han the 3rd ventricle goes to the cerebral aqueduct han the cerebral aqueduct goes to the 4th ventricle that goes around the dura , around the spinal cord. • This system is connected through foramens: - Between the lateral ventricles and the 3rd ventricle we have the interventricular foramen - Between the 4th and the paradural/paraspinal region we have the foramen of Luschka and magendie - The foramen of Monro lies at the junction between the paired lateral ventricles and the third ventricle of the brain. <-- This slide to memorize TOO Venous blood supply • • • • Sinuses around the brain collect all the blood the superior sagittal sinus ( at the top + very large) the transverse sinus the inferior sagittal sinus ( in the middle + very large) Ø between the superior and the inferior sagittal sinus , we have a division that separates the brain in 2 parts or hemispheres ( right and left ) Ø this division is called : the falx cerebri The sphenoparietal veine is located between the sphenoid and the parietal bones. We have the petrosal bone , lech esma hek? La2ano bl temporal bone 3na 2 parts , wahad ne3im esmo os squameux w wahad mhajar esmo l os petreux , so 3na superior petrosal sinus w inferior petrosal sinus. Hol l 2 sinus byjtem3o bi a confluence(grp of veines) 3a yamin w chmel l sella turcica esma l cavernous sinus .The 2 cavernous sinus byjtem3obi a grp of veines wara w edem l sella turcica esmoun l intercavernous sinus. (posterior view) The cavernous sinus sinus is very important la2ano bi albo by2ta3 l carotid artery (yaene l artery bto2ta3 bl vein) w this vein allows the exchange of temperature to maintain the temperature of the blood in the carotid artery at 37º. Bi alb l cavernous sinus fi 3na kmn nervs, 3na l nerv 3, 4 , 5(1 ), 5(2) hene haddo lal cavernous sinus(outside le2yin 3le) bs l nerv 6(the abducent nerv) actually houwe bi albo lal cavernous sinus. Superior sagittal sinus drains to the transverse sinus at the level of confluence of sinuses. Transverse be keb fi el inferior sagittal w fi one big vein men aleb el brain esmo the great cerebral vein. Transverse sinus be sir sigmoid sinus yalle be sir internal jugular sinus. The internal jugular also drains from the anterior vein, so technically, the majority of the blood heading out of the brain is thanks to the internal jugular vein. Frontal branch passes behind the pterion, so if someones has an injury to the head, he will rip the anterior branch of the middle maninngal artery. Two types of bleeding in the brain : 1)The bleeding that happens between the dura and the skull called extra dural (biconvexe :llental shape) 2)Sub dural concavo convexe • • • The subdural is concavo-convex. The extradural is arterial The subdural is venous How does the brain feel? Eza ana chelet l skull w da2aytello bi dmegho, bi 7ess? The dura is sensate à yaane bas de2 bel dura fi ehses The brain is not sensate The dura has innervation from V1, V2, V3 So these supply part of the dura and also from the cervical à from the nerves of C2 and C3, mainly to the posterior fossa So the dura has sensation, the brain has not Hanabel Lecture à cut the brain of a person alive à brain insensate à person not feeling any pain Brain is painless à we can do surgeries on the brain in awake patients à if there is lesions on the brain in a very particular area à and we need to work on a part of the brain that is next to the frontal or motor cortex or the speech area à surgeons prefer that the patients do these activities (speak, play violin etc…) in order to monitor if they lose it or not We anesthetize the dura and the skin and we can work quite easily on the brain If we have a tumor in the brain à we do a section to operate on this tumor and remove it, is there damage on the brain? Yes, there is damage but the goal is to be able to get to it without causing damage à the deeper the tumor is the more damage we have to do to get to it, or we can decide to go another route (mnousalla men fo2 aw tahet aw aa janab) And the tumors that are on the surface are the tumors that cause the least damage The tumors that are the deepest (next to the thalamus, speech area etc… ) à cause the most damage VERY IMPORTANT!!! à BLA3OUWA (avec les numéros w kel chi) This is a randering of the cranial nerves, men eddem la wara è è è è è è è è è 1: olfactory nerve, cribriform plate 2: optic canal 3, 4 and V1 and 6 à soff V2 à rotundum V3 à oval Spinosum bi rouh menno artery 7 and 8 bi rouho auditory canal 9 10 amd 11 à bi rouho aal jugular 11 accessory bi rouh aal foramen magnum è 12 hypoglossal canal These are the different parts of the brain macro anatomy of brain Further, he mentioned that the spinal cord contains the ependymal canal that contain the CSF, plus the CFS surround also the spinal cord. The CSF mano 5et may all around, There are collections named cisterns, and the name of those cisterns is based on their location: One of the big cisterns are ventricles, most of the cisterns are not surrounded by a ventricular area, example: • • • Posterior cerebello- medullary cistern: between the cerebellum and the medulla posteriorly Pontocerebellar cistern: between the pons and the cerebellum Interpeduncular cistern: between the 2 pedunculus What we are supposed to know are the cisterns mentioned in this important image: A. B. C. D. Suprasellar cistern Quadrigeminal cistern Peripontine cistern Infrapontine cistern Explication of their nomination: We have the hypophysis inside the cella turcica, A fo2 l hypophyse so suprasellar, l B quadrangular form so quadrigeminal, C edm l pons cerebri so peripontine, l D ta7t l pons cerebri so infrapontine The posterior cerebello medullary cistern hiye akbar we7de fiyun so sar esma cisterna magna. 1. 2. 3. 4. 5. Lateral ventricle Third ventricle Aqueduct of sylvius Fourth ventricle Luschka and magenta THE BLOOD SUPPLY: The blood supply of the brain comes from • • Vertebral artery Internal carotid artery Brachiocephalic trunk then common carotid then internal carotid, that goes up along the neck enter the skull through the carotid canal, to the base of the skull, Then it becomes the middle cerebral artery that gives 2 branches the anterior cerebral artery that communicate with each other through the anterior communicating. The vertebral artery, comes from the right and the left, inside the foramen of transverse than enter the foramen magnum where the 2 vertebral arteries right and left, meet fuse together, ta7t l pons cerebri, to form the basilar artery, and the terminal branch of the bifurcation of the basilar is the posterior cerebral arteries, whereas the middle and anterior arteries are the branches from the internal carotid. Kell l arteries of the cerebellum comes from the basilar artery or vertebral: • • • Posterior inferior cerebellar Anterior inferior cerebellar Superior cerebellar Posterior communicating joins the posterior cerebellar and the internal carotid, This is very important image to memorize. All the arteries of the cerebellum come from the basilar. The posterior inferior cerebellar artery à“pica” • The anterior inferior cerebellar artery à “ica” • The superior cerebellar All of them come from the Basilar or the Vertebral. And the Basilar gives the posterior cerebral (left and right) • The posterior cerebral and the Carotid are connected by the posterior communicating. • The anterior cerebrals are connected by the anterior communicating. So the carotid system and the vertebral system have communication. Which is very important à eza fi hal sakar artery, l areries mawssulin b baad, b dal yejiun dam à Cerebral arterial circle or the circle of Willis We don’t have to know this What is important for the exam? The circle of Willis is veryyy important We have to memorize the image of the CSF system The extradural bleeding is biconvex biconcave concavo-convex, it’s arterials or veins? Eza fi kisser bel Pterion which artery is affected?