1、Chapter 6 The Meninges and Blood Vessels of Brain , Spinal Cord and the Cerebrospinal Fluid,Section 1 The Meninges of Brain and Spinal Cord,The brain and spinal cord are enclosed by three layers of meninges:,the dura mater; the arachnoid(蛛网膜); the pia mater.,l The Dura Mater,1. The spinal dura mater
2、 The epidural space* is a space between the dura and the periosteum , contains a quantity of loose areolar tissue, lymphatic vessels and venous plexus.,The spinal nerves on each side pass through the epidural space which is applicable for block anesthesia.,2. The cerebral dura mater,It is tightly fu
3、sed together with the inner periosteum of the skull in one layer.,The cranial dura is in loose contact with the skull cap, so the epidural hematoma is often happened in this area.,The cranial dura is closely attached to the base of the skull, so the cerebrospinal fluid may leaks out from the nose or
4、 ear when the fracture of the cranial base,The cranial dura gives rise to several septa, namely the cerebral falx(大脑镰), the cerebellar tentorium (小脑幕), with the free anterior margin called tentorial incisure surrounding the midbrain.,Because the parahippocampal gyrus and uncus are located just above
5、 the tentorial incisure, the increased intracranial pressure can move the parahippocampal gyrus and uncus downwards to form the tentorial hernia.,At certain sites the cranial dura mater is separated and forms large venous sinuses called the dural venous sinuses. The dural sinus and the direction of
6、blood flow in dural sinus are sum up as:,II The arachnoid:,It is a delicate, avascular membrane lying between the dura and pia maters, and covers the surfaces of the brain and spinal cord, and so is divided into spinal arachnoid, cerebral arachnoid.,It is separated from the pia mater by the subarach
7、noid space containing the cerebrospinal fluid.,The arachnoid bridges over some places around the brain to form some side spaces called the subarachnoid cisterns, such as, the largest cerebellomedullary cistern, the pontine cistern, the interpeduncular cistern, the chiasmatic cistern, the ambient cis
8、tern.,The arachnoid granulations are arachnoid which protrude in the superior sagittal sinus or other sinuses.,The cerebrospinal fluid in the subarachnoid cavity passes through this thin membrane into the encephalic dural sinuses and is taken up finally by the venous blood stream.,The spinal subarac
9、hnoid space becomes wider from the inferior end of the spinal cord to about the level of the second sacral vertebra, which is called terminal cistern containing the cauda equina.,Here it is the best site for lumbar puncture because of avoiding the injury of spinal cord.,III The pia mater:,It is a de
10、licate vascular membrane, closely attached to the surfaces of the brain and spinal cord and dipped into the fissures and sulci of the brain and spinal cord, and so is divided into the spinal and cranial pia maters.,The denticulate ligament, composed of spinal pia mater, is attached along the lateral
11、 surface of the spinal cord, midway between the dorsal and ventral nerve roots.,At certain sites of the cerebral ventricular walls, the cranial pia mater and its blood vessels combine with the ependyma to form the choroids plexuses, which are the main source of cerebrospinal fluid (CSF).,Section 2 T
12、he blood vessels of brain and spinal cord,I The blood vessels of brain The brain receives the blood from the vertibral a. and the internal carotid a.,1. The vertebral a.,left vertebral a.,basilar a.,post. cerebral a.,right vertebral a., The vertebral a. gives off ant. and post. spinal a., post. inf.
13、 cerebellar a. The basilar a. gives off ant. inf. Cerebellar a., pontine a., sup. Cerebellar a.,2. The internal carotid a.,The branches of internal carotid a. : ant. cerebral a. middle cerebral a. post. communicating a.,3. The cerebral arterial circle ( Willis circle) *, It is formed by: The anterio
14、r and posterior cerebral arteries The anterior and posterior communicating arteries, A short segment of internal carotid arteries.,This circle encircles the optic chiasma, the tuber cinereum, and the mammillary bodies. It may regulate the blood flow of brain.,4. The br. of arteries of the brain are
15、as follows:, Cortical br.: to supply the cortex and the medulla deep to the cortex. Central br.: to supply the basal nuclei and medulla especially the internal capsule.,II The veins of brain,The cerebral veins of the brain do not run together with the arteries, and usually are divided into superfici
16、al and deep groups.,The superficial veins are situated on the surface of the brain, drain the blood from the cerebral cortex and empty into the adjacent cerebral dural sinuses.,The deep veins drain the blood from the deep structures, terminate in the great cerebral vein which empty into the straight
17、 sinus.,大脑外静脉,III The blood vessels of spinal cord,The blood of the spinal cord comes from the anterior and posterior spinal arteries of the vertebral artery, and also from the posterior intercostals and the lumbar arteries,脊髓的静脉,根V,The distribution of the spinal veins are similar to that of the art
18、eries.,IV The circulation of CSF*,1. Production of CSF: The CSF is produced by the choroids plexuses of the lateral, the third and the fourth ventricles. 2. Circulation of CSF are showed in the chart:,CSF from lat. ventricle,interventricular foramen,the third ventricle,mesencephalic duct,the fourth
19、ventricle,median and lat. foramina,subarachnoid space,arachnoid granulations,dural sinus (vein), The cerebrospinal fluid (CSF) has the following functions:, Nutritive function and serving to remove the waste products of neuronal metabolism;, Supporting and cushioning the central nervous system against trauma; Regulating the intracranial pressure.,
