� Intro
� Afferent
� Controller
� Efferent
Definition |
� Forceful expiration to expel mucous or foreign material from airways. Keeps lower resp tract sterile. � Can be voluntary or involuntary |
Sequence |
� Fast inspiration � Close glottis � Contract chest and abdo wall � ↑Intrathoracic pressure (ITP) ~100mmHg � Release glottis � Expiration fast (80km/h) and turbulent (to expunge wall-adherent material) |
Purpose |
� Keep airways sterile |
Significance to anaesthesia |
� Suppressed under GA � hypnotics, opioids � Risk of aspiration |
Sensors |
� Mucosal irritant receptors on C fibres � Mechanical or chemical stimuli. E.g. water, food, dust � From pharynx to resp bronchioles, esp carina |
Pathway |
� General visceral afferents: via dorsal horn and spinomedullary tract � CNIX: pharynx -> nucleus tractus solitarius (NTS) � CNX: -> the NTS o Pharynx: own branch x 2 o Larynx above vocal cords: internal branch of superior laryngeal nerve x 2 o Larynx below vocal cords, trachea, bronchi: recurrent laryngeal nerve x 2 |
Afferents to |
� Nucleus tractus solitarius |
Integration |
� Medullary respiratory centre |
Efferents from |
� Nucleus ambiguus (pharynx, larynx) � Dorsal motor nucleus of vagus |
|
Muscle |
Innervation |
Inspiration |
Diaphragm |
C3-5 |
External intercostals |
Intercostal nerves |
|
Pharyngeal dilators |
CNIX CNX pharyngeal branches |
|
Glottic closure |
Lateral cricoarytenoid Interarytenoid |
CNX recurrent laryngeal |
Increased intrathoracic pressure |
Internal intercostals |
Intercostal nerves |
Abdominals (rectus, transversus, internal and external obliques) |
Lower intercostal nerves Subcostal nerves Iliohypogastric Ilioinguinal |
|
Latissimus dorsi |
Thoracodorsal nerve |
|
Serratus posterior inferior |
Intercostal nerves |
|
Quadratus lumborum |
Subcostal nerve |
|
Glottic release |
Posterior cricoarytenoid (and relax glottic closure muscles) |
CNX recurrent laryngeal |
Forceful expiration |
(as for increased intrathoracic pressure) |
|
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