Session 1 - Anatomy of the Scalp Flashcards
What are the layers of the scalp?
Skin Dense connective tissue Aponeurosis Loose connective tissue Pericranium
Following a non-penetrating injury to the scalp, a patient presents with a well circumcised lump. Within which layer of the scalp has bleeding occurred, and why does it form such a well defined lump?
Dense connective tissue.
Blood cannot move easily within this layer so collects in a lump.
Why do scalp wounds involving the dense connective tissue layer bleed profusely?
The scalp has a rich blood supply, with many arteries coursing through the dense connective tissue layer. Arterial walls are firmly attached to the dense connective tissue in which they are embedded, limiting their ability to constrict when cut. Also, arteries anastomose freely with adjacent arteries.
Why do scalp wounds involving the aponeurosis gape where as superficial wounds do not?
Deep scalp wounds gape widely when the aponeurosis has been lacerated due to the frontal and occipital bellies of the occipitofrontalis muscle pulling in opposite directions. Because the epicranial aponeurosis is very strong, superficial scalp wounds don’t gape because the margins of the wound are held together by the aponeurosis.
What is a cephalohaematoma?
Haematoma that occurs between the pericranium and the skull (subperiosteal haematoma)
Does a cephalohaematoma pose a risk to the brain?
No, bleeding occurs outside the skull so does not impact/put pressure on the brain
What limits the spread of bleeding within the subperiosteal layer?
Blood cannot pass suture lines. This is because the pericranium is continuous with fibrous tissue in the cranial sutures that blood cannot cross.
How might infections beneath the aponeurotic layer of the scalp spread intracranially?
Blood and pus spreads easily through the loose connective tissue layer. Infection in this area can then pass into the cranial cavity through small emissary veins, which pass through the parietal foramina in the calvaria and reach intracranial structures such as the meninges.
Which fascial spaces extend inferiorly into the mediastinum?
Retropharyngeal space
Pre-tracheal space
The retropharyngeal space is actually split in the centre by what fascia?
The alar fascia
What two spaces does the alar fascia spilt the retropharyngeal space into?
True retropharyngeal space (anterior) Danger space (posterior)
Are the true retropharyngeal and danger spaces distinguishable from each other in radiological imaging of a healthy person?
No, you can only see the retropharyngeal space as a whole in a healthy person
When can the danger space become visible in radiological imaging?
Only visible when distended by fluid/pus below the level at which the true retropharyngeal space ends (variable between T1-T6).
