Arterial Circulatory System Flashcards
What are the small vessel capilliaries in the tunica adventitia called?
Vasa vasorum
What do arterioles provide and how?
Provide resistance to blood flow by contraction of the smooth muscle.
What are arterioles known as in the vascular system?
“Stopcocks”
What arteries are considered “small and medium”?
All arteries except the aorta and its major branches.
What are small and medium arteries composed of?
Both smooth muscle layers as well as elastic and fibrous tissue.
What are large arteries composed of?
More elastic fibres and less smooth muscle cells than arterioles/smaller arteries/
What branches of the aorta are considered large arteries?
- Brachiocephalic
- Common carotids
- Subclavian
- Common iliacs
What arteries supply the brain?
- Two internal carotid arteries
2. Two vertebral arteries
What supplies the central nervous system with blood?
The great vessels coming off the aortic arch (brachiocephalic, left common carotid, left subclavian).
What is another name for the innominate artery?
The brachiocephalic
How does the innominate travel/divde and what does it divide into?
The innominate (brachiocephalic) travels superior and posterior from the aortic arch to the right side of the neck where is divides into the RCCA and the R subclavian.
Where does the brachiocephalic artery divide?
At the upper border of the right sternoclavicular junction.
How does the left CCA travel?
It ascends from the aortic arch and passes beneath the left sternoclavicular joint
Do the CCA’s have any branches?
No
Where does the CCA divide into the internal and external carotid arteries?
Where the vessel becomes enlarged (carotid bulb) at the upper border of the thyroid cartilage.
Where do the ICA bifurcate?
Once they enter the cranium
What do the ICA’s supply?
The anterior circulation of the cerebrum (brain).
Do the ICA have branches?
Not until they enter the cranium
What is the first branch of the ICA?
The ophthalmic artery
What are the segments of the ICA from proximal to distal?
- Cervical
- Petrous (through bone)
- Cavernous
- Supraclinoid
Where does the ophthalmic artery branch from the ICA?
At the carotid siphon
What is the carotid siphon?
The cavernous and supraclinoid segments of the ICA
What does the ICA bifurcate into?
In the cranium the ICA bifurcates into the middle cerebral artery and the anterior cerebral artery
If the ICA becomes occluded how is collateral flow created?
The ophthalmic artery anastomoses with the 3 branches of the ECA.
What 3 branches of the ECA can help with collateral flow in the event the ICA is occluded?
- Supraorbital (over eye)
- Frontal Artery (inner eye)
- Nasal artery (medial bridge of nose)
What does the nasal artery terminate as?
The angluar artery
What other artery also terminates near the nasal/angular artery?
Facial artery
What is the first branch of the ECA?
Superior thyroid
When does the ECA provide flow to the brain?
In the event of an occlusion
What ECA branches are most vital to collateral circulation?
- Ophthalmic artery
2. Arteries that interconnect between the muscular branches of the occipital and vertebral arteries
What is the atlanto-occipital interspace?
Where C1 meet the skull and the vertebral arteries course into the subarachnoid space.
Where do the vertebral arteries join and what do they form?
At the pontomedullary level to form the basilar artery
What does the basilar artery contain?
4 branches that feed the pons and anterior ad posterior cerebellum
What arteries join to form the circle of willis?
The cerebral branches of the internal carotid arteries and the vertebral arteries at the base of the brain
What is the most important collateral circulation intercranially?
The circle of willis because it connects the anterior and posterior circulation
What branch artery supplies most of the blood to the brain?
Anterior cerebral artery
What is the most common congenital variation of the circle of willis out of how many?
Out of Nine
Absence or hypoplasia of one of the communicating arteries is the most common
How may an obstuction of an artery affect flow in collateral pathways?
- Increase volume
- Increase velocity
- Reverse flow
- Varying pulsatility
What muscle does the subclavian artery pass posterior to?
The scalenus anterior muscle
Where does the subclavian artery become the axillary?
As it passes the lateral border of the first rib
What does the axillary artery become and where?
The axillary artery becomes the brachial artery at the lower border of the teres major muscle in the axilla
What branch comes off the brachial artery?
The profunda brachii artery
What does the brachial artery bifurcate into and where?
The radial and ulnar arteries at the antecubital fossa
What is the most common variant of the upper extremity arteries?
Common origin of the brachiocephalic (innom) and the left common carotid
What are other variants of the UE?
- High origin of the radial artery
- Duplicated brachial artery
What are the rare but more common locations of stenosis in the UE?(5)
- Prox subclav
- Innom
- Distal subclav
- Axillary
- Brachial or branches
Where do the External iliacs become the common iliacs?
Inguinal ligament
What does the Common femoral bifurcate into and where?
Superficial femoral artery and the deep femoral (profunda) 4cm distal to the inguinal ligament
What is another name for the adductors canal and where is it?
Hunters canal (distal thigh)
What are the small branches off of the popliteal artery?
- Gastocnemius
- Medial and lateral superior genicular
- Medual and lateral inferior genicular
- Middle genicular
What does the popliteal bifurcate into?
The tibioperoneal trunk and the anterior tibial artery
How does the anterior tibial artery course?
Anterior and lateral between the tibia and fibula
What does the anterior tibial artery become?
The dorsalis pedis artery when it travels across the dorsal side of the foot
What does the dorsalis pedis artery bifurcate into?
The metetarsal arteries
What does the tibioperoneal trunk bifurcate into?
Posterior tibial artery and the peroneal artery
How does the posterior tibia travel?
Posterior to the medial malleolus
How does the peroneal artery travel?
Down the middle of the calf
What does the posterior tibial artery bifurcate into?
The medial plantar and lateral plantar arteries of the foot.
What is the most common anatomic variant of the LE?
Hypoplasia/aplasia of the anterior tibial artery
What is the most common collateral route of a unilateral CIA obstruction?
The contralateral iliac/femoral provides flow through the pelvic arteries (hypogastric/internal iliac = most common)
What makes up the tunica intima?
Endothelial lining with connective tissue behind.
What makes up the tunica media?
Smooth muscle cells arranged circularly around the vessel (thickest layer).
What makes up the tunica adventitia?
Connective tissue, nerve fibres and vasa vasorum.
What are the most common collateral routes for a distal AO or bilateral CIA obstruction? (3)
- Thoracic and abd wall arteries
- Mesenteric arteries
- Lumbar arteries
What is the most common collateral route for an external iliac and CFA obstruction?
Ipsilateral pelvis and femoral artery branches
What are the most common collateral routes for a deep femoral (profunda) obstruction? (3)
- Prox ipsilateral pelvic and femoral arteries
- Distal SFA
- Popliteal
What are the most common collateral routes for a SFA or Pop obstruction? (2)
- Deep femoral branches
- Pop to trifurcation
What are the most common collateral routes for a trifurcation (calf) obstruction? (2)
- Prox calf branches
- Distal peoneal branches to ATA and PTA
