Date of lecture: 21-2-2011 Mon
No of lecture: 4
SCALP
First: Layers of the scalp
Scalp is the layer of structures covering the cap of the skull, & it’s formed
by 5 layers which are:
1. Skin
2. Connective tissue
3. Aponeurosis
4. Loose connective tissue
5. Pericranium
NOTE … The word SCALP is the key memory for the layers forming the
scalp
Below the 5 layers there is:
6. Bone of the skull
7. Meninges
8. Brain
*Now let’s talk in details about each layer:
1. Skin: Contains numerous hair follicles & sebaceous glands.
2. Connective tissue: Thick, tight and tough because it contains collagen
fiber (which is harder than steal), and it’s a dense type, contains
arteries, veins and nerves supplying the scalp.
NOTE ... Wounds of scalp after injury gaps widely (open), so if a person had
a serious injury in the scalp then he could have coma and bleed freely till
death.
3. Aponeurosis: Tendinous sheet between Frontalis anterior & Occipitals
posterior. This tendinous sheet is the insertion of two muscles in a
region called Galia Aponeurotica.
4. Loose connective tissue: Like a sponge, distend with fluids, tend to be
site of infections (Danger area of the Scalp), so if someone had
injury, collection of blood will be in this layer.
5. Pericranium: Periosteum covering outer surface of the skull. (the inner
surface is called endostium).
-The first 3 layers are tightly connected together forming what we called
SCALP PROPER as one layer, that’s why if we want to do surgery in scalp in
a process called craniotomy, we remove the scalp proper as one layer.
Second: Arterial supply of the scalp
 Richly supplied with blood
 Arteries anastomose freely within the 2nd layer which is the dense
connective tissue
 Supplied from:
1. Anterior by branches of Internal Carotid artery which are
Supratrochlear artery and Supraorbital artery
2. Posterior by branches of External Carotid artery which are
Superficial Temporal artery, Posterior Auricular artery,
Occipital artery.
Third: Sensory nerves of the scalp
First you should know that motor supply of the scalp is by Frontalis nerve &
Occipitalis nerve which are branches from facial nerve.
The sensory innervation is:
1. Anterior to the ear from Trigeminal nerve that gives 3 branches V1
(Supratrochlear nerve & Supraorbital nerve), V2(Zygomaticotemporal
nerve) & V3 (Auriculotemporal nerve).
2. Behind the ear from Cervical plexus which originate from C1, C2, C3,
C4.
*Remember brachial plexus starts from C5 till T1.
Fourth: Cranial Meninges
 They are 3 layers that cover the brain & spinal cord
 They have spaces between them like Extradural space & Subarachnoid
space (that contains CSF) which are very important in homeostasis &
diseases.
 When there is meningitis, we take a sample of CSF (craniospinal fluid).
NOTE … Meningitis is an inflammation in meninges.
 Brain and spinal cord are surrounded by 3 meninges:
1. Outer tough layer: Dura mater.
2. Middle spongy layer: Arachnoid mater, it is formed by fibrous
tissue and spaces in between, and is the site of collection of
fluids.
3. Inner delicate layer: Pia mater, it is like the visceral layer of
pleura & visceral layer of pericardium.
NOTE … Most brain bleeding occurs in the subarachnoid space and it’s
venous.
The pain of headache comes from meninges not from frontal bones because
the meninges have sensory nerve supply (skin is the major sensory part of
the body which contains nerve endings. Also meninges have sensory nerve
ending so it’s like the skin of the brain specifically Dura mater).
Dura mater is divided into 2 layers:
1. Inner Meningeal layer that surrounds cranial nerves outside the skull
clearly in optic nerve. The Meningal layer will continue outside with
the optic nerve until sclera of the eye. That’s why it appears white in
adult, blue in babies, yellow in old ages.
2. Outer Periosteal layer that covers the anterior of the skull and is
continuous with the outer skull Periosteum at sutures and foramens.
So, the skull is covered from inside by Endosteum and Meningeal layer of
Dura and continues with Periosteum from outside.
-All
cranial
meninges
are
continuous
throughout
foramen
magnum
posteriorly to cover the spinal cord except the meningeal layer of dura that
fuse with perioteum of the skull, so the periosteal canal will continue lining
the vertebral canal.
Fifth: dural partition.
The 2 Dura mater will separate during developing forming folds because the brain
grows and dives down from superior to inferior in process called partitions.
The meningeal layer of dura will dive down between parts of the brain forming Cshaped partition project in two directions:
1. Falx
cerebri (vertical) separating right cerebral and left cerebral
hemisphere.
2. Tentorium cerebella (horizontal) and there is opening called tentorial
notch transmitting midbrain.
NOTE … when we want to take a sample of CSF we take from lumbar region
(mainly L3, L4).
This partition divides cranial cavity into 3 compartments
1. two for cerebral hemispheres
2. one for Cerebellum, Pons and Medulla
Sixth: Dural arterial supply
Mainly by middle meningeal artery, which is a branch from maxillary artery which
is a branch from external carotid artery which is a branch from common carotid
artery…
Seventh: Dural innervations
1. Supratentorial dura: supplied by trigeminal nerve
2. Infratentorial dura supplied by cervical nerve C1, C2, & sometimes C3.
Done by : Isra’a Qasem
Dear collogues I hope this sheet is gd & u understand everything … I almost write
everything the Dr. said in the lecture even if he said this isn’t important just 4 knowing, but
I guess it’s all important … gd luck in studying the sheet 