Session 1.4a - Self-Study Flashcards
Clinical Presentations - Retropharyngeal Abscesses https://www.youtube.com/watch?v=VnFDdC9sfYM
Why is an understanding of the cervical fascial layers and deep neck spaces important clinically?
(Clinical Presentation: Retropharyngeal abscesses)
When thinking about relation to deep neck space infections and their potential route of spread.
What might a presenting complaint and population be for those presenting with retropharyngeal abscesses?
(Clinical Presentation: Retropharyngeal abscesses)
Population - children under 5
Presenting complaint - unable to move her neck/neck stiffness
https://www.youtube.com/watch?v=VnFDdC9sfYM
Try and tie in her clinical symptoms with what you understand of the anatomy of the cervical fascial layers: for example, why might swallowing and moving the head prove painful for the young girl?
(Clinical Presentation: Retropharyngeal abscesses)
The retropharyngeal space is located directly behind the oesophagus. An infection here would cause this space to distend, hence impinging on the oesophagus, and making swallowing hard (substances pass from the mouth, pharynx to the oesophagus; while shutting the epiglottis).
Normally, the fascia also allows for ease of movement between structures, e.g. when swallowing - due to infection the fascia would be inflamed causing friction as the planes rub over each other, making movement difficult and painful.
Similarly, movement of the neck is difficult because posteriorly, the retropharyngeal space when distended would impinge on the muscles associated with the vertebral column; making it hard to move the neck.
https://www.youtube.com/watch?v=VnFDdC9sfYM
What would be another very important differential diagnosis to consider when a patient presents unwell, with apparent neck stiffness?
(Clinical Presentation: Retropharyngeal abscesses)
Meningitis
One of the differential diagnoses can be the Brudzinski sign
https://en.wikipedia.org/wiki/Brudzi%C5%84ski%27s_sign
IMAGE 1 - 00:08
What are we looking at?
(Internal Carotid Artery Route)
A model showing the skull, brain, and some of the important arteries that run up through the neck to supply various structures of the face and structures intracranially.
IMAGE 2 - 00:30
What can we see in this view?
(Internal Carotid Artery Route)
- Looking at the lateral aspect of the neck
- We see the main artery and its branches
- This essentially supplies the entirety of the structures of the face, the skull and intracranial contents
IMAGE 2 - 00:30
- Label the CCA, ICA and ECA.
- Label the vertebra
- Draw on the thyroid cartilage
(Internal Carotid Artery Route)
- The CCA bifurcates into the ICA and ECA
- The ECA gives off branches in the neck, whereas the ICA gives off no branches
- The CCA bifurcates at the level of C4
- The superior edge of the thyroid cartilage is C4 (thyroid cartilage roughly C4-C5)
How can you identify the difference between the ECA and ICA? What does the ECA supply?
(Internal Carotid Artery Route)
The ECA gives branches within the neck to supply various structures of the face, bones of the face, scalp and tissues of the scalp.
The ICA runs right up the length of the neck without giving any branches, and instead will pass through a tiny hole in the base of the skull, known as the carotid canal.
IMAGE 3 - 01:30
Where does the ICA enter the skull (answer without image and then show)
(Internal Carotid Artery Route)
Through the carotid canal
- 01:30
IMAGE 4 - 01:36
Label the image
(Internal Carotid Artery Route)
- Foramen ovale
- Pterygoid plates & fossa
- Carotid canal
- Jugular foramen
In relation to the ICA, what do we normally find at the site of bifurcation?
(Internal Carotid Artery Route)
A slight swelling, known as the carotid sinus
What does the carotid sinus do?
Important baroreceptors that monitor pressure within the vasculature (blood pressure)
Why is the carotid sinus important clinically?
Applying firm pressure over the area of carotid sinus (carotid sinus massage) can stimulate baroreceptors - this increases parasympathetic drive to the heart to terminate, hopefully, any potential supraventricular tachycardias (SVTs).
IMAGE 5 - 02:15
Label the image
(Internal Carotid Artery Route)
- Carotid sinus
- Vagus nerve
IMAGE 6 - 03:00
This view involves removing the brain. Here we can visualise a number of blood vessels.
Label the front and back of the skull.
What will these blood vessels ultimately give rise to?
Front, back - see image.
Arteries supplying the brain
How can you potentially terminate a SVT?
By applying a carotid sinus massage.
IMAGE 6 - 03:00
Label the ICA
ICA enters through the carotid canal
IMAGE 6 - 03:00
Label the carotid canal
See image
IMAGE 6 - 03:00
Label the sphenoid bone/body of sphenoid
See image (central bone)
What is the dural venous sinus which sits either side of the sella turcica known as?
Cavernous sinus
IMAGE 6 - 03:00
Label the sella turcica
See image (central depression)
IMAGE 6 - 03:00
Label the petrous bone
Bone on middle lateral edges
Describe the route of the ICA in the skull.
The ICA arises from the carotid canal in the petrous bone, coming through and running towards the body of the sphenoid bone. Here it runs into the cavernous sinus, which is a dural venous sinus which sits either side of the sella turcica. As it emerges through the top of the cavernous sinus, this is when it gives its branches.
IMAGE 7
Label the image and caption it with specific description of image.
- ORBIT and EYE
- OPTIC CANAL with ophthalmic artery from ICA
- ophthalmic vein
- posterior clinoid process (sella turcica)
- superior petrosal sinus
- inferior petrosal sinus
- petrous part of temporal bone
- carotid canal
- cavernous sinus
- emissary vein connecting to pterygoid venous plexus
- ICA
Looking laterally towards right hand side of sella turcica on cranial floor
The ophthalmic artery is a branch of which artery?
The ICA
IMAGE 8
Label the ophthalmic artery
Runs through the optic canal
Where does the ophthalmic artery lie in the skull?
Essentially arises just after the CCA (ICA?) has emerged to the top of the cavernous sinus
The ophthalmic artery gives a branch that runs through where with the optic nerve?
Optic canal
The optic nerve runs through where with what?
The optic canal with a branch of the ophthalmic artery.
The opthalmic artery gives branches that will supply what?
Structures of the eye
Name the artery that supplies the sight-sensing part of the eye.
Sight-sensing part = retina
Central retinal artery
Name the branch and its origin artery to the retina.
The central retinal artery, from the ICA.
What is the function of the retina?
Senses sight
IMAGE 9
Label the central retinal artery, optic nerve, and internal carotid artery.
Label any other arteries if known.
Give this image a caption.
Medial palpebral artery; short posterior ciliary arteries; anterior ethmoidal artery; central retinal artery; posterior ethmoidal artery; optic nerve; internal carotid artery; supraorbital artery; long posterior ciliary artery; lacrimal artery
Looking from above at the right orbit.
The ICA gives off other branches which you will learn about in SEM4. However, as well as the ophthalmic artery, when the ICA emerges from the top of the cavernous sinus, which two arteries does it give off?
The anterior cerebral artery and the middle cerebral artery.
IMAGE 9
Label the anterior and middle cerebral arteries.
See image
What do the branches of hte ICA do in the skull?
They form an arterial circuit known as the circle of Willis
IMAGE 10
Identify the circle of Willis.
See image
Where does the circle of Willis sit?
Right at the base of the skull
IMAGE 10
Label the foramen magnum
At back of skull
IMAGE 10
Label the spinal cord
Yellow - cut through
What are the arteries running up through the foramen magnum?
Vertebral arteries
Where do the vertebral arteries run through?
The transverse foramen of the cervical vertebrae, through the foramen magnum.
The two vertebral arteries join to form which artery?
The basilar artery
The basilar artery is formed from which arteries?
The two vertebral arteries (from the left and right side)
IMAGE 10
Label the basilar artery
Runs along clivus (slope) of occipital bone
Where does the basilar artery run?
Along the sloping part (clivus) of the occipital bone
Which bone does the basilar artery lay on?
The occipital bone
What does clivus mean?
Latin for slope
The basilar artery joins which arteries to form what?
Branches of the ICA to form the circle of Willis
What supplies blood to the brain tissue itself?
Branches of the circle of Willis
Branches of the circle of Willis supply blood to what?
The brain tissue itself
The petrous bone is part of which bone?
The temporal bone
On a cadaveric specimen, we wouldn’t actually see the cavernous sinus. Why is this?
A dural fold would sit around it
Describe the ICA and its route intracranially.
It comes up through the common carotid canal in the petrous part of the temporal bone, through the cavernous sinus (covered by a dural fold) and as it emerges gives rise to the ophthalmic artery and other arteries involved in the circle of Willis.
What is the normal heart rate?
Clinical Presentation: SVT and Carotid Sinus Massage
Anywhere between 60, and if you’re active, a 100.
What is a typical heart rate of someone with SVT?
Clinical Presentation: SVT and Carotid Sinus Massage
Can go suddenly to beats such as 170 (or higher)!
A racing heart can be a result of many things. Suggest some.
Clinical Presentation: SVT and Carotid Sinus Massage
- Anxiety
- Stress
- Medications
- Heart disease
What could happen to an older patient who’s had heart disease or a weak heart?
(Clinical Presentation: SVT and Carotid Sinus Massage)
- Collapse (syncope)
- Heart attack (myocardial infarction)
- Low blood pressure (hypotension)
What patients are at risk of collapse/heart attack/hypotension following heart disease/weak heart?
(Clinical Presentation: SVT and Carotid Sinus Massage)
Older patients
Why wasn’t the patient ‘given a shot’ or even asked to take any medicine immediately?
(Clinical Presentation: SVT and Carotid Sinus Massage)
By the time you get the medication out it may have gone into cardiac collapse
How can you slow a SVT?
Clinical Presentation: SVT and Carotid Sinus Massage
Carotid sinus massage - press and gently massage the carotid artery
What does a carotid sinus massage do? Explain as if you were describing to a patient.
(Clinical Presentation: SVT and Carotid Sinus Massage)
That sends a message to the heart to slow down by releasing some chemicals at the vagus nerve, and it stops the rhythm.
How long do you need to perform a carotid sinus massage for?
Clinical Presentation: SVT and Carotid Sinus Massage
A few seconds, then check whether the heart rate is back to normal.
What are some contraindications before performing a carotid sinus massage?
(Clinical Presentation: SVT and Carotid Sinus Massage)
Doctors must check for clots that could rupture and could lead to stroke before doing the massage.
Should you teach patients to be able to perform carotid sinus massages on themselves (if needed)?
(Clinical Presentation: SVT and Carotid Sinus Massage)
Some patients are taught to do it at home when their medications don’t work.
Can carotid sinus massages reduce length of hospital stays?
Clinical Presentation: SVT and Carotid Sinus Massage
If nothing else is wrong, patient’s may be able to go home the next day!
Question:
Can you recall the ECG appearance of an SVT?
(Clinical Presentation: SVT and Carotid Sinus Massage)
Normal QRS complexes, but very narrow (i.e. rapid)
> 150 bpm
(Bpm calculated by 300/number of large squares in R-R interval
e.g. 300/2 big squares = 150 bpm = tachycardia)
Question:
Can you explain why external massage over the carotid sinus can help terminate an SVT?
(Clinical Presentation: SVT and Carotid Sinus Massage)
The carotid sinus is the location of baroreceptors, which allows for a procedure known as the carotid sinus massage.
If a patient has a SVT (heart racing because of something happening above ventricles and atria) then you can slow conduction getting through AVN by increasing vagal tone.
To increase vagal tone you can massage in the carotid triangle area to massage over the carotid sinus, activating baroreceptors, which will, in turn, enhance vagal input (parasympathetic drive to the heart), and therefore, slow down heart rate.
(It may also be that in massaging this area the VN is there as well so you can directly stimulate VN)
