Session 1.3d - Lecture (Blood Vessels of the Head and Neck) Flashcards
Major Blood Vessels of the Head & Neck - ILO
- Arteries and veins in the neck
- Carotid triangle
- Blood supply/venous drainage
- Clinical relevance
- Arteries and veins in the neck
- Review the carotid triangle
- Blood supply and venous drainage of the neck, face, scalp, dura and skull
- Clinical relevance
- —- Pulses and JVP (how that’s measured)
- —- Routes of infection
- —- Atheroma
Slide 4
Label the:
- Left and right side
- Sternocleidomastoid (and its two heads)
- External jugular vein (x2)
- Internal jugular vein
- Common carotid artery
- Sternohyoid muscle
See lecture
Slide 4
Identify SCM and its two heads.
(See slides) SCM muscle and its two heads visible on the RHS.
LHS - SCM has been removed.
Slide 4
Identify the sternohyoid muscle.
(See Notability) Thin, narrow, muscle that runs longitudinally from the hyoid bone down to the sternum. Visible on the RHS behind (deep) the SCM; partially cut away on the LHS.
Slide 4
Identify the:
- thyroid gland
- trachea
- thyroid cartilage
See Notability
Where does the common carotid artery lie?
Lies deep to the SCM - cannot be viewed until SCM has been moved aside
(apart from in a section just inferior to the hyoid bone, and medial to the SCM - shown on Slide 4 RHS)
Where does the internal jugular vein lie?
Lateral to the CCA, but similarly to the CCA it is hidden by the SCM muscle.
Where does the IJV drain into?
This major vein drains into the brachiocephalic vein (also covered by the SCM).
Which vein in the neck is more readily visible?
The EJV is more readily visible because it’s coursing more superficially over the SCM.
Slide 5
Label the: - left and right - arch of aorta - brachiocephalic trunk - left subclavian artery - left common carotid artery (And any other structures [not arteries] you can label)
See slides
The brachiocephalic trunk is found on which side of the body?
Right
The brachiocephalic trunk gives rise to which two arteries?
The common carotid artery and the subclavian artery.
The right CCA and right subclavian artery arise from where?
Brachiocephalic trunk
The left CCA and left subclavian artery arise from where?
Directly off the arch of aorta
The arch of aorta gives rise to which arteries?
The brachiocephalic trunk (right), the left CCA and the left subclavian artery.
The CCA bifurcates to give what?
The internal and external carotid arteries
The internal and external carotid artery arise from where?
The bifurcation of the CCA (at about C4 level)
Where does the CCA bifurcate?
At the superior border of the thyroid cartilage - which is approximately C4 level.
Which artery(s) gives off branches in the neck - the external, internal or common carotid artery?
ECA
The ICA and CCA do not give off any branches in the neck.
The vertebral artery comes from which artery on which side?
The subclavian artery on both sides
the right and left vertebral artery arise from the right and left subclavian artery, respectively
What branches does the vertebral artery give off in the neck?
It doesn’t (like the ICA, heads up into the skull)
The thyrocervical trunk arises from which artery?
The subclavian artery
The inferior thyroid artery arises from where?
The thyrocervical trunk (from the subclavian artery).
It loops behind the CCA so appears that it branches off there but it doesn’t, it arises from the subclavian
What does the inferior thyroid artery supply?
The lower lobe of the thyroid gland.
What is the arterial supply to the lower lobe of the thyroid gland?
The inferior thyroid artery
The internal thoracic artery comes from which artery?
The subclavian artery (we have one on each side)
What is another name for the internal thoracic artery?
The internal mammary arteries
The internal mammary arteries can also be known as ___?
The internal thoracic artery
Where does the internal thoracic artery travel?
Down within the thoracic cage
The internal thoracic artery travels down within the thoracic cage, and continues down to become what?
The superior epigastric arteries
The vertebral, internal thoracic and thyrocervical arteries all arise from where?
The subclavian artery in the base of the neck
The subclavian artery gives rise to which arteries?
The vertebral, internal thoracic and thyrocervical arteries in the base of the neck.
Slide 5
Identify the following arteries:
- common carotid
- subclavian
- external carotid
- internal carotid
- vertebral
- thyrocervical trunk
- inferior thyroid
- internal thoracic
See slides
Describe the inferior thyroid artery.
It comes off the thyrocervical trunk, curving behind the CCA and supplies the inferior lobe (lower pole) of the thyroid gland.
The suprascapular artery arises from where?
The thyrocervical trunk
The suprascapular artery supplies what?
The shoulder
The ascending cervical artery arises from where?
The inferior thyroid artery
The transverse cervical artery arises from where?
The inferior thyroid artery
The transverse cervical artery supplies what?
Structures in the neck
The thyrocervical trunk gives off which arteries?
The inferior thyroid and the suprascapular arteries.
The suprascapular and the inferior thyroid arteries come from where?
The thyrocervical trunk (off the subclavian artery).
The inferior thyroid artery gives off which branches?
The ascending cervical and transverse cervical
The ascending cervical artery supplies what?
Structures in the neck
The ascending cervical and transverse cervical arise from where?
The inferior thyroid artery
Describe the route from the arch of aorta to the ascending cervical artery on the right hand side. Name all the branches each structure gives off.
- Arch of aorta (braciocephalic trunk, left subclavian, left CCA)
- Brachiocephalic trunk (right subclavian, right CCA)
- Right subclavian artery (vertebral, internal thoracic, thyrocervical)
- Thyrocervical trunk (suprascapular, inferior thyroid)
- Inferior thyroid artery (ascending cervical, transverse cervical)
- Ascending cervical artery
Slide 6
Label the following arteries.
(Top to bottom)
- Ascending cervical
- Transverse cervical
- Suprascapular
- Inferior thyroid
What do the vertebral and ICA supply?
Intracranial structures - hence why they do not give off any branches in the neck, and head straight up into the skull.
The vertebral arteries arise from ___?
The subclavian arteries on the left and right
The vertebral arteries travel up the neck how?
Through the transverse foramina of cervical vertebrae 6-1
The vertebral arteries travel up the neck via which part of the cervical vertebra?
The transverse foramina
The vertebral arteries travel through the transverse foramina of which vertebrae?
C6 up to C1
The vertebral arteries enter the skull via the ___?
Foramen magnum
The vertebral arteries of each side (left and right) fuse to form ___?
The basilar artery
The basilar artery is created by the ___?
Left and right vertebral arteries fusing together
The ICA enters the skull via the ___?
Carotid canal
Where do the vertebral and ICA enter the skull?
Vertebral - foramen magnum
ICA - carotid canal
The ICA after it enters the skull, and the basilar artery, along with other arteries form what?
An anastomosing circle of arteries called the circle of Willis in the brain.
What do the vertebral and ICA do?
Supply structures within the skull (intracranial structures) i.e. the brain.
Slide 7
Label the: - vertebral artery - internal carotid artery - subclavian artery (right) - transverse foramina of cervical vertebra - C1-C6 - foramen magnum - basilar artery - carotid canal (And any other structures)
- Vertebral: runs up through transverse foramina of cervical vertebra
- ICA: runs up from bifurcation of CCA into skull
- Subclavian: off brachiocephalic trunk from arch of aorta
- Transverse foramina: holes in which vertebral artery pass
- C1-C6: from top to bottom
- Foramen magnum: place where vertebral artery enters skull
- Basilar artery: junction where vertebral arteries fuse in skull
- Carotid canal: where ICA enters skull
What muscle forms the medial border of the carotid triangle?
Superior belly of omohyoid
What muscle forms the medial border of the carotid triangle?
A. anterior belly of digastric B. inferior belly of omohyoid C. posterior belly of digastric D. sternocleidomastoid E. superior belly of omohyoid
E. Superior belly of omohyoid
What are the boundaries of the carotid triangle?
Superior belly of omohyoid, Sternocleidomastoid, Posterior belly of digastric
What are the boundaries of the carotid triangle?
A. Midline of anterior aspect of the neck, Sternocleidomastoid muscle, Lower border of the mandible
B. Inferior belly of omohyoid, Sternocleidomastoid, Anterior belly of digastric
C. Superior belly of omohyoid, Sternocleidomastoid, Posterior belly of digastric
D. Superior belly of omohyoid, Sternocleidomastoid, Lower border of the mandible
E. Inferior belly of omohyoid, Sternocleidomastoid, Posterior belly of digastric
C. Superior belly of omohyoid, Sternocleidomastoid, Posterior belly of digastric
What occurs in the carotid triangle?
This is the location of the bifurcation of the CCA into the ICA and ECA.
The CCA bifurcates at which level (roughly)?
At the superior border of thyroid cartilage (C4 level)
Where does the IJV lie?
Lateral to the CCA, mostly under SCM.
Slide 9 (left)
Label the:
- superior belly of omohyoid
- anterior belly of digastric
- posterior belly of digastric
- sternocleidomastoid
- internal jugular vein
- common carotid artery
- external carotid artery
- internal carotid artery
See Notability
- SCM is cut back and reflected to show IJV and CCA
- ECA has many branches
- ICA has no branches in the neck
Slide 9 (right)
Label CCA, ICA, ECA and the thyroid cartilage
Arrow (CCA)
ICA - No branches
ECA - branches
Thyroid cartilage - grey pentagon
http://www.netanatomy.com/GAs/GAhns/hnGAcommon1si.html
Identify the:
- carotid triangle
- its borders
- IJV
- ECA
- ICA (not visible here but locate)
See Extra Notes (also website for further information/tests)
*Note: ICA cannot be seen; the IJV would have to be reflected to visualise it!)
Describe the borders of the carotid triangle in detail.
Lateral border - anterior border of SCM
Medial border - superior belly of omohyoid
Superior border - posterior belly of digastric
Where does the ICA lie?
Behind the IJV, so cannot see it on this cadaver
Bifurcation of the carotid artery is a common site for what?
Atheroma formation
Why is the bifurcation of the CCA a common site for atheroma formation?
Bifurcation at this point causes turbulence, and where you get turbulence is where you can have an atheroma forming
What do atheromas do to an artery?
They cause a narrowing (stenosis) of the artery
How much does the artery need to be narrowed by to cause symptoms?
> 70%
What complications can occur from an atheroma
Ischaemia - not enough blood getting to the brain
Embolus
Other than ischaemia, what complications can occur from an atheroma?
Rupture of the clot can cause an embolus to travel to the brain.
Rupture of an atheromatic clot can cause what?
An embolus
How can an embolus in the CCA be a cause of TIA or stroke?
If an embolus comes off the ICA, it will travel up the brain, and if it lodges in an artery supplying a region of the brain then it will cause TIA or a thrombotic stroke.
What can an embolus in the CCA be a cause of?
- Transient ischaemic attack (TIA)
- Thrombotic stroke
Slide 10
Describe the picture, and explain how you can get TIA or stroke.
- Bifurcation of the carotid artery causes turbulence
- Turbulence is a common place for atheroma formation
- This causes an artery to narrow (stenosis
- If the artery is stenoses by >70%, then that can cause symptoms such as ischaemia
- Another complication is an embolus, due to rupture of the clot
- If this occurs in the ICA, then this can travel straight up to the brain, lodging in an artery there
- If this artery supplies the brain, then this can be the cause of TIA or stroke
What structures appear at the site of bifurcation of the carotid artery?
- Carotid sinus
- Carotid body
What is the bulge of the ICA, at the bifurcation point, called?
Carotid sinus
Where is the carotid sinus?
It is a swelling on the ICA at the region of bifurcation.
Where are baroreceptors located?
Within the artery wall of the carotid sinus
The carotid sinus is the location for what?
Baroreceptors
What are baroreceptors?
Pressure sensors for detecting changes in arterial blood pressure
What detects changes in blood pressure?
Baroreceptors (found in the carotid sinus)
How do baroreceptors act to change blood pressure?
If the blood pressure is higher, then the baroreceptors stretch and send more action potentials to the cardiovascular control centre in the brain.
What does the carotid body do?
They are a small cluster of peripheral chemoreceptors which detect arterial oxygen.
What is the carotid body?
A cluster of richly vascularised cells (getting a really rich blood supply - they are not in the artery wall)
Where are the chemoreceptors that detect arterial oxygen found?
In the carotid body
Describe the similarities and differences between the carotid sinus and carotid body
Similarities:
- both occur due to the bifurcation of the carotid artery
Differences (Carotid sinus/Carotid body):
- Swelling at region of bifurcation/cluster of richly vascularised cells not in the arterial wall
- Location of baroreceptors/chemoreceptors
- Detects changes in blood pressure/arterial oxygen
Slide 11
Label the carotid sinus and the carotid body. Describe their structure and function.
See slides
Carotid sinus/carotid body:
- swelling/cluster of cells
- location of baroreceptors/chemoreceptors
- arterial BP/arterial O2
Why is the carotid triangle important clinically?
- Surgery, e.g. if someone has an atheroma present and the artery is really narrow (>70%) then may need plaque removed via surgery
- For reaching the IJV
What is the most appropriate method of removing an atheroma in the carotid artery?
- Patients assessed individually, so many factors will be looked at
- For some patients, most appropriate treatment is surgery (carotid endarterectomy)
Explain how a surgeon would remove an atheromatous plaque in the carotid artery.
- Find the carotid triangle, as the carotid artery is easily accessible here
- Surgically open the carotid artery to remove the plaque
- Stitch it up again
What is a carotid endarterectomy?
Carotid endarterectomy is a surgical procedure to remove a build-up of fatty deposits (plaque), which cause narrowing of a carotid artery. (NHS)
What is the name for the surgical procedure which involves a removal of the fatty deposits in a carotid artery?
Carotid endarterectomy.
What is an SVT?
Supraventricular tachycardia
What is SVT?
When the heart is racing because of a problem above the ventricles and atria
What is a treatment for SVT?
Carotid sinus massage
What is the physiological mechanism of a carotid sinus massage for patients with SVT?
- The carotid sinus is the location of the baroreceptors.
- If a patient has SVT, then you want to slow conducting getting through the AVN by increasing vagal tone (reduce the heart rate)
- Massaging the carotid triangle area allows you to massage over the carotid sinus
- This activates baroreceptors, which in turn, will enhance vagal input
- Similarly, the vagal nerve is found in this area so you may be stimulating the vagus nerve directly to increase vagal tone
Which nerves can be accessed in the carotid triangle?
The vagus and hypoglossal nerves
Where can the carotid pulse be felt?
In the carotid triangle, just below the bifurcation
- may also be palpated more inferiorly
Slide 12
Explain the picture (top)
1) Before - plaque - restricted blood flow
2) Plaque is removed
3) After - Normal blood flow
Slide 12
What procedure is this image showing (bottom)?
Carotid sinus massage
Where does the ICA enter the skull?
Through the carotid canal
Where is the carotid canal?
A canal in the petrous part of the temporal bone
What happens to the ICA when it enters the skull through the carotid canal?
It immediately turns medially and horizontally
Slide 13
Identify the ICA and carotid canal
The artery that arises from the bifurcation point of the CCA, where it enters the skull is the carotid canal. Note how it turns medially and horizontally as it enters the skull.
What is the route of the ICA?
It enters the skull through the carotid canal in the petrous part of the temporal bone, then turned medially and horizontally.
What happens to the ICA when it enters the skull?
It enters the cranial cavity then makes S-shaped bend - it appears tortuous and curved.
What sort of shape does the ICA make when it enters the cranial cavity?
It appears tortuous and curved, making an S-shaped bend
After the ICA makes its S-shaped bend once it enters the cranial cavity, what does it do?
It courses through the cavernous sinus
must know this!
Slide 14
What section is the right image taken from?
Coronal, see left image
Slide 14
Describe the route of the ICA.
Correctly identified:
- carotid canal
- temporal bone
- S-shaped curve of the ICA
- cavernous sinus
How many cavernous sinuses are there?
Two, one on each side
Where does the cavernous sinus sit?
Either side of the sphenoid bone, in the sella turcica, where the pituitary gland sits.
Which bone is the cavernous sinus associated with?
The sphenoid bone
What is the depression in which the cavernous sinus lies called?
The sella turcica
What sits in the sella turcica?
The cavernous sinus and the pituitary gland
What is the sella turcica?
A depression in the sphenoid bone in which the pituitary gland sits.
What lies either side of the sphenoid bone?
The cavernous sinus which is part of the dural venous plexuses
Within the venous plexus, what structures pass through?
Many other structures, including:
- ICA
- many other cranial nerves
What is found on the upper surface of sphenoid?
A plexus of extremely thin-walled veins
What and where is the cavernous sinus?
A plexus of extremely thin-walled veins on the upper surface of sphenoid
What structures are found in the cavernous sinus?
- Internal carotid artery
- CNIII oculomotor
- CNIV trochlear
- CNVI abducent
- 2 branches of trigeminal
- —- CNV1 ophthalmic and CNV2 maxillary
Which cranial nerves are found in the cavernous sinus?
Cranial nerve 3, 4 and 6; plus two branches of cranial nerve 5
i.e. oculomotor, trochlear, abducent and two branches of trigeminal (opthalmic and maxillary)
What is cranial nerve III?
Oculomotor
Oculomotor is cranial nerve ___?
III (3)
What is cranial nerve IV?
Trochlear
Trochlear is cranial nerve ___?
IV (4)
What is cranial nerve VI?
Abducent
Abducent is cranial nerve ___?
VI (6)
What is cranial nerve V?
Trigeminal
Trigeminal is cranial nerve ___?
V (5)
Which cranial nerve has two branches found in the cavernous sinus?
Trigeminal
Which two branches of the trigeminal nerve are found in the cavernous sinus?
Ophthalmic and maxillary (CNV1 and CNV2)
What nerves are CNV1 and CNV2?
The ophthalmic and maxillary branches of the trigeminal nerve
(Mandibular = CNV3)
What do the oculomotor, trochlear and abducent cranial nerves supply?
The muscles controlling the movement of the eye
Which cranial nerves control the movement of the eye?
III, IV and VI = oculomotor, trochlear and abducent
Slide 15
What section is this image (bottom)?
Coronal section of cavernous sinus (see top image)