Session 1.1c - Lecture (General Organisation Of The Head And Neck) Flashcards
Lecture
Describe the major muscle groups of the head and neck (ILO)
Two broad categories:
Muscles of facial expression
Muscles of mastication
Describe the nerve innervation of the major muscle groups of the head and neck (ILO)
Facial expression = 5 branches of facial nerve
Mastication = branches of the trigeminal nerve
Describe the broad action of the major muscle groups of the head and neck (ILO)
Facial expression - dilator or sphincter muscles which pull your face in a certain way i.e. give you a facial expression
Mastication - act on temporomandibular joint to open or close your jaw
Describe the boundaries of the anterior triangle (ILO)
- The anterior edge of SCM (medial)
- Imaginary line down the midline (right down the mid-sagittal plane there is an imaginary line)
- Lower border of the jaw (mandible)
There is one on either side of the midline
Describe the boundaries of the posterior triangle (ILO)
- SCM (posterior/lateral border)
- Trapezius (anterior border)
- Clavicle (superior/middle 1/3 border)
There is one either side of the neck
Describe the boundaries of the carotid triangle (ILO).
- Medial/anterior border of SCM
- Lateral border of omohyoid (infrahyoid muscle)
- Inferior border of the posterior belly of the digastric muscle (suprahyoid muscle)
Identify the surface anatomy of the anterior triangle (ILO)
SCM, midline and jaw
Identify the surface anatomy of the posterior triangle (ILO)
SCM, traps and clavicle
Identify the surface anatomy of the carotid triangle (ILO)
SCM, omohyoid, digastric muscle
What are the important anatomical triangles in the neck?
Anterior, posterior and carotid triangles.
Why is it important to know about anatomical triangles of the neck clinically?
It can be helpful in determining where a neck lump may have originated from/how it arose.
Identify and describe the general anatomical organisation of neck structures when viewed in cross-section (ILO)
ILO
Recall the arrangement of neck structures within the cervical fascial layers (ILO)
Superficial -
Investing -
-
-
Recall the arrangement of neck structures within the cervical fascial layers and their relation to the anatomical triangles of the neck (anterior, posterior and carotid triangles) (ILO)
ILO
Have a look at the muscles as well
Understand the implications for the spread of deep neck space infections due to the compartmentalisation and boundaries of the cervical fascial planes (ILO)
ILO
Why are the cervical fascial planes important, and their clinical application in terms of potential spaces between these fascial planes where infection can collect, and why deep neck space infections are rare but quite concerning and potentially life-threatening.
How is the head organised into the face and scalp?
Face = eyebrows to chin Scalp = eyebrows to back of skull (occipital region)
What is significant about how the two broad groups of muscles of the head are divided?
Overview
They share commonalities in function and nerve supply.
What are the nerves and blood vessels of the face?
Overview
Will be touched upon in the next lecture
What are the key components of the neck?
Overview
Think about what’s in the neck, and how is it arranged
What are the neck muscles?
Overview
There are a lot of neck muscles but we’ll highlight the ones you really need to know and how they help form the boundaries of the anatomical triangles
Describe the anatomical triangles of the neck?
Overview
Describe the fascial compartments of the neck.
Overview
These help organise everything
What is the cranium?
Skull
What is another word for skull?
Cranium
How many bones of the skull are there?
22
What is the collective name for bones that surround the brain?
The neurocranium
What is the neurocranium?
A collective name for bones that surround the brain
What is the collective name for bones that surround the face?
The viscerocranium
What is the viscerocranium?
A collective name for bones that surround the face
What are the layers of skin that lie over the neurocranium and the viscerocranium?
The face and the scalp
Where is your scalp?
The scalp goes from your eyebrows right the way round to the back of the skull (occipital region)
Where is the occipital region of the skull?
At the back
Where is your face?
From the eyebrows to your chin
Where is your forehead?
Just above your eyebrows
What is interesting about the forehead?
It is shared between the scalp and face (despite eyebrow boundary)
Is the forehead part of the scalp or face?
Although the boundaries of the scalp/face are at the eyebrows, we still sometimes consider the forehead as part of your face as well.
Which part of the head overlaps in face and scalp?
The forehead
What does mastication mean?
Chewing
What do muscles of mastication do?
Act on the temporomandibular joint to open or close (move) the jaw
Mastication = chewing
The facial nerve and trigeminal nerves are what type of nerves?
Cranial nerves
What are cranial nerves?
Nerves that come from the brainstem
What nerve supplies the muscles of facial expression?
Branches of the facial nerve
What nerve supplies the muscles of mastication?
Branches of the trigeminal nerve
What do branches of the facial nerve supply?
The muscles of facial expression
What do branches of the trigeminal nerve supply?
Muscles of mastication
What is the main artery that supplies your face?
The facial artery
helpfully named
What is the main vein that supplies your face?
The facial vein
The facial artery mainly supplies what?
Your face
The facial vein mainly supplies what?
Your face
The facial blood vessels come from where?
They are branches of much bigger, important vessels found in the neck.
Where are the muscles of facial expression found?
In your face/scalp
They tend to attach to bits of bone, the other end to the skin/fascia (superficial fascia of the face) or even other muscles
What do muscles of facial expression do?
They are dilators or sphincter muscles which pull your face in a particular way to elicit facial expression
Roughly speaking, what type of muscles are your muscles of facial expression?
Dilators or ‘constrictors’
Where and how are the ‘constrictor’ muscles of the face arranged?
In a circular fashion around the orifices of the face (e.g. eyes, mouth etc.)
What is a sphincter muscle?
A circular muscle that maintains constriction of a natural body orifice
Give example of sphincter muscles.
The muscles around your eyes, mouth
- Generally found in orifices around body cavities
- If it’s a round-shaped muscle it’s going to act like a sphincter
What are dilator muscles?
Muscles that pull parts of the face or other muscles in a particular direction
How are dilator muscle fibres arranged?
Linearly
Broadly speaking, what is the function of the linearly-arranged and circular muscles of the face?
Linearly-arranged muscles are dilators which pull rather than constrict.
Circular muscles (sphincters) act to constrict.
(This is helpful to be aware of to appreciate what they’re doing to your face when you use them - relating structure to function)
Why are we able to create such a vast range of facial expressions?
- There is a huge variety of facial muscles
- They’re very much connected to the skin
How many muscles of mastication are there?
4
What joint do the muscles of mastication act on?
The temporomandibular joint (TMJ)
What is the temporomandibular joint?
The bit where your jawbone joins the rest of your skull.
What is the part where your jawbone joins the rest of your skull called?
The temporomandibular joint (TMJ).
Which cranial nerve are muscles of facial expression innervated by?
Cranial nerve VII (facial nerve)
Which cranial nerve is the facial nerve?
VII (7)
Which nerve is cranial nerve VII?
Facial nerve
Which cranial nerve are muscles of mastication innervated by?
Cranial nerve V (trigeminal nerve)
Which cranial nerve is the trigeminal nerve?
V (5)
Which nerve is cranial nerve V?
Trigeminal nerve
There are ____ key _____-_______ ________ (terminal) of the facial nerve.
There are five key extra-cranial branches (terminal of the facial nerve.
Define “extra-cranial branches of the facial nerve”?
Branches that have arisen from the facial nerve outside of the skull
What happens to the facial nerve when it branches in terms of extracranial or intracranial?
Some of these nerves become extra-cranial (terminal branches) - these have arisen from the facial nerve outside of the skull. This is just a little portion of the facial nerve!
A large portion of the facial nerve has remained through the bones of the skull, and there’s lots of branches that it gives off inside the skull as well.
Image (page 6):
Label the branches of the facial nerve
Temporal Zygomatic Buccal (Marginal) Mandibular Cervical
Where is the temporal branch of the facial nerve (roughly)?
Temporal i.e. temple
Indicates side of the head behind the eyes
Self-note: remember the location by the name.
What are muscles in your forehead supplied by?
The temporal branch of the facial nerve
(The temporal branch of the facial nerve runs up the temporal region towards your forehead, so you can work out that muscles in your forehead are supplied by the temporal nerve without having to specifically learn innervations for every muscle)
What is the zygoma?
A bone in your face that forms your cheek.
What is the bone in your face that forms your cheek called?
The zygoma
Where is the zygomatic branch?
It runs in close proximity to the zygoma (your cheekbone), hence the name.
What does buccal mean?
Cheek
What is another word for cheek?
Buccal
What is the cheek muscle called?
Buccinator (buccal = cheek)
Where is the buccal branch of the facial nerve?
It is the branch that goes to your cheek
What muscles does the buccal branch of the facial nerve supply?
Supplies muscles of the face in your cheek region
buccal = cheek
The mandibular branch’s full name is …?
Marginal mandibular
The marginal mandibular branch’s name can be shorted to …?
Mandibular
Where is the mandibular branch of the facial nerve?
Runs across the jaw, i.e. the mandible
Where is the cervical branch of the facial nerve?
It goes to your neck towards the platysma muscle
What is the platysma muscle?
A sheet-like muscle in the neck that lies in the superficial cervical layer. It is a muscle of facial expression despite being in your neck, and not the face.
Name the 5 extra-cranial branches of the facial nerve - you can use a mnemonic to remember them first.
To Zanzibar By Motor Car
Temporal Zygomatic Buccal Mandibular Cervical
*Think about their names to figure out their location and vice versa!
Where do most of your cranial nerves arise from?
Your brainstem
The cranial nerves need to travel from where to where?
The inside of your skull to the outside.
When the facial nerve comes out of your skull, where does it pass into?
The parotid gland (an important salivary gland)
Where does the parotid gland lie?
Just in front of and inferior to your ear
What is the gland anterior and inferior to your ear known as?
The parotid gland
The facial nerve runs through the substance of the parotid gland. What can this mean clinically?
If you have pathology, particularly malignant pathology of the parotid gland, patients may present with weakness of the muscles of that side of their face because you’re affecting the facial nerve.
Why do patients with parotid gland malignancy present with weakness to muscles of the ipsilateral side of their face?
The facial nerve runs through the substance of the parotid gland, so any pathology affects the facial nerve and therefore the muscles it innervates on that side of the face.
Image (page 6):
Which side of the face is this showing?
Right
How many facial nerves in the body are there?
2 - one on your left and one on your right side.
What do the left and right facial nerves supply?
The left facial nerve supplies all the muscles on the left-hand side of the face, and the superficial muscle of the neck. The right facial nerve mirrors this on the right-hand side.
The facial nerve has an important relationship with what gland?
The parotid gland
What is the main sensory nerve of your face and scalp?
The trigeminal nerve
How can we feel if someone tickles your forehead or touches your nose (i.e. which nerve)?
This is sensed by the branches of the trigeminal nerve taking that sensory signal back to your brain.
How many branches of the trigeminal nerve supply motor innervation?
Just the one (the rest all supply sensory, including this one), which carries the motor signals to the muscles of mastication. You can remember which division as it is the branch that’s heading in the direction towards the jaw that carries the motor innervation.
What are the three key branches/divisions of the trigeminal nerve (cranial nerve V)?
Va ophthalmic division
Vb maxillary division
Vc mandibular division
The ophthalmic division of the trigeminal nerve supplies what?
Sensory innervation to all of your forehead and most of your eye, including the front of your eye; your conjunctiva and cornea.
Your forehead is supplied by which nerve?
Ophthalmic division of the trigeminal nerve
The front of your eye is supplied by which nerve?
Ophthalmic division of the trigeminal nerve (opthalmic = eye)
Your conjunctiva is supplied by which nerve?
Ophthalmic division of the trigeminal nerve
Your cornea is supplied by which nerve?
Ophthalmic division of the trigeminal nerve
What can the ophthalmic nerve be abbreviated to?
Va
V = cranial nerve V (facial nerve) a = first sub-division of cranial nerve V
Image page 4:
Label the neurocranium
Image
Image page 4:
Label the viscerocranium
Image
Image page 4:
Label the cranium
Image
Image page 4:
Label the sutures
Image
Image page 4 (bottom):
Label the scalp
Image
Image page 4 (bottom):
Label orbicularis oculi
Image
Image page 4 (bottom):
Label orbicularis oris
Image
Image page 4 (bottom):
Label the face
Image
Image page 4 (top):
Which view is this?
Lateral aspect
Image page 5:
Label a sphincter muscle
Orbicularis oculi
Image page 6:
Label the 5 branches of facial nerves
Temporal Zygomatic Buccal Mandibular Cervical
Where does the maxillary division of the trigeminal nerve lie?
It sits near the maxilla bone, so in the cheek region.
What can the maxillary division of the trigeminal nerve be abbreviated to?
Vb
What is the full name of the Vb division of the trigeminal nerve?
The maxillary division
After ophthalmic and maxillary, what is the final third key branch of the trigeminal nerve?
The mandibular division
*Note: do not confuse with mandibular branch of FACIAL nerve! When talking about facial nerve it may be easier to refer to as marginal mandibular to prevent confusion with branches of the trigeminal nerve.
Which nerve gives rise to motor fibres to muscles of mastication?
The mandibular division of the trigeminal nerve
*Think - branch is going that way, so it makes sense that motor fibres that are carrying that branch to get to muscles that are all down there and moving the jaw.
What is significant about the mandibular division of the trigeminal nerve (compared to the other divisions)?
It gives rise to motor fibres to muscles of mastication (the others are only sensory innervation)
What can the mandibular division of the trigeminal nerve be abbreviated to?
Vc
Which division of the trigeminal nerve is also known as Vc?
The mandibular division
What supplies the main sensory sensation from the face?
The trigeminal nerve
What supplies the motor innervation to the muscles of mastication?
The mandibular division of the trigeminal nerve
What does the trigeminal supply?
The main sensory sensation to the face, and the mandibular division supplies the motor innervation to the muscles of mastication.
How do we test the function of the trigeminal nerve?
We touch the face of the person but within the dermatomal distribution to check each branch (ophthalmic, maxillary, mandibular). This occurs on both sides because one half will be the right trigeminal and the other half the left trigeminal
Why do we touch the face of the person within dermatomal distributions when testing the function of the trigeminal nerve?
To check each branch is working
Why do we test both sides of the face when testing the function of the trigeminal nerve?
Because each half is supplied by the corresponding nerve i.e. the right half is supplied by the right trigeminal.
What is the main arterial supply to the head and neck?
The common carotid artery via its terminal branches (internal and external carotid arteries)
What two arteries does the common carotid artery split into?
The internal and external carotid arteries
Where does the CCA split into two arteries?
Further up the neck, above C4
The internal and external carotid arteries are branches of which artery?
The common carotid artery
Does the internal carotid artery give off any branches?
No, it goes straight up to the base of the skull and does stuff there.
Which of these does not give off any branches, the internal or external carotid arteries?
Internal carotid artery
Where does the internal carotid artery go?
It goes straight up into the base of the skull and supplies structures in the skull
Which of these arteries give off further branches - internal or external carotid artery?
The external carotid artery
Which artery supplies the tissues of your face?
The facial artery
Where does the facial artery arise from?
The external carotid artery (which is a branch of the common carotid artery)
What does the external carotid artery do?
It gives off branches that supply the tissues of the neck and face
Where does the facial artery run?
It runs up your face towards the medial part of your eye
Which artery runs up your face towards the medial part of your eye?
The facial artery
How can you palpate your facial artery?
At the edge of your jaw - clench your teeth where you feel the masseter bulk up on your jaw - just in front of that muscle as it’s clenched, you’ll feel the pulse of the facial artery as it’s running over the edge of the bone.
How can you palpate the masseter muscle?
Clench your teeth and feel your jaw - that is the masseter muscle
Where can you palpate the facial artery in relation to the masseter?
Just in front of the masseter
Where does the facial artery come from?
The ECA as it comes up through the neck.
Where does venous drainage from the face go?
It has to get away from the face back to the heart
Which vein does the head and neck drain from?
The facial vein
Where does the facial vein run in relation to the facial artery?
In exactly the same direction as the facial artery (but obviously going into a different direction)
Where does the facial vein drain into?
Ultimately into the internal jugular vein
What drains into the internal jugular vein?
The facial vein
Do the facial artery and vein generally run superficially or deep to a lot of the face muscles?
Deep
What is the route of the facial vein (and artery)?
From the medial angle of the eye, it runs to the edge of the mandible, where it leaves the head and drains into other venous structures that are much deeper inside the neck.
The facial vein drains into structures inside the neck. Are these superficial or deep?
Deep
What is the main vein draining head and neck structures?
The internal jugular vein (IJV)
What does the IJV do?
It is the main vein draining head and neck structures
What does the IJV receive?
Venous drainage from the face (facial vein)
Where can we find the external jugular vein in comparison to other structures?
Quite superficially
Which vein can you see quite superficially in the neck?
External jugular vein
Which vein is quite regularly seen in the neck when you’re angry or tensing?
The external jugular vein
The external jugular vein can be seen in the neck. When can the EJV be seen more prominently?
When you’re angry, tensing or anything that increases thoracic pressure
What does the external jugular vein receive?
Along with the IJV, it also receives veins draining from the scalp and face
Which runs more superficially, the external jugular vein or internal jugular vein?
EJV
Note: think external
Which runs more deep, the external jugular vein or internal jugular vein?
IJV
Note: think internal
What is your face?
Boundaries
What is your scalp?
Boundaries
What are some of the muscles that we can broadly think about?
- Function
- Innervation
Describe
What structures does the neck have running up the length of it?
Nerves and blood vessels
How far do nerves and blood vessels run up the neck?
Along the length of it
What do the nerves and blood vessels of your neck do?
Run up the length of the neck, and therefore feed structures in your face and brain
The veins will also be draining structures of your face/brain/neck to return them to the heart.
What are the bony structures found in your neck?
Cervical vertebrae
How many cervical vertebrae are there?
7
There are _ of which type of vertebrae, found in your neck?
7 cervical vertebrae
Describe the osteology of cervical vertebrae.
See MSK
What types of structures do we find in the neck?
- Nerves
- Blood vessels
- Cervical vertebrae
- Muscles
- Cartilages and glands
- Aerodigestive tract
What is significant about the cartilages and glands found in the neck?
They are actually quite palpable
Which tract begins in the neck?
Respiratory and digestive tracts i.e. the aerodigestive tract
What is the aerodigestive tract?
The combined organs and tissues of the respiratory tract and the upper part of the digestive tract.
Together, the beginning of the respiratory and digestive tract is known as what?
The aerodigestive tract
Suggest 4 structures that are found in your aerodigestive tract.
- Pharynx (connects to larynx & oesophagus) [respiratory & digestive]
- Larynx (connects to trachea, below pharynx) (voice box) [respiratory]
- Trachea (windpipe) [respiratory]
- Oesophagus (tube) [digestive]
What is the pharynx?
- Pharynx (connects to larynx & oesophagus) [respiratory & digestive]
What is the larynx?
- Larynx (connects to trachea, below pharynx) (voice box) [respiratory]
What is the trachea?
- Trachea (windpipe) [respiratory]
What is the oesophagus?
- Oesophagus (tube) [digestive]
Where are the pharynx, larynx, trachea and oesophagus found?
In your neck
Which structures sits superiorly but connects to the larynx and oesophagus?
Pharynx
Which structure sits inferiorly to the pharynx but connects to the trachea, involve in the respiratory tract? It is also colloquially known as the voice box.
Larynx
Which respiratory structure is colloquially known as the windpipe?
Trachea (connects inferiorly to larynx)
Which digestive structure is a tube connected inferiorly to the pharynx?
Oesophagus
What is clinically significant about the surface anatomy of the neck?
Much of the anatomy of the neck is palpable
Give a clinical example of why it is important that the anatomy of the neck is palpable in pathology.
Patients may present with neck lumps, so knowing the anatomy and being able to palpate the lump is important to determine what might contribute or be accounted for this lump.
Other than a pathological reason, why might being able to palpate the surface anatomy of the neck be important?
To do emergency airways (cricothyrotomy)
When are emergency airways used?
When someone has a blocked airway and you can’t intubate them
Where in the neck is the needle place for emergency surgical airways?
Between the thyroid cartilage and cricoid cartilage.
What is the reasoning for doing an emergency airway?
To get into the airway to oxygenate the patient (until you find something more definitive to stabilise the airway)
How often are emergency airways used?
Very rare, but it is life-saving if ever needed and done properly.
How do you find the location for incision in emergency airways?
Purely via palpation
What is inserted into the neck during emergency airways?
A cannula
Have a feel of your thyroid gland. What does it feel like?
TRICK QUESTION
You shouldn’t be able to feel a normal thyroid gland!
In what condition may you be able to feel your thyroid gland?
Goitre
Is normal thyroid gland palpable?
No
What would you do if you can feel someone’s thyroid?
Send off a thyroid function test (blood tests measuring thyroid hormones).
Where is the thyroid gland commonly mislocated?
At the top of neck, under your chin
Where is the thyroid gland (approximately)?
Quite far down your neck!
Why is it important to know the location of the thyroid gland?
For neck examinations, you need to know where to put your fingers to actually feel the thyroid gland, to feel whether there is a goitre/lump.
Why might you try and palpate the thyroid gland?
To feel for a goitre/lump. You will need to know where the thyroid gland is located though!
What is the Adam’s apple?
The thyroid cartilage (more prominent in men)
What can the thyroid cartilage be colloquially known as?
Adam’s apple
Is the thyroid cartilage easier to palpate in men or women?
Men - ‘Adam’s apple’
How can you find your thyroid cartilage?
Feel down the front of your neck
Whereabouts on the neck should you palpate to find the different structures, such as the thyroid and cricoid cartilage?
Slide your fingers down the front of your neck, down the midline.
How does the membrane between the thyroid and cricoid cartilage feel?
‘Squishy’
How does the cartilage of the neck feel upon palpation?
Firm
How can you find the membrane between the thyroid and cricoid cartilage?
Down the midline from the top of the neck underneath the chin, palpate with fingers the thyroid cartilage (firm). (If you are male, this will be your Adam’s apple!) Slide the fingers down until you find a second firm part - this is the cricoid cartilage. The membrane between the two will be a ‘squidgy’ bit in between the two firm cartilages you have just palpated.
What structure is immediately inferior to the thyroid cartilage, and how does it feel upon palpation?
The cricoid cartilage - and hard.
Why is it important to learn the anatomy of the neck?
So we can palpate for surface anatomy markings.
Name 6 important muscles or groups of muscles of the neck.
Note: need to know these!
- Platysma
- Trapezius
- Sternocleidomastoid
- Scalene muscles
- Supra- and infra-hyoid muscles
Note: There are quite a lot of muscles of the neck - these are the muscles of the neck we need to know! - Know roughly where they are and what they’re doing, and the relevance of these muscles to the anatomical triangles
Which two muscles of the neck (that we need to know) form the boundaries of two neck “triangles”?
Trapezius and sternocleidomastoid
Which muscle or group of muscles form the floor of one of the neck triangles?
Scalene muscles
Trapezius and sternocleidomastoid form the __________ of ___ neck “triangles”
boundaries, two
The scalene muscles form the _____ of ___ of the neck triangles
floor, one
Where are the supra- and infra-hyoid muscles located?
Above and below the hyoid bone, respectively
What are the supra-hyoids supplied by (nerve)?
Cranial nerves
What are the infra-hyoids supplied by (nerve)?
Cervical nerves C1-3
Which muscles are located above and below the hyoid bone?
Supra- and infra-hyoid muscles, respectively
Cranial nerves supply the _____-hyoid muscles
Supra
Cervical nerves (C1-3) supply the _____-hyoid muscles
Infra
Describe roughly where each of the neck muscles are
Platysma Traps SCM Scalene Supra-/infra-hyoids
Describe the action of each of the neck muscles
Platysma Traps SCM Scalene Supra-/infra-hyoids
What is the relevance of the muscles to the anatomical triangles?
Platysma Traps SCM Scalene Supra-/infra-hyoids
What is the layer seen immediately below the skin?
Superficial cervical fascia
How does superficial cervical fascia appear?
It looks like fatty yellow stuff
What is superficial cervical fascia?
Fat and connective tissue
Which muscle lies most superficially in the neck, within the superficial cervical fascia?
The platysma muscle
Describe the platysma muscle
It is a thin, broad muscle of which you have two of (one on your left and one on your right)
Where does the platysma muscle lie?
Within the superficial fascia of the neck, just beneath the skin
Where does the platysma muscle originate and insert?
From the lower mandible (lower jaw) down, blending with the muscles of your chest
Which muscle originates at the lower mandible, and inserts within the muscles of your chest?
The platysma
What is the action of the platysma muscle?
Because it is so superficial, when you contract it, it tethers up the skin.
When can the platysma muscle be seen?
When someone gets worked up, you can really see the furrowing of the neck due to contraction of the platysma muscle. (Think Dierdre Barlow!)
Which animals use the platysma muscle?
Horses/cows - when they get flies landing on their neck and their muscle twitches they use the platysma muscle!
As humans, we don’t really need the platysma muscle anymore unless you have flies landing on your neck …
When do men use the platysma muscle?
Men use it when shaving, to tense up the skin
When do we use the platysma muscle in facial expression?
When grimacing - if you’re drawing down the angles of your mouth, then that would be platysma.
Name 4 facts about the platysma muscle
- Broad, flat muscle
- Draws down sides of your mouth
- Tenses skin of the neck
- Very superficial
What muscle can we see posterior to the platysma muscle?
Trapezius (one on each side).
How can the trapezius muscle be divided up?
Into a superior, middle and inferior part.
Which part of the trapezius muscle is in your neck?
The superior part.
What is the function of the trapezius muscle?
Shrugs your shoulders
Rotates the scapula - e.g. when you put your arm up to brush your hair, some of that rotation depends on the superior fibres of the trapezius
How would you test the action of the trapezius muscle, and what is this testing?
Put your hand on someone’s shoulders, and ask them to try and push their shoulders up against resistance.
This tests the integrity of the muscle, to check whether the nerve supply is okay.
What are the individual attachments of the trapezius muscle?
See MSK for individual attachments but -
Running from the back of the neck, involving the scapula and the spinous processes of the cervical and thoracic vertebrae.
it is a huge, expansive muscle!
What action can the trapezius muscle help with, other than shrugging your shoulders?
Rotating the scapula, e.g. when putting your arm up to brush your hair
Which fibres of the trapezius muscle is involved in brushing your hair?
The superior fibres
Which are the most superficial muscles of the neck?
Anteriorly - platysma, a flat sheet either side of the midline
Posteriorly - trapezius, similar muscle at the very back of your neck.
Which strap-like muscle can you find immediately deep to the platysma muscles?
The sternocleidomastoid muscle
What sort of shape is the SCM muscle?
Strap-like
Where is the SCM located?
Immediately deep to the platysma muscle
Which strap-like muscle runs obliquely across the neck?
SCM
The SCM runs _________ across the neck
Obliquely
What does “sterno” mean?
Sternum
What does “cleido” mean?
Clavicle
Where does the SCM originate?
Its two heads originate from the sternum and the clavicle (sternocleidomastoid)
Where does the SCM insert?
The mastoid process (sternocleidomastoid)
What is the mastoid process?
A little rounded bony bump that can be palpated immediately behind your ear.
What occurs when you contract SCM?
It flexes the head laterally and the chin moves from the superior onto the opposite side
(i.e. when your chin is pointing superiorly on the left side, it is your right SCM that has contracted)
What is it about SCM’s shape that means it is the contralateral SCM which laterally flexes your head and chin?
Because of the SCM’s oblique nature; because it runs at an angle at your neck.
What occurs when you move your chin superiorly?
The opposite SCM contracts and shortens, pulling the mastoid process down, hence rotating the head slightly.
How do we test the action of SCM on a patient?
We ask the patient to flex their head laterally and move their chin to the opposite side, but using our hands to resist that action. This tenses up the contralateral SCM muscle and tells you whether it is working as it actually should.
Name the origin, insertion and function of SCM.
There are two SCM muscles, one on either side of the midline.
SCM has two heads, originating from the sternum and the clavicle.
They both insert into the mastoid (process).
The SCM helps to laterally flex the head and rotate the chin on the opposite side.
Name 3 key muscles of the neck.
Platysma
Trapezius
Sternocleidomastoid
What is the nerve supply to platysma?
The facial nerve
What is the nerve supply to trapezius?
Spinal accessory nerve
What is the nerve supply to sternocleidomastoid?
Spinal accessory nerve
Which neck muscle does the facial nerve supply?
Platysma
Which neck muscles does the spinal accessory nerve supply?
Trapezius and SCM
What is the lateral border of the anterior triangle of the neck?
The anterior edge of SCM
What is the medial border of the anterior triangle of the neck?
An imaginary line down the midline/mid-sagittal plane
What is the superior border of the anterior triangle of the neck?
The lower border of the jaw (mandible)
How can we find the posterior triangle?
Looking at the neck laterally, and underneath the platysma muscle
What is the anterior border of the posterior triangle of the neck?
The posterior border of SCM
What is the posterior border of the posterior triangle of the neck?
The anterior border of the trapezius muscle
What is the inferior border of the posterior triangle of the neck?
The superior border of the clavicle
Note: TeachMeAnatomy says middle 1/3
Why is it important to know the anatomical location of the anterior and posterior triangles?
It is clinically important to know the location if a patient presents with a neck lump - different things will cause lumps in those areas of the neck, and you will find different structures inside these triangles.
Anatomical borders divide the neck into ___ triangles
Two (anterior and posterior)
Anything inside your anterior triangle will communicate with your ______?
Thorax
Structures coursing between ____ and thorax are associated with the ________ triangles
head, anterior
Anything inside your posterior triangle will communicate with your _____ ____?
Upper limb
Structures coursing between ______/____ and upper limb are associated with the _________ triangles
thorax/neck, posterior
What might you find in the posterior triangle?
If you know that the posterior triangle communicates with the upper limb, and you know the anatomy of the upper limb - you can guess that vessels and nerves involved in supplying the arm will be found in the posterior triangle of the neck.
Identify the borders of the anterior and posterior triangles.
Anterior
- Inferior margin of mandible
- Midline of neck
- Anterior margin of SCM
Posterior
- Posterior margin of SCM
- Anterior margin of trapezius
- Clavicle
Image page 17:
Identify the borders of the anterior and posterior triangles.
Anterior
- Inferior margin of mandible
- Midline of neck
- Anterior margin of SCM
Posterior
- Posterior margin of SCM
- Anterior margin of trapezius
- Clavicle
Other than platysma, trapezius and SCM, name some other structures of the neck that can be identified in DR or even on each other.
- EJV
- Scalenes
- Brachial plexus
- Subclavian artery and vein
- Omohyoid
Which vein can be seen superficially on the neck?
External jugular vein
How deep does the EJV lie?
It runs quite superficially; underneath the platysma but on top of SCM.
What is the origin and insertion of the scalene muscles?
You do not need to know this!!
What type of muscles are the scalene muscles?
Strap-like muscles
What forms the floor of the posterior triangle?
Scalene muscles
Scalene muscles form the _____ of the _________ triangle.
Floor, posterior
What passes through the scalene muscles?
The brachial plexus and some subclavian vessels.
Where does the brachial plexus travel?
it comes from the cervical spine, passes through the posterior triangle to get into the arm
The brachial plexus lies within the _________ triangle.
Posterior
The posterior triangle has communications with the upper limb. Suggest a structure that might run through the posterior triangle
The brachial plexus
The subclavian ______ lies behind the subclavian ____.
Artery, vein
Where do the subclavian vessels lie?
Root of the neck
Where do the subclavian vessels run through?
Inside the posterior triangle
What do you find in the posterior triangle?
Vessels and nerves going through into your arm.
Which muscle spans across your posterior triangle?
Omohyoid
Where does omohyoid originate?
The hyoid bone
Can the hyoid bone be palpated?
Yes
What muscles are attached below the hyoid bone?
Infra-hyoid muscles (including omohyoid)
What sort of structures are the muscles attached below the hyoid bone?
Long, strap-like
How can we visualise the omohyoid (e.g. on dissection, or on an app)?
By removing the SCM
Where do the infrahyoid muscles lie?
Below the hyoid
infra = below
What are infrahyoid muscles also known as?
Strap muscles
What are strap muscles also known as?
Infrahyoid muscles
What are the series of muscles just underneath your chin, above the hyoid bone known as?
Suprahyoid muscles
Where do the suprahyoid muscles run from?
The hyoid bone, up to the mandible and base of the skull.
Name 2 important vascular structures that run the length of the neck.
Internal jugular vein
Carotid artery
In reference to another structure, where does the carotid artery split into two?
Just at the top of your thyroid cartilage
What does the carotid artery split into?
The internal and external carotid artery
What are the two palpable cartilages of the neck?
Thyroid and cricoid cartilage
Which is more superficial, thyroid or cricoid cartilage?
Thyroid
What structures lies at the very low part of your neck?
Thyroid gland
Do the infrahyoid muscles lie superficial or deep to the thyroid cartilage, cricoid cartilage and thyroid gland?
The infrahyoid muscles are more superficial
Order these from superior to inferior: -
Cricoid cartilage
Hyoid bone
Thyroid gland
Thyroid cartilage
Hyoid bone
Thyroid cartilage
Cricoid cartilage
Thyroid gland
How many supra-hyoid muscles are there?
4
Where do the supra-hyoid muscles attach?
Above the hyoid bone - attach to jaw or base of skull to hyoid bone
What is the function of the suprahyoid muscles?
To elevate the hyoid and depress the mandible
Infrahyoid muscles are ‘_____-____’ hence also known as ‘_____ muscles’
strap-like, strap muscles
The infrahyoid muscles overlie the ______ and _______ _____
larynx, thyroid gland
The infrahyoid muscles _______ the larynx and thyroid gland
overlie
What is the function of the infrahyoids?
Depress the hyoid and stabilise it
What do the hyoid muscles do?
Elevate or depress the hyoid bone!
What structure is attached to the hyoid bone
The larynx
What will happen if you elevate the hyoid bone?
You will bring up the thyroid cartilage and larynx with it!
What is the superior border of the carotid triangle?
The inferior border of the posterior belly of the digastric muscle (a suprahyoid muscle)
What is the medial border of the carotid triangle?
The lateral border of the omohyoid muscle (infrahyoid muscle)
What is the lateral border of the carotid triangle?
Sternocleidomastoid
Why is the carotid triangle important?
This is a bit of the neck where the carotid sheath and its contents (including the carotid artery) can be found and readily accessible, as the SCM does not cover this area.
Why is it important for the carotid sheath and its contents to be readily accessible in the carotid triangle?
- For surgical purposes
- Palpating the pulse
- Carotid sinus massage
Why is it important to understand the anatomy of the neck in cross-section?
You will be viewing the neck anatomy in CT scans/imaging, which is always cross-sectional i.e. relates to radiographic appearance
It also helps us to appreciate the organisation and structural relationships in 3D
__________ fascial layers create ____________ of structures running _______ the neck
Concentric fascial layers create compartments of structures running through the neck
Fascial layers form _______ ______
Fascial layers form natural planes
Why do we need fascial layers?
There are lots of things packed in the neck, and the neck is a very mobile part of the body, so things need to move smoothly over each other.
Fascial planes allow for ease of movement between structures e.g. when swallowing
Are fascial layers helpful or unhelpful in terms of infection?
They can be helpful because they restrict the spread of infection, but also unhelpful because they sometimes permit the spread of infection to places we really don’t want it to go, like the thorax!
(This is due to organisation of the planes and deep neck spaces)
Image page 25:
Label anterior, posterior, left and right of cross-section
See image
How do we visualise anatomy and imaging?
We always look at it from the patient’s perspective, from the feet up - same as with CT scans (looking up through the neck from the edge of the bed essentially, looking up through their feet).
if we were to do an incision through the neck, what would we encounter first?
The skin and superficial cervical fascia
What muscle would we find within the superficial cervical fascia?
A very thin muscle called the platysma, at the front of your neck on both sides.
Image page 25:
Label the platysma
Muscle
Image page 25:
Identify the midline of your neck and the posterior portion
Imaginary midline (vertical centre) and posterior (horizontal centre)
If we were to cut through the platysma and superficial cervical fascia, what’s the first set of muscles we’d come to?
The infra-hyoids, which are all lined in front of the thyroid gland.
What are the infra-hyoids?
Long, strap-like muscles from the hyoid bone.
How would a surgeon get to the thyroid gland?
By moving the infra-hyoid muscles either side (like curtains), as they sit right in front of the thyroid gland.
Image page 25:
Label structure 1.
Thyroid gland.
Describe the structure of the thyroid gland.
Two lateral lobes, connected via a central isthmus
How can you tell at what sort of vertebral level this cross-section is taken at?
This section must be taken quite low down the neck because
1) we have the thyroid gland
2) we have gone right through the central isthmus
This gives us an indication of how low down we are on the neck.
Image page 25:
What is the structure sitting immediately behind the thyroid gland (structure 12)?
Trachea
Image page 25:
What is structure 13?
(Clue - Immediately behind trachea.)
Oesophagus
What structures were the trachea and oesophagus more superiorly?
The larynx and pharynx, respectively.
What does it tell us if we can visualise the trachea and oesophagus in a cross-section?
This is another indication that we’re quite far down the neck as more superiorly these structures were the larynx and pharynx, respectively.
Which bony structure do we find at the back of the neck?
Cervical vertebra
What surrounds the cervical vertebra?
Lots of muscles that form a muscular column right at the back of the neck (Note: do not need to know that names of the muscles!)
What is the muscle that runs obliquely in the anterior of the neck?
Sternocleidomastoid
Image page 25:
What is structure 3?
Sternocleidomastoid
Which muscle forms the sheet at your neck posteriorly?
Trapezius
Image page 25:
What is structure 14?
Trapezius
How are veins and arteries depicted?
Veins - blue
Arteries - red
What is the blue vein shown?
Internal jugular vein
Where does the IJV head?
Quite deeply down the neck, heading towards the heart
What artery do we find medial to the IJV?
Common carotid artery
Image page 25:
If this cross-section was taken slightly higher up, what artery would we find (structure 4)?
Internal carotid artery
What structure lies posterior to the CCA and IJV?
The vagus nerve
Image page 25:
Label structure 6.
Vagus nerve
What is important about knowing the location and position of the vagus nerve?
It is a very important nerve that runs the length of the neck, in very close proximity to the artery and vein.
Why is it important to look at structures in 3D and in cross-section?
To appreciate their orientation
What are all the structures of the neck compartmentalised by?
Fascia
What type of fascia is immediately below the skin?
Superficial cervical fascia, which is quite loose - shown because you can move the skin around.
What are properties of the deeper cervical fascial layers?
They’re much denser/tougher than superficial cervical fascia.
What is the first of the deep cervical fascial layers?
Investing layer
What does the investing layer encompass?
As the name suggests; it completely encompasses (invests) the structures of the neck.
Image page 25:
Draw on the investing layer
Image
What does the investing layer do with regards to trapezius and SCM muscles?
It splits
What does the investing layer split around?
The trapezius and SCM muscles
How does trapezius and SCM appear on a cadaver?
You will find that once you have removed the skin and superificla fascia, you have to dig away at a lot of other dense fascia to see these muscles (i.e. see the splitting of the investing layer).
After the investing layer, what is the next layer of deep cervical fascia?
Pre-tracheal fascia
What does the pre-tracheal fascia encompass?
The infrahyoid muscles, the thyroid gland, trachea and oesophagus (pharynx if higher up)
What is the structure of pre-tracheal fascia?
It splits to encompass the infrahyoid muscles (they have their own ‘compartment’ in the pre-tracheal fascia); and encompasses the thyroid gland, trachea and oesophagus together.
What is the name of the fascia that is immediately posterior to the oesophagus (or pharynx), as part of the pre-tracheal fascia?
Buccopharyngeal fascia
Where does the buccopharyngeal fascia lie?
Immediately posterior and in conjunction to the oesophagus (or pharynx), and is part of the pre-tracheal fascia.
Note: pharyngeal, think pharynx
- Therefore behind the pharynx and oesophagus
Where is the pre-vertebral fascia?
Posterior
Note: It relates to the vertebrae at the back
What does the pre-vertebral fascia compartmentalise?
It completely ensheaths the vertebrae and muscles associated with it
The pre-vertebral fascia forms columns that span …?
The length of the neck (in most part, superior and inferior boundaries covered in pre-reading)
The pre-vertebral fascia blends into what?
Structures inside the thorax
What is the neurovascular bundle in the neck encompassing the CCA, IJV and VN known as?
The neurovascular bundle is the carotid sheath (this is its own little fascial tube)
How do we find the CCA, IJV and VN in a dissection?
Open up the carotid sheath to expose the neurovascular bundle.
Image page 25:
What is different to this image compared to real life?
In a real neck, the structures would be much more squashed together, so we wouldn’t have these gaps (the pale yellow areas) - but they are real and are potential spaces between the fascial compartments where things can sometimes collect, like infections.
How can infections collect in the neck?
Spaces between the fascial compartments
Name and locate an important deep neck space
The retropharyngeal space
Behind the buccopharyngeal fascia, but in front of the pre-vertebral fascia
What does ‘retropharyngeal’ mean?
Retro = behind Pharyngeal = pharynx
Can we find the retropharyngeal space on a cadaver?
Yes, you can put your hands into the space
Where can an infection in the retropharyngeal space spread?
It is limited laterally due to the carotid sheath, but can spread right down into the thorax, specifically, the mediastinum
What is a complication of infection in the retropharyngeal space?
Infections spreading to the mediastinum, causing mediastinitis: this is nasty and has a high mortality.
What do deep neck spaces communicate with?
The mediastinum
Give an example of an infection within the deep neck space
A retropharyngeal abscess
What can occur with retropharyngeal abscesses?
They can spread inferiorly into the mediastinum
What can occur if a retropharyngeal abscess spreads into the mediastinum?
Involvement of mediastinal structures cause mediastinitus
What are the symptoms of retropharyngeal abscesses and how do they relate to the structure and location of the retropharyngeal space?
Knowing where the space is and what structures relate to the space help you understand why a patient with a retropharyngeal abscess might drool and not want to move her neck - due to the relationship of some other structures in the neck to that space or potential space.
Image (page 7):
Label the distribution of the cranial nerve to the face.
Opthalmic, maxillary, mandibular
Image (page 8):
Label the right external jugular vein.
Image
Image (page 8):
Label the right common carotid artery.
Image
Image (page 8):
Label the sternocleidomastoid muscle.
Image
Image (page 8):
Label the superior vena cava.
Image
Image (page 8):
Label the aorta.
Image
Image (page 8):
Label the left external jugular vein.
Image
Image (page 8):
Label the left internal jugular vein.
Image
Image (page 8):
Label the left common carotid artery
Image
Image (page 8):
What has been cut on the left side to visualise the blood vessels?
Sternocleidomastoid muscle and clavicle cut
Image (page 10):
What broad structures of the neck do these images represent?
- Nerves and Blood vessels
- Cervical Vertebrae
- Muscles
- Cartilages and Glands
- Aerodigestive tract
Image (page 11):
Image (left), label the structures
Thyroid cartilage
Cricoid cartilage
Thyroid gland
Image (page 11):
Image (right), label the structures
Hyoid Thyroid Cricoid Thyroid gland Trachea
Image (page 13):
Label the platysma, trapezius and SCM (include both heads)
See image
Image (page 14):
Label the platysma, trapezius and SCM
In order
Image (page 15):
Label the trapezius and SCM
See image
Image (page 16):
Label the triangles and their borders
See image
Image (page 19):
Label the EJV; scalenes; brachial plexus; subclavian artery and vein; and omohyoid.
See slides
Image (page 20):
Label the hyoid bone; infrahyoid muscles (strap muscles); suprahyoid muscles; internal jugular vein; carotid artery; thyroid gland; thyroid cartilage and cricoid cartilage.
See slides
Image (page 15):
Label the anterior and posterior triangles
See image
Image (page 17):
Label the anterior and posterior triangles
See image
Image (page 21):
Label the diagram.
- Digastric, anterior belly
- Intermediate tendon of omohyoid
- Digastric, posterior belly
- Omohyoid, superior and inferior belly
Image (page 23):
Label the triangle and its borders.
Carotid triangle
- Digastric (posterior belly)
- Omohyoid
- Sternocleidomastoid
Image (page 2):
Label structure 2.
Infrahyoids
Image (page 4):
Label structure 4.
Common carotid artery (note: level of this cross-section)
Image (page 25):
Label structure 5.
Internal jugular vein
Image (page 25):
Label structure 7.
Lymphatic?
Glossopharyngeal?
Image (page 25):
Label structure 8.
Platysma
Image (page 25):
Label structures 9-11.
Cervical vertebrae muscle.
Don’t need to know the name
Image (page 25):
Label structure 12.
Trachea
Image (page 26):
Label the diagram.
- Pharynx
- Buccopharyngeal fascia
- Retropharyngeal space
- Prevertebral layer of deep cervical fascia
- Oesophagus
- Investing layer of deep cervical fascia
- Pretracheal layer of deep cervical fascia
- Pre-tracheal space
