Larynx & Pharynx Flashcards
(53 cards)
1
Q
Describe the larynx
A
Modified upper part of the respiratory tract made up of cartilages, ligaments, muscles and lined with mucous membranes.
2
Q
Functions of the larynx
A
- Protection of lower respiratory tract
- Effort closure: coughing, sneezing, abdominal straining
- Phonation: relies on precise balance of activity of all intrinsic muscles of the larynx
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
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
5
Q
Cartilages of the larynx
A
3 unpaired:
- Cricoid
- Thyroid
- Epiglottis
1 paired:
- Arytenoids
* i.e. 5 cartilages in total*
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
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
8
Q
Where are foreign bodies likely to lodge?
A
Sites of natural constriction/blind-ending structures
- Base of tongue
- Tonsils
- Valleculae
- Piriform fossae
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
10
Q
Articulations of cricoid
A
- Facets on superior rim for arytenoids
- Facets on external surface for inferior horn of thyroid cartilage
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)
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
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
14
Q
Laryngeal membranes
A
- Thyrohyoid membrane
Intrinsic membranes:
- Quadrangular membrane
- Cricothyroid membrane
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:
- Midline: median thyrohyoid ligament
- Posterior edges: lateral thyrohyoid ligaments
- Superior horn → greater horn
16
Q
Discuss the quadrangular membrane
A
- Fibroelastic: epiglottis → arytenoid cartilages
- Upper margins form aryepiglottic folds
- Lower margins form vestibular folds (false cords)
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
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
19
Q
Interior of larynx - diagram
A
20
Q
Describe the laryngeal inlet
A
Communication of larynx & pharynx, boundaries:
- Anteriorly: epiglottis
- Posteriorly: arytenoids
- Laterally: aryepiglottic folds
21
Q
Discuss the vestibule
A
Space from laryngeal opening → vestibular folds
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
Functional groups of intrinsic laryngeal muscles
1. Action on laryngeal inlet
2. Abduction-adduction of vocal cords
3. Changes in length and tension of vocal cords
26
Muscles with an action on laryngeal inlet
* Aryepiglotticus: closes inlet
* Runs in aryepiglottic fold, extension of oblique arytenoids
* Thyroepiglotticus: opens inlet
27
Muscles which abduct/adduct vocal cords
* 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
Muscles which alter length/tension of the vocal cords
* 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
Extrinsic muscles of the larynx
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
Innervation of intrinsic muscles of the larynx
* Recurrently laryngeal nerve (X) except cricothyroid:
* External branch of superior laryngeal nerve (X)
* Only muscle on external surface
31
How do neurovascular structures enter the larynx?
Above vocal cords: pierce thyrohyoid membrane
Below vocal cords: enter/leave beneath inferior constrictor of pharynx
32
Arterial & venous supply to larynx
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
Lymphatic drainage of larynx
Above vocal cords:
* Anterosuperior group of deep cervical nodes
Below cords:
* Posteroinferior group of deep cervical nodes
34
Innervation of the larynx
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
Discuss recurrent laryngeal nerve injury
* 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
Discuss external branch of the superior laryngeal nerve damage
* 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
Describe sequence of swallowing
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
Discuss effort closure
Vocal cords powerfully abducted:
* Coughing: cords suddenly abducted = explosion of air
* Straining: closed cords prevent upward displacement of diaphragm - increases intra-abdominal pressure
39
Discuss the Valsalva manoeuvre
* 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
Discuss laryngitis
* 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
Discuss the effect if cigarette smoke
Paralyses cilia and can result in squamous metaplasia, a precursor for cancer
42
Discuss the position of the larynx & implications
* 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
Discuss the trachea
* 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
Blood supply to trachea
Branches of interior thyroid & bronchial arteries
45
Tracheal lymph drainage
Upper part: paratracheal & deep cervical nodes
Lower part: tracheobronchial nodes
46
Innervation of trachea
Sensory & secretomotor: recurrent laryngeal n.
Sympathetic: thoracic sympathetic chain
47
Relations of trachea in the neck
* Oesophagus posteriorly - can bulge trachealis in swallowing
* Thyroid
* CCA, IJV
* Phrenic & vagus nerves
* Recurrent laryngeals ascend bilaterally between trachea & oesophagus
48
Describe the pharynx
* 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
Muscles of the pharynx: outer layer
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
Muscles of the pharynx: inner layer
* Stylopharyngeus: arises from styloid process
* Palatopharyngeus: from palatine aponeurosis
* Salpingopharyngeus: medial end of aud. tube
Pull larynx & pharynx upwards during swallowing
51
Innervation to pharynx
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
Discuss lymphatic tissue at the entrance of the respiratory/digestive tract
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
Discuss tonsilitis
* 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
