The Airways Flashcards
Respiratory system comprises:
Nose, pharynx, larynx, trachea, bronchi and lungs.
Classification:
> Upper airways:
Nose
Pharynx
Associated structures.
> Lower airways: Larynx Trachea Bronchi Lungs 5
The nose
- Provides an airway for resp.
- Moistens and warms air
- Filters inhaled air
- Resonating chamber for speech
- Houses olfactory receptors
- External nose and internal nasal cavity
External nose:
Apex and root
-dorsum, nares (nostrils), alae and vestibule
Bony framework
– Nasal part of frontal bone, nasal bones, frontal processes of maxillae and bony parts of nasal septum
Cartilaginous framework
– septal cartilage, 2 lat. nasal cartilages, and 2 alar cartilages
Nasal septum
- 1/2s nasal cavities
- Found between nares ant. and choanae post.
- Inf. 2⁄3 of made up of nasal mucosa = Respiratory area, warms
and moistens air - Sup. 1⁄3 = Olfactory area for smell
Components:
Bony part
- Perpendicular plate of ethmoid bone, Cribriform plate and crista
galli
- Vomer --> Postero-inferior part
Cartilaginous part
- Septal cartilage (hyaline cartilage)
Nasal cavity: BoundariesLook at nasal 1 - 7 diagrams
Nasal cavity: Boundaries
Roof:
Nasal, frontal, sphenoid, cribriform plate of ethmoid
Floor:
Maxilla and palatine bones
Medial wall: (septum)
Ethmoid (perp. Plate)
Vomer, septal cartilage
Lateral wall:
Three shelves, formed by projections of the sup., middle, and inf. nasal conchae, extend out of each lat. wall
= nasal conchae (actual bones) / turbinates (still covered by resp. epithelium.)
Clean and humidifies air
Meatuses – groovelike passageways
Posterosuperior spheno- ethmoidal recess
Lateral wall of the nasal cavity contains the following openings:
Sphenoethmoidal recess - Between sup. Nasal concha and sphenoid - Contains opening from sphenoid sinus Superior meatus - Inf. To sup. Nasal concha - openings of post. Ethmoidal air cells Middle meatus - Inf. To middle nasal concha - Opening for frontal sinus (nasofrontal duct) - Middle ethmoidal air cells (ethmoidal bulla) - Ant. Ethmoidal air cells - Maxillary sinus (hiatus semilunaris) Inferior meatus - Inf. To inf. Nasal concha - Opening for nasolacrimal duct (drains tears from Eye)
Paranasal sinuses
air-filled extensions of respiratory part of nasal cavity into frontal, ethmoid, sphenoid bone and maxilla
Functions:
↑ surface area for cleaning & humidifying air
and lightens weight of skull
Arterial supply of the nasal cavity:
Branches off one another:
1. Internal carotid artery - ophthalmic artery - Ant. And post.
Ethmoidal arteries
2. External carotid artery - Maxillary A - Sphenopalatine artery
3. External carotid artery (External nose from other branches) -
Facial artery - Septal branches
Venous drainage of the nasal cavity:
Medial & lat. Walls drain via submucosal venous plexus into sphenopalatine, facial & opthalmic vv.
–> Thermoregulation (altering the temperature of air.)
Nerve supply of nose
Opthalmic n. Branch of Trigeminal n – cranial n V1 • Anterior and posterior ethmoidal nn. from nasociliary n. Maxillary n. Branch of Trigeminal n – cranial n V2 • Nasopalatine n. - septum • Greater palatine n. - lateral wall Dorsum & apex: Mostly opthalmic n. • Infratrochlear n. • Anterior ethmoidal n. Alae: Maxillary n. • Infra-orbital n.
Pharynx
• Extends from the skull base to the inferior border of the cricoid
cartilage (at the level of C6), and is continuous with the esophagus
• Ant. to vertebral bodies
•Divided into 3 parts according to the part with which it communicates:
nasopharynx, oropharynx and laryngopharynx
Nasopharynx
Posterior to nasal cavities
superior to soft palate
Begins behind Choanae
Nasopharynx Contains lymphoid tissue:
- pharyngeal tonsil (adenoids) in roof & post. Wall
- tubal tonsils adjacent to opening auditory tube
Openings of pharyngotympanic tubes (Eustachian) on lat. walls
- connect the nasopharynx to each tympanic cavity.
- Equalize pressure middle ear with atmospheric pressure
Pharyngeal recess
Respiratory function
Pharyngotympanic tube
- Part of nasopharynx
• Opening post. to inf. nasal meatus
• Posterolat. 1⁄3 is bony remainder cartilaginous
• Equalize pressure middle ear with atmospheric pressure
• Opened by mm.levator veli palatini & tensor veli palatini
• Salpingopharyngeal fold covers those muscles
• Tubal tonsils adjacent to openings of tubes
Pharyngotympanic tube
Oropharynx
- Posterior to oral cavity
- Boundaries:
• Extends from soft palate sup. to sup. border epiglottis
• Palatoglossal and palatopharyngeal arches laterally
• Soft palate sup. & base tongue inf. - Lymphoid tissue:
o Palatine tonsils between palatoglossal and palatopharyngeal arches/folds
o Lingual tonsils on post. third of tongue - Digestive function
Laryngopharynx
- Posterior to the larynx.
- Ant.C4–C6
- Extending from the superior border of the epiglottis to the inferior border of the cricoid cartilage.
- Walls Constrictor muscles
- Laryngeal inlet. (entrance)
- Piriform fossa (recess) – where inhaled objects can get stuck
Laryngopharynx is a shared pathway for food and air.
Food:
Moves from the oral cavity, through the oropharynx and then into the esophagus
Air:
Nasopharynx/Oropharynx – depends on if you’re mouth breathing or not –> into the larynx
[So overlap]
When a bolus of food is swallowed – pushes epiglottis closed – so it flaps down over the opening of the larynx = food directed into esophagus
Muscles of the pharynx
External circular layer consists of:
o sup.,
o middle &
o Inf. constrictor
internal longitudinal layer - 3 muscles:
o Palatopharyngeus
o Stylopharyngeus
o salpingopharyngeus
Internal fascial lining - pharyngobasilar fascia
External fascial covering - buccopharyngeal fascia
Circular muscles of pharynx
o sup.,
o middle &
o Inf. constrictor
internal longitudinal layer - 3 muscles:
o Palatopharyngeus
o Stylopharyngeus
o salpingopharyngeus
Gaps between muscles of pharynx and what they contain
- Between superior pharyngeal constrictor and cranium
• Levator veli palatini
• Pharyngotympanic tube
• Ascending palatine a. - Between Superior & middle constrictor
• Stylopharyngeus
• Glossopharyngeal n.
• Stylohyoid ligament - Between Middle and inferior constrictor
• Internal laryngeal n.
• Superior laryngeal a. & v. - Inferior to inferior constrictor
• Recurrent laryngeal n.
• Inferior laryngeal a
Nerve supply of the pharynx
The nerve supply of the pharynx (motor and most of sensory) derives from the pharyngeal plexus of nerves. Located on posterolat. aspect of pharynx
• N glossopharyngeus (CN IX)
• N vagus (CN X)
• Sympathetic branches
Motor supply:
all the muscles of the pharynx are supplied by N. vagus (CN X) via pharyngeal plexus, except stylopharyngeus [supplied by N. glossopharyngeus (CN IX)]
Sensory:
mainly fibres of N. glossopharyngeus (CN IX) for mucosa of all
three parts.
Mucosa ant. and sup. nasopharynx additionally from maxillary nerve (CN V2)
Blood supply of: Pharynx – upper parts
Branches from: a. carotis externa : • ascending pharyngeal a. • lingual a. • facial a. • maxillary a. • sup. thyroid a Thyrocervical trunk • ascending cervical artery.
Blood supply of: Pharynx – lower parts:
• Branches inf. thyroid a. (subclavian)
Blood supply of: Pharyngeal venous plexus
• On post. wall and borders of pharynx
• Drains sup. into pterygoid plexus of veins in infratemporal
fossa, and inf. into internal jugular vein
Larynx
• Produces sound and acts as valve to close lower respiratory
tract
• Ant. to C4 – C6, between oropharynx and trachea
Position & structure of cartilages of larynx
• Laryngeal skeleton - 9 cartilages:
3 single:
o thyroid(2 hyaline laminae & laryngeal prominence)
o cricoid(Signet-shaped. Hyaline cartilage inf. to thyroid cartilage)
o epiglottis(Elastic leaf-shaped plate, attached to thyroid
cartilage)
3 paired:
o arytenoid(pyramidal, on cricoid cartilage)
o corniculate(on apex of arytenoid cartilage)
o cuneiform(in ary-epiglottic folds)
Membranes of Larynx
Larynx situated inf. To hyoid bone and is attached to it via the:
Thyrohyoid membrane
• On outside of larynx
• Extends from thyroid cartilage up to inner surface of hyoid
bone
• Thickened in center to form median thyrohyoid ligament
• Posterior free edges thickened to form lateral thyrohyoid
ligaments
• Allows internal laryngeal nerve + superior laryngeal artery to
pass through
Quadrangular membrane
• Submucosal sheet of connective tissue
• Between lateral border of epiglottis and arytenoid on each
side
• [2 on each side] Inferior free edge is vestibular lig. (false
vocal chord)
- covered with mucosa = vestibular fold (protective in function)
• [2 on each side] Superior free edge is aryepiglottic lig
Marks entrance to larynx
Conus elasticus
Extends from upper edge of cricoid up to midline of thyroid cartilage
• Lateral & median cricothyroid ligament
(Cricovocal membrane = lat. part conus elasticus)
• Thickened sup. border is vocal lig., between vocal proc. of
arytenoid to junction of laminae of thyroid cartilage = true
vocal chords
Ligaments of Larynx - summary
• Hyo-epiglottic – between hyoid and epiglottis
• Median and lateral thyrohyoid – thickenings in thyrohyoid
membrane
• Median and lateral cricothyroid – between cricoid and thyroid
cartilages
• Thyro-epiglottic – attaches stalk epiglottis to inside thyroid
laminae
• Ary-epiglottic – thickening of upper free edge of quadrangular
membrane, covered with mucosa = ary-epigglotic fold
• Vestibular – thickening of lower free edge of quadrangular
membrane
• Vocal – thickening of upper free edge of conus elasticus
Laryngeal ventricle
= space between Vestibular fold and vocal fold
- Superior to it = laryngeal vestibule; supraglottic cavity
- Inferior to it = infraglottic cavity
Vocal folds
Contains:
• Vocal lig. – thickened elastic tissue in medial free edge of
conus elasticus
• Vocalis muscle – fine muscle fibres lateral to vocal ligaments
Vocal lig. and thyro- arytenoid muscles covered by mucosa
= vocal folds
= true vocal chords
Control sound production
Interior of larynx – laryngeal cavity
laryngeal cavity
Extends from laryngeal inlet to inferior border of cricoid cartilage
Cavity includes:
Laryngeal vestibule
Middle part of cavity
Laryngeal ventricle
Infraglottic cavity
Rima vestibuli (opening between vestibular folds)
Rima glottidis (opening between vocal folds) – Shape of rima glottidis varies with resp – E.G: gets bigger during forced expiration
Glottis
= vocal folds and processes, & rima glottidis
Muscles of larynx
Extrinsic laryngeal muscles
Intrinsic laryngeal muscles
Extrinsic laryngeal muscles
> move larynx as whole
- Suprahyoid & stylopharyngeus elevate larynx and hyoid
- Infrahyoid muscles depress larynx and hyoid
Originate from somewhere else (head and neck) and attach onto larynx – Usually onto the hyoid bone
Intrinsic laryngeal muscles
move parts of larynx on each other
- Concerned with changes in length & tension of vocal folds in production of sound, and changing size of Rima glottidis to facilitate passage of air
- Divided into functional groups
> Adductors & abductors – move the arytenoid cartilages
> Sphincters – close off the glottis completely
> Tensors & relaxers
Blood supply of larynx
Arteries:
All come from laryngeal branches of superior and inferior thyroid artery
Veins:
superior and inferior laryngeal veins join thyroid veins
Nerve supply of larynx
Motor supply:
o All intrinsic muscles of larynx supplied by:
- (Vagus) Recurrent laryngeal nerve
o except cricothyroid muscle
- (Vagus) External laryngeal nerve supplies
Sensory:
o Mucosa above vocal folds
- internal branch of superior laryngeal nerve
o Below: recurrent laryngeal nerve
