W2: Nose, nasopharynx and larynx

Question 1

Where is nasal cavity

Answer 1

Nose→ nasopharynx

Question 2

What is the septum formed from?

Answer 2

Septal cartilage and vertical plates of ethmoid and vomer bones

Question 3

4 major functions of nasal cavity

Answer 3

Humidify and warm inhaled air

Olfaction (olfactory nerve fibres innervating olfactory epithelium within superior nasal cavity, via cribriform plate).

Drainage of lacrimal ducts and para-nasal sinuses

Trap particles from inhaled air

Question 4

What do lateral walls contain? What do they do? What are the channels of air that are formed between them called?

Answer 4

The lateral walls of the nasal cavity contain projections of bone called the superior, middle and inferior conchae (or turbinate bones).

The conchae function to increase the surface area of the highly vascularised epithelium within the nasal cavity, maximising the level of humidification and warming.

The channels of air created between the conchae are called the superior, middle and inferior meati.

Question 5

Discuss structures draining into meati

Answer 5

Frontal, maxillary and anterior ethmoidal sinuses – drain into the middle meatus.

Nasolacrimal duct(tears), Eustachian tube – drains into the inferior meatus.

Superior - Posterior ethmoid

The only structure not to empty out onto the lateral walls of the nasal cavity is the sphenoid sinus. It drains onto the posterior roof.

Question 6

Discuss innervation of nasal cavity

Answer 6

General sensation of the nasal cavity is provided by branches of the ophthalmic and maxillary nerves (CN V). The nasal mucous glands and lacrimal glands are supplied by parasympathetic branches from the facial nerve (VIA THE PTERYGOPALATINE GANGLION).

Question 7

Discuss sinusitis

Answer 7

Due to the communication between the nasal cavity and para-nasal air sinuses, an upper respiratory tract infection can extend to the mucosa of the sinuses.Additionally, sinusitis may develop if the normal drainage of mucus from the sinuses is disrupted, for example by allergic inflammation. Infection may also originate from the maxillary posterior teeth, which subsequently extends into the maxillary sinus. Inflammation re- sults in pain and swelling within the sinuses. Since the maxillary branch of the trigeminal nerve innervates the maxillary sinus and maxillary teeth, inflammation within the maxillary sinus can present as toothache

Question 8

What does ophthalmic branch into?

Answer 8

Frontal - upper eyelid, conjuctiva, scalp

Lacrimal - lacrimal gland, upper eyelid and conjuctiva

Nasociliary - sinuses, nasal cavity, also bridge of nose, upper eyelid and conjuctiva, eye (from long ciliary)

Question 9

Discuss blood supply of nasal cavity

Answer 9

The nasal mucosa is highly vascularised to maximise air humidification and warming.

Blood is supplied via branches of the internal carotid arteries (ethmoidal branches of the ophthalmic artery) (this is similar to the nerve) and external carotid arteries (including the sphenopalatine and greater palatine arteries from the facial artery).

These arteries form anastomoses with each other, which is particularly well developed in the anterior part of the nose, known as Little’s area.

This is a common site for bleeding (90% of nosebleeds), particularly in younger people.

Question 10

Discuss floor of the nasal cavity

Discuss roof

Answer 10

The floor of the nasal cavity is formed by the hard palate, separating it from the oral cavity. The hard palate consists of the palatine bone posteriorly, and the palatine process of the maxilla anteriorly. The cribriform plate of the ethmoid bone forms the roof of the nasal cavity.

Question 11

What level is larnyx found in?

Answer 11

C3-C6

Question 12

Describe cartilages of the larynx

Answer 12

Thyroid cartilage – the largest, most prominent cartilage of the larynx that forms the Adam’s apple in males (karyngeal prominence)

Cricoid cartilage – a complete ring of hyaline cartilage, forming the shape of a signet ring.

Arytenoid cartilages – pyramidal cartilages that sit on top of the cricoid cartilage.

Epiglottis – a leaf shaped elastic cartilage structure that flattens during swallowing to close off the larynx, preventing aspiration of food into the lungs.

Corniculate cartilages – minor cartilages that articulate at the apices of the arytenoid cartilages.

Cuneiform cartilages – function to strengthen the aryepiglottic folds at the entrance of the larynx.

Question 13

What is vallecula? What runs under it?

Answer 13

Depression between back of tongue and epiglottis

Hypoepiglottic ligament runs under vallecular mucosa and connects hyoid to back of epiglottis

Question 14

Discuss the 3 anatomical regions the larynx can be divided into?

Answer 14

Supraglottis – From the inferior surface of the epiglottis to the vestibular folds (false vocal cords).

Glottis – Contains vocal cords and 1cm below them. The opening between the vocal cords is known as rima glottidis, the size of which is altered by the muscles of phonation.

Subglottis – From inferior border of the glottis to the inferior border of the cricoid cartilage.

Question 15

Discuss vasculature of larynx

Answer 15

The arterial supply to the larynx is via the superior and inferior laryngeal arteries:

Superior laryngeal artery – a branch of the superior thyroid artery (derived from the external carotid). It follows the internal branch of the superior laryngeal nerve into the larynx.

Inferior laryngeal artery – a branch of the inferior thyroid artery (derived from the thyrocervical trunk). It follows the recurrent laryngeal nerve into the larynx.

Venous drainage is by the superior and inferior laryngeal veins. The superior laryngeal vein drains to the internal jugular vein via the superior thyroid, whereas the inferior laryngeal vein drains to the left brachiocephalic vein via the inferior thyroid vein.

Question 16

Discuss innervation of the larynx

Answer 16

The larynx receives both motor and sensory innervation via branches of the vagus nerve:

Recurrent laryngeal nerve – provides sensory innervation to the infraglottis, and motor innervation to all the internal muscles of larynx (except the cricothyroid).

Specifically it is the inferior part of the recurrent laryngeal nerve

Superior laryngeal nerve – the internal branch provides sensory innervation to the supraglottis, and the external branch provides motor innervation to the cricothyroid muscle.

or

Sensory: above vocal folds = internal laryngeal (from superior laryngeal) and below = recurrent

Motor: recurrent laryngeal or for cricothyroid external laryngeal (from superior laryngeal)

Question 17

What type of cartilage is circoid?

Answer 17

Hyaline - only complete circular ring of cartilage

Question 18

What type of cartilage is the epiglottis? Where does it attach? What happens to it during swallowing?

Answer 18

Elastic

Its ‘stalk’ is attached to the back of the anterior aspect of the thyroid cartilage. During swallowing, the epiglottis flattens and moves posteriorly to close off the larynx and prevent aspiration.

Question 19

Discuss vocal folds

Answer 19

The vocal folds, formed from the vocal ligaments and vocalis muscle, produce audible vibrations when their free margins are closely apposed whilst air is forced across them.The vocal ligaments run from the junction of the thy- roid cartilage lamellae anteriorly to the vocal processes of the arytenoid cartilages posteriorly.

Variation in the size of the aperture (known as the rima glottis) by varying the length and tension of the vocal folds, changes the pitch of the sound.

Question 20

Discuss vestibular folds

Answer 20

The vestibular folds (false vocal cords) lie superiorly to the true vocal cords. They consist of the vestibular ligament (free lower edge of the quadrangular membrane) covered by a mucous membrane, and are pink in colour. They are fixed folds, which act to provide protection to the larynx.

Question 21

Thyrohyoid membrane

Answer 21

Spans between the superior aspect of the thyroid cartilage and the hyoid bone. It is pierced laterally by the superior laryngeal vessels and internal laryngeal nerve (branch of the superior laryngeal nerve).

Question 22

Cricothyroid ligament

Answer 22

Also known as cricothyroid membrane or cricovocal membrane

Originates from the cricoid cartilage and extends superiorly, where it terminates with an free (unattached) upper margin – which forms the vocal ligament. It is additionally attached anteriorly to the thyroid cartilage, and posteriorly to the arytenoid cartilage.

Question 23

Aryepiglottic fold

Answer 23

Folds in mucus membrane of the larynx

Extend from lateral epiglottis to arytenoid cartilage

Can take part in phonation - growling

Question 24

Draw and label laryngeal inlet

Answer 24

Question 25

What is the piriform fossa

Answer 25

Bounded medially by aryepiglottic fold

Laterally bounded by thyroid cartilage and thyrohyoid membrane

Question 26

Discuss laryngeal ventricle

Answer 26

The laryngeal ventricle is the fossa or sinus that lies between the vocal and vestibular folds on either side. The vocal folds are commonly referred to as the vocal cords and the vestibular folds as the false vocal cords

Question 27

Which muscle controls pitch of voice? Where is it?

Answer 27

Cricothyroid

Originates from the anterolateral aspect of the cricoid cartilage, and attaches to the inferior margin and inferior horn of the thyroid cartilage.

Can feel this

Question 28

Discuss intrinsic muscles (not including cricothyroid)

Answer 28

All intrinsic adduct cords (close glottis) expect posterior cricoartyenoids, which abduct

Cricoartyenoids - Originates from the posterior surface of the cricoid cartilage, and attaches to the muscular process of the arytenoid cartilage.

Question 29

What do the extrinsic muscles of the larynx do?

Answer 29

Move larynx superiorly and inferiorly

Question 30

Discuss strap msucles

Answer 30

Also called infrahyoid

Group of 4 muscles - generally depress the larynx

Question 31

Discuss cough reflex

Answer 31

Mechano/chemoreceptors → vagus nerve → medulla oblongata NTS → motor:

• Diaphragm contracts - increases thoracic cavity space
• Laryngeal muscles contract to close
• External intercostals contract
• Rectus abdominis contracs to depress rib cage and decrease space in thoracic cavity

Question 32

Tracheoesophageal Fistula

Answer 32

This is an abnormal connection between the lumens of the oesophagus and the trachea and may occur as a congenital abnormality or as a result of surgical procedures.

Usually they are two separate tubes

Congenital fistulation is associated with other congenital malformations, particularly cardiac defects, and results from abnormal formation of the tracheoesophageal septum that separates the trachea from the developing foregut in gestation.

Need an operation

Otherwise lead to pneumonia for example

Question 33

Oesophageal Atresia

Answer 33

This is a congenital abnormality in which the oesophagus is blind-ending. Diagnosis may be suspected on antenatal scans because of polyhydramnios (too much amniotic fluid around the baby) and an absence of a foetal stomach bubble. Babies with atresia commonly present with breathing difficulties, choking and feeding difficulties. Surgical correction of the abnormality is required.

Question 34

Difficulty with Speech

Answer 34

There is a risk of damage to the exposed left recurrent laryngeal nerve as it loops around the ligamen- tum arteriosum during cardiothoracic surgery. Since this nerve innervates most of the intrinsic laryngeal muscles ipsilaterally, damage will cause an ipsilateral cord paresis, presenting as voice hoarseness.Although the damage is usually permanent, voice weakness can be improved by surgical medialisation of the vocal cords, to improve their apposition.

Question 35

Where is cardiac notch?

Answer 35

Superior lobe of left lung

Question 36

Where is lingula?

Answer 36

Bottom of left lung

Question 37

Where is pulmonary embolism?

Answer 37

Pulmonary arteries

Question 38

Why doesnt pulmonary embolism lead to infarction?

Answer 38

Bc of collateral supply from systemic circulation

Question 39

The vocal folds are found within the space enclosed by the…

Answer 39

Thyroid cartilage