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2 - HNA > Larynx & Pharynx > Flashcards

Larynx & Pharynx Flashcards

1
Q

Describe the larynx

A

Modified upper part of the respiratory tract made up of cartilages, ligaments, muscles and lined with mucous membranes.

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2
Q

Functions of the larynx

A
  1. Protection of lower respiratory tract
  2. Effort closure: coughing, sneezing, abdominal straining
  3. Phonation: relies on precise balance of activity of all intrinsic muscles of the larynx
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3
Q

Common laryngeal insults

A
  • Inflammation - laryngitis (inflammation of vocal cords causing hoarseness or aphonia)
  • Neoplasms - carcinoma (mainly squamous cell - especially in smokers)
  • Vocal nodules

NB: laryngeal nerves at risk during thyroid surgery

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4
Q

Relations of the larynx

A

Located in anterior triangle of neck

  • Superiorly: hyoid bone (level of C3)
  • C4: CCA bifurcates (thyroid cartilage, sup border)
  • Inferiorly: trachea
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5
Q

Cartilages of the larynx

A

3 unpaired:

  1. Cricoid
  2. Thyroid
  3. Epiglottis

1 paired:

  1. Arytenoids
    * i.e. 5 cartilages in total*
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6
Q

Discuss the epiglottis

A
  • Leaf-shaped ‘yellow-elastic’ cartilage
    • Never calcifies
    • NB: other laryngeal cartilages = hyaline
  • Tip rises ~1cm above the hyoid
  • Mucous membrane reflected from its anterior surface to the back of the tongue
    • Forms the glossoepiglottic folds
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7
Q

Discuss the glossoepiglottic folds

A
  • 3 longitudinal ridges
  • Valleculae are depressions either side of the median fold
  • Piriform fossae are depressions inferior to the lateral folds
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8
Q

Where are foreign bodies likely to lodge?

A

Sites of natural constriction/blind-ending structures

  • Base of tongue
  • Tonsils
  • Valleculae
  • Piriform fossae
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9
Q

Discuss the cricoid

A

Signet ring - lamina much taller than arch - C6-7

  • Only complete cartilaginous ring in resp tract
  • Foundation of laryngeal skeleton
  • Articulates with thyroid & arytenoid cartilages
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10
Q

Articulations of cricoid

A
  1. Facets on superior rim for arytenoids
  2. Facets on external surface for inferior horn of thyroid cartilage
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11
Q

Discuss the thyroid cartilage

A

C4-5

  • Two pentagonal laminae fused anteriorly to form the laryngeal prominence
    • M ~90º, F ~120º (little difference in children)
  • Posterior projects superiorly & inferiorly
    • Superior/inferior horns (cornu)
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12
Q

Effect of puberty on the larynx

A

Enlargement of all cartilages in males produces the laryngeal prominence

Length of vocal cords nearly doubled but change in pitch in males due to mass/structural changes

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13
Q

Discuss the arytenoid cartilages

A
  • Triangle-based pyramid, apex superiorly
  • Anterior point elongated - vocal processes
  • Lateral projections - muscular processes
    • Muscle attachments
  • Base articulates with cricoid lamina
    • Synovial joint - rotation/gliding
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14
Q

Laryngeal membranes

A
  • Thyrohyoid membrane

Intrinsic membranes:

  • Quadrangular membrane
  • Cricothyroid membrane
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15
Q

Discuss the thyrohyoid membrane

A
  • Upper border of the thyroid cartilage → upper border of the posterior surface of the hyoid bone
  • Pierced by superior laryngeal vessels & internal laryngeal branch of superior laryngeal n.

Two thickenings:

  1. Midline: median thyrohyoid ligament
  2. Posterior edges: lateral thyrohyoid ligaments
    • Superior horn → greater horn
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16
Q

Discuss the quadrangular membrane

A
  • Fibroelastic: epiglottis → arytenoid cartilages
  • Upper margins form aryepiglottic folds
  • Lower margins form vestibular folds (false cords)
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17
Q

Discuss the cricothyroid membrane

A
  • Highly elastic
  • Superior rim of cricoid arch & vocal process of arytenoids → internal surface of thyroid angle
  • Superior edge forms vocal ligaments
    • Together with overlying membrane = vocal folds
  • Thickening of anterior fibres: median cricothyroid ligament
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18
Q

Discuss surgical airway access

A
  • Emergency: pierce median cricothyroid ligament to gain access to subglottic airway if choking
  • Elective tracheostomy: between 2nd/3rd tracheal rings
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19
Q

Interior of larynx - diagram

A
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20
Q

Describe the laryngeal inlet

A

Communication of larynx & pharynx, boundaries:

  • Anteriorly: epiglottis
  • Posteriorly: arytenoids
  • Laterally: aryepiglottic folds
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21
Q

Discuss the vestibule

A

Space from laryngeal opening → vestibular folds

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22
Q

Discuss the ventricle

A

Space produced by small amounts of membrane herniating through an opening in the saccule

Contains the mucous glands: lubricate vocal cords

23
Q

Discuss the glottis & rima glottidis

A

Glottis: formed by the two vocal folds

Rima glottidis: space within glottis

24
Q

Discuss the epithelium lining the larynx

A

Vocal cords/epiglottis:

  • Non-keratinising stratified squamous
    • Thickened on cords: greater wear & tear

Rest:

  • Pseudostratified ciliated columnar (respiratory)
25
Q

Functional groups of intrinsic laryngeal muscles

A
  1. Action on laryngeal inlet
  2. Abduction-adduction of vocal cords
  3. Changes in length and tension of vocal cords
26
Q

Muscles with an action on laryngeal inlet

A
  • Aryepiglotticus: closes inlet
    • Runs in aryepiglottic fold, extension of oblique arytenoids
  • Thyroepiglotticus: opens inlet
27
Q

Muscles which abduct/adduct vocal cords

A
  • Posterior cricothyroid: sole abductor of cords
    • Posterior surface of cricoid lamina → muscular process of ipsilateral arytenoid
  • Lateral arytenoids & interarytenoids: adductors

NB: motion occurs at the cricoarytenoid joints

28
Q

Muscles which alter length/tension of the vocal cords

A
  • Cricothyroid: increases tension (thyroid cartilage moves forward)
  • Thyroarytenoid: decreases tension (and adducts)
    • Medial part = vocalis lies in vocal fold
      • Decreases length and alters thickness
      • Effect on pitch dep. on other muscles
29
Q

Extrinsic muscles of the larynx

A
  1. Elevators of the larynx:
    • Via hyoid: mylohyoid, stylohyoid, geniohyoid & digastric
    • Directly: stylopharyngeus, palatopharyngeus, salpingopharyngeus
  2. Depressors of the larynx:
    • Via hyoid: sternohyoid, omohyoid & thyrohyoid
    • Directly, sternothyroid

NB: generally elevated larynx returns to rest by elastic recoil of trachea. Active depression occurs in deep inspiration

30
Q

Innervation of intrinsic muscles of the larynx

A
  • Recurrently laryngeal nerve (X) except cricothyroid:
  • External branch of superior laryngeal nerve (X)
    • Only muscle on external surface
31
Q

How do neurovascular structures enter the larynx?

A

Above vocal cords: pierce thyrohyoid membrane

Below vocal cords: enter/leave beneath inferior constrictor of pharynx

32
Q

Arterial & venous supply to larynx

A

Above vocal cords:

  • Superior laryngeal branch of superior thyroid artery (from ECA)
  • Superior laryngeal veins (→ superior thyroid veins → IJV)

Below vocal cords:

  • Inferior branch of inferior thyroid artery (from thyrocervical trunk of subclavian)
  • Inferior laryngeal veins (→ inferior thyroid veins → brachiocephalic vein, mainly left)
33
Q

Lymphatic drainage of larynx

A

Above vocal cords:

  • Anterosuperior group of deep cervical nodes

Below cords:

  • Posteroinferior group of deep cervical nodes
34
Q

Innervation of the larynx

A

Above the vocal cords

  • Mucosal sensation: internal branch of the superior laryngeal nerve (X)
  • Sympathetic: from superior cervical ganglion

Below the vocal cords

  • Mucosal sensation: recurrent laryngeal nerve (X)
  • Middle cervical ganglion

NB: sympathetics run with arteries

35
Q

Discuss recurrent laryngeal nerve injury

A
  • Unilateral: affected cord semi-abducted, other cord crosses midline to compensate = minimal defects to phonation
  • Bilateral: both cords semi-abducted = difficulties in: protecting glottis, phonation & coughing
    • Very serious
36
Q

Discuss external branch of the superior laryngeal nerve damage

A
  • Problems with phonation: esp at higher freq
  • If internal branch also injured, supraglottic sensation may be lost

NB: intraoperative electrophysiological monitoring of nerves during thyroid surgery

37
Q

Describe sequence of swallowing

A
  1. Closure of vestibular & vocal folds
  2. Closure of laryngeal inlet (aryepiglotticus)
  3. Elevation of larynx (extrinsic muscles)
  4. Protection of inlet with epiglottis, flaps down

NB: once bolus reaches oesophagus, inlet opens to resume respiration, epiglottis/larynx return to rest by elastic recoil

38
Q

Discuss effort closure

A

Vocal cords powerfully abducted:

  • Coughing: cords suddenly abducted = explosion of air
  • Straining: closed cords prevent upward displacement of diaphragm - increases intra-abdominal pressure
39
Q

Discuss the Valsalva manoeuvre

A
  • Contraction of abdominal wall muscles against closed glottis with lungs filled
  • Increases intra-abdominal and intrathoracic pressures
    • Useful in expelling faeces, parturition & coughing (sudden abduction)
40
Q

Discuss laryngitis

A
  • Inflammation of larynx/vocal cords due to infection or chemical irritation

Presentation:

  • Breathing harsh & difficult, coughing painful
  • Voice becomes husky or lost completely

‘Treatment’:

  • Remain in warm, moist atmosphere & rest voice
41
Q

Discuss the effect if cigarette smoke

A

Paralyses cilia and can result in squamous metaplasia, a precursor for cancer

42
Q

Discuss the position of the larynx & implications

A
  • At birth: superior tip of epiglottis lies behind the soft palate
    • Oropharynx is very small & develops concomitantly with descent of larynx
  • Position allows simultaneous swallowing and breathing - outgrow this before larynx descends
43
Q

Discuss the trachea

A
  • Midline structure from cricoid cartilage → carina
  • Composed of c-shaped tracheal rings
    • Embedded in connective tissue of trachea
  • Rings deficient posterior: spanned by trachealis
    • Smooth muscle, contract decrease tracheal diameter - reduce dead space in quiet respiration
  • Mucosa = ciliated pseudostratified columnar
    • Especially sensitive to irritation at carina
44
Q

Blood supply to trachea

A

Branches of interior thyroid & bronchial arteries

45
Q

Tracheal lymph drainage

A

Upper part: paratracheal & deep cervical nodes

Lower part: tracheobronchial nodes

46
Q

Innervation of trachea

A

Sensory & secretomotor: recurrent laryngeal n.

Sympathetic: thoracic sympathetic chain

47
Q

Relations of trachea in the neck

A
  • Oesophagus posteriorly - can bulge trachealis in swallowing
  • Thyroid
  • CCA, IJV
  • Phrenic & vagus nerves
    • Recurrent laryngeals ascend bilaterally between trachea & oesophagus
48
Q

Describe the pharynx

A
  • Fibromuscular tube extending from the base of the skull to the lower border of the cricoid
  • Has three parts: naso-, oro- & laryngo-pharynx
    • Posterior to nasal cavity, oral cavity & larynx
49
Q

Muscles of the pharynx: outer layer

A

The constrictors - insert on midline pharyngeal raphé

  • Superior: arises from pterygomandibular raphé
  • Middle: arises from stylohyoid ligament & horns of the hyoid
  • Inferior: arises thyroid & cricoid cartilages
    • Lower fibres = cricopharyngeus: don’t insert into midline raphé
50
Q

Muscles of the pharynx: inner layer

A
  • Stylopharyngeus: arises from styloid process
  • Palatopharyngeus: from palatine aponeurosis
  • Salpingopharyngeus: medial end of aud. tube

Pull larynx & pharynx upwards during swallowing

51
Q

Innervation to pharynx

A

Motor:

  • Pharyngeal nerves (X) from pharyngeal plexus
    • XI Cranial root contributes motor fibres to X
  • Inferior constrict receives additional fibres from external & recurrent laryngeal n.s (X)

Sensation:

  • Branches of glossopharyngeal (IX)
    • Nerves convey preganglionic parasymp. fibres to pharyngeal glands
52
Q

Discuss lymphatic tissue at the entrance of the respiratory/digestive tract

A

Waldeyer’s ring: 4 groups of specialised lymphatic tissue at entrance to the respiratory/digestive tracts

  1. Pharyngeal tonsils
  2. Tubal tonsils - medial end of auditory tube
  3. Palatine tonsils - between palatoglossal & palatopharyngeal arches in oropharynx
  4. Lingual tonsils - posterior surface of tongue
53
Q

Discuss tonsilitis

A
  • Enlarged, inflamed tonsils due to infection
  • If chronic may have to be removed: tonsillectomy
    • Facial artery: many branches to tonsillar bed
    • Post-op haemorrhage may occur, stay overnight
  • May have referred pain to ear: IX gives tonsillar branches & innervates middle ear

2 - HNA (11 decks)

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