Meninges And Blood Vessels And Csf(2).ppt

The meninges and blood vessels of brain and spinal cord, and the cerebrospinal fluid

Sanqiang Pan Department of Anatomy Medical College of Jinan University

Part one The meninges (or coverings) of brain and spinal cord Three meninges envelop the brain and spinal cord (from outer to inner): the dura, the arachnoid and the pia maters.

Meninges

I . The dura mater 1 The spinal dura mater • The epidural space: A space between the spinal dura and the periosteum of the vertebral canal, which contains the loose areolar tissue, lymphatic vessels and venous plexuses. The spinal nerves pass through the space. • Epidural block

Spinal dura mater

epidural space

2. The cerebral dura mater (1) Characteristics: • loose contact with the calvaria, closely attached at the base of skull; • form dura septa: the cerebral falx and the cerebellar tentorium • form dura venous sinuses(lack smooth muscle): Inferior sagittal sinus→straight sinus→(superior sagittal sinus→)confluence of sinuses→(cavernous sinuses→) transverse sinuses→sigmoid sinuses → internal jugular vein

Epidural hematoma

CSF leak

(2) The cavernous sinuses • Location: on either side of the sella turcica. • Communication: with the facial vein via the ophthalmic vein, and with the pterygoid plexus through the foramen ovale. • Structures passing through the sinuses: the internal carotid artery, the oculomotor nerve (III), trochlear nerve (IV) ,the ophthalmic and the maxillary divisions of the trigeminal nerve(V), and the abducens nerve(VI).

II. The arachnoid mater is a avascular membrane. 1.The subarachnoid space: between the arachnoid and the pia maters, filled with the cerebrospinal fluid(CSF). 2. The subarachnoid cisterns: these widened the subarachnoid space. 3. The arachnoid granulations: berry-like clumps of the arachnoid protruding into superior sagittal sinus and other sinuses.

III. The pia mater contains rich blood vessels. And combines with the ependyma and choroids vessels to form the choroid plexus of the third , fourth and lateral ventricles. Between the dorsal and ventral nerve roots of the spinal cord to form the denticulate ligament.

Spinal pia mater

Part two The blood vessels of the brain and spinal cord I. The arteries of brain come from two pairs of large vessels: the internal carotid arteries and vertebral arteries . The internal carotid arteries supply the anterior two-thirds of the cerebral hemisphere and parts of the diencephalon. The posterior one-third of the cerebral hemispheres , the remainder of the diencephalons,brain stem and cerebellum are supplied by the vertebral arteries.

Arteries of brain

1. (1) (2) • • • •

The internal carotid artery Course Segments Cervical Petrous Caverous Cerebral (supraclinoid) Carotid siphon: includes caverous and cerebral segments. Present U or V shape. Atherosclerosis occures here.

(3) Main branches: • Anterior cerebral A. • Middle cerebral A.: runs in the lateral sulcus and supply most of the dorsolateral surface of the cerebral hemisphere and the lentiform nucleus, caudate nucleus, the internal capsule. • Posterior communicating A. • Anterior choroidal A. • Ophthalmic A.

Ant. cerebral A.

Anterior cerebral A.

Middle cerebral A.

Middle cerebral A.

Posterior communicating A.

2 The vertebral artery Two vertebral arteries unit to form the basilar artery. (1) Main branches of the vertebral A. • Anterior and posterior spinal A. • Posterior inferior cerebellar A. (2) Main branches of the basilar artery • Anterior inferior cerebellar A. • Pontine A. • Superior cerebellar A. • Posterior cerebral A.

Vertebral arteries

3 The circle of Willis(cerebral arterial circle) formed by the anterior and posterior cerebral arteries, the anterior and posterior communicating arteries, and a segment of internal carotid arteries. This is important for the functionally adequate anastomosis to occur.

II. The veins of the brain do not run together with the arteries, and usually are divided into superficial and deep groups.

(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 intercostal and the lumbar arteries.

Spinal arteries

Spinal arteries

Part three Cerebrospinal fluid(CSF) Normal CSF is clear, colorless, and odorless. And fills with ventricles, the subarachnoid space and the central canal of the spinal cord. And produced by the choroids plexuses of the ventricles.

1 Function: play a role like lymph in the central nervous system, has function of the support, protection, nutrition, and carries away metabolites.

2 Circulation: Lateral ventricles (through the interventricular foramens) → the subarachnoid space the third ventricle(through the cerebral aqueduct) →the fourth ventricle(through lateral and medial apertures) →the subarachnoid space (through the arachnoid granulations)→ dura sinuses → veins

Part four Barriers in the nervous system 1 Blood-brain barrier(BBB): consists of the endothelial cell and basement membrane of capillaries, and the processes of astrocyte.This barrier is absent in several specialized regions of the brain: the basal hypothalamus, the pineal gland, the small area near the third ventricle, and area postrema of the fourth ventricle. 2 Blood-CSF barrier 3 CSF-brain barrier