Cranial Cavity It Is Box Like Cavity Containing Brain, Coverings, Blood Vessels and Nerves of Brain

Cranial cavity It is box like cavity containing brain, coverings, blood vessels and nerves of brain. Coverings of brain in cranial cavity From outer to inner coverings are:  Dura mater: It is tough outer covering  Arachnoid mater: It is middle layer having web like communications to pia mater.  Pia mater: It is thin transparent membrane like a skin of brain and spinal cord. Between arachnoid and pia mater there is space known as Subarachnoid space containing cerebrospinal fluid.

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Dura matter in cranial cavity Dura matter in cranial cavity is having two layers.  Endosteal layer: It is outer layer of dura mater. It is endocranium of skull bones.  Meningeal layer: It is inner layer towards the brain. Iy folds upon itself & encloses sinuses between it and endosteal layer.

Folds of dura mater (***long question/viva)

Dura mater is cranial cavity forms folds which make compartments in cranial cavity and also encloses venous sinuses. Following folds are formed in cranial cavity by dura matter:  Falx cerebri  Falx cerebelli  Tentorium cerebelli  Diaphragma sellae

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Draw this diagram for falx cerebri & Falx cerebelli Falx cerebri (****Short note/viva) It is a sickle shaped fold of dura mater between cerebral hemispheres in the median longitudinal fissure. Parts of falx cerebri:  Ends: Anterior end attached to crista galli and posterior end attached to superior surface of tentorium cerebelli.  Borders (Margins): o Superior border (Attached margin): Attached to lips of sulcus for superior sagittal sinus. It is convex. o Inferior border (Free margin): It is concave and rest on corpus callous.  Surfaces: o Right and left surfaces are related to medial surface of cerebral hemishpere. Sinuses enclosed in falx cerebri:  Superior sagittal sinus in the upper attached margin.  Inferior sagittal sinus in lower free margin.  Straight sinus at the junction of posterior end with tentorium cerebelli.

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Functions of falx cerebri:  Keeps parts of brain in position.  Makes compartmentalization in the cranial cavity.  Encloses the venous sinuses. Falx cerebelli (**viva) It is a small sickle shaped fold of dura mater between two cerebellar hemispheres. It is attached to internal occipital crest. In the attached margin it encloses occipital sinus. Near foramen magnum it splits in two parts and merges with endocranium.

Draw this diagram for tentorium cerebelli

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Tentorium cerebelli: (****Short note/viva) It is tent shaped fold in posterior cranial fossa dividing the posterior cranial fossa in to supratentorial compartment (for occipital lobe of cerebrum) and infratentorial compartment (for cerebellum). Attachments of tentorium cerebelli:  Free margin: attached to anterior clinoid processes. Free margin forms boundary of tentorial notch which transmits brain stem.  Attached margin: attached to posterior clinoid processes, superior border of petrous temporal bone and lips of groove for transverse sinus.  There is triangular area at the crossing over of attached margin & the free margin. This area forms posterior part of roof of cavernous sinus which is pierced by occulomotor (3rd cranial nerve) and trochlear (4th cranial nerves.  The attached margin forms an evagination & contain trigeminal ganglion into it. Such area is known as Cavum trigeminum/Meckel’s cave. Sinuses enclosed in Tentorium cerebelli:  Superior petrosal sinus.  Transverse sinus.  Straight sinus. Functions of tentorium cerebelli to Make compartments in the cranial cavity and enclose venous sinuses.

Diaphragma sellae (**viva) It is a circular fold attached to margin of sella turcica. It is attached anteriorly to tuberculum sellae and posteriorly to dorsum sellae. It forms roof of pituitary fossa.

It is pierced in the center by infundibulum of No need to draw this diagram pituitary gland.

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