1 the SCALP Meninges E-learning

8/2/2019 1 the SCALP Meninges E-learning

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The SCALPThe SCALP

&&Cranial MeningesCranial Meninges


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SCALPSCALP

The skin & subcutaneous tissue that covers the cranial vault

Extent:

sup. Nuchal lines (post.)

Supraorbital margins (ant.)

Zygomatic arches (lat.)

5 layer:

indicated by its letters


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S:Skinthin except??

many hair follicles & ?

rich in bld. Supply

C:Connective tissue thick, dens C.T. septa

& fat lobules

rich in bld. Supply

* Bld. Vessels of scalp are

running within this layer


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A: Aponeurosis (flat tendon)Epicranial aponeurosis

Galea Aponeurotica

strong tendinous sheet

provides attachment for:

occipitofrontalis m.

& ?? laterally

*1st 3 layers move together as

one unit & called:

Scalp proper


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L:Loose C.T.has many potential spaces

sponge like layer

* allows free movement of

scalp proper over bone.

P:Periosteumouter C.T. layer that surrounds

the bones of calvaria

firmly attached to the bone


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Innervations to The ScalpInnervations to The Scalp

Ant.:

Supratrochlear & Supraorbital n.

(from ??)

Lat.:

Zygomaticotemporal n. (from?)Auriculotemporal n. (from?)

Post.:

lesser occipital n.

(C2, ant. ramus)

Greater occipital n.

(C2, post. ramus)


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Arteries of The ScalpArteries of The ScalpIn Which Layer?In Which Layer?

Ant.:

Supratrochlear &Supraorbital a. (ICA)

Lat.:

Superficial temporal a.

(ECA)

Post.:

Post. Auricular a.

Occipital a.(ECA)

* Scalp is an area of anastomosisbetween branches of ICA & ECA


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Clinical: Injuries to The ScalpClinical: Injuries to The Scalp

* The scalp is one of the richest areas of bld. Supply in the body.2 Sources: ECA & ICA

Small inj. to the scalp can result in sever prolonged bleeding

Due to:

1. rich blood supply

2. separation of vessel ends

by C.T. Septa & the aponeurosis

Rx.: suturing the injury


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Scalp InfectionsScalp Infections

- Pus or blood spreads easily in The loose connective tissue layerof SCALP (Danger area of scalp)

- Infection or fluid in this layer (pus or bld.) cannot pass posteriorlyor laterally, WHY??

Post.:Lat.:

-instead, Infection or fluid in this layer (pus or bld.) can spreadeither:

anteriorly

eyelids & root of noseblack eye orEcchymosis

into the cranial cavity throughemissary veins meninges


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The Cranial MeningesThe Cranial Meninges

3 layers of C.T.,that:

1. protect the brain

2. provide supportingframework for a. & v.

3. enclose fluid-filled

cavity (CSF)

3 layers:Dura mater

Arachnoid mater

Pia mater


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Dura Mater

most external partdouble layered membrane

2 layers:

ext. periosteal layer

(periosteum of calvarian bones)

Int. meningeal layer

- tough, thick fibrous membrane

continues at F. magnum to SC

* Brain Venous Sinuses are located between periosteal &

meningeal layers of dura


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Dural ReflectionsDural Reflections

Foldings of internal meningeal layer between brain compartments

(septa) to restrict the rotatory displacement of the brain (fxn.)

4 main reflections:

falx cerebri

falx cerebelli

tentorium cerebelli

sellar diaphragm


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Arachnoid MaterArachnoid Mater

Thin, intermediate layer that attaches to pia mater throughweb-like arachnoid trabeculae

Avascular layer

Held against dura by pressure of CSF

Subarachnoid space:

between arachnoid & pia

contains: arachnoid trabeculae & Cerebrospinal fluid (CSF)


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Pia MaterPia Mater

Very thin & delicate membrane that is highly

vascularized

Adheres to brain surface & follows its contours


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Meningeal SpacesMeningeal Spaces

Epidural Space:between dura & bone

not present normally

happens pathologically

(as hemorrhage)

Subdural Space:

between ?

not present normally

Subarachnoid Space:

a real space

contains CSF


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Arterial Supply to MeningesArterial Supply to Meninges

(Dura & Calvaria)(Dura & Calvaria)

Middle Meningeal a. & Accessory Meningeal a.:

Main meningeal artery

From??

Pass through??

2 Anterior meningeal a.:

From ethmoidal a.from ??

4 Post. Meningeal a.:

2 from ascending pharyngeal a.

Pass through ??

& 2 smaller branches from??


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Clinical: Epidural HemorrhageClinical: Epidural Hemorrhage

Due to injury to a meningeal arterymiddle meningeal a. (pterion)

Bld. Collects between:

bones of clavaria & periosteal layer

or periosteum & meningeal layers

Complications:

bld. Mass compress the brain loss of consciousness & coma

Rx.:

draining bld. & closure of the artery (ligation)

Read the clinical note in your textbook Intracranial Hemorrhage


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Dural Venous SinusesDural Venous Sinuses

Blood filled spaces within dura matter that lined with endothelium

and drain all bld. from brain and meninges.Location: Between the periosteal and meningeal layers of dura,

where dural infoldings attach.

Main :

Sup. Sgittal sinusInf. Sagittal sinus

Straight sinus

Transverse sinus (2)

Sigmoid sinus (2) IJVCavernous sinus (2):venous plexus lat. to sella turcica

Receives sup. & inf. Ophthalmic v.

From the orbit

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