Space Occupying Lesions and Head Trauma Flashcards
There is not a lot of spare room in the skull. Describe what happens if there is development of a space occupying lesion?
The base of skull foraminae do not readily allow ‘escape’ of contents to make up for this increased volume. This can lead to a steady increase in ICP until the body can no longer compensate for this which results in an exponential increase in ICP which can lead to brain herniation.
Name the 5 layers of the skull from external to internal?
Skin, connective tissue, aponeurosis, loose connective tissue, pericranium
What does the connective tissue layer of the skull contain?
Arteries of the scalp
What is the tendinous layer of the skull?
Aponeurosis
The scalp arteries arise from which vessels?
External carotid arteries
The ophthalmic arteries arise from which vessels?
Internal carotid arteries
Describe where the scalp arteries are found and what the significance of this is?
They form an anastamotic network just deep to the skin - means that scalp lacerations and incisions will bleed excessively
What type of joints are the sutures of the skull? What is the function of these?
Fibrous joints, prevent skull fractures from spreading
What is the pterion?
An H shaped suture which forms the thinnest part of the skull
The connections of which bones of the skull form the pterion?
Frontal, sphenoid, temporal, parietal
The mastoid and styloid processes are both features of which bone of the skull?
Temporal bones
Where is the middle meningeal artery found?
Coursing over the deep aspect of the pterion
What is the function of the meninges?
To form a protective covering around the brain and spinal cord
Stretching of which structure causes the pain in meningitis?
Dura mater
The dura mater is a tough, fibrous layer of meninge which receives a sensory supply from where?
CNV
The dura mater is actually composed of 2 layers - describe these? What structure does this allow the formation of?
Superficial layer (periosteal) and deep layer (meningeal) allow the formation of the dural venous sinuses
What is found in the subarachnoid space?
Circulating CSF
How is CSF in the subarachnoid space reabsorbed back into the venous circulation? Where is it reabsorbed back into?
Via arachnoid granulations which are strands of arachnoid mater projecting into the subarachnoid space / dural venous sinuses
What is the pia mater adherent to?
The brain, and all blood vessels and nerves entering/leaving the brain
Where is the dura mater adherent to?
The internal aspects of all bones of the skull
What is the diaphragm sellae?
A tough sheet of dura mater forming a roof over the pituitary fossa
What is the tentorium cerebelli?
A tough sheet of dura mater over the cerebellum
Where does the tentorium cerebelli attach to?
The ridges of the petrous part of the temporal bone
The tentorium cerebelli has a central gap to allow what structure to pass through?
The brainstem
What is the falx cerebri?
A midline structure made of dura mater which separates the left and right cerebral hemispheres
The falx cerebri is attached to the deep aspect of the skull - describe which structures specifically?
It begins by attaching to the crista galli of the ethmoid bone anteriorly and then runs along the deep aspect of the sagittal suture until it attaches to the internal occipital protuberance posteriorly
In what plane do each of the following structures sit a) falx cerebri? b) tentorium cereblli?
a) Sagittal b) Axial
If there is infection in the danger triangle of the face, what is the risk of this?
That infection will spread into the facial veins which can then lead back to the ophthalmic veins and to the cavernous sinus
What are the cavernous sinuses? Where are they found?
They are plexuses of dural venous sinuses - lateral to the body of the sphenoid bone on right and left sides