SDL 1 - FRONT OF NECK Flashcards
What are the boundaries of the posterior triangle?
- middle one third of the clavicle
- anterior margin of trapezius
- posterior margin of sternocleidomastoid
What may be damaged by stab wounds in the posterior triangle?
The apex of the lung and the brachial plexus
Would would be the consequence of a brachial plexus injury via a stab wound in the posterior triangle?
Erb’s Palsy as this is an upper trunk injury
What muscles are paralysed in Erb’s palsy?
Complete paralysis:
- biceps brachii
- deltoid
- brachialis
- brachioradialis
Partial paralysis:
- supraspinatus
- infraspinatus
- supinator
What is the deformity associated with Erb’s palsy?
Arm:
- Hangs by the side, adducted and medially rotated
Forearm:
- Extended and pronated
This is due to injury of the C5 and C6 nerve roots
The accessory nerve runs posteroinferiorly through the posterior triangle.
Which muscles are supplied by this nerve?
sternocleidomastoid and deltoid
What are the boundaries of the anterior triangle?
- median vertical line of the neck
- inferior margin of the mandible
- anterior margin of sternocleidomastoid
Label the features of the larynx
What is the suprasternal notch?
A large visible dip between the neck and the two collarbones
What is shown by the letters on this image?
RL and LL - right lobe and left lobe
S - isthmus of thyroid gland
H - hyoid bone
T - thyroid cartilage
C - cricoid cartilage
What is the passage of the external jugular vein in the neck like?
What are the surface markings of this vessel?
it descends through the subcutaneous tissue of the neck on the surface of the sternocleidomastoid muscle
surface marking is a line from the angle of the mandible to the middle of the clavicle
Where are the infrahyoid muscles found?
What is their important function?
They lie distal to the hyoid bone
They depress the hyoid bone during swallowing
What are the 4 infrahyoid muscles and how can they be divided into 2 groups?
Superficial plane
- omohyoid and sternohyoid muscles
Deep plane:
- sternothyroid and thyrohyoid muscles
Label the infrahyoid muscles
What is the innervation of the infrahyoid muscles?
Thyrohyoid muscle:
- Anterior ramus of C1, carried within the hypoglossal nerve.
All others:
- Anterior rami of C1-C3, carried by a branch of the ansa cervicalis.
What components of the larynx can be identified in the gap between the left and right infrahyoid muscles?
- Thyroid cartilage
- Laryngeal prominence
- Cricoid cartilage
- Cricothyroid membrane
- Trachea
- Isthmus of thyroid gland
What is a cricothyroidotomy?
Under what circumstances would this be performed?
An incision made through the skin and cricothyroid membrane
It is used to establish a patent airway during life-threatening situations such as airway obstruction by a foreign body, angiodema or massive facial trauma
What is a tracheostomy?
Under what circumstances is this performed?
This involves creating an opening in the neck so that a pipe can be placed within the trachea temporarily or permanently
tracheostomy is performed because of airway obstruction, problems with secretions, and inefficient oxygen delivery
What is the role of the suprahyoid muscles?
they lie above the hyoid bone and have attachments to it
they form the floor of the mouth and have an important function in moving the hyoid bone during swallowing
What are the 4 suprahyoid muscles?
- Diagastric
- Stylohyoid
- Geniohyoid
- Mylohyoid
Label the suprahyoid muscles
What are the attachments of the two bellies of diagastric?
The anterior belly arises from the digastric fossa of the mandible
The posterior belly arises from the mastoid process of the temporal bone
They insert onto a common tendon which attaches to the hyoid bone via a fibrous sling
What is the function of diagastric muscle?
It depresses the mandible and elevates the hyoid bone
What is the carotid sheath?
a thick layer of fascia that binds together the common carotid artery, internal jugular vein and the vagus nerve in the neck
in the upper part of the neck it contains the internal carotid artery, internal jugular vein and last four cranial nerves
What are the surface landmarks of the internal jugular vein?
Midpoint between the sternal notch and the mastoid process
From which nerve(s) do the roots of ansa cervicalis take origin?
Originates from upper cervical spinal nerves C1, C2 and C3
At which vertebral level does the carotid bifurcation lie?
Which laryngeal landmark lies at this level?
The common carotid artery bifurcates into external and internal carotid arteries
this happens between C3 and C4
at the superior border of the thyroid cartilage of the larynx
How should the common carotid pulse be palpated?
palpate lateral to the upper border of the thyroid cartilage and just medial to the anterior border of sternocleidomastoid
DO NOT palpate both sides at once and DO NOT rub the vessel
What are the branches of the internal carotid artery?
it has no branches in the neck
it ascends to supply the brain
label the major anterior branches of the external carotid artery
What happens as the vagus nerve descends within the carotid sheath?
it gives off important branches that are involved in the control of speaking and swallowing
How is the vagus nerve involved in speaking and swallowing?
Speech:
- Recurrent laryngeal nerve controls muscles of the larynx
Swallowing:
- Pharyngeal branch innervates the salpingopharyngeus, palatopharyngeus and palatoglossus
- This aids in speech and swallowing
What is meant by phonation?
The production of sound, which begins in the larynx
the larynx also aids in breathing and prevents foreign objects from entering the lungs
Other than phonation, what are the roles of the larynx?
It allows air to pass through the respiratory tract, whilst preventing aspiration
it aids in breathing
How is sound produced?
How do the vocal cords change position during sound production?
sound is produced by vibration of the vocal cords in the larynx
at rest, the folds are separated
during phonation, the folds are adducted, obstructing the flow of air
What happens during sound production when pressure builds up?
pressure builds up, then the folds are forced apart
air escapes and then the folds return to the adducted position
rapid repetition of these movements results in vibration of the folds, giving rise to sound waves
How is pitch varied in the larynx?
Pitch is varied by altering the length and tension of the vocal folds
(this alters the frequency of their vibration)
these features are adjusted by the intrinsic muscles of the larynx
What is meant by “intrinsic muscle of the larynx”?
Intrinsic muscles both originate and insert on the larynx
They move the arytenoid cartilages and adjust the tension applied to the vocal folds and ligaments
What are the intrinsic muscles of the larynx?
- Cricothyroid
- Thyroarytenoid
- Posterior cricoarytenoid
- Lateral cricoarytenoid
- Transverse and oblique arytenoids
Label the muscles of the larynx
Which cranial nerves supply the intrinsic muscles of the larynx?
How does the innervation of the cricothyroid muscle differ from the others?
Cricothyroid muscle:
- innervated by external laryngeal nerve
Others:
- Innervated by inferior laryngeal nerve
These are both branches of the vagus nerve (cranial nerve X)
How is the loudness of sound and quality of the voice produced in the larynx?
the loudness of sound is related to the pressure of the expired air
the quality or timbre of the voice depends on resonating chambers above the vocal cords
Through which spaces do sound waves pass to reach the outside world?
- Air passes through the larynx and into the vocal tracts
- This ends at the mouth and nostrils
*
What is meant by the process of articulation?
sound is broken up into recognisable vowels and consonants by movements of the lips and tongue
Which cranial nerves supply the muscles responsible for movements of the lips?
Orbicularis oris muscle is a complex of muscles that encircles the mouth
It is innervated by cranial nerve VII
Which cranial nerves supply the muscles responsible for movements of the tongue?
Sensory - glossopharyngeal (IX)
Motor - hypoglossall (XII)
What 2 branches does the vagus nerve give off to the larynx?
Superior laryngeal nerve runs towards the upper boundary of the larynx
Recurrent laryngeal nerve runs towards the lower boundary of the larynx
What structures lie close to the external laryngeal nerve?
The external laryngeal nerve is a branch of the superior laryngeal nerve
Both of these lie close to the superior thyroid artery
This is a branch of the external carotid artery
What does the internal laryngeal nerve supply?
Where does it enter the larynx?
It descends to the thyrohyoid membrane and pierces it with the superior laryngeal artery
It is distributed to the mucous membrane of the larynx
Some sensory branches are distributed to the epiglottis, base of the tongue and epiglottic glands
It also supplies the mucous membrane surrounding the entrance to the larynx as far down as the vocal folds
Where does the superior laryngeal nerve divide?
It divides into the internal and external laryngeal nerves
The internal laryngeal nerve (sensory) supplies the laryngeal mucosa
The external laryngeal nerve (motor) supplies the cricothyroid muscle
Where does the left recurrent laryngeal nerve arise?
It arises from the vagus nerve to the left of the arch of the aorta
why does hoarseness sometimes occur following thyroid surgery?
The recurrent laryngeal nerve is closely related to the inferior thyroid artery
hoarseness arises due to damage to the recurrent laryngeal nerve
Label vessels of the larynx
Label the nerves
Which cranial nerves pass out of the skull alongside the vagus nerve?
Glossopharyngeal nerve (CN IX)
Accessory nerve (CN XI)
They pass out of the skull via the jugular foramen
What are the 3 subdivisions of the pharynx and the structures that separate them?
nasopharynx:
- begins at the base of the skull
- Ends at the soft palate
oropharynx:
- Runs between the soft palate and the superior border of the epiglottis
laryngopharynx:
- Runs between the superior border of the epiglottis and the inferior border of the cricoid cartilage
What is the first stage of swallowing?
It is voluntary and involves the passage of the bolus of food from the oral cavity into the oropharynx
How is the first stage (oral stage) of swallowing achieved?
It involves the contraction of the tongue to push the bolus up against the soft palate and then posteriorly into the oropharynx by both the tongue and the soft palate
What nerves are involved in the oral phase of swallowing?
cranial nerves: V (trigeminal), VII (facial) and XII (hypoglossal).
How do the pharyngeal and oesophageal stages of swallowing differ from the oral phase?
These stages are involuntary
they are controlled by a series of reflexes involving cranial nerves IX, X and XI
Which cranial nerve supplies sensory fibres to the posterior third of the tongue and oropharynx?
Glossopharyngeal nerve (CN IX)
When the bolus of food comes into contact with the posterior third of the tongue and oropharynx, what happens and why?
the soft palate is tensed and elevated
This closes off the airway and nasal passages
When the bolus comes into contact with the posterior third of the tongue and oropharynx, what happens to the hyoid bone?
It is pulled forwards and upwards, bringing the larynx and root of the tongue with it
these movements open the laryngopharynx and tilt the epiglottis downwards over the laryngeal inlet
this helps to close off the laryngeal inlet during swallowing
What muscle contractions are involved in closing off the laryngeal inlet during swallowing?
contraction of the aryepiglottic and transverse arytenoid muscles
What is the purpose of contraction of the circular (constrictor) muscles of the pharynx?
It moves the bolus of food down over the closed inlet of the larynx and on into the oesophagus
Where do the majority of the muscles of the pharynx and soft palate receive their innervation from?
The pharyngeal plexus
this is a complex network of nerves within the pharyngeal wall
What forms the pharyngeal plexus?
- pharyngeal branch of glossopharyngeal nerve
- pharyngeal branch of vagus nerve
- autonomic fibres
