Respiratory anatomy

Relations

Inferior: roof of mouth

superior: cribriform plate

posterior: nasopharynx

anterior: external nose, nares

lateral: orbit, maxillary sinus

medial: septum

Features

Vestibular area (skin, at nares), olfactory area (at roof), respiratory area (ciliated columnar)

Contains hairs which filter large particles

Chonchae: promote turbulant flow to faciliate heating and humidification of inspired gas, and reclaimiation of expired gas

Function

  Humidification and warming of inspired air

  Reclamation of expired moisture and heat

  Olfaction and sense information about air temperature

  Speech (nasalisation)

  Sneezing (protective reflex)

Relations

Superior: hard and soft palate

inferior: tongue

lateral: cheeks

anterior: lips

posterior: oropharynx

Features

Tongue sensory: 

    Anterior 2/3: lingual nerve & chorda tympani

    Posterior 1/3: Glossopharyngeal nerve

Tongue taste:

Anterior 2/3: facial

Posterior 1/3: Glossopharyngeal

Tongue motor: Hypoglossal, nerve, except for the palatoglossus muscle (supplied by cranial part of the vagus)

Function

Respiration (alternative airway, low resistance at high MV)

Mastication

Saliva (digestive and immunological roles)

Speech

Sensory roles, including taste

Pharyngeal dilator reflex

Negative upper airway pressure \(\to\) mucosal stretch receptors \(\to\) hypoglossal nucleus \(\to\) genioglossus and other dilator muscles

Genioglossus pulls base of tongue anterior (hypoglossal N) and maintains upper airway patency

Relations

  Superior: hyoid

  Anterior: skin, thryoid

Inferior: becomes trachea at c6

  Posterior: laryngeal inlet

Laryngeal inlet

    Faces backwards and upwards

    Bounded anteriorly by the upper edge of the epiglottis,

    Bounded laterally and postriorly by the aryepiglottic folds

    Bounded posteriorly by the interarytenoid fissure

  Divided by the vocal folds into upper and lower half

Features

Supply: superior and inferior thyroid arteries

Innervation: all muscles by the recurrent laryngeal nerve except cricothyroid (external laryngeal nerve)

Function

  Respiration (conductive airway)

  Swallowing

  Phonation

  Cough reflex

Relations:

Superior: larynx at c6

Inferior: carina at t5

Features

Innervations by vagus and recurrent laryneal nerves

Posterior wall formed by trachealis muscle (constricts during coughing \(\to\) increased gas velocity)

Function

  Airway

  Cough

  Mucus clearance: mucociliary escalator function

  Restoring the position of the larynx during swallowing

Diaphragm is dome-shaped fibromuscular structure. Separates thoracic and abdominal cavities. Primary muscle of inspiration

Origin: L1-L3 posteriorly, costal cartileges 6-12 anterolaterally

Insertion: central aponeurotic tendon continuous with inferior pericardium + liver capsule

Openings:

1. Caval hiatus @ T8: contains IVC
2. Oesophaeal hiatus @ T10 contains oesophagus, vagal trunks
3. Aortic hiatus @ T12 contains aorta, azygous vein

Supply: aorta \(\to\) superior and inferior phrenic arteries

Innervation: Motor and senosry by paired phrenic nn (C3-5)

Function:

1. Diaphragm contracts \(\to\) flattens and descends
2. Ribs pushed outwards
3. AP, lateral, and vertical dimensions of chest increased, abdomen compressed
4. \(\uparrow\)intrabdominal pressure, \(downarrow\)intrathoracic pressure
5. Inhalation occurs
6. Oesophageal hiatus constricts \(\to\) prevents reflux