Scalp And Cranial Caivty Flashcards
What are the boundaries of the scalp
From the superior nuchal line of the occipital bone to the supraorbital margins of the frontal bone
What are the 5 layers of the SCALP
S - Skin ; outermost layer
C - (dense) Connective tissue
A - Epicranial Aponeurosis
L- Loose connective tissue
P - Pericranium
Which three layers make up scalp proper?
Skin, Dense connective tissue and Aponeurosis
Where is skin on the scalp the thickest
Over the occipital bone
Which layer of scalp proper is richly vascularised and contains cutaneous nerves
Dense connective tissue - An injury to scalp and it will bleed profusely
What is the epicranial aponeurosis - what does it prevent
Tendon and muscle layer of occipitofrontalis
This layer prevents superficial wounds from gaping open, if this area is compromised sutures are required
What is the function of the two bellies of the occiptofrontalis
The frontal belly functions to wrinkle the forehead while the occipital belly functions to then smooth it back out.
These muscle bellies create tension between each other and an injury here will cause a lot of gaping
What is the purpose of the loose layer of connective tissue in the scalp
This area allows for movement of the outer layers of the scalp;
This area contains spaces ( spongy bone)susceptible to distension or infection spread
What is the pericranium
It is the external periosteum of the skull, it is firmly attached
Between the Aponeurosis and the pericranium there are poteintal spaces for accumulation of fluid( e.g. blood) or spread of infection.
This fluid or infection can spread to the eyelids or the root of the nose, why?
This is because the frontal belly of the occipitofrotnalis inserts into skin and subcutaneous tissue and NOT BONE.
- this means that there is no bony attachment to stop the infection from spreading so it continues to plead to eyes and root of nose
Why can the brain be at risk in an infection of the loose connective tisssue
This is due to the emissary veins which can spread the infection to the brain causing things such as meningitis
What is the arterial supply of the scalp
Internal and external carotid arteries supply the scalp
Internal ( anteior scalp) - supraorbital and supratrochlear branches
External (posterior scalp) ) - superficial temporal, posterior auricular and occipital branches
Why does the scalp tend to bleed profusely when lacerated and why is this bleeding difficult to stop
This is due to the presence of many arterial anastomoses which lie superficially hence leading to profuse bleeding when lacerated
The connective issue layer is dense and therefore the anrites cannot constrict as much making it difficult to stop the bleeding
The veins of the scalp run along with the arteries of the scalp and have the same names.
Where do the veins drain into and which one is the exception
They all drain into the external jugular vein with the one exception of the occipital vein which drains into the internal jugular vein
The lymphatic drainage of the scalp is via 2 means, what are these
Anterior ; Pre-auricular and parotid nodes
Posterior; mastoid and occipital nodes and these drain into the deep cervical nodes
Cribriform plate fractures can present with what and note three symptoms
CSF rhinorrhoea
-metallic taste at back of throat
- headache that worsens when you sit up improves when you lie down
- watery discharge from nose or ear
Where does the pituitary gland lie
It lies in the hypophyseal fossa (deepest part of the sella turcica) in the middle cranial fossa
What is the function of arachnoid granulations
Returning CSF to the venous circulations
What is the function of the buttresses in the bone structure of the skull
These are thicker portions of cranial bone ( pillars) that transmit forces around weaker regions of the cranium
- bypassing orbits and nasal cavity
What are the cranial meninges
They are membranous layers that help in the protection of the brain
Including ;
Dura Mater
Arachnoid mater
Pia mater
What is the outermost layer of the cranial meninges and what is its two layers ( where are these two layers separate )
Dura mater
It has two layers
- periosteal layer which is connected to the bone
- meningeal layer which is isn contact with the arachnoid layer
These two layers are separate at the venous sinuses and the dura folds
The second layer of the meninges is the arachnoid mater, why does it have the spider web appearance
It is attached to the pia mater by tubercles which give it the spider like appearance
These tubercles extend cross the subarachnoid space and are continuous with the pia mater
What is the subarachnoid space
It is a fluid filled space which contains CSF and blood vessels, provides a bit of cushioning for the brain.
Arachnoid villi are responsible for the resorption of CSF into the venous system, collections o these villi are called what and where can they be found
Collections of arachnoid villi can be found in the saggital sinus and lateral lacunae - these collections are known as arachnoid granulations
What it the thin membrane which is attached to the surface of the brain called?
Pia mater
What is the purpose of the dura mater folds
They limit the movement of the brain within the cavity
- they follow the fissures and anchor the brain in the skull
For example if there was a blunt force trauma there is something to hold the brain into place
Which dura mater fold covers the sella turcia and is the roof over the pituitary fossa
The flax cerebri
In which dura mater fold does the venous sinus run
Falx cerebelli - this fold runs in between the nodes of the cerebellum
What is the main blood supply of the dura mater
The meningeal Arteries - in particular the middle
The herpes zoster virus may lie dormant in ganglia of nerves and then become active again what is the most common nerve for it to affect
Supra-orbital nerve
