L8: Blood vessels of the head and neck Flashcards
What is the route of the internal carotid artery?
- ascends up the neck
- enters the base of the skull through the carotid canal
What is the route of the vertebral arteries?
-arise from the subclavian artery
-ascend up through the neck passing through the transverse foramina of cervical vertebra
-enter the base of the skull via the formaen magnum
Right and left vetebral arteries then fuse together to form the basilar artery, which forms the posterior portion of the Circle of Willis which supplies the brain
What opening does the internal carotid enter except the carotid canal?
Cavernous sinus (inside the skull)
What passes through the cavernous sinus?
-carotid artery
-CN 3 (occulomotor)
-CN 4 (trochlear)
-CN 6 (abducens)
All nerves above are responsible for the eyes
-2 branches of CN5 (trigeminal- opthalmic and maxillary branches)
What is the first branch off the internal carotid artery?
Opthalmic artery
- this gives off a branch called the central retinal artery which goes into the optic nerve
- then gives off the supra-orbital atery
- then gives off the supratrochlear artery
Why is the central retinal artery important?
If this is cut off, you lose your blood supply to that eye- blocks vision e.g. embolus here
Why are the branches of the internal carotid artery important?
They supply blood to the brain and forms the anterior circulation of the Circle of Willis
e.g. anterior cerebral artery/middle cerebral artery/posterior communicating artery
How many branches does the external carotid give off?
8 branches (some anatomists like freaking out poor medical students) Superior thyroid artery Ascending pharyngeal artery Lingual artery Facial artery Occipital artery Posterior auricular artery Maxillary artery (terminal branch) Superficial temporal artery (terminal branch)
Why is the superficial temporal artery important clinically?
Condition called Giant cell arteritis/Temporal arteritis
-frequent, severe headaches
-scalp tenderness
-jaw pain while eating/talking
-loss of vision/visual changes
Superficial temporal artery becoming inflamed due to vasculitis, reducing blood supply to structures that they supply
TREAT WITH HIGH DOSE STEROIDS
What is the blood supply to the scalp?
Supplied by the internal and external carotid arteries
-supraorbital and supratrochlear arteries from the internal carotid (at front of scalp)
-superficial temporal/posterior auricular/occipital artery from external carotid
Both of these anastamose with each other forming an anastomotic network of vessels with majority of blood from the external carotid
What are the layers of the scalp?
SCALP Skin Connective tissue Aponeurosis Loose areolar tissue Periosteum
Which layer do the vessels of the scalp lie in?
Connective tissue layer
Why does the scalp bleed a lot?
- Arterial walls are held open by connective tissue so can’t constrict
- lots of anastomoses
- if you cut the aponeurosis, the muscles attached at either end pull the cut further open
Which artery do the superficial arteries of the face arise from?
External carotid artery (except the supraorbital and supratrochlear)
What are the branches of the facial artery?
- superior and inferior labial arteries (around lips)
- lateral nasal artery (nose)
- angular artery (nose)
