Lec 2 - Major Blood Vessels of Head and Neck

Question 1

What are the main arteries of the neck?

Answer 1

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

Question 2

Where does the subclavian and common carotid arteries arise?

Answer 2

on the right, these arise from the the brachiocephalic trunk.

Question 3

Where do the vertebral, internal thoracic and thyrocervical arteries arise from?

Answer 3

arise from the subclavian artery at the base of the neck.

Question 4

Do the common carotid arteries branch?

Answer 4

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.

Question 5

Describe the thyrocervical trunk?

Answer 5

• 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.

Question 6

Describe the pathway of the Vertebral arteries?

Answer 6

• 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.

Question 7

Where does the common carotid artery bifurcate?

Answer 7

It bifurcates at about the level of the superior border of the thyroid cartilage.

Question 8

What is the location of the IJV in relation to the common carotid?

Answer 8

The IJV lies lateral to the common carotid, mostly under the SCM.

Question 9

What can carotid artery atheroma cause and why is it likely?

Answer 9

• 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.

Question 10

What is the Carotid Sinus?

Answer 10

• It is a swelling at the region of bifurcation.

- It is the location of baroreceptors for detecting changes in arterial blood pressure.

Question 11

What is the Carotid Body?

Answer 11

• It is a bulge in the internal carotid artery.

- It is the location of peripheral chemoreceptors which detect arterial oxygen.

Question 12

Why is the carotid triangle important?

Answer 12

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.

Question 13

What is the use of the carotid sinus massage?

Answer 13

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.

Question 14

Describe the route of the internal carotid artery

Answer 14

1. enters the skull through the carotid canal in the petrous part of the temporal bone.
2. turns medially and horizontally.
3. enters the cranial cavity, then makes S-shaped bend.
4. Courses through the Cavernous sinus.

Question 15

What is the Cavernous sinus and what is in it?

Answer 15

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.

Question 16

Describe the distribution of the External Carotid Artery?

Answer 16

There are 6 branches:

1. superior thyroid - supplies the thyroid gland
2. lingual
3. facial
4. ascending pharyngeal
5. occipital - supplies the scalp
6. posterior auricular - goes behind the ear and supplies the scalp.

There are also two terminal branches.

1. superficial temporal
2. maxillary

Question 17

What is the blood supply to the scalp?

Answer 17

From the internal carotid

1. supra- orbital artery
2. supratrochlear artery

From external carotid

3. superficial temporal artery
4. posterior auricular artery
5. occipital artery

Question 18

Describe the features of the blood supply to the scalp?

Answer 18

• 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.

Question 19

What are the components of the scalp?

Answer 19

• S - skin
• C - Connective tissue - dense
• A - Aponeurosis
• L - Loose connective tissue
• P - Periosteum

Question 20

What is the clinical relevance of blood supply to the scalp?

Answer 20

• 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.

Question 21

Why does the loss of scalp not lead to bone necrosis?

Answer 21

This is because the blood supply to the skull is mostly by the middle meningeal artery.

Question 22

What are the superficial arteries of the face?

Answer 22

1. supra-orbital artery
2. supratrochlear artery
3. transverse facial artery
4. angular artery
5. lateral nasal artery
6. maxillary artery
7. superior and inferior labial artery
8. facial artery.

Question 23

Where can the facial artery pulse be felt?

Answer 23

Can be felt at the inferior border of the mandible, anterior to the master muscle.

Question 24

What are the two branches of the maxillary artery we need to know?

Answer 24

Middle Meningeal

Sphenopalatine.

Question 25

Describe the blood supply to the nasal septum?

Answer 25

• There are an anastomosis of arteries in the Kiesselbach area.
• The most important branches are:
• —-the septal branch of sphenopalatine artery from the maxillary artery.
• —-Anterior ethmoidal arteries from the ophthalmic artery.
• The Kiesselbach area is a common site for nose bleed (epistaxis).

Question 26

What is the Pterion and why is it important?

Answer 26

Here there is a number of bones that join together.
You can get damage to the middle meningeal here as here it is thinner and more easily damaged.
- Fracture of the skull at the Pterion can rupture the middle meningeal artery resulting in extradural haemorrhage.
—— you’ll see a crescent shape as it is limited by the dura.

Question 27

What is the blood supply to the skull and dura by?

Answer 27

The Posterior branch and anterior branch of the middle meningeal artery.
- It enters the skull then splits into posterior and anterior.

Question 28

What is a craniotomy?

Answer 28

• it is used to gain access to cranial activity.

- The bone and scalp is rejected inferiorly (downwards) to preserve blood supply.

Question 29

What is the venous drainage of the scalp?

Answer 29

supraorbital and supratrochlear veins unite at medial angle of the eye to form angular vein which drains into the facial vein.
some deep parts of the scalp in the temporal region have veins that drain into the pterygoid venous plexus.

Question 30

What is the connection between venous drainage of the scalp and dural venous sinuses?

Answer 30

• Veins of the scalp connect to diploid veins of the skull through several emissary veins and thus to dural venous sinuses.
• The emissary veins are valveless. - this is a root for the spread of infection.
• Infection from the scalp can spread to the cranial activity and affect meninges.

Question 31

What are the veins involved in the venous drainage of the face?

Answer 31

1. supraorbital vein
2. supratrochlear vein
3. angular vein.
4. superior and inferior labial veins
   5, facial vein
5. common facial vein
6. internal jugular vein
7. external jugular vein

Question 32

What is the connection of facial veins with cavernous sinus and pterygoid venous plexus?

Answer 32

• the veins of the face are valveless.
• at the medial angle of the eye, the facial vein communicates with the superior ophthalmic, which drains into the cavernous sinus.
• the deep facial veins drain into pterygoid venous plexus
• ——- so infection from facial vein can spread to dural venous sinuses.
• ——-Thrombophlebitis of facial vein – infected clot can travel to the intracranial venous system.

Question 33

What is the pathway of the sigmoid sinus?

Answer 33

The sigmoid sinuses continue as the IJV, leaving the skull through the jugular foramina.

Question 34

Why is it called the danger triangle of the face?

Answer 34

This is because infections in a vein in this region of the face can spread through the venous system to the dural venous sinuses.

Question 35

what are the dural venous sinuses?

Answer 35

superior sagittal sinus - where veins drain into.
inferior sagittal sinus
cavernous sinus 
sigmoid sinus 
transverse sinus

Question 36

What are the differences between the EJV and IJV?

Answer 36

The EJV vein is more superficial.
EJV is much easier to see
IJV is under the SCM
The IJV is better indication of pressure in the right atrium.

Question 37

How do you measure JVP?

Answer 37

1. Use the right IJV as it is like a direct connection to the right atrium.
2. have the patient at 45 degree angle with their head slightly to the left.
3. The IJV is largely hidden by the SCM, so pulsations are observed through the muscle.
4. Measured in cmH20
   The height from sternal angle + 5cm