How many layers does the scalp consist of?
Which of the layers of the scalp are tightly bound together?
The first three
What is the result of the first three layers of the scalp being tightly bound together?
They move as a unit
What are the layers of the scalp?
- Dense connective tissue
- Epicranial aponeurosis
- Loose areolar connective tissue
What does the skin layer of the scalp contain?
- Numerous hair follicles
- Sebaceous glands
What is the skin of the scalp a common site for?
What does the dense connective tissue in the scalp do?
Connects skin to epicranial aponeurosis
What is true of the blood and nerve supply of the dense connective tissue of the scalp?
- Richly vascularised and innervated
- Blood vessels within the layer are highly adherent to connective tissue
What is the result of the blood vessels in the dense connective tissue of the scalp being highly adherent to connective tissue?
Renders them unable to constrict fully if lacerated, and therefore scalp can be a site of profuse bleeding
What is the epicranial aponeurosis of the scalp?
Thin, tendon-like structure
What does the epicranial aponeurosis of the scalp do?
Connects occipitalis and frontalis muscles
What is the loose arerolar connective tissue layer of the scalp?
Thin connective tissue layer that seperates the periosteum of skull from epicranial aponeurosis
What does the loose areolar connective tissue of scalp contain?
Numerous blood vessels
What clinically important blood vessels does the loose areolar connective tissue of the scalp contain?
What do the emissary veins do?
Connect the veins of the scalp to the diploic veins and intracranial venous sinuses
What is the loose areolar connective tissue of the scalp known as?
The danger area of the scalp
Why is the loose areolar connective tissue of the scalp known as the danger area of the scalp?
Because pus and blood can easily spread within it, and can pass along the cranial cavity along emissary veins
Where can infection spread from the scalp?
The meninges, causing meningitis
What is the periosteum of the scalp?
Outer layer of skull bones
What does the periosteum become continuous with?
Where does periosteum become continuous with endosteum?
Where do blood vessels supplying the scalp arise from?
Branches of the internal and external carotid arteries
Via what do the internal cartoid arteries supply the scalp?
Via the branch, the opthalmic artery
Where does the opthalmic artery supply the scalp?
Via what does the opthalmic artery supply the scalp?
- Supraorbital artery
- Supratrochlear artery
What do the supraorbiral and supratrochlear artery accompany?
The supraorbital and supratrochlear nerves respectively
Via what does the external carotid artery supply the scalp?
- Superficial temporal
- Posterior auricular
What does the superficial temporal artery supply?
Frontal and temporal regions
What does the posterior auricular artery supply?
The area superior and posterior to auricle
What does the occipital artery supply?
Back of scalp
What provides a rich blood supply to the tissues of the scalp?
What is the clinical relevance of the anastomoses supplying the scalp?
Scalp wounds often bleed heavily
What can the venous drainage of the scalp be divided into?
Superficial and deep components
What arteries does the superficial drainage of the scalp follow?
- Posterior auricular
Note: Veins are named after their respective arteries
What is the deep (temporal) region of the skull drained by?
Pterygoid venous plexus
What is the pterygoid venous plexus?
A large plexus of veins
Where is the pterygoid venous plexus situated?
Between temporalis and lateral pterygoid muscles
What does the pterygoid venous plexus drain into?
The maxillary vein
What do the veins of the scalp connect to?
The diploic veins
How do the veins of the scalp connect to the the diploic veins of the skull?
Via valveless emissary veins
What does the connection of the veins of the scalp and the diploic veins of the skull establish?
Connection between scalp and dural venous sinuses
How does the scalp recieve its cutaneous innervation?
Six main nerves
What do the main nerves of the scalp arise from?
The trigeminal or cervical nerves
What does the trigeminal nerve give rise to?
- Supratrochlear nerve
- Supraorbital nerve
- Zygomaticotemporal nerve
- Auriculotemporal nerve
What is the supratrochlear nerve a branch of?
What does the supratrochlear nerve supply?
What is the zygomaticotemporal nerve a branch of?
What does the zygomaticotemporal nerve supply?
What is the auriculotemporal nerve a branch of?
What does the auriculotemporal nerve supply?
Skin anterosuperior to auricle
What does the cervical nerve give rise to?
- Lesser occipital nerve
- Greater occipital nerve
What is the lesser occipital nerve a branch of?
The anterior rami of C2 and 3
Where does the lesser occipital nerve supply?
Behind the ear
What is the greater occipital nerve a branch of?
Anterior rami of C2 and C3
Where does the greater occipital nerve supply
Posterior scalp up to vertex
What is the problem with deep lacerations of the scalp?
They tend to blled profusely
Why do deep lacerations of the scalp tend to bleed profusely?
- Pull of occipitofrontalis muscle prevents closure to bleeding vessel and surrounding skin
- Blood supply of scalp made up of many anastomoses, which contribute to produse bleeding
- The blood vessels of the scalp are connective to dense connective tissue
Why does the blood vessels of the scalp being connected to dense connective tissue lead to deep lacerations bleeding profusely?
Prevents vasoconstriction that normally occurs in response to damage
Does loss of blood supply to scalp lead to bone necrosis?
Why does loss of blood supply to the scalp not lead to bone necrosis?
Because most of the blood supply to scalp comes from middle meningeal artery
Label this diagram of the layers of the scalp
Add diagram with labels