S1) Anatomy of the Scalp Flashcards
What are the five layers of the scalp?
- Skin
- Dense Connective tissue
- Epicranial Aponeurosis
- Loose areolar connective tissue
- Periosteum
Describe the properties of the skin layer of the scalp
Skin – contains numerous hair follicles and sebaceous glands
Describe the structure and function of the dense connective tissue layer of the scalp
- Structure: richly vascularised and innervated
- Function: connects the skin to the epicranial aponeurosis
What feature about the dense connective tissue layer makes the scalp prone to profuse bleeding?
- The blood vessels within the layer are highly adherent to the connective tissue
- This renders them unable to constrict fully if lacerated
Describe the structure and function of the epicranial aponeurosis in the scalp
- Structure: thin, tendon-like structure
- Function: connects the occipitalis and frontalis muscles
Describe the structure and function of the loose areolar connective tissue layer of the scalp
- Structure: a thin connective tissue layer
- Function: separates the periosteum of the skull from the epicranial aponeurosis
The loose areolar connective tissue layer of the scalp also contains numerous blood vessels.
What is the function of the emissary veins?
Emissary veins connect the veins of the scalp to the diploic veins and intracranial venous sinuses
Describe the properties of the periosteum layer of the scalp
Periosteum – the outer layer of the skull bones, becomes continuous with the endosteum at the suture lines
The ‘danger of the scalp’ is the loose connective tissue.
Why is this important when considering infections?
- Pus and blood easily spread within this area and pass into the cranial cavity through the emissary veins
- Hence, infection can spread from the scalp into the meninges, causing meningitis
Which two main arteries provide the scalp with a rich blood supply?
- External carotid artery
- Opthalmic artery
Which three branches of the external carotid artery are involved in supplying the scalp with blood?
Which region does the superficial temporal artery supply?
Superficial temporal artery supplies the frontal and temporal regions
Which region does the posterior auricular artery supply?
Posterior auricular artery supplies the area superiorly and posteriorly to the auricle
Which region does the occipital artery supply?
Occipital artery supplies the back of the scalp
Anteriorly and superiorly, the scalp receives additional supply from two branches of the opthalmic artery.
Which are these?
- Supraorbital artery
- Supratrochlear artery
These vessels accompany the supraorbital and supratrochlear nerves respectively
The venous drainage of the scalp can be divided into superficial and deep components.
Identify the superficial veins
- Superficial temporal vein
- Occipital vein
- Posterior auricular vein
- Supraorbital vein
- Supratrochlear vein
What drains the deep (temporal) region of the scalp?
Pterygoid venous plexus
Describe the action and location of the pterygoid venous plexus
The pterygoid plexus is a large plexus of veins situated between the temporalis and lateral pterygoid muscles, and drains into the maxillary vein
How is a connection between the scalp and the dural venous sinuses established?
The veins of the scalp connect to the diploic veins of the skull via valveless emissary veins
Branches of which two main nerves innervate the scalp?
- Trigeminal nerve
- Cervical nerve
Identify the four main nerves which arise from the trigeminal nerve and provide cutaneous innervation to the scalp?
- Supratrochlear nerve
- Supraorbital nerve
- Zygomaticotemporal nerve
- Auriculotemporal nerve
Explain the branching and supply of the supratrochlear nerve
Supratrochlear nerve is a branch of the opthalmic nerve which supplies the anteromedial forehead
Explain the branching and supply of the supraorbital nerve
Supraorbital nerve is a branch of the opthalmic nerve which supplies the anterolateral forehead and the vertex
Explain the branching and supply of the zygomaticotemporal nerve
Zygomaticotemporal nerve is a branch of the maxillary nerve which supplies the temple
Explain the branching and supply of the auriculotemporal nerve
Auriculotemporal nerve is a branch of the mandibular nerve which supplies skin anterosuperior to the auricle
Identify the two main nerves which arise from the cervical nerve
- Lesser occipital nerve
- Greater occipital nerve
Explain the branching and supply of the greater occipital nerve
Greater occipital nerve is a branch of the anterior rami of C2-3 which supplies the posterior scalp up to the vertex
Explain the branching and supply of the lesser occipital nerve
Lesser occipital nerve is a branch of the anterior rami of C2-3 which supplies behind the ear
What is a cephalohaematoma?
A cephalohaematoma is a traumatic subperiosteal haematoma that occurs underneath the skin, in the periosteum of an infant’s skull bone
Does a cephalohaematoma pose a risk to the baby’s brain?
No, as the blood hasn’t entered the cranial cavity and is restricted to the subperiosteal layer (between skull bones and periosteum)
