Skull Osteology and Cranial Structures

The skull comprises the cranium (calvarium, base/fossae, and facial bones) and mandible. Joined by sutures (fibrous joints).

The base of the cranium has three depressions (anterior, middle, and posterior).

The skull is composed of 22 bones, including 8 cranial and 14 facial bones. (excluding small ear bones).

Protective membranes (layers) surrounding the brain and spinal cord.

Bleeding within the skull, affecting brain function.

Inner layer of dura mater in the skull; smooth, avascular, and continuous with spinal dura.

Venous channels within the dura that drain blood from the brain.

Major dural sinus running in the falx cerebri, draining to transverse sinus.

Dural sinus that receives blood from superior sagittal sinus, becomes sigmoid sinus.

Dural fold separating the two cerebral hemispheres

Dural fold separating the occipital lobe from the cerebellum

Potential space in skull & true space in spine.

Dural sinus that receives blood from the transverse sinus and drains into jugular vein.

A venous sinus located on either side of the sphenoid bone, surrounding the pituitary gland.

A venous sinus that connects to the transverse sinus and drains into the internal jugular vein.

Venous sinus channels connecting cavernous and transverse/sigmoid sinuses.

A rare and dangerous blood clot within the cavernous sinus.

The middle meningeal layer lining the brain.

The space between the arachnoid mater and pia mater, containing cerebrospinal fluid (CSF).

Structures that drain CSF into dural sinuses to remove excess fluid.

An area of the face where infections can spread to the cavernous sinus, possibly causing thrombosis.

A point on the skull where the frontal, parietal, temporal, and sphenoid bones meet, crucial for understanding potential intracranial bleeding.

Fibrous joints connecting skull bones, allowing for flexibility during birth and preventing movement in the adult.

Unossified gap in the fetal skull, located at bregma, that closes around 18 months.

Unossified gap in the fetal skull, located at lambda, that closes by 2-3 months.

Unossified spaces in a baby's skull that allow for its growth.

Indents on the skull's base, dividing the brain into anterior, middle, and posterior regions.

The skull's deepest bony cavity housing the frontal lobe of the brain. Formed by frontal, ethmoid, sphenoid bones.

Middle bony cavity housing important structures like the pituitary gland. Formed by the sphenoid and temporal bones

The lowermost bony cavity, housing the cerebellum and brainstem. Formed By temporal and occipital bones.

Protective membranes (layers) surrounding the brain and spinal cord.

The outermost layer of meninges; a tough fibrous membrane.

Middle layer of meninges; a thin, webby structure.

Innermost layer of meninges; directly adheres to the brain.

The potential space between the Dura and Arachnoid membranes.

The space between the Arachnoid and Pia mater; contains cerebrospinal fluid.

The skullcap (vault) covering the cranial cavity.

Bleeding outside the dura mater, often from a meningeal artery.

An artery that frequently causes extradural hemorrhages.

Bleeding beneath the dura mater.

Bleeding into the subarachnoid space.

A period of apparent recovery after head injury, followed by rapid deterioration.

A distinctive shape of an extradural hematoma, appearing lens-like (like a lentil).

Temporary or prolonged state of unconsciousness.

A dilated pupil on the side affected by the brain injury, often associated with increased intracranial pressure and herniation.

Bleeding between the dura mater and arachnoid mater, often caused by stretched cerebral veins and minimal trauma in elderly patients.

Bleeding in the subarachnoid space, often caused by ruptured aneurysm in the Circle of Willis, associated with sudden, severe headache.

Displacement of brain tissue due to swelling, bleeding, or tumors, leading to compression of brain structures.

Displacement of the uncus (part of the temporal lobe) through the tentorial notch, pressing on cranial nerve III and causing a sluggish light reflex.

Displacement of cerebellar tonsils into the foramen magnum, potentially impacting the cardiorespiratory center, potentially causing abnormalities in BP and pulse, and respiratory issues(Cheyne-Stokes).

Pressure within the skull; Increased pressure causes herniation and can lead to neurological problems.

Avoid lumbar puncture when intracranial pressure is elevated.

Structures (Tumors, hematomas) that expand within the skull affecting brain and CSF distribution and pressure by pushing on the brain.

The skull is composed of the cranium (calvarium, base/fossae, and facial bones) and the mandible, joined by sutures (fibrous joints).

The base of the skull has three depressions: anterior, middle, and posterior, which accommodate different brain regions.

The skull includes 22 bones, 8 cranial and about 14 facial bones. (excluding inner ear bones).

Protective membranes surrounding the brain and spinal cord: dura mater, arachnoid mater, pia mater.

Bleeding within the skull affecting brain function.

Enlargements of the subarachnoid space in the brain, including the cerebellomedullary and chiasmatic cisterns.

Structures that absorb CSF into venous sinuses.

The delicate innermost meningeal layer adhering to brain surface.

Bleeding outside the dura mater, usually caused by a skull fracture.

Bleeding between the dura and arachnoid mater in the potential subdural space

Bleeding into the subarachnoid space.

Bleeding within the brain tissue itself.

The width of the subarachnoid space around the spinal cord is more regular, while around the brain it's irregular and forms cisterns

The inner layer of the dura mater in the skull; it's smooth, avascular, continuous with spinal dura, and forms folds to prevent brain displacement.

Venous channels within the dura that drain blood from the brain.

A major dural sinus running along the top of the falx cerebri, draining into the transverse sinus.

A dural sinus that receives blood from the superior sagittal sinus and continues as the sigmoid sinus.

A dural fold that separates the two cerebral hemispheres.

A dural fold that separates the occipital lobe from the cerebellum.

A potential space (skull) / true space (spinal column) in vertebrates, between the dura mater and the skull/vertebra.

A dural sinus that continues from the transverse sinus and drains into the internal jugular vein.

Junction of frontal, parietal, temporal, and sphenoid bones; where middle meningeal artery runs; common site of intracranial bleeds.

Unossified gap in fetal skull at bregma; closes around 18 months.

Unossified gap in fetal skull at lambda; closes by 2-3 months.

U-nossified spaces in newborn skull; allow for growth.

Artery frequently involved in extradural bleeds.

Indentations on the skull base, housing different brain parts (anterior, middle, posterior).

Skull's deepest area, holding frontal lobe. Formed by frontal, ethmoid, and sphenoid bones.

Skull's middle area, holding pituitary and other structures. Formed by sphenoid and temporal bones.

Skull's bottom area, holding cerebellum and brainstem. Formed by temporal and occipital bones.

Outermost meningeal layer, tough fibrous membrane adhering to the skull.

Middle meningeal layer, web-like structure.

Innermost meningeal layer, directly covering the brain.

Potential space between dura and arachnoid.

Space between arachnoid and pia mater; holds CSF.

Venous sinus on either side of sphenoid bone, surrounding pituitary gland.

Dural sinus connecting transverse sinus and internal jugular vein.

Rare, life-threatening blood clot in cavernous sinus, often from infections.

Middle meningeal layer, separating dura and pia, with CSF-filled space.

Space between arachnoid and pia mater, filled with CSF, protecting CNS.

Venous channels connecting cavernous and transverse/sigmoid sinuses.

Area where infections can spread to cavernous sinus, risking thrombosis.

Structures that drain cerebrospinal fluid (CSF) into dural sinuses.

Bleeding between the dura and arachnoid mater, often from stretched cerebral veins in the elderly.

Bleeding into the subarachnoid space, usually caused by a ruptured aneurysm.

Displacement of brain tissue due to swelling, bleeding, or tumors, leading to compression.

Displacement of the uncus (temporal lobe) through the tentorial notch, pressuring cranial nerve III.

Displacement of cerebellar tonsils into the foramen magnum, potentially affecting cardiorespiratory function.

Temporary recovery period after head injury, followed by deterioration.

Do not perform lumbar puncture when intracranial pressure is elevated.

Structures pushed inward due from intracranial pressure, causing compression at various brain levels.