Lecture 3 - Blood Vessels of the Head & Neck

Question 1

Locate the brachiocephalic trunk, common carotid artery + internal/external carotid arteries.

Describe the course of the common carotid artery and where it arises from on the left and right side of the body

Answer 1

Right side: common carotid arises from brachiocephalic trunk.
Left side: common carotid arises individually from the aorta

Common carotid ascends giving off multiple branches and forming the carotid sinus (where baroreceptors lie) and bifurcates at the C4 level/superior border of thyroid cartilage to form the internal and external carotid artery.

Question 2

What features form the border of the carotid triangle?

Give 2 reasons why the carotid triangle is so important

Answer 2

Medial/Inferior = superior belly of omohyoid muscle
Lateral = medial border of SCM
Superior = posterior belly of diagastric muscle

1) Bifurcation of common carotid occurs within the carotid triangle
2) Important clinically for atherosclerosis, carotid sinus massage and central pulse - also access site for vagus and hypoglossal nerves

Question 3

Where within the carotid triangle is a common site for atherosclerosis?
What potential consequences can this have?
How is this treated?

Answer 3

• At the point of bifurcation, particularly in internal carotid area
• Causes artery to narrow (stenose), plaque can rupture leading to embolus travelling to brain causing TIA (mini stroke) or stroke. Or can block artery that supplies eye and cause Amaurosis Fugax.
• Treated with carotid endarterectomy, incision to carotid artery, removal of plaque.

Question 4

What is the purpose of a carotid sinus massage?

Answer 4

Pressure at the site of the carotid bodies to increase baroreceptor activity in tachycardic patients in order to reduce HR

Question 5

Describe the course and the purpose of the internal carotid and vertebral arteries

Answer 5

• Internal carotid gives off no branches, enters base of the skull via carotid canal & supplies intracranial structures
• Vertebral arteries arise from the L+R subclavian arteries, ascend up cervical vertebrae through the transverse foramina and enter the base of the skull via the foramen magnum.
• Both of these supply the brain with blood.

Question 6

Describe the course of the internal carotid artery once it enters the carotid canal

Answer 6

• Enters carotid canal within petrous part of temporal bone
• Turns medially and horizontally
• Enters cranium and makes S-shaped bend, moving through cavernous sinus

Question 7

Once in the cranium, what branches does the internal carotid artery give off?

Answer 7

• First is ophthalmic artery

- Then anterior + middle cerebral artery PLUS posterior communicating artery which provide arterial blood to brain.

Question 8

What are the 8 branches that the external carotid artery gives off as it ascends?

Answer 8

Superior Thyroid, Ascending Pharyngeal, Lingual, Facial, Occipital, Posterior Auricular, Maxillary & Superficial Temporal

Some Anatomists Like Freaking Out Poor Medical Students

Good pneumonic to remember.

Question 9

Why is the superficial temporal artery important clinically?

Answer 9

Giant Cell Arteritis (GCA) - inflammation of the artery leading to headaches, scalp tenderness over temple, jaw pain and loss of vision

Needs to be treated quickly or can lead to permanent loss of sight

Question 10

What are the 5 layers of the scalp?

Answer 10

S - skin
C - connective tissue
A - aponeurosis 
L - loose areolar tissue
P - periosteum 

SCALP - pneumonic fits the word :)

Question 11

Why are scalp wounds prone to heavy bleeding?

Answer 11

A cut in the connective tissue pulls on arteries preventing them from constricting as well as the high number of anastomoses within the scalp.

Question 12

Describe the course of the middle meningeal artery

What does the middle meningeal artery supply?

Answer 12

• Enters skull via foramen spinosum + splits into anterior and posterior meningeal artery
• Anterior meningeal passes under the Pterion on the skull

Question 13

How are middle meningeal artery ruptures typically caused?
What consequence can this have?
What is the management for this consequence?

Answer 13

• Blow to side of the head, particularly at pterion area (thin area of bone)
• Extradural haemorrhage/haematoma, i.e.: blood collecting outside the dura
• Needs surgical intervention with craniotomy (opening of cranium to relieve pressure) and evacuation of blood clot to stop bleeding

Question 14

Where does blood from the scalp drain into?

Answer 14

Scalp drains via emissary veins through the skull into venous sinuses

Question 15

Locate the internal and external jugular vein

Which one lies over the SCM?

Answer 15

• External lies over SCM, internal can only be seen when SCM is cut

Question 16

How is jugular venous pressure measured?

Answer 16

• On right internal jugular vein
• Patient at 45 degree incline w/head turned slightly to left
• Look for pulsations through SCM as IJV is hidden by it
• Measure the height from the sternal angle and add 5cm, gives estimate of right atrial pressure