Session 1.4b - Examplify Session 1A Flashcards
Headandneckanatomy2018
A mother brings her 2 year old child to the Emergency Department with a 1 week history of an upper respiratory tract infection, which initially seemed to be improving. However, over the last couple of days the child has been feverish, irritable, and refusing food and drink.
On examination the astute Foundation Year 1 doctor (a Leicester graduate) notices that the child is holding their neck in a fixed position, refusing to turn their head to either side and is dribbling. A retropharyngeal abscess is suspected.
Which of the following complications could occur due to extension of the infection from this deep neck space? (select any that apply)
A. Difficulty breathing due to tracheal compression
B. Extension of infection into the mediastinum
C. Painful or difficulty swallowing due to oesphageal compression
D. Spread of infection into the skin of the neck
A. Difficulty breathing due to tracheal compression
B. Extension of infection into the mediastinum
C. Painful or difficulty swallowing due to oesphageal compression
This question requires an understanding of the relationships of anatomical structures within the neck. An important differential to be considered in this child would be epiglottitis, which presents with very similar signs to those described and is also rare, but potentially life threatening.
Complications relating to tracheal compression, extension into the mediastinum, and painful/difficult swallowing could all occur. The spread of infection in to the skin of the neck is unlikely though.
Recall that the retropharyngeal space is a deep space within the neck and infection here is unlikely to reach the skin due to the number of deep cervical fascial layers (and their structures) surrounding it. Thus, a retropharyngeal abscess will not present with an obvious redness/swelling that is visible when viewing the neck externally.
Given that the retropharyngeal space is bounded anteriorly, posteriorly, and laterally by a number of the deep cervical fascia layers, the path of least resistance for spread would be inferiorly in to the mediastinum. Inflammation of the mediastinum is called mediastinitis, which has a significantly high
mortality.
However, other complications can occur due to an abscess in this space as a result of mass effect (causing compression of other structures), rupture (including through a fascial layer) and/or spread of infection.
Anterior to the retropharyngeal space are the oesophagus and trachea. Compressive effects of an infection or abscess within the space can therefore squash these anterior lying structures. This manifests itself as difficulty and/or painful swallowing (oesophageal compression) and airway compromise e.g. breathlessness, stridor (tracheal compression). Rupture of the abscess may also compromise the airway from asphyxiation and/or cause an aspiration pneumonia.
Posteriorly to the retropharyngeal space lies the pre vertebral fascia surrounding the vertebrae and associated pre- and paraspinal muscles. Should infection penetrate this fascial layer it can involved the bone and cause osteomyelitis.
Vascular complications can also occur due to the close proximity of the carotid sheaths, which lie laterally on either side of the retropharyngeal space. Should infection infiltrate the carotid sheath complications such as an internal jugular vein thrombosis can occur.
Fortunately retropharyngeal space infections/abscess (and its potential complications) are quite rare. You can have a quick read of this if you want to find out more: http://patient.info/doctor/retropharyngeal-abscess (FOR INTEREST).
While examining a patient you ask them to raise their eyebrows in order to wrinkle
their brow.
Which muscle performs this action?
A. Orbicularis oculi B. Frontalis C. Temporalis D. Levator palpebrae superioris E. Risorius
B. Frontalis
The frontalis muscle (anterior portion of the occipitofrontalis muscle) raises the eyebrows.
Which branch of the facial nerve do you think innervates this muscle?
[Temporal]
The carotid sheath extends from the base of the skull inferiorly to the:
A. Sternum
B. Pericardium
C. Diaphragm
D. Aortic arch
D. Aortic arch
The carotid sheath is the fibrous connective tissue layer (a deep cervical fascia) that surrounds the main vascular components of the neck.
The carotid sheath extends from the base of the skull, where the internal carotid artery, internal jugular vein and vagus nerve will all be found (having just entered/or left the cranial cavity). The sheath, along with these structures runs the entire length of the neck. More inferiorly down the neck (C4 and below) the artery will be the common carotid. The sheath extends down in to the thorax, from where these blood vessels arise from or drain in to, and blends with the adventitia of the aortic arch.
The carotid sheath includes the following structures except which two:
A. External carotid artery B. Internal jugular vein C. Vagus nerve D. External juglar vein E. Common carotid artery
A. External carotid artery
D. External jugular vein
For the majority of its course the carotid sheath contains the IJV, common carotid (and more superiorly the internal carotid) artery and the vagus nerve. There are also deep cervical lymph nodes, closely associated with the IJV and sympathetic nerves, that are closely associated with the internal carotid artery.
The external carotid artery does not run in the carotid sheath, but exits from the common carotid artery at its bifurcation. The external jugular vein does not enter the carotid sheath. It runs much more superficially, in the superficial cervical fascia.
A helpful mnemonic for recalling the key structures within the carotid sheath is:
I See 10 CCs in the IV
I See = IC (internal carotid)
10 = CN X (vagus nerve)
in the
IV = internal jugular vein
During its path down the neck there are other structures that pass in to, then out of the carotid sheath but do not descend down its entire length e.g. the glossopharyngeal, spinal accessory and hypoglossal nerves. These nerves have to pass through and then exit the carotid sheath because of where they exit the skull (many through the same ‘hole’ as the IJV). Further down the neck a loop of cervical spinal nerves from the cervical plexus called the ansa cervasalis associates with the anterior wall of the carotid sheath (note some sources state the ansa cervasalis enters into the sheath).
A 60 year old man is admitted to ITU with septic shock.
The ITU FY2 doctor is asked to insert a central line (central venous catheter) into
the patient’s neck.
Which triangle will help the junior doctor anatomically locate where to insert the
line (1 mark)?
A. Occipital triangle B. Carotid triangle C. Muscular triangle D. Submental triangle E. Submandibular triangle
B. Carotid triangle
The carotid triangle, is one of the subdivisions of the anterior triangle in the neck. The boundaries of the carotid triangle are: the posterior belly of the digastric, superior belly of omohyoid and anterior border of SCM muscle.
Important structures within this area of the neck include the common carotid artery and the internal jugular vein. For the FY2 doctor, in this scenario, to insert a central line, the site of the internal jugular vein needs to be identified.
An appreciation of where the carotid triangle is (and its contents) is therefore important clinically.
A tracheostomy is a surgical procedure creating an opening into a patient’s
trachea, in the lower part of the anterior neck.
Through which structures (and in which order) would the incision have to be made
to reach the tracheal lumen?
Select the letter which corresponds to the row showing the correct order of
structures.
A. Skin, Superficial, Investing layer, Pre tracheal, Trachea
B. Skin, Pre tracheal, Investing layer, Pre vertebral, Trachea
C. Skin, Investing layer, Pre vertebral, Pre trachea, Trachea
D. Skin, Pre tracheal, Superficial, Investing layer, Trachea
A. Skin, Superficial, Investing layer, Pre tracheal, Trachea
If you weren’t sure of this question, revisit your cross-sectional drawing of the neck. This questions is simply getting you to recall the fascial layers- rather than the structures within them that you would meet
You should see that, anteriorly, on incising the skin, the first layer you enter into would be the superficial cervical fascia. Following this the first of the deep cervical layers would be the investing layer, before passing into the pre tracheal fascial layer to reach the tracheal lumen.
Note that in performing a tracheostomy (putting a hole and a tube into the trachea- as often is required in patients requiring long term intubation or have had their larynx removed due to cancer), the site of the incision is made below the isthmus of the thyroid gland. If it were made into the trachea at the level where the isthmus sits just in front, you would risk damaging the gland and causing a significant amount of bleeding.
Recall which tracheal rings sit just behind the isthmus (Body Log Sem 1), and therefore what tracheal level is just below.
Which of the following muscles are innervated by the facial nerve (tick any that
apply):
A. Platysma B. Orbicularis oris C. Temporalis D. Oribicularis oculi E. Levator palpebrae superioris F. Trapezius G. Occipitofrontalis
A. Platysma
B. Orbicularis oris
D. Oribicularis oculi
G. Occipitofrontalis
All muscles of facial expression are innervated by the facial nerve. These muscles includes the constrictors of the mouth and eye (orbicularis oris and oculi respectively). Levator palpebrae superioris is a muscle in the eyelid, that causes it to retract (open the eyes), and is not considered a muscle of facial expression. It is innervated by another cranial nerve, the occulomotor (CN III).
Temporalis is a muscle of mastication, so innervated by the trigeminal nerve. Trapezius is innervated by the accessory nerve.
Which of the following does NOT form a border of the anterior triangle (tick any
that apply)?
A. Clavicle B. Sternocleidomastoid C. Trapezius D. Mandible E. Midsagital plane (midline)
A. Clavicle
C. Trapezius
Have another look at the borders forming the anterior triangle, if you didn’t get this question right.
The trapezius and clavicle help form the boundaries of the posterior triangle, not the anterior triangle.
During a cranial nerve examination, you ask a patient to squeeze their eyes tightly together and to prevent you from trying to prise them open. What muscle are they using?
A. Orbital part of orbicularis oculi B. Palpebral part of orbicularis oculi C. Orbital part of orbicularis oris D. Palpebral part of orbicularis oris E. Frontalis F. Levator palpebrae superioris
D. Orbital part of orbicularis oculi
The orbital part of orbicularis OCULI acts to squeeze the eye tightly shut. The palpebral part gently closes the eyelid (as when sleeping).
The oribularis ORIS muscle encircles the mouth and does not have orbital or palpebral parts.
The Levator Palpebrae Superioris, as its name suggests, eLEVATes the eye lid (i.e. is a muscle that allows you to open your eye). This muscles is supplied by a different cranial nerve- the oculomotor- and is not considered a muscle of facial expression.
The trigeminal nerve is the main sensory nerve of the head. It also supplies motor innervation to the muscles of mastication.
But which branch of the trigeminal nerve carries these motor fibres?
A. Ophthalmic
B. Maxillary
C. Mandibular
D. All of them
C. Mandibular
The mandibular branch of the trigeminal is the biggest of the three branches of CN V. It not only carries sensory innervation from the lower part of the face and jaw, but it also innervates all the muscles of mastication. It also supplies a couple of other muscles that lie deeper in the neck, under the jaw; the anterior belly of digastric and the mylohyoid.
The ophthalmic and maxillary do not carry motor fibres to muscles- they are purely sensory.
The pre tracheal and buccopharyngeal fascia envelops all of the following
structures except:
A. Thyroid gland B. Oesophagus C. Larynx D. Sternocleidomastoid E. Pharynx F. Infrahyoid muscles (strap muscles) G. Suprahyoid muscles
D. Sternocleidomastoid
G. Suprahyoid muscles
Pre tracheal fascia surrounds the thyroid gland, oesophagus (and pharynx more superiorly), trachea (and larynx more superiorly). It does not surround the sternocleidomastoid muscle, which is within the deep investing layer (splits to surround SCM and trapezius).
The pre tracheal fascia also encloses the infrahyoid muscles (in their own little muscle compartment). The pre-tracheal fascia (anteriorly) only extends up as far as the hyoid bone, to which it is attached- that is, it does not run up the entire length of the neck to the bone of your chin (mandible)! Thus, anything above the hyoid lying anteriorly in the neck-will not have a layer of pretracheal fascia in front of it (i.e. supra hyoids).
The posterior part of the pretracheal fascia, however, that which lies behind the pharynx/oesophagus (known by a different name…buccopharyngeal fascia) does run right the way up to the very top of the neck- to the base of the skull.
Inferiorly the pretracheal fascia (and its posterior part, buccopharyngeal fascia) run into the thorax. Anteriorly, when in the thorax, the pre tracheal fascia will blend with the pericardial sac, and posteriorly the buccopharyngeal fascial component descends further, following the oesophagus right down to where it meets the diaphragm.
Which of these branches does not arise from the facial nerve (tick all that apply)?
A. Cervical B. Temporal C. Posterior auricular D. Maxillary E. Mandibular F. Zygomatic
D. Maxillary
The facial nerve has five terminal branches; the temporal, zygomatic, BUCCAL, mandibular, and cervical. There is no maxillary branch (it is the trigeminal nerve that has a maxillary branch).
The posterior auricular nerve is a branch of the facial nerve (though not mentioned in the lecture today as it doesn’t supply the face). It arises just after the facial nerve exits from its foramen in the skull (stylomastoid foramen) and runs up to supply the muscle behind the ear and the occipitalis muscle.
Do not confuse the mandibular branch of the facial nerve, with the branch of the trigeminal nerve, which has the same name. Referring to the mandibular branch of the facial nerve as the “marginal mandibular nerve”, can help make it clear which branch you are referring to i.e. that of the facial nerve vs that of the trigeminal.
Which of the following muscles is NOT a muscle of mastication:
A. Temporalis
B. Lateral pterygoid
C. Buccinator
D. Masseter
C. Buccinator
There are four muscles of mastication, all innervated by the trigeminal nerve.
Buccinator is a muscle of facial expression and is supplied by the facial nerve. While it isn’t classed as a muscle of mastication, it plays an important role in keeping the cheeks taut, especially when chewing, ensuring food doesn’t collect in the oral vestibule (the horse-shoe shaped space between the teeth and the cheek/lips).
A patient presents to the Emergency Department complaining of palpitations. He is cardiovascularly stable, but the ECG reveals a supraventricular tachycardia.
The junior doctor decides to perform carotid sinus massage, recalling that the carotid sinus is found within the carotid triangle.
Which row correctly identifies the boundaries of the carotid triangle (left to right: superior, lateral and medial boundaries)
A. Lower border of mandible, Sternocleidomastoid, Midline of neck
B. Superior belly of omohyoid, Anterior belly of digastric, Sternocleidomastoid
C. Posterior belly of digastric, Sternocleidomastoid, Superior belly of omohyoid
D. Anterior belly of digastric, Superior belly of omohyoid, Sternocleidomastoid
C. Posterior belly of digastric (superior boundary), Sternocleidomastoid (lateral boundary), Superior belly of omohyoid (medial boundary)
Correct answer is C. If you weren’t too sure of this question, refer back to any image showing the boundaries of the carotid triangle (on in Session 1 lecture slides). If you’re not too sure of the digastric and omohyoid muscles, have another look at these and generally where they run from and to. The digastric is one of the supra-hyoid muscles and the omohyoid is one of the infra-hyoid muscles. Supra- and infra-hyoids are essentially a collection of muscles (of which some attach to the hyoid bone) and are either found above or below the hyoid. Their main action is to act to raise or depress the hyoid bone and stabilise it during swallowing.
The carotid triangle is a subtriangle of the anterior triangle. Its boundaries include part of the SCM muscle, but part of the digastric muscle and omohyoid muscle form its other boundaries.
There are quite a few ‘other’ subtriangles of the neck- please do not worry about these others (e.g. muscular triangle, submandibular) they are less important at your stage of training.
The carotid triangle, however is quite important. It helps you to anatomically locate a number of important structures that may be accessed surgically e.g. carotid arteries, IJV, vagus nerve, but also the site at which carotid sinus massage can be performed (a technique that can be used to terminate SVT). The carotid pulse is also palpated quite easily within the carotid triangle, though it may also be palpated more inferiorly in the neck.
