Meninges and dural folds P.Ravishankar Senior Lecturer in Anatomy SRM Dental college SRM University Ramapuram Campus,Chennai,INDIA Brain and spinal cord are surrounded by meninges 1. Outer layer-Duramater 2. Middle layer –Arachnoid mater 3. Inner layer-Piamater Meninges covering brain Meninges covering spinal cord • Epidural /extradural space:- space between the dura and the skull • Subdural space:- space between the dura and the arachnoid mater • Subarachnoid space:- space between arachnoid and piamater ,filled with CSF Cerebral duramater 2 layers of Duramater • Endosteal layer • Meningeal layer The Meningeal layer of Dura mater • Falx cerebri • Tentorium cerebelli • Falx cerebelli • Diaphargma sellae Falx cerebri • Sickle shaped,present at median longitudinal fissure between two cerebral hemispheres 2ends- Anterior end – attached to crista galli Posterior end – attached to tentorium cerebelli 2 margins Upper margin- attached to lips of sagittal sulcus Lower margin-free 2 surfaces-right and left surfaces Falx cerebri Dural venous sinuses related to Falx cerebri • Superior sagittal sinus • Inferior sagittal sinus • Straight sinus Dural venous sinuses related to Falx cerebri Superior sagittal sinus enclosed by Falx cerebri Tentorium cerebelli • Tent shaped fold of duramater forming the roof of posterior cranial fossa Attachment:- Free margin- U shaped- attached to anterior clinoid process Attached margin:-Lips of transverse sulcus, posteroinferior angle of parietal bone, superior border of petrous part of temporal bone, posterior clinoid process Tentorium cerebellai Dural folds Dural venous sinus related:- • Superior petrosal sinus • Straight sinus • Transverse sinus Falx cerebelli:- Small sickle shaped ,present at the posterior cerebellar notch, Base:-tentorium cerebelli Apex:-sides of foramen magnum Posterior margin:- Internal occipital crest Anterior margin:- free Dural venous sinus related :- occipital sinus Falx cerebellai Diaphargma sellae:- • Circular , horizontal fold , roofs hypophyseal fossa • Anteriorly attached to tuberculum sellae • Posteriorly attached to Dorsum sellae Blood supply:- • Supratentorial space-Middle meningeal artery • Anterior cranial fossa:-meningeal brs. Of anterior ethmoidal artery, posterior ethmoidal artery, ophthalmic artery • Middle cranial fossa:- Middle meningeal artery, accessory middle meningeal artery, internal carotid artery,meningeal br. Of ascending pharyngeal artery • Poserior cranial cavity:-meningeal br. Of Vertebral ,occipital and ascending pharyngeal artery Nerve supply:- Dura of vault-ophthalmic division of trigeminal nerve Dura of floor:- • Anterior cranial cavity-anterior ethmoidal nerve,maxillary nerve • Middle cranial cavity-maxillary nerve and brs. From mandibular nerve • Posterior cranial cavity:- recurrent brs. from C1,C2,C3 and meningeal brs of 9th and 10th cranial nerves Applied anatomy • Pterion is the weakest point of skull any fracture to pterion will tear middle meningeal artery and results in epidural hematoma. ( epidural hematoma is arterial in nature) • Subdural hematoma - bleeding from the veins Subdural and epidural hematoma Headache may be caused by • Dilatation of intracranial arteries • Dilatation of extracranial arteries • Traction or distraction of intracranial pain sensitive structures • Infection and inflammation of intracranial and extracranial structures .