PHARYNX & LARYNXJAMES GOADSBY & PATRICK ELDER

MiddleEar

InnerEar

Nasopharynx

CN VIIIExternal Acoustic Meatus

Pharyngotympanic tube

Oropharynx

Laryngopharynx

Mouth

Lary

nx

Oespo

hagus

Nose

Choanae

Soft palate

Epiglottitis

Cricopharyngeus / inferior border of cricoid cartilage

Structural Overview

R G Tunstall 2013

MiddleEar

InnerEar

Nasopharynx

CN VIIIExternal Acoustic Meatus

Pharyngotympanic tube

Oropharynx

Laryngopharynx

Mouth

Lary

nx

Oespo

hagus

Nose

R G Tunstall 2013

CNVb & CNIX

CNIX

CNIX & X

Innervation of the pharynx

Note that CN IX carries sensory info from all pharyngeal areas – and also from auditory tube and middle ear.

MUSCLES OF THE PHARYNX

Superior constrictor

Middle constrictor

Inferior constrictor

Cricopharyngeus

What is the motor supply of the pharyngeal muscles?

Vagus nerve

MUSCLES OF THE PHARYNX

Midline Raphe(Similar to a long tendon)

‘Weak Spot’Pharyngeal

pouch / diverticulum

SC

MC

IC

The constrictors are stacked inside each other, with the superior constrictor on the inside and the inferior constrictor on the outside

A 23 YR OLD MALE, HAMISH AULD PRESENTS WITH HALITOSIS AND TELLS YOU HE HAS BEEN COUGHING UP FOOD. WHAT IS YOUR DIAGNOSIS?

Pharyngeal diverticulum

• There is a week area in the mucosa between the inferior constrictor and the cricopharyngeus.

• If coordinated relaxation of the cricopharyngeus does not occur during swallowing, intrapharyngeal pressure tends to rise.

• Pharyngeal mucosa forms a midline diverticulum in between the two muscles.

• Food can accumulate here and go rotten, and may also cause dysphagia.

LARYNX

What are the three main functions of the larynx?

• Prevents ingress of fluid and particles: guards the entrance to the tracheobronchial tree

• Allows regulation of intrathoracic & intra-abdominal pressure (Valsalva)

• Enables phonation (production of sound).

LARYNX

Hyoid bone

Thyrohyoid membrane

Thyroid cartilage

Superior hornLamina

Laryngeal prominenceInferior horn

Cricoid cartilage

Cricothyroid membrane(emergency airway)

Cricoid cartilage

Arytenoid cartilage

Epiglottis(elastic cartilage)

VERTEBRAL LEVELS IN THE LARYNX

Hyoid:• C2/C3

Thyrohyoid membrane:• C4

Laryngeal prominence:• C5

Cricoid cartilage and start of trachea:• C6

Ant. Post.

C3

C4

C5

C6

C2

VOCAL FOLDS

Cricovocal membrane (elastic)Passes from cricoid to vocal process of arytenoidsThickened free edge = vocal ligament

Arytenoid cartilagesArticulate with cricoid cartilage via synovial joint that permit pivoting movements

Anterior

Posterior

VOCAL FOLDS

Arytenoids as viewed from above in transverse section

Posterior

Vocal Process

Anterior

Joint position

Posterior cricoarytenoid muscles

Lateral cricoarytenoid muscle

• Lateral cricoarytenoid muscles adduct the vocal folds – phonation

• Posterior cricoarytenoid muscles abduct the vocal cords – breathing! They are the only muscles that can do this. So they are very important

Posterior cricoarytenoid muscleLateral cricoarytenoid muscle

Posterior cricoarytenoid muscle(abducts vocal ligaments)

Lateral cricoarytenoid muscle(adducts vocal ligaments)

Larynx – Muscles & Nerves

Nerve supply = recurrent laryngeal nerve

Ant.

Post.

Ant.

Post.

R G Tunstall 2013

LARYNGEAL MEMBRANESHow many membranes are there in the larynx?

• Two: aryepiglottic and cricovocal

Aryepiglotic (Quadrangular) MembranePasses from the arytenoids (body & apex) to the epiglottisFree lower border forms vestibular fold

Cricovocal membrane (Lat. cricothyroid membrane)Passes from cricoid cartilage & vocal process of arytenoid to thyroid cartilage anteriorlyFree upper border forms the vocal ligament

Ventricle & SacculeMucosal pouch between aryepiglotic & cricovocal membranes

Larynx – Clinical Examination

Vocal Folds

Vestibular folds(false vocal folds)

Epiglottis

Aryepiglotic fold

Rima glottidis(gap between vocal folds)

Glottis = vocal folds & processes, & rima glottidis

Posterior

Anterior

R G Tunstall 2013

One day The Rock walks into your clinic. After gathering all the composure you can muster you ask him about his symptoms…”I’ve been getting terribly tired, losing weight and I’m hungry all the time!”. You then look at The Rock and he doesn’t seem himself...he’s got a tremor in his hand, seems sweaty and when you finally get to shake the great man’s hand you notice his pulse seems rather fast.

Diagnose The Rock!

Hyperthyroidism!

Fantasy Clinical Cases

Being the good medical student that you are, you take note of The Rock’s ideas,

concerns & expectations.

Ideas: “my great rival Triple H is trying to sabotage my reign by putting thyroxine in

my protein shakes”

Concerns: “I won’t be able to deliver the type of wrestling spectacle that the

millions…and millions of The Rock’s fans have come to enjoy and expect. They’re a

demanding crowd and I need to stay relevant”

Expectations: “Fix me up quickly so that I can return to being The Most Electrifying

Man in Sports Entertainment”

Luckily the most electrifying surgical registrar in UHCW, Mr Papez is on hand to perform a thyroidectomy that very

day.

The Rock wakes up from his enormous dose of anaesthetic and is surprised

to find that his voice has changed. His once commanding tone has become

significantly more hoarse.

What has happened??

Recurrent Laryngeal

Nerve Injury!

Which well-known nerve is the Recurrent (and Superior) Laryngeal

Nerve a branch of?

The Vagus Nerve - CNX

What are its functions? Sensory: laryngeal cavity below the level of the vocal folds

Motor: all intrinsic muscles of the larynx except the cricothyroid

What are the potential complications of the injury?

Loss of function causes vocal cord paralysis

Unilateral injury – hoarse or weakened voice

Bilateral injury:

• cords in mid abduction-adduction• voice becomes weak • loose vocal cords can occlude the

respiratory tract

Larynx – Muscles & Nerves

Superior Laryngeal Nerve (SLN) Mucosal sensation above vocal folds (Internal LN) Cricothyroid muscle (External LN)

Inferior Laryngeal Nerve Continuation of recurrent laryngeal nerve Supplies all laryngeal muscles except for cricothyroid Sensory below vocal folds

All motor and sensory innervation is of the larynx is from CN X (Vagus)

All nerve supplies are ipsilateral e.g. The right RLN supplies the right side of larynx

R G Tunstall 2013

Vocal fold level

What other injury was The Rock at risk of during Mr Papez’s operation?

Superior Laryngeal Nerve Injury

Function?

External Branch: motor supply to cricothyroid

muscle

Internal Branch: mainly sensory – supplies

laryngeal cavity down to level of vocal folds

Sequelae of injury?

Monotonous tone of voice Loss of sensation above

vocal cords increases risk of aspiration

Bonus Question: Who first described the Recurrent Laryngeal Nerve?

Claudius Galen (circ.130 AD – circ.210 AD) - physician, writer and philosopher

During the second century A.D., Galen described a nerve that came from the brain on each side of the neck, went down toward the heart, and then reversed course and ascended to the larynx and caused the vocal cords to open. He called these "reversivi" (or recurrent nerves) and stated that he was the first to discover "these wonderful things." Demonstrating before the elders of Rome, he showed that cutting the recurrent laryngeal nerve in the neck caused a live pig to stop squealing-an extraordinary feat. Because of Galen's fame and influence, this nerve retained great importance in dissections by later anatomists and surgeons before and throughout the Renaissance. This paper documents many of these anatomical findings and highlights the importance of a careful, delicate, recurrent laryngeal nerve dissection during thyroidectomy, as popularized by Dr. Frank Lahey in 1938

History of the recurrent laryngeal nerve: from Galen to Lahey.Kaplan EL1, Salti GI, Roncella M, Fulton N, Kadowaki M.