2.2.2 Internal & External Carotid Arteries Flashcards
Do ICAs branch in the neck?
No
What is the course of the ICAs?
Enters base of the skull via carotid canal (petrous bone of the temporal bone)
Turns medially and horizontally
Enters cranium, makes s-shaped bend
Moves through cavernous sinus
Supplies intracranial structures
What do verterbral arteries arise from?
Left and right subclavian arteries
What is the course of the vertebral arteries?
Ascend up the cervical vertebrae through the transverse foramina
Enter base of skull via Foramen Magnum
What do internal carotids arteries and vertebral arteries supply?
Brain
What is the Cavernous Sinus?
Venous type structure on upper surface of the sphenoid bone
What runs through the cavernous sinus?
Associated with lateral wall:
* CN III
* CN IV
* CN Va and Vb
Not associated with lateral wall:
* Carotid artery
* CN VI
What is the first branch of the ICA?
Opthalmic artery
What are the 3 main branches of the opthalmic artery?
Central retinal artery- if blocked can cause vision loss
Supratrochlear artery
Supra-orbial artery
(these supply blood to scalp)
What are the other branches of the ICA?
Other branches provid arterial supply to brain
- Anterior cerebal artery
- Middle cerebral artery
- Posterior communicating artery
External Carotid Artery branches pnemonic
Some – Superior thyroid
Anatomists – Ascending pharyngeal
Like - Lingual
Freaking - Facial
Out - Occipital
Poor – Posterior auricular
Medical - Maxillary
Students – Superficial Temporal
What are the two terminal branches of the ECA?
Maxillary
Superficial Temporal
Why is the superficial temporal artery important clinically?
Can get Giant cell arteritis/ temporal arteritis
What are the symptoms of GCA?
- Frequent, severe headaches
- Scalp tenderness, particularly over temple
- Jaw pain while eating/talking
- Loss of vision/ visual changes
What happens if you don’t treat GCA/temporal arteritis?
Patients can permanently lose eye sight
What is the blood supply to the scalp?
ICA supply:
- Supraorbital
- Supratrochlear
ECA supply:
- Superficial temporal
- Posterior Auricular
- Occipital
What are the layers of the scalp?
Skin
Connective tissue
Aponeurosis
Loose areolar tissue
Periosteum
Why does the scalp bleed so heavily?
Artery walls held open by connective tissue and so cant constrict
Lots of anastomoses
Lacerations that are deep enough to involve epicranial aponeurosis of occipitofrontalis can pull cuts open
Label the image- DO NOT JUST LEARN ORDER OF ARTERIES ACTUALLY LOOK AT WHAT IT’S POINTING TO!!!
What does the maxillary artery supply?
Supplies deeper facial structures
What are the key branches of the maxillary artery?
Middile Meningeal artery- dura mater, next to pterion
Sphenopalatine artery- nasal septum
What is the course of the middle meningeal artery
Enters skull via Foramen Spinosum
Splits into anterior and posterior middile meningeal artery
Anterior passes under Pterion
Image of Foramen Spinosum
What is the Pterion?
Very thin part of bone where the frontal,parietal,temporal and greater wing of the sphenoid bones come together
How can the Middle meningeal artery rupture?
Middle meningeal artery passes under the pterion which is very thin
Pterion very susceptible to breaking, blow to side of the head can cause artery to rupture
Extradural haemorrhage forms on top of the periosteal dura and below skull
Needs surgical treatment to drain blood otherwise compresses the brain
What is an extradural haemorrhage?
Intracranial haemorrhage, normally caused by pterion fracture, ruptures MMA
How are extradural haemorrhages managed?
Need specialist neuosurgery
Craniotomy- open cranium to relieve the pressure
Evacuate the clot and stop the bleeding
