Week 2 - Blood Vessels of the H+N Flashcards
What is the fate of the common carotid in the neck -
Does it have any branches?
No branches
Bifurcates into internal and external carotids
At what level does the common carotid artery bifurcate?
Level of the superior border of the thyroid cartilage (C4)
What is the carotid sinus?
What is its purpose?
Swelling of the ICA in the region of the bifurcation of the common carotid.
Contains baroreceptors
Which nerve carries signals from the baroreceptors?
Glossopharyngeal nerve
What is the carotid body?
What is its function?
Cluster of nerve cells sitting at bifurcation of common carotid.
Contains peripheral chemoreceptors
Why might a young man experience syncope whenever he wears a tie?
Hypersensitive baroreceptors - external pressure on neck stimulates them. Pushes HR and BP down –> syncope.
Does the ICA have any branches in the neck?
NO!
Through what hole does the ICA enter the skull?
Carotid canal
What is the most important branch of the ICA?
Which superficial arteries does this give rise to?
Ophthalmic artery –>
- Supraorbital artery
- Supratrochlear artery
Name the 6 branches of the ECA in the H+N
- Superior thyroid artery
- Ascending pharyngeal artery
- Lingual artery
- Facial artery
- Occipital artery
- Posterior auricular artery
How and where does the ECA terminate?
In the parotid, terminates by dividing into:
- Maxillary artery
- Superficial temporal artery
What are the 4 important branches of the facial artery?
- Angular artery
- Superior and inferior labial arteries
- Lateral nasal artery
List the layers of the scalp from superficial to deep
Skin CT Aponeurosis (epicranial) Loose CT Periosteum
In which layer of the scalp would you find the blood vessels?
The CT layer
Which 5 arteries supply the scalp?
For each, does it arise from the ICA or ECA?
- Supraorbital - from ICA
- Supratrochlear - from ICA
- Superficial temporal - from ECA
- Posterior auricular - from ECA
- Occipital - from ECA
Give 3 reasons why scalp injuries bleed profusely
1) Densely vascular as numerous anastomoses
2) Walls of arteries bound to underlying CT which holds their lumens open
3) If the laceration is deep enough the involves the epicranial aponeurosis, the pull of occipitofrontalis also holds the vessels open
Why is the middle meningeal artery clinically relevant?
From which vessel does it arise?
Anterior middle meningeal artery lies immediately under the pterion - prone to fracture. Rupture of the artery leads to extradural haemorrhage.
Arises from the maxillary artery
What are the 3 branches of the subclavian artery?
- Vertebral artery
- Internal thoracic artery
- Thyrocervical artery
What structures drain the:
- Brain and meninges
- Scalp and face
- Neck
- Dural venous sinuses
- Veins synonymous with the arteries
- Anterior jugular veins
Describe the relative sizes and positions of the jugular veins
- EJV - smaller and superficial to muscles
- IJV - larger, deep to SCM - can be accessed in carotid triangle
How would you measure JVP?
What is an abnormally high JVP?
- Patient at 45*
- Look for pulsations between the 2 heads of SCM
- Measure the height above the sternal angle + 5cm, as RA is 5cm below the angle
- > 9cm = high
Which 2 veins unite to form the EJV?
Where?
Posterior auricular vein and retromandibular vein
Join immediately posterior to the angle of the mandible
Give 2 reasons why pressure must be applied to a severed EJV?
- Stop bleeding
- Prevent air entry
Where does the IVJ begin?
In the cranial cavity, as a continuation of the sigmoid sinus
Through which hole does the IJV leave the skull?
Jugular foramen
Regarding venous drainage of the scalp and face, how do the veins relate to the arteries?
- Arteries from ECA have synonymous veins which follow the same course.
- Arteries from the ICA have synonymous veins but they DO NOT follow the same course
Describe the course of the Supraorbital and Supratrochlear veins
- Unite at medial angle of eye
- Form angular vein
- Drains into facial vein
What are the Dural sinuses?
- Endothelium-lined spaces between the periosteal and meningeal layers of dura mater –> meningeal layer folds in at Dural septae
- Collect venous blood from the veins draining the brain and skull
How might infection spread from the scalp to the brain?
Via the emissary veins which connect the veins of the scalp to the Dural sinuses
What is thrombophlebitis?
How can it spread from the face to the brain?
Infected blood clot
Flows backwards from the facial vein to the cavernous sinuses as there are no valves.
Which nerves are found within the cavernous sinus?
Anything else?
- III
- IV
- V - ophthalmic and maxillary branches only
- VI
- the ICA
Which vessels arise from the arch of the aorta?
Left - Subclavian and common carotid
Right - brachiocephalic trunk –> gives off subclavian and common carotid
