Scalp Flashcards
What does the scalp extend to anteriorly?
Supra-orbital margins of frontal bone
What does the scalp extend to posteriorly?
Superior nuschal line of occipital bone
What does the scalp extend to laterally?
Zygomatic arches
How many layers is the scalp made up of?
Five
What are the five layers of the scalp?
Skin
Dense connective tissue
Epicranial aponeurosis
Loose areolar connective tissue
Pericranium
How are the different layers of the scalp related to each other?
First three are connected to each other
What does the dense connective tissue layer of the scalp contain?
Arterial blood supply
Sensory innervation
What is the epicranial aponeurosis made up of?
Tendinous sheet
What does the epicranial aponeurosis run between?
Frontal belly of occipitofrontalis
Occipital belly of occipitofrontalis
How do the frontal and occipital bellies of occipitofrontalis affect the epicranial aponeurosis?
Frontal belly pulls it anteriorly
Occipital belly pulls it posteriorly
What does the loose areolar connective tissue layer contain?
Potential spaces
Emissary veins
What is the pericranium made up of?
Dense connective tissue
How does the pericranium relate to the calvaria?
It is the periosteum of the calvaria
What is the arterial supply of the scalp?
Supra-trochlear artery
Supra-orbital artery
Occipital artery
Posterior auricular artery
Superficial temporal artery
What do the arteries supplying the scalp arise from?
External carotid artery
- occipital artery
- posterior aurticular artery
- superficial temporal artery
Internal carotid artery, opthalamic artery
- supra-trochlear artery
- supra-orbital artery
What can the venous drainage of the scalp be divided into?
Superficial
Deep
What is the superficial venous drainage of the scalp?
Veins accompanying arteries
have same name
What is the deep venous drainage of the scalp?
Pterygoid venous plexus
Emissary veins
What does the pterygoid venous plexus drain into?
Maxillary vein
What do the emissary veins drain into?
Diploic veins
Where are diploic veins located?
Diploic cavity of calvaria
Where do the emissary veins travel?
From the veins of the scalp, through the outer table and diploic cavity of the calvaria
into the diploic veins
Do emissary veins have valves?
No
What do the diploic veins drain into?
Dural venous sinuses
Where do the diploic veins travel?
From the diploic cavity, through the inner table, periosteal layer of the dura
into the dural venous sinuses
How much does a scalp laceration bleed?
Bleeds a lot
Why do scalp lacerations bleed a lot?
Lots of anastamoses between arteries supplying it
Walls of arteries attached to dense connective tissue, so cannot vasoconstrict to limit blood flow
Epicranial aponeurosis pulled in opposite directions by frontal and occipital bellies of occipitofrontalis, prevents closure of ruptured artery
What is the danger area of the scalp?
Loose areolar connective tissue layer
Why is the loose areolar connective tissue layer of the scalp known as the danger area?
Because blood and pus can easily accumulate and spread in it
Also contains emissary veins, which drain into the dural venous sinuses, so infection can spread into the cranial cavity
Where can blood in the loose areolar connective tissue layer travel to?
Eyelids
Root of nose
Why can blood in the loose areolar connective tissue layer spread to the eyelids and the root of the nose?
Because the occipitofrontalis muscle attaches to the skin and subcutaneous tissue, not bone
this creates a passageway for the blood into this area
What is the sign of blood accumulated around the eyelids?
Purple-black colour around the eyes
called peri-orbital ecchymosis
Where can infection in the loose areolar connective tissue layer of the scalp not travel to?
Neck
Why can infection in the loose areolar connective tissue layer of the scalp not travel to the neck?
Because the occipital belly of the occipitofrontalis muscle inserts into bone
Because the epicranial aponeurosis is continuous with temporal fascia which inserts into the zygomatic arches
Why does a haematoma in the dense connective tissue layer of the scalp form a tight lump?
Because the dense connective tissue layer contains lots of collagen fibres
these contain the blood
blood accumulates in a smaller area
With a scalp laceration, how are the wound margins affected if they involve the epicranial aponeurosis? Why?
Wound margins are pulled apart
because of epicranial aponeurosis being pulled in opposite directions by frontal belly and occipital belly
this layer is connected to the more superficial layers of the scalp
With a scalp laceration, how are the wound margins affected if they do not involve the epicranial aponeurosis?
Wound margins are held together
by the epicranial aponeurosis
since it attaches to the more superficial layers of the scalp
