Skull and cranial cavity Flashcards
How many layers does the scalp consist of?
5
Describe the innervation of the scalp
Trigeminal nerve(V) and spinal cutaneous nerves
What are the bones of the neurocranium?
Occipital, two temporal, two parietal, sphenoid, ethmoid and frontal
What are the bones of the viscerocranium?
Two nasal conchae, two nasal bones, two maxilla, two palatine, two zygomatic, two lacrimal, vomer and mandible
What are the extra bones in the skull called?
Wormian bones(sutural bones)
Why are wormian bones also called sutural bones?
They are called sutural bones because they can occur within a suture(joint) in the cranium
What is the base of the skull divided into in terms of foramina?
Anterior, middle and posterior cranial fossa
Name the main foramina of the skull
- Cribiform plate
- Optic canal
- Superior orbital fissure
- Foramen rotundum
- Foramen ovale
- Foramen spinosum
- Internal acoustic meatus
- Stylomastoid foramen
- Foramen lacerum
- Jugular foramen
- Hypoglossal canal
- Foramen magnum
What are the names of the meningeal layers?
- Dura mater
- Arachnoid mater
- Pia mater
What are the functions of the meninges?
- Protection
- Support network for blood vessels
- Form a fluid-filled cavity for cushion and nourish the brain
What are the two layers of the dura mater?
- Endosteal layer
- Meningeal layer
What does the meningeal layer of the dura mater surround?
- The brain and spinal cord
What does the endosteal layer surround?
- Only the skull
What is the dura mater innervated by?
- CN V, X, C1-3 and sympathetic
What does the middle meningeal artery enter through?
- Foramen spinosum
Where is the foramen spinosum located?
- The base of the human skull on the sphenoid bone
How is trauma to the head likely to affect the middle meningeal artery?
Can cause an extradural hematoma
What is an extradural haematoma?
- Also known as epidural haematoma
- Is a collection blood between the endosteal layer of the dura and the inner surface of the skull
- They are usually associated with a history of head trauma and frequently associated skull fracture
What can the dura mater split to form?
A venous dural sinus
How is the meningeal layer of dura arranged?
- Arranged in a series of folds/septa which divide the cranial cavity
- Folds or reflections prevent/restrict movement of the brain
Purpose of falx cerebri
- Separates cerebral hemispheres
Purpose of tentorium cerebelli
- Separates cerebellar hemispheres from cerebral hemispheres
Purpose of falx cerebelli
- Separates cerebellar hemispheres
What causes a dural headache?
- The dura is sensitive to stretching which can cause a headache
- Extraction of CSF can cause strain on the dura resulting in a dural headache
What is a tentorial herniation?
- caused by space occupying lesion which causes a herniation of temporal lobe
What is the arachnoid mater?
- Thin avascular layer between pia and dura
- It is loosely applied layer with projections
What do all structures passing to/from the brain pass through?
The subarachnoid space
What space should not exist unless there is a pathology
The subdural space should not exist unless there is a pathology
What are arachnoid granulations
- Arachnoid granulations from the arachnoid layer project into the venous sinus(for filtration of CSF)
What does the subarachnoid space(real space) contain?
- Contains CSF: produced by choroid plexus in brain ventricles
Purpose of arachnoid granulations
- Arachnoid granulations affect the transfer of CSF to venous sinuses
What is the pia mater?
- Very delicate vascular membrane(nourish)
- Closely invests brain following gyri/sulci
- Cerebral arteries enter brain carrying sheath of pia mater with them
What gives the brain a slightly shiny appearance?
- Pia mater
What is meningitis an infection of?
- Leptomeningitis is an infection and inflammation in the arachnoid and pia mater(the lepto
What is a complication of meningitis?
- The infection may enter into the subarachnoid space and enter into blood(septicemia)
Where are dural sinuses located?
- Positioned in the dural fold
What do the dural sinuses contain?
- Drained blood and CSF from the brain via cerebral veins
Describe the walls of the dural sinuses
- Thick walled endothelium
- No valves or smooth muscle
Where does blood from the dural sinuses drain into?
- Internal jugular vein
