16.2 Osteology Flashcards
What does the falx cerebri separate?
the left and right cerebral hemispheres
What does the tentorium cerebelli separate?
Cerebrum from the cerebellum
Spans the transverse plane from the inner surface of the occipital bone
Where does the spinal subarachnoid space extend to (at lumbar end)?
This space expands at the level of the conus medullaris of the spinal cord, forming the lumbar cistern.
What are the 3 meningeal layers?
Dura mater, arachnoid mater, pia mater
What is the dura mater?
- Dense, irregular connective tissue that surrounds the brain and the spinal cord
- Outermost layer
- Made up of 2 layers in the skull, but these fuse into one in the vertebral column
What is the arachnoid mater?
- Middle layer that surrounds the brain and the spinal cord
- Contains arachnoid granulations that allow for the reabsorption of CSF into the circulation
- Has a spiderweb appearance
- Fibrous tissue, covered in flat cells thought to be impermeable to fluid
- Arachnoid trabeculae anchor the arachnoid mater to the pia mater
What is the pia mater?
- Innermost layer of the 3 layers/meninges covering the brain and the spinal cord
- Made up of collagen and reticular fibres
- Delicate, innermost layer
- Attached directly to the basement membrane and astrocyte foot processes (fairly secure)
What is this and what are its principle components?
Foramen rotundum
*maxillary trigeminal
What is this and what are its principle components?
Foramen Ovale
*Mandibular trigeminal
What is this and what are its principle components?
Foramen spinosum
*Middle meningeal artery
What is this and what are its principle components?
Jugular foramen
*CN9,10,11 and internal jugular vein.
What is this and what are its principle components?
Carotid canal and foramen lacerum
*Internal carotid artery
What is this and what are its principle components?
Sylomastoid foramen
*CN7
What is this and what are its principle components?
Foramen magnum
*Spinal cord and vertebral arteries
What is this and what are its principle components?
Hypoglossal canal
*CN12
What is this and what are its principle components?
Optic foramen - opening to the optic canal.
*CN2, ophthalmic artery
What is this and what are its principle components?
Superior orbital fissure
*CN3, CN4, CN6, Ophthalmic branch of CN5
What is this and what are its principle components?
Internal acoustic meatus
*CN7, CN8, labyrinthine artery
What bone is C?
Temporal
what bone is A?
Frontal
What bone is B?
Sphenoid
What bone is this?
Zygomatic
What bone is E?
Occipital
What bone is D?
Parietal
What bone is F?
Ethmoid
What are the three divisions of the floor of the cranial cavity?
Anterior, middle and posterior cranial fossa
Which bones make up the cranial roof?
Frontal, occipital and two parietal
What is F?
Temporal process of zygomatic bone
What is K?
Greater wing of sphenoid bone
Name the four air sinuses
Frontal
Ethmoid
Sphenoid
Maxillary
Which bone are mastoid air sinuses located in?
Temporal bone
Which cranial fossa is highlighted? What does it contain?
Posterior cranial fossa
-Brainstem (medulla and pons) and cerebellum
BONES:
-petrous part of temporal bone
-occipital bone
Which cranial fossa is this? Which bones make it up?
Anterior cranial fossa
-contains frontal lobe of brain
FLOOR:
-Frontal (Orbital plates)
-Ethmoid (cribriform plate/ crista Galli etc.)
-Sphenoid (anterior aspects + lesser wings)
Which cranial fossa is highlighted? What does it contain?
Middle cranial fossa
-Temporal lobe
-Pituitary gland
BONES: SPHENOID AND TEMPORAL
-Tuberculum sellae (sphenoid)
-Hypophysial/pituitary fossa (sphenoid)
-Dorsum sellae (sphenoid)
-Anterior and posterior Clinoid processes (sphenoid) around sella turcica (depression in body of sphenoid)
-Greater wings of sphenoid bones form lateral parts
-Squamous and petrous parts of temporal bone
What is A?
Pituitary fossa / sella turcica
Which bone does the pituitary gland lie in?
Sphenoid bone in the sella turcica
What is D?
External auditory meatus
What is this?
Lesser wing of the sphenoid bone
Which part of the temporal bone is highlighted in pink?
Squamous
Which part of the temporal bone is highlighted in purple?
Petrous
What is this?
Cribriform plate
What is this?
Anterior clinoid process
What is this?
Posterior clinoid process
Label the different air sinuses
What are mastoid air cells?
The mastoid cells (also called air cells of Lenoir or mastoid cells of Lenoir) are air-filled cavities within the mastoid process of the temporal bone of the cranium.
What is the subarachnoid space?
A space between arachnoid mater and pia mater, surrounding brain and spinal cord
How is the dura related to the skull and the vertebral canal?
- Dura mater is adhered to the skull (epidural space only occurs in the skull in cases of pathology, e.g. epidural haematoma)
- Epidural space seen in the vertebral canal, therefore dura mater is not attached to the vertebral canal
- The meninges extend down to the layer of S2
What are the dural folds?
- Tentorium cerebelli
- Spans in a transverse plane from the inner surface of the occipital bone
- Separates the cerebellum from the cerebrum (separates the forebrain and the hindbrain)
- Contains the transverse, straight and superior petrosal sinuses
- Falx cerebelli
- Projects from the midline of the occipital bone
- Seperates the hemispheres of the cerebellum
- Contains the occipital sinus
- Falx cerebri
- Largest of the fibrous septa
- Extends across the midline
- Seperates the right and left hemispheres
- Contains the superior and inferior sagittal sinuses
- Diaphragma sellae [EXTRA]
- Flat membrane, surrounds the pituitary stalk and forms a roof over the hypophyseal fossa
- Contains the anterior and posterior intercavernous sinus
Label these dural folds.
What is the relationship of the dura to blood vessels?
- Blood supply mostly seen to the outer layer of the dura mater
- Pia mater is highly vascular, using smaller vessels from the internal carotids and vertebral arteries like the underlying neural and glial tissue
- The arachnoid mater is avascular
- Dura mater receives vascular supply from many different branches, including:
- Internal carotid artery
- Maxillary artery
- Ascending pharyngeal arteries
- Occiptal artery
- Vertebral artery
- Meningeal arteries form anastomoses with cerebral arteries and supplies some regions of the brain
- Skull has grooves/sulci to facilitate the passage of blood vessels supplying the dura
- Dural veins accompany the arteries and are essentially a set of sinuses
What innervates the dura?
Sensory innervation to the dura mater: CN V and CN X
What are the CSF cisterns?
These are compartments within the subarachnoid space that have large gaps between the pia and the arachnoid mater that allow for the accumulation of fluid. Cisterns may have vessels or cranial nerves passing through them.
Label these cisterns.
