SCALP - book notes

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5 Scalp layers:: Skin
Connective Tissue
Aponeurosis
Loose areolar tissue
Pericranium
What is the skin of the scalp like?: Thin (except in occipit)
Sweat/sebacious glands
Hair
Good vascular supply/drainage
What is the scalp connective tissue like?: Thick, dense, rich vasculature
Innervated by cutaneous nn.
another name for the scalp aponeurosis:: epicranial apon.
what is the epicranial aponeurosis?: Broad/strong tendon sheet covering calvaria; attachment for muscles.
what muscles are attached to the aponeurosis?: -Occipitofrontalis
-Temporoparietalis
-Superior auricular
What is the collective name for the muscles and aponeurosis connecting them?: Epicranius
What is the epicranius innervated by?: The facial nerve - CN VII
What is the Scalp Proper?: -Skin
-Connective tissue
-Aponeurosis
The first three layers
What is the function of the Loose areolar layer?: Allows free movement of the scalp proper over the calvaria
What is the Loose areolar layer?: Spongey layer with potential space for infection/injury fluid
What is the pericranium?: Dense connective tissue - forms ext. neurocranium periosteum.
What holds superficial scalp wounds together?: Aponeurosis
How do deep and superficial scalp wounds caused by coronal lacerations differ?: Superfic: don't gape
Deep: gape - b/c the aponeurosis is cut and the occipitofrontalis muscle pulls apart.
Which layer of the scalp is the "Danger Area"?: Layer 4 - Loose Areolar
Why is the loose areolar layer dangerous?: Because pus/blood spread easily within it; can spread infection both within, and into cranium via emissary veins.
What forms when hair follicles get obstructed?: sebacious cysts
What is a Cephalhematoma?: Benign area of blood trapped btwn the pericranium/calvaria in a newborn; caused by traumatic birth.
What are cranial meninges and where are they?: Brain coverings immediately internal to the cranium (bone).
What are the 3 functions of the meninges?: 1. Protection of brain
2. Framework for vasculature
3. Allow for subarachnoid space
What are the 3 layers of the meninges?: 1. Dura mater
2. Arachnoid mater
3. Pia mater
What is each layer like in general?: Dura = tough/thick
Arachnoid = thin
Pia = delicate
What is the relationship between the arachnoid/pia maters?: -Continuous; together they are the leptomeninx.
-Separated by subarachnoid space
What lies within the subarachnoid space?: CSF!!
What is the purpose of the subarachnoid space?: to maintain the balance of CSF in the brain.
Where is CSF produced?: From choroid plexuses in the ventricles within the brain.
What is the dura mater structure like in general?: Bilayered - aka pachymeninx
What are the dura mater's 2 layers?: 1. External periosteal layer
2. Internal meningeal layer
Where is the external periosteal layer of the dura mater?: just inside the cranium surface; it is continuous with external periostium at cranial foramina.
Which dura mater layers are continuous with that of the spinal cord?: Only the internal meningeal layer.
What is the internal meningeal layer of the dura like?: Strong and fibrous; continus w/ spinal dura at foramen magnum.
Which layer of dura mater forms dural infoldings, and what are the four infolding names?: -Meningeal layer of dura - forms
1. Falx cerebri
2. Tentorium cerebelli
3. Falx cerebelli
4. Diaphragma sellae
What brain compartments are separated by falx cerebri? In what plane does it lie?: Lies in vertical longitudinal cerebral fissure; separates R/L cerebral hemispheres.
What are the cranial attachments of falx cerebri?: Anterior: Frontal crest
Posterior: Internal occipital protuberance
How does the falx cerebri end?: B/c contin w diphragm sellae
What brain regions does tentorium cerebelli separate? In what plane does it lie?: Lies somewhat horizontally; separates occipital cerebral lobes from the cerebellum.
What are the cranial attachments of tentorium cerebelli?: -Front/rostral: clinoid processs
-Side/rostral: Petrous temporal
-Side/posterior: occipital and parietal bones.
Into what compartments does tentorium cerebelli segment the brain?: -Supratentorial
-Infratentorial
What is the medial/anterior side of tentorium cerebelli like?: Concave and open - free to provide a gap that lets the brainstem continue into middle cranial fossa.
What is the gap created by tent. cerebelli called (for continuance of brainstem)?: Tentorial notch
What does falx cerebellum separate, and what is its cranial attachment?: Vertically oriented to separate R/L cerebellar hemispheres; attached to internal occipital crest
What is diaphragma sellae? What are its attachment points?: The bedcovers for the pituitary gland; circular sheet of dura; suspends from clinoid processes.
What is a tentorial herniation?: Slippage of a tempora lobe through the tentorial notch
What can cause tentorial herniation? (2 contributors): 1 Supratentorial brain tumors increase intracranial pressure; 2 Tentorial notch is a little bigger than it needs to be.
What can result from tentorial herniation?: -Temporal lobe laceration by the tentorium itself
-Occulomotor lesions from stretching/compression.
Pituitary tumors making diaphragma sellae bulge may result in what 2 symptoms?: 1. Hormone disturbances (disturbance of pituitary gland)
2. Visual - from pressure on the optic chiasm.
What important circulatory structures lie between the periosteal/meningeal layers of dura mater?: Dural venous sinuses
What is the function of the dural venous sinuses?: To recieve blood from surface veins and the brain in general; return it to IJV.
What is the highest sinus? Where does it end?: Superior sagittal sinus; ends at the confluence of sinuses.
What meets at the confluence of sinuses?: -Superior sagittal sinus
-Straight sinus
-Occipital sinus
-Transverse sinuses
What are lateral venous lacunae?: Lateral expansions of the superior sinus
What are arachnoid granulations?: Tufts of arachnoid extending into the sinuses - esp lateral venous lacunae.
What is the purpose of arachnoid granulations?: To allow transfer of CSF from the arachnoid space to the venous system.
Where is the inferior sagittal sinus located, & how does it end?: -Inferior border of falx cerebri
-Ends into straight sinus
What 2 structures form the straight sinus?: -Inferior sagittal
-Great cerebral vein
Where does the straight sinus run?: -From the union point of inf sagittal/great cerebral vein;
-To confluence of sinuses
What happens to blood circulation at the confluence of sinuses?: It is drained into transverse sinuses
Where does blood flow from the transverse sinuses?: Into sigmoid sinuses
Where does blood flow from sigmoid sinuses?: Into IJV after the sigmoids course through the jugular foramen.
What does the occipital sinus allow to communicate w/ the sinus system?: Internal vertebral venous plexuses.
Where is the cavernous sinous located?: On either side of sella turcica on the sphenoid bone
Where does blood flow into the cavernous sinus from?: -Superior/inferior opthalmic v.
-Superfic. middle cerebral vein
-Sphenoparietal sinus
What do the cavernous sinuses communicate with?: Intercavernous sinuses around the pituitary gland stalk.
Where do the cavernous sinuses drain into?: Down/backward into superior adn inferior petrosal sinuses.
Where do the superior petrosal sinuses run?: From cavernous sinus to transverse sinuses (where they become sigmoid)
Where do the inferior petrosal sinuses run?: In a groove between petrous temporal & basilar occiput. Empty into IJV directly.
Finish up neurovasculature of dura: ok
What structures make up the ventricular system of the brain?: -2 lateral ventricles
-3rd ventricle
-4th ventricle
-Cerebral aqueduct
What fills the ventricules?: CSF - produced from choroid plexuses.
How do the lateral ventricles communicate with the 3rd?: Through interventricular foramen
What does the 3rd ventricle flow into?: The cerebral aqueduct
What does the cerebral aqueduct connect?: The 4th aqueduct w/ the 3rd.
What does the 4th ventricle drain into?: -Spinal cord
-Median aperture
-2 Lateral Apertures
What do the median/lateral apertures flow into?: Subarachnoid space
What is special about these apertures?: It is the only site where ventricular CSF can get into the subarachnoid space!
How much CSF is secreted daily?: 400-500 mL
What secretes CSF?: Choroid plexuses within the ventricles.
What happens to CSF after it circulates thru subarachnoid space and into cisterns?: Absortn via subarachnoid granulations extending into venous system.
What venous structures recieve CSF from subarachn. granules?: -Superior sagittal sinus
-Lateral lacunae
What cranial site is used for CSF puncture? In whom is this the preferable site?: Cerebellomedullary cistern - site of choice in infants and young kids.
What is obstructive hydrocephalus?: Enlargement of the head due to overproduction of CSF, obstruction of CSF flow, or interference w/ CSF absorption.
Finish vasculature of brain: ok

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