S2 L1 Blood vessels of Head and Neck Flashcards
- *Vessels in the neck**
- Why are they important?
- Major vessels in the neck
- Which muscle covers some of them?
Why are they important?
Major vessels supplying and draining the brain
Access route
Important in clinical examination
Pathology can be seen in disease or injury to these vessels
- *Major vessels in the neck:**
- Internal Jugular vein
- External Jugular vein
- Common carotid artery
Which muscle covers some of them?
Sternocleidomastoid
- *Arteries of the neck**
- List the branches of the carotid artery
- List the branches of the Subclavian artery
- Name of the place the common carotid artery bifurcates (and antomical landmarks around it)
- Where do the baroreceptors in the carotid artery sit?
List the branches of the carotid artery:
Common carotid, cartoid sinus, internal carotid artery, external carotid artery
List the branches of the Subclavian artery:
Subclavian artery, Vertebral artery, thyrocervical trunk, inferior thyroid artery, internal thoracic artery
Name of the place the common carotid artery bifurcates (and antomical landmarks around it):
The bifurcation of common carotid artery to internal and external carotid artery occurs at the superior border of thyroid cartilage (above C4)
Where do the baroreceptors in the carotid artery sit?
Carotid sinus
- *Carotid Triangle:**
- Borders
- Contents
- *Borders:**
- Posterior: Digastric muscle
- Lateral: Medial border of SCM
- Medial/inferior: Superior belly of omohyoid muscle
Contents:
Carotid sheath:
- Common and internal carotid artery
- Internal jugular vein
- Vagus nerve
Importance of the Carotid Triangle:
- Bifurcation of the common carotid occurs within the carotid triangle
- Important clinically for surgery
- Contains clinically important artery:
◦ Atherosclerosis
◦ Carotid sinus massage
◦ Central pulse - Access site for vagus and hypoglossal nerves
- Contains internal jugular vein
◦ Access site for central line placement
- *Artherosclerosis**
- Common where?
- Process of artherosclerosis?
- What can it cause?
- One other condition…
- *Carotid endarterectomy**
- What is this procedure
- Where is the incision?
- Bifurcation is a common site of atherosclerosis
- Causes the artery to narrow (stenose)
- Plaque rupture can release an embolus which can travel to the brain
- Can cause a stroke or TIA depending on the size
- Can also course transient loss of vision (Amaurosis Fugax)
I - side of the internal carotid artery
E - side of the external carotid artery
Cardiac endarterectomy:
This is why its important to know your carotid triangle boundaries!
- Incision in to the neck and the carotid
- Removal of plaque tissue and stitched back up
- *Cardiac sinus massage**
- What is this?
- Why do you do it?
Carotid body - cluster of chemoreceptors
Pressure at the site of the carotid bodies
Increased baroreceptor activity feedback to the heart to the heart rate slow down
Important area to feel in clinical examination to determine the pulse
To find: Find Adam’s apple (thyroid cartilage, then move right)
- *Internal Jugular vein**
- Characteristics of this vein
- Clinical links
Large central vein
Superficial
Easily accessible
Good site for central venous line
Can canulate to get access
Central line
- *Internal carotid artery (1/4)**
- Route of the internal carotid artery
Internal carotid arteries give off no branches in the neck – enters the base of the skull via the carotid canal and supplies intracranial structures
- Carotid canal is within the petrous part of the temporal bone
Allows the Internal carotid to pass through the base and enter the skull - Turns medially and horizontally
- Enters the cranium and makes an s-shaped bend
- Moves through cavernous sinus (located in the centre of the skull)
- *Cavernous Sinus (2/4)**
- What is this structure?
- Which nerves and arteries run through this?
Cavernous Sinus
- What is this structure?
Venous type structure on the upper surface of the sphenoid bone
- Which nerves and arteries run through this?
◦ Carotid artery
◦ CN III (Oculomotor)
◦ CN IV (Trochlear)
◦ CN VI (Abducens)
◦ 2 branches of CN V (Trigeminal) ( CN V1 ophthalmic and CN V2 maxillary)
(3/4)
Vertebral arteries
- *Opthalmic artery**
- Which big artery has this come from?
- Which 3 important branches come off it?
Vertebral arteries arise from the left and right subclavian arteries Ascend up the cervical vertebrae through the transverse foramina They enter the base of the skull via the foramen magnum
Opthalmic artery:
Which big artery has this come from?
Internal carotid artery
Which 3 important branches come off it?
- Central retrinal artery (this supplies the optic nerve), if loss blood supply to retina = loss of vision in this eye
- Supra-orbital artery
- Supratrochlear artery
- *Other branches of the interal carotid artery (4/4)**
- Opthalmic is the first one
- List 3 more
Other branches provide arterial blood to the brain
◦ Anterior cerebral artery
◦ Middle cerebral artery
◦ Posterior communicating artery
Clinical correlate: Amaurosis Fugax
An Embolus gets lodged into the central retinal artery.
Loss of blood supply to retina = loss of vision in this eye
- *Distribution of the External Carotid artery (1/2)**
- Acronym
- Name of the 8
Some Anatomists Like Freaking Out Poor Medical Students
- *Clinical correlate: Giant cell arteritis (CGA)/Temporal arteritis (2/2)**
- Which artery?
- What happens in this condition?
- Symptoms
- Without treatment, what can happen?
- Treatment
- Which artery?
Superficial temporal artery - What happens in this condition?
Becomes inflamed due to vasculitis, this reduces blood supply to structures they supply - Symptoms
– Frequent, severe headaches
– Scalp tenderness particularly over the temple
– Jaw pain while eating/talking
– Loss of vision/visual changes - Without treatment, what can happen?
Can permanently lose their eye sight - Treatment
High does of steroid
- *Blood supply to the scalp:**
- List 5 (they are either from the internal or external carotid artery)
- *Scalp**
- Layers in the scalp
- How to remember them
Remember them as: SCALP
Vessels are in the connective tissue layer
- *Why does the scalp bleed?**
- 4 reasons
- Heavy bleeding seen in scalp injuries
- Artery walls held open by connective tissue and so cant constrict (artery walls are found within the connective tissue, when there is a cut in this tissue, it pulls on the arteries, preventing them contricting (usually elastic recoil would close them, but being pulled open by the connective tissue)
- Lots of anastomoses
- Lacerations deep enough to involve the epicranial aponeurosis of occipitofrontalis can pull cuts open (muscles can pull cut open more)
M: muscle
A: Aponeurosis
Superficial arteries of the face
- 2 from internal carotid
- 7 from external carotid
- *Maxillary Artery**
- Supplies ______ facial structures
- Key branches?____
deep
Middle meningeal
Sphenopalatine
- *Middle meningeal artery**
- Enters skull via ____________
- Spilts into: _____ and _____
- _______ passes under area of the skull called ______
- Foramen Spinosum
- Anterior and posterior middle meningeal artery
- Anterior part passes under area of the skull called the pterion
Foramen Spinosum
- Where is this in the skull?
Blood supply to the dura and skull
- Layers of dura meter (name - theres 2)
- Name of artery that supplies the dura and some of the skull
External periosteal layer of the dura meter
Internal meningeal layer of the dura meter
Middle meningeal artery
(this artery is right up against the bone, sandwiched between the external periosteal layer of the dura meter and bone)
- *Clinical correlate: Middle meningeal artery rupture**
- What happens (steps)
- Where most likely to occur?
- Which artery?
- What is this condition called?
- Surgical procedure
- If someone recieves a blow to the head, will compress skull bones, to cause a fracture
- Likely to occur in the pterion (where it is thinner)
- Fractuing can cause the middle meningeal artery under the pterion to rupture (as MMA is in close relation to the pterion)
- Rupture will cause the arterial blood to leak out to the area below it
- This will cause the external periosteal layer of the dura meter to rip away from the wall and blood will fill the gap
- Name: Extradural intracranial heamorrhage (bleeding outside of the dura)
- Perfom a craniotomy - open the cranium to relieve the pressure, evaluate the clot forming and stop the bleeding
- *Venous drainage of the scalp**
- Main vein
- 7 veins coming off
- *Drainage of the scalp**
- ‘Deep’ drainage
- How does this work?
- Where does the blood drain into?
- Risk of ______
Brain structures drain into areas containing venous blood called dural venous sinus
Scalp drains via emissary veins through the skull into dural venous sinuses
Risk of infection (as direct connection between scalp and intercranial structure)
- *Venous drainage of the face (superficial - not deep drainage)**
- List
- *Facial veins and the cavernous sinus**
- Names of veins that drain into deep structures (i.e. cavernous sinus)
Drainage of some structures into the cavernous sinus
Risk of infection to the intracranial cavity as directly connected
- *Danger triangle of the face**
- What is this?
- Why is it called the ‘danger triangle’
The region where the facial vein can drain backwards into the cavernous sinus
Infections in that area can spread via the facial vein and ultimately end up in the dural venous sinuses
- *Dural venous sinuses**
- List of the sinuses and there drainage
- Cerebral veins drain into superior sagital sinus
- Drains as shown by arrow
- Superior and inferior sagittal sinus join and form the transverse sinus
- Sigmoid sinus exits through the jugular foremen (circled)
Formation of the internal jugular vein
- When the sigmoid sinus exits through the jugular foramen = now called the internal jugular vein
- *Jugular vein and JVP**
- Reminder anatomy of the jugular veins and the made artery of the neck
- How is JVP measured?
Right Int. Jugular Vein
Patient at 45 degrees
Head turned slightly to the left
IJV mostly hidden by sternocleidomastoid
Look for pulsations through the muscle
Measure the height from the sternal angle and add 5cm, gives an estimate of the right atrial pressure in cmH2O
