The Scalp Flashcards
what does the scalp refer to?
layers of skin and subcutaneous tissue that cover the bones of cranial vault
what are the layers of the scalp?
Skin dense Ct epicranial Aponeurosis Loose areolar ct Periosteum
which layers are tightly bound together?
first 3 - move together as a unit
skin, dense Ct, epicranial Aponeurosis
what does the skin contain?
numerous hair follicles and sebaceous glands - site for sebaceous cysts
what does the dense Ct do?
connects the skin to the epicranial aponeurosis
richly vascularised and inervated
why can the scalp be a site of profuse bleeding?
the blood vessels within the dense Ct are high adherent to the Ct
this renders them unable to fully constrict if lacerated
what is the epicranial aponeurosis?
a thin, tendon-like structure that connects the occipitalis and frontalis muscle
describe the loose areolar ct
a thin ct layer that separates the periosteum of the skull form the epicranial aponeurosis
what does the loose areolar ct consist of?
numerous blood vessels - including emissary veins which connect the veins of the scalp to the diploic veins and intracranial venous sinuses
describe the periosteum
outer layer of skull bones
what does the periosteum become continuous with? where?
becomes continuous with the endosteum at the suture lines
Clinical: scalp infections, where is the danger area of the scalp?
loose CT
clinical: why is the loose CT the danger area of the scalp?
because pus and blood spreads easily within it, and can pass into the cranial cavity along the EMISSARY veins
therefore, infection can spread from scalp to meninges - can lead to meningitis
where does the scalp receives its rich blood supply via?
external carotid artery and opthalmic artery
what is the opthalmic artery a branch of?
internal carotid
how many branches of the external carotid artery are involved? what are they?
3
superficial temporal
posterior auricular
occipital
what is the mnemonic for remember the branches of the external carotid artery?
some anatomists like freaking out poor medical students
what are the all the branches of the external carotid artery?
S: superior thyroid artery A: ascending pharyngeal artery L: lingual artery F: facial artery O: occipital artery P: posterior auricular artery M: maxillary artery S: superficial temporal artery
what does the superficial temporal artery supply?
frontal and temporal regions
what does the posterior auricular artery supply?
area superiorly and posteriorly to the auricle
what does the occipital artery supply?
back of the scalp
anterior and superiorly, where else does the scalp receive blood supply from?
2 branches of the opthalmic artery:
supraorbital artery
supratrochlear artery
how is the venous drainage of the scalp divided?
into superficial and deep components
what does the superficial venous drainage follow?
the arteries: (SOP,SS) superficial temporal occipital posterior auricular supraorbital supratrochlear
what is the deep region of the skull drained by?
deep (temporal) region
drained by pterygoid venous plexus
what does the pterygoid venous plexus drain to?
maxillary vein
where is the pterygoid venous plexus situated?
between the temporalis and lateral pterygoid muscles
what is the innervation of the scalp?
cutaneous innervation from 6 main nerves
arise from trigeminal or cervical nerves
what are the branches of the trigeminal nerve which innervates the scalp?
supratrochlear nerve
supraorbital nerve
zygomaticotemporal nerve
auriculotemporal nerve
what are the branches of the cervical nerve which innervates the scalp?
lesser occipital nerve
greater occipital nerve
what are main branches of the trigeminal nerve?
tri = 3 (OMM) ophthalmic nerve (V1) maxillary nerve (V2) mandibular nerve (V3) (all converge on the trigeminal ganglion)
what is the supratrochlear nerve (trigeminal) a branch of? supplying where?
branch of opthalmic nerve (V1)
supplies anteromedial forehead
what is the supraorbital nerve (trigeminal) a branch of? supplying where?
branch of opthalmic nerve (V1)
supplies large portion of scalp between anterolateral forehead and vertex
what is the zygomaticotemporal nerve (trigeminal) a branch of? supplying where?
branch of maxillary nerve (V2)
supplies temple
what is the auriculotemporal nerve (trigeminal) a branch of? supplying where?
branch of mandibular nerve (V3)
supplies skin anterosuperior to the auricle
what is the lesser occipital nerve (cranial) a branch of? supplying where?
branch of anterior rami of C2 & C3
supplies behind the ear
what is the greater occipital nerve (cranial) a branch of? supplying where?
branch of anterior rami of C2 & C3
supplies posterior scalp up to vertex (top)
clinical: why do lacerations to the scalp bleed profusely?
- pull of occipitofrontalis muscle prevents the closure of the bleeding vessel and surrounding skin
- blood vessels to the scalp are adhered to dense CT, preventing vasoconstriction that normally occurs in damage response
- blood supply to the scalp is made up of many anastomoses - contribute to profuse bleeding
what can loss of blood supply to scalp lead to? why?
bone necrosis
as most of blood supply to skull comes from middle meningeal artery
