Lec 2 - Major Blood Vessels of Head and Neck Flashcards
(37 cards)
What are the main arteries of the neck?
Internal Carotid Artery External Carotid Artery Common carotid artery - bifurcates at C4 Inferior carotid artery - supplies lower lobe of the thyroid gland. Vertebral artery. Thyrocervical trunk subclavian artery internal thoracic artery
Where does the subclavian and common carotid arteries arise?
on the right, these arise from the the brachiocephalic trunk.
Where do the vertebral, internal thoracic and thyrocervical arteries arise from?
arise from the subclavian artery at the base of the neck.
Do the common carotid arteries branch?
No they do not give off any branches in the neck.
They bifurcate to give external and internal carotid arteries.
The internal carotid artery gives off no branches in the neck and enters the skull through the carotid canal.
Describe the thyrocervical trunk?
- the ascending cervical and transverse cervical supply the neck.
- the suprascapular supplies the shoulder.
- the Inferior thyroid supplies the lower pole of the thyroid gland.
Describe the pathway of the Vertebral arteries?
- arise from the subclavian arteries on the left and right.
- ascend in the neck through transverse foramina in cervical vertebrae 6-1 and pass through the foramen magnum.
- the vertebral arteries supply the brain along with the internal carotid arteries.
Where does the common carotid artery bifurcate?
It bifurcates at about the level of the superior border of the thyroid cartilage.
What is the location of the IJV in relation to the common carotid?
The IJV lies lateral to the common carotid, mostly under the SCM.
What can carotid artery atheroma cause and why is it likely?
- It is likely because the bifurcation of the carotid artery is a common site for atheroma formation, as you get turbulence here.
- carotid artery atheroma causes narrowing (stenosis) of the artery. - if this narrows by more than 70% you get ischaemia.
- Rupture of the clot can cause an embolus to travel to the brain, resulting in TIA (transient ischaemic attack) or stroke.
What is the Carotid Sinus?
- It is a swelling at the region of bifurcation.
- It is the location of baroreceptors for detecting changes in arterial blood pressure.
What is the Carotid Body?
- It is a bulge in the internal carotid artery.
- It is the location of peripheral chemoreceptors which detect arterial oxygen.
Why is the carotid triangle important?
important for surgical approach to the carotid arteries or internal jugular vein.
- also access to the vagus and hypoglossal nerves via the carotid triangle.
- the carotid pulse can be felt in the carotid triangle just below bifurcation.
What is the use of the carotid sinus massage?
If you have supra-ventricular tachycardia, it can slow down the conduction getting through the AV node by increasing the vagal tone/ input.
- the massage can result in bradycardia.
Describe the route of the internal carotid artery
- enters the skull through the carotid canal in the petrous part of the temporal bone.
- turns medially and horizontally.
- enters the cranial cavity, then makes S-shaped bend.
- Courses through the Cavernous sinus.
What is the Cavernous sinus and what is in it?
The Cavernous sinus is a plexus of extremely thin-walled veins on the upper surface of the sphenoid.
Contents
- internal carotid artery.
- CNIII oculomotor
- CNIV trochlear
- CNVI abducent
- 2 branches of trigeminal - CNV1 ophthalmic and CNV2 maxillary.
Describe the distribution of the External Carotid Artery?
There are 6 branches:
- superior thyroid - supplies the thyroid gland
- lingual
- facial
- ascending pharyngeal
- occipital - supplies the scalp
- posterior auricular - goes behind the ear and supplies the scalp.
There are also two terminal branches.
- superficial temporal
- maxillary
What is the blood supply to the scalp?
From the internal carotid
- supra- orbital artery
- supratrochlear artery
From external carotid
- superficial temporal artery
- posterior auricular artery
- occipital artery
Describe the features of the blood supply to the scalp?
- rich blood supply with many anastomoses.
- largely branches of the external carotid artery
- —– except the supratrochlear and supraorbital arteries ( branches of the opthalmic artery) which arise from the internal carotid artery.
What are the components of the scalp?
- S - skin
- C - Connective tissue - dense
- A - Aponeurosis
- L - Loose connective tissue
- P - Periosteum
What is the clinical relevance of blood supply to the scalp?
- The walls of the arteries are closely attached to the connective tissue, which limits the constriction of the artery - can get profuse bleeding.
- There are numerous anastomoses - causes profuse bleeding and makes it hard to apply pressure to stop bleeding.
- There are deep lacerations involving epicranial aponeurosis, which causes profuse bleeding because of opposing pull of occiptofrontalis.
Why does the loss of scalp not lead to bone necrosis?
This is because the blood supply to the skull is mostly by the middle meningeal artery.
What are the superficial arteries of the face?
- supra-orbital artery
- supratrochlear artery
- transverse facial artery
- angular artery
- lateral nasal artery
- maxillary artery
- superior and inferior labial artery
- facial artery.
Where can the facial artery pulse be felt?
Can be felt at the inferior border of the mandible, anterior to the master muscle.
What are the two branches of the maxillary artery we need to know?
Middle Meningeal
Sphenopalatine.
