(5) Cranial Cavity BMC (2).pdf

Head and Neck The Cranial cavity I Meninges & Dural Folds Dr. Mohamed Elfiky Professor of anatomy and embryology Identifiers Meninges and dural folds e In Ine Coverings of central nervous system (CNS): A- Skeletal Coverings: x 1- Brain is covered by bones of the cranium (calvaria). 2- Spinal cord co...

Head and Neck The Cranial cavity I Meninges & Dural Folds Dr. Mohamed Elfiky Professor of anatomy and embryology Identifiers Meninges and dural folds e In Ine Coverings of central nervous system (CNS): A- Skeletal Coverings: x 1- Brain is covered by bones of the cranium (calvaria). 2- Spinal cord covered by a cylindrical case of bone (vertebral canal). B- Meningeal Coverings: 1- Pia matter 1stlaser 2- Arachnoid matter_andlaser 3- Dura matter 3rdlayerouter contain 2layers cover theCNS boneotfhe skullorcranialcavity tothe endosteallayerouter layerrelated meningeallayerinner layerrelatedtothebrain theinnerlayerwillgivefoldswillbebetweendifferentpartofthebrain 7 flaxcerebrienterbetween2 cerebralhemisphere 2 tentoriumcerebellienterbetweencerebrumandcerebellum 3 cerebelli enterbetween cerebellarhemisphere MOHAMED EL FIKY Meninges (Cranial and Spinal Meninges) It is located in in the cranial cavity inside the skull and covered by 3 layers of meninges II 3- Dura Mater i 2- Arachnoid Mater 1- Pia Mater MOHAMED EL FIKY Dura Mater Delicate Non-Vascular Membrane Terminates at S2 of 2layer formed 3- Dura Mater of Endosteal Layer i Meningeal Layer Venous Sinus Dural Fold MOHAMED EL FIKY Coronal Section Subarachnoid Villi and Emissary Vein Endosteal Layer Granulations Meningeal Layer Venous Sinus Cerebral Vein Pia Arachnoid Termination of Dura Matter at The Level of S2 Meningeal Spaces Subdural Space Sub arachnoid Space Superficial Cerebral Veins Epidural Space Meningeal Blood Vessels Contain CSF and Cerebral Arteries MOHAMED EL FIKY Epidural Space (contains internal vertebral venous plexus) Spinal Dura Mater Spinal Arachnoid Mater Subarachnoid space MOHAMED EL FIKY Dural Folds 9 Falx Cerebri Tentorium Cerebelli FITTER Falx Cerebelli MOHAMED EL FIKY 1- Falx Cerebri I Definition: It is a large sickle-shaped reduplication of the inner layer of dura mater Site: Occupies the median longitudinal fissure between the two cerebral hemispheres. Features: (a) Apex: is narrow and is attached to the crista galli. 1st sep (b) Base: is broad and is attached to, the tentorium cerebelli in the median plane. (c) Upper margin: is convex and is attached to the lips of the sagittal sulcus on the inner surface of the vault of the skull. (d) Lower margin: is concave and free. It encloses the inferior sagittal sinus in its posterior two-thirds. (e) Right and left surfaces: are related to the medial surface of the corresponding cerebral hemispheres. Sinuses enclosed in it: (1) Superior sagittal sinus: in its upper convex margin. (2) Inferior sagittal sinus: in the posterior 2/3 of its lower margin. (3) Straight sinus: within the junction of the falx cerebri with the tentorium cerebelli in the median plane. MOHAMED EL FIKY Upper Attached border Superior Sagittal Sinus Left Surface Apex Inferior Sagittal Sinus Base Straight Sinus Lower Free border MOHAMED EL FIKY 2- Tentorium Cerebelli Definition: It is a tent-shaped reduplication of the inner layer of the dura. Site: between the cerebellum and the cerebrum. Features: It has: (1) Two surfaces, Superior and inferior. Superior surface: gives attachment to the falx cerebri in the median plane. Inferior surface: concave to fit the superior convex surface of the cerebellum (2) Two border , attached and free (Attached border: is attached on either sides to: (a) Posterior clinoid process. (b) Lips of superior petrosal sulcus along the upper border of petrous temporal bone. (c) Lips of transverse sulcus of the occipital bone. Free border: U-shaped (a) tentorial notch which transmits the midbrain. (b) it crosses the attached border at the apex of petrous temporal to be attached to the anterior clinoid process. Sinuses enclosed in it: (1) Transverse sinus: in the attached border along the transverse sulcus. (2) Superior petrosal sinus: in the attached border along the superior petrosal sulcus. (3) Straight sinus: In the midline along of its attachment with the falx cerebri. Cranial nerves piercing it: In (1) Oculomotor: in front of the point of crossing of the free and attached borders. e (2) Trochlear: at the point of crossing. (3) Trigeminal nerve: behind the point of crossing MOHAMED EL FIKY Attachments of Tentorium Cerebelli MOHAMED EL FIKY Falx Cerebri Sinus Content of Tentorium Cerebelli Tentorium Cerebelli Falx Cerebelli MOHAMED EL FIKY Sinus Content of Tentorium Cerebelli 1. Superior petrosal sinus e 3. Straight sinus 2. Transverse sinus MOHAMED EL FIKY 3- Falx Cerebelli C Definition: is a reduplication of the inner layer enterbetween 2 cerebellarhemisphere of the dura which projects forwards into the are posterior notch of the cerebellum. Shape: inverted triangle. Features: (1) The base: is directed upwards and is attached to the tentorium cerebelli in the median plane. (2) The apex: is directed downwards till the foramen magnum. (3) Posterior margin:encloses the occipital sinus. (4) Anterior margin: is free and projects in the posterior notch of the cerebellum. Sinuses enclosed in it: The occipital sinus in its posterior border MOHAMED EL FIKY Falx Cerebelli 4- Diaphragma Sellae Definition: is a small circular fold of the inner layer of the dura which covers the pituitary in the hypophyseal fossa. Attachments: (1) Anteriorly: to the tuberculum sellae. (2) Posteriorly: to the dorsum sellae. Features: has a central aperture which transmits the infundibulum (Pituitary stalk). Sinuses enclosed: intercavemous sinuses. Intercavernous Sinus Hypophyseal Fossa Diaphragma Sellae Pituitary Gland MOHAMED EL FIKY Outer Endosteal Layer of the Dura Inner Meningeal Layer of the Dura Pituitary Gland Diaphragma Sellae Intercavernous Dural Sinuses MOHAMED EL FIKY 5- Cavum Trigeminale Cavum trigeminale : is reduplication of the inner layer of the dura, to form a special space which is occupied by the trigeminal ganglion. Trigeminal Ganglion Cavum Trigeminale Inner Meningeal Layer of the Dura Outer Endosteal Layer of the Dura MOHAMED EL FIKY Nerve supply of the dura Isf 1- The dura of anterior cranial fossa : supplied by the anterior and posterior ethmoidal Geffen nerve. 2- The dura of the middle cranial fossa : Ine supplied by nervous spinosus (br. of mandibular ) and meningeal branch of maxillary nerve. 3- The dura of posterior cranial fossa : supplied by the meningeal branches of the 9th , 10th &12th cranial nerves. 4- The dura around foramen magnum : supplied by 1st, 2nd &3rd cervical nerves. nerve spinal from f MOHAMED EL FIKY Arterial supply of the dura ____ 1- The dura in the anterior cranial fossa : is supplied by anterior and posterior ethmoidal arteries (branches of ophthalmic artery) 2- The dura in the middle cranial fossa : is supplied by : a. Accessory and middle meningeal arteries (branches of maxillary a.) b. Recurrent branch of lacrimal artery (br. of ophthalmic a.) 3- The dura of posterior cranial fossa : is supplied by vertebral , occipital and ascending pharyngeal arteries MOHAMED EL FIKY Head and Neck The Cranial cavity part II Meninges & Dural Folds Dr. Mohamed Elfiky Professor of anatomy and embryology Dural Venous Sinuses Definition: Are venous spaces between the two layers of the dura. Classification: They are classified into paired and unpaired sinuses. Unpaired sinuses present inmidline 1)Superior sagittal 2) Inferior sagittal 3) Straight. 4) Occipital 5)Three intercavernous 6) Basilar plexus of sinuses Paired sinuses leftside presentinrightand (1)Sphenoparietal (2) Cavernous (3) Superior petrosal (4) lnferior petrosal. (5) Transverse (6) Sigmoid MOHAMED EL FIKY Coronal Section Subarachnoid Villi and Emissary Vein Endosteal Layer Granulations Meningeal Layer Cerebral Vein Venous Sinus Pia Arachnoid MOHAMED EL FIKY Single Dural Venous Sinuses Superior Sagittal Sinus Inferior Sagittal Sinus Straight Sinus Intercavernous Sinuses Occipital Sinus Basilar Plexus of Sinuses MOHAMED EL FIKY MOHAMED EL FIKY Paired Dural Venous Sinuses Sphenoparietal sinus Inferior petrosal sinus Cavernous sinus Superior petrosal sinus Sigmoid sinus Transverse sinus MOHAMED EL FIKY 1- Superior Sagittal Sinus Site: Occupies the upper convex margin of the falx cerebri. Beginning: Begins anteriorly at the foramen caecum. Course: Runs upwards and backwards, making a groove on the inferior surface of the vault of the skull. Termination: At the internal occipital protuberance by becoming one of the transverse sinuses usually the right. Lumen: Becomes progressively larger from before backwards and is triangular in cross section. Direction of blood flow: From before backwards. Tributaries: (1) Superior cerebral veins. (2) Parietal emissary veins: connecting it with the veins of the scalp, (3) Emissary vein: passing through the foramen caecum to connect it with the veins of the nose MOHAMED EL FIKY Termination of Superior Sagittal Sinus Superior Sagittal Sinus MOHAMED EL FIKY run inthemiddle ofthehead then it will runs horizontally called righttransversesinusthen it willform s shapecalledrightsigmoidsinusthen it will pass hrowjugularforamen and itwillcontinue intheneckcalledrightinternal jugularvein superiorsagetalsinus inferiorsagetalsinus first itgivestraightsinusthen itwillgivelefttransversesinus then eftsigmoid sinusthenleftinternal jugularvein Straight sinus Right Transverse sinus Left Transverse sinus Superior Sagittal Sinus MOHAMED EL FIKY 2- Inferior Sagittal Sinus Site: Enclosed in the posterior 2/3 of the lower concave free margin of the falx cerebri. Termination: Ends at the middle of the anterior free margin of tentorium cerebelli by joining the great cerebral vein to form the straight sinus. 3- The Straigt Sinus Site: In the median plane within the junction of the falx cerebri and tentorium cerebelli. Formation: By the union of the inferior sagittal sinus with the great cerebral vein. Termination: Ends at the internal occipital protuberance by becoming one of the transverse sinuses, usually the left MOHAMED EL FIKY Inferior Sagittal Sinus Straight Sinus Great Cerebral Vein MOHAMED EL FIKY 4- The Occipital Sinus Site : Lies in the attached margin of falx cerebelli. Beginning: Near the foramen magnum. Termination: In the confluence of sinuses. (5) Intercavernous sinuses Number three. Site: (1) The anterior: in the anterior margin of the diaphragma sellae. (2) The posterior: in the posterior margin of the diaphragma sellae. (3) The middle: below the hypophysis.. Communications: connects the cavernous sinuses of the two sides. MOHAMED EL FIKY 6- Basilar Plexus of Sinuses Site: over the basilar part of the occipital bone. Formation: formed of several interconnecting venous channels between the two layers of the dura. Communications: connects the inferior petrosal sinuses of the two sides. Intercavernous Sinuses Basilar plexus of Sinuses MOHAMED EL FIKY II- Paired Sinuses 1- Sphenoparietal Sinus Site: Lies along the posterior free margin of the lesser wing of the sphenoid. Termination: In the cavernous sinus. 2- Cavernous Sinus Introduction: It is a large venous space between the two layers of the dura. It is called cavernous because of its spongy structure. Site: In the middle cranial fossa, on either sides of the body of the sphenoid. MOHAMED EL FIKY Sphenoparietal sinus Inferior petrosal sinus Cavernous sinus Superior petrosal sinus Sigmoid sinus Transverse sinus MOHAMED EL FIKY Extent: From the medial end of the superior orbital fissure anteriorly to the apex of the petrous temporal posteriorly. Size: It is about 2 cm long, and 1 cm wide. Relations: (a) Superiorly: optic chiasma & internal carotid artery (b) Inferiorly sphenoidal air sinus. (c) Medially: hypophysis cerebri. (d) Laterally: temporal lobe. (e) Anteriorly: superior orbital fissure. (f) Posteriorly: apex of petrous temporal. MOHAMED EL FIKY Optic Chiasma Internal Carotid Artery Pituitary Gland Sphenoidal AirSinuses Uncus of Temporal Lobe Body of Sphenoid Bone Sphenoidal Air Sinus Medial end of The superior orbital fissure Uncus Optic Chaisma Temporal lobe MOHAMED EL FIKY Apex of petrous Trigeminal Ganglion Contents of Cavernous Sinus Cavernous Sinuses 1- Occulomotor Nerve 2- Trochlear Nerve 3- Ophthalmic Nerve 4- Maxillary Nerve 4- Abducent Nerve 5- Internal carotid Artery with Sympathetic Plexus MOHAMED EL FIKY Tributaries of Cavernous Sinus Superior petrosal sinus Superficial middle Cerebral vein Sphenoparietal sinus Inferior cerebral veins Inferior cerebral veins Superficial middle Cerebral vein Sphenoparietal sinus MOHAMED EL FIKY Tributaries of Cavernous Sinus (A) Anteriorly: receives : (1) Superior ophthalmic vein: connecting it with the facial vein. (2) Branch or whole of inferior, ophthalmic vein. (3) Central vein of the retina: may 'drain either into the superior ophthalmic vein or into the cavernous sinus. (B) Posteriorly: receives: (1) Superior petrosal sinus: connecting it with the transverse sinus. (2) Inferior petrosal sinus: connecting it with the internal jugular vein. (C) Superiorly: receives : (1) Superficial middle cerebral vein. (2) Inferior cerebral veins from the temporal lobe. MOHAMED EL FIKY (D) Inferiorly: Communicates with the venous plexus outside the skull by emissary veins, which pass through: (1) Foramen lacerum: to connect it with the pharyngeal plexus. (2) Foramen ovale or emissary sphenoidal foramen: to connect with the pterygoid plexus of veins. (E) Medially: the two sinuses communicate with each other through the intercavernous sinuses. MOHAMED EL FIKY 4- Superior Petrosal Sinus Beginning: Posterior end of the cavernous sinus. Site: Lies along the upper border, of petrous temporal in the attached margin of the tentorium cerebelli. Termination: In the transverse sinus. 5- Inferior Petrosal Sinus Beginning: Posterior end of the cavernous sinus. Site: Lies in the petro-occipital fissure, then passes through the anterior compartment of jugular foramen. Termination: Into the internal jugular vein. MOHAMED EL FIKY 5- Transverse Sinus Origin: (a) The right sinus is usually the continuation of the superior sagittal sinus, and the left one is a continuation of the straight sinus. (b) The reverse of the above arrangement may happen. (c) From the confluence of sinuses which, is formed by the meeting of superior sagittal, straight and the two transverse sinuses. Site: Along the transverse sulcus in the attached margin of the tentorium cerebelli, Termination: Ends by becoming the sigmoid sinus. MOHAMED EL FIKY Posterior Temporal Diploic Vein The superior petrosal sinus The occipital sinus Inferior cerebral veins Occipital Diploic Vein The Transverse sinus MOHAMED EL FIKY 6- Sigmoid Sinus Origin: Is the direct continuation of the transverse sinus at the postero inferior angle of the parietal bone. Shape: S-shaped. Course: Runs downwards and medially in the sigmoid sulcus. Termination: ends by passing through the posterior compartment of the jugular foramen to become the internal jugular vein. MOHAMED EL FIKY Sigmoid Sinus Communication with Suboccipital plexus of veins Occipital Sinus Communication with Occipital and / or Posterior auricular veins MOHAMED EL FIKY Thank You Head and Neck The Cranial cavity part III Middle meningeal artery and hypophysis gland Dr. Mohamed Elfiky Professor of anatomy and embryology The Middle Meningeal Artery Origin : Branch of the first part of the maxillary artery, given off in the infratemporal fossa. Course in the middle cranial fossa : Enters the fossa through the foramen spinosum. Has an extradural course, but the middle meningeal vein, in closer to the bone than the artery. Runs forwards and laterally on the floor of the cranial cavity and at a variable point it divides into anterior (frontal) and posterior (parietal) branches. (1) Anterior (frontal) branch: Larger and more important than the posterior. First it runs upwards on the side of the skull till it reaches opposite the pterion, then it runs obliquely upwards and backwards towards the midpoint between the root of the nose and the external occipital protuberance, Opposite the pterion it deeply grooves the bone: Lies parallel to and a little in front of the central sulcus of the brain: thus it is closely related to the motor area. (2)Posterior (parietal) branch: Runs backwards and upwards on the sidewall of the cranial cavity towards the lambda approximately 6 cm from the external protubetance. MOHAMED EL FIKY