Meninges, Ventricles and CSF Neuroanatomy block-Anatomy-Lecture 19 Editing file Objectives At the end of the lecture, students should be able to: 01 Describe the cerebral meninges & list the main dural folds. 02 Describe the spinal meninges & locate the level of the termination of each of them. 03 Describe the importance of the subarachnoid space. 04 List the Ventricular system of the CNS and locate the site of each of them. 05 Describe the formation, circulation, drainage, and functions of the CSF. Color guide 06 Know some clinical point about the CSF. ● Only in boys slides in Green ● Only in girls slides in Purple ● important in Red ● Notes in Grey Meninges The brain and spinal cord are invested by three concentric membranes: Dura Mater Arachnoid Mater Pia Mater The outermost layer. The middle layer. The innermost layer. Dura Mater The cranial dura is a two layered tough, fibrous thick membrane that surrounds the brain. Formed of two layers meningeal :is folded forming the dural folds : Two large periosteal :attached to the skull. reflection of dura extend into the cranial cavity: Tentorium cerebelli: Falx cerebri: -A horizontal shelf of dura, lies between the -It is a vertical sickle shaped sheet of dura, in the posterior part of the cerebral hemispheres and the midline. cerebellum. -Extends from the cranial roof into the great -It has a free border that encircles the midbrain. longitudinal fissure between the two cerebral -Its superior surface in the middle line it is hemispheres. continuous above with the falx cerebri, separated by -It has an attached border adherent to the skull and a straight sinus. free border lies above the corpus callosum. Sensory innervation of the dura mater: is mostly from : meningeal branches of the: trigeminal and vagus nerves & C1 to C3. 3 Arachnoid Mater & Pia Mater Arachnoid Mater Pia Mater - It is a soft, translucent membrane loosely envelops - It is the innermost, thin, delicate & highly vascular the brain. membrane that is closely adherent to the gyri and - It is separated from the dura by a narrow subdural fitted into the sulci. space. Between the pia and arachnoid mater lies the subarachnoid space which contains; fibrous trabeculae, main blood vessels and CSF. Subarachnoid Space The subarachnoid space is varied in depth forming; subarachnoid cisterns. ● lies between the inferior surface of the Cisterna magna, or cerebellum and the back of the medulla. cerebllomedullary cistern: ● At this cistern CSF flows out of the fourth ventricle 01 via the 2 lateral aperture and median aperture. ● Is located at the base of the brain, where the arachnoid Interpeduncular cistern: spans between the two cerebral peduncles of midbrain. 02 ● It contains the optic chiasma & circulus arteriosus of Wills . 4 Spinal Meninges ● Spinal cord terminates at level L1-L2. ● The dura and arachnoid and, subarachnoid space, continue caudally to S2. ● Pia extends downwards forming the filum terminale which pierces the arachnoid and dural sacs and passes through the sacral hiatus (11) to be attached to the back of the coccyx. ● The spinal cord, is invested by three meningeal coverings: Meningeal coverings Dura Mater Arachnoid Mater Pia mater -The outer covering; is a thick, -The innermost covering, is a tough fibrous membrane. -is a translucent membrane delicate fibrous membrane -It envelopes the cord loosely. lies between the pia and dura, closely envelops the cord and -It is separated from -Between arachnoid and pia nerve roots. arachnoid mater by the lies the subarachnoid space -It is attached through the subdural space, and from the contains CSF. arachnoid to the dura by the bony wall of the vertebral denticulate ligament. canal by the epidural space. 5 Ventricular System 1. Interconnecting channels within the CNS. 2. In the spinal cord; represented by the central canal. 3. Within the brain; a system of ventricles is found. 4. The central canal of the spinal cord is continuous upwards to the fourth ventricle. 5. On each side of the fourth ventricle laterally, lateral recess extend to open into lateral aperture (2 foramen of Luschka), central defect in its roof (1 foramen of Magendie). 6. The fourth ventricle is continuous up with the cerebral aqueduct, that opens in the third ventricle. 7. The third ventricle is continuous with the lateral ventricle through the interventricular foramen (foramen of Monro). lateral recess 6 Cerebrospinal Fluid ● Present in the ventricular system, together with the cranial and spinal subarachnoid spaces. ● It is colourless clear fluid containing little protein and few cells. It is about 150 ml. ● It acts as a cushion for the brain from sudden movements of the head. ● It’s circulates in the subarachnoid space. 9 Arachnoid villi 10 It is produced by the (1) choroid plexus, which is located in the lateral, third & 01 fourth ventricles. 1 From (2) lateral ventricle it flows: through the (3) interventricular foramen or 02 foramen of monro into the (4) 3rd ventricle and, by way of the (5) cerebral 2 aqueduct (aqueduct of sylvius), into the (6) 4th ventricle. 3 It leaves the ventricular system through the three apertures of the 4th ventricle 4 03 ( 7) median foramen of Magendie & (8) 2 lateral foramina of Luschka, to enters 5 the subarachnoid space. 6 8 foramina of Luschka 7 Reabsorbed finally into the venous system along (9) arachnoid villi, and arachnoid granulation (larger than villi) that project into the dural venous 04 sinuses , mainly (10)superior sagittal sinus. 7 Cerebrospinal Fluid flow diseases Clinical point The obstruction of the flow of CSF leads to a rise in fluid pressure causing swelling of the ventricles (hydrocephalus). Causes Congenital Acquired Obstruction of the Stenosis of the interventricular foramina ( Arnold-Chiari cerebral aqueduct secondary to tumors, malformation). by tumor of pineal hemorrhages or infectious such region. as meningitis Hydrocephalus shunt Decompression of the dilated ventricles is achieved by inserting a shunt connecting the ventricles to the jugular vein or the abdominal peritoneum. 8 Practice Q1: The subarachnoid space terminates at: Q5: the CSF flows through foramen of monro (interventricular foramen) from (...) to (...) A. Coccyx A. Cerebral aqueduct , 3rd ventricle B. L1-L2 B. 4th ventricle , central canal C. S2 C. 3rd ventricle, lateral ventricle D. S1 D. Lateral ventricle, 3rd ventricle Q2: The CSF is about: Q6: which one of these does not supply the dura mater ? A.50 ml A. Facial B. 150 ml B. vagus C. 250ml C. C1-C3 D. 300 ml D. Trigeminal Q3: cerebrospinal fluid is produced by: Q7: the Cisterna magna is between ? A. 3rd ventricle A. posterior surface of the cerebellum and the back of the medulla B. Choroid plexus B. cerebrum and the back of the medulla C. Lateral ventricle C. at the base of the brain between the two cerebral peduncles of midbrain D. 4th ventricle D. inferior surface of the cerebellum and the back of the medulla Q4: which layer of dura mater that form falx cerebri and tentorium cerebelli ? Q8 : hydrocephalus shunt is connecting the ventricles to A. meningeal layer A. Carotid artery B. pia mater layer B. jugular vein C. periosteal layer C. Abdominal peritoneum D. subarachnoid layer D. B & C Answers: Q1(C) Q2(B) Q3(B) Q4(A) Q5(D) Q6(A) Q7(D) Q8(D) 9 Members board Team leaders ● Abdulrahman Shadid ● Ateen Almutairi Girls team : Boys team: ● Ajeed Al Rashoud ● Mohammed Al-huqbani (legend)- LR ● Taif Alotaibi ● Salman Alagla ● Noura Al Turki ● Ziyad Al-jofan ● Amirah Al-Zahrani ● Ali Aldawood ● Alhanouf Al-haluli ● Khalid Nagshabandi ● Sara Al-Abdulkarem ● Omar Alammari ● Renad Al Haqbani ● Sameh nuser ● Nouf Al Humaidhi ● Abdullah Basamh (ily) -lecture reviewer ● Jude Al Khalifah ● Alwaleed Alsaleh ● Nouf Al Hussaini ● Mohaned Makkawi ● Rahaf Al Shabri ● Abdullah Alghamdi ● Danah Al Halees ● Rema Al Mutawa ● Amirah Al Dakhilallah ● Maha Al Nahdi Contact us: ● Razan Al zohaifi ﺑﺪر There are 3 easter eggs in this lecture, try to find them - Lecture reviewer reviewer Lecture - them find to try lecture, this in eggs easter 3 are There اﻟﺸﮭﺮي Ghalia Alnufaei ● اﻟﻈﺮﯾﻒ Editing file most probably you don't need this .