Respiratory tract
Citation, DOI, disclosures and article data
Citation:
Bell D, MacManus D, Respiratory tract. Reference article, Radiopaedia.org (Accessed on 21 Mar 2025) https://doi.org/10.53347/rID-87037
rID:
87037
Article created:
Disclosures:
At the time the article was created Daniel J Bell had no recorded disclosures.
View Daniel J Bell's current disclosures
Last revised:
Disclosures:
At the time the article was last revised Daniel J Bell had no financial relationships to ineligible companies to disclose.
View Daniel J Bell's current disclosures
Revisions:
5 times, by
2 contributors -
see full revision history and disclosures
Systems:
Sections:
Tags:
Synonyms:
- Upper respiratory tracts (URTs)
- Upper respiratory tract (URT)
- Lower respiratory tract (LRT)
- Lower respiratory tracts (LRTs)
- Upper airways
- Lower airways
- Airways (anatomy)
- Airway (anatomy)
- Respiratory tracts
The respiratory tract refers to the portion of the respiratory system that conducts air into and out of the body. It is conventionally divided into upper and lower tracts.
The upper respiratory tract (URT), also known as the upper airways, is the collective term for the components of the respiratory system proximal to the trachea:
Some texts include the paranasal sinuses in the upper respiratory tract as they are in direct communication with the nasal cavity, lined by a thin layer of respiratory epithelium and play a role in humidification of the inspired air and phonation.
The lower respiratory tract (LRT), also known as the lower airways, is the collective term for the components of the respiratory system distal to the larynx:
-
tracheobronchial tree
- trachea
- main bronchi
- bronchial tree
- functional airways (distal to the terminal bronchioles)
References
- 1. Wynn Kapit, Lawrence M. Elson. The Anatomy Coloring Book. (2014) ISBN: 9780321832016 - Google Books
- 2. Patwa A & Shah A. Anatomy and Physiology of Respiratory System Relevant to Anaesthesia. Indian J Anaesth. 2015;59(9):533-41. doi:10.4103/0019-5049.165849 - Pubmed
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- thoracic cage
- thoracic spine
- articulations
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- diaphragm
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- intercostal muscles
- variant anatomy
- spaces of the thorax[+][+]
- thoracic viscera
-
lower respiratory tract
- tracheobronchial tree
-
lungs
-
bronchopulmonary segmental anatomy (Boyden Classification) (mnemonic)[+][+]
- left lung
- right lung
- variant anatomy
- lung parenchyma[+][+]
- hilum[+][+]
- pleura[+][+]
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bronchopulmonary segmental anatomy (Boyden Classification) (mnemonic)[+][+]
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heart[+][+]
- cardiac chambers
- heart valves
- cardiac fibrous skeleton
- innervation of the heart
- development of the heart
- cardiac wall
-
pericardium
- epicardium
- epicardial fat pad
- pericardial space
- oblique pericardial sinus
- transverse pericardial sinus
-
pericardial recesses
- aortic recesses
- pulmonic recesses
- postcaval recess
- pulmonary venous recesses
- pericardial ligaments
- myocardium
- endocardium
-
pericardium
- esophagus[+][+]
- thymus[+][+]
- breast[+][+]
-
lower respiratory tract
- arterial supply of the thorax[+][+]
-
thoracic aorta (development)
-
ascending aorta
-
aortic root
- aortic annulus
-
coronary arteries
- coronary arterial dominance
- myocardial segments
-
left main coronary artery (LMCA)
- ramus intermedius artery (RI)
-
circumflex artery (LCx)
- obtuse marginal branches (OM1, OM2, etc))
- Kugel's artery
-
left anterior descending artery (LAD)
- diagonal branches (D1, D2, etc)
- septal perforators (S1, S2, etc)
-
right coronary artery (RCA)
- conus artery
- sinoatrial nodal artery
- acute marginal branches (AM1, AM2, etc)
- inferior interventricular artery (PDA)
- posterior left ventricular artery (PLV)
- congenital anomalies
- sinotubular junction
-
aortic root
- aortic arch
- aortic isthmus
- descending aorta
-
ascending aorta
- pulmonary trunk
-
thoracic aorta (development)
- venous drainage of the thorax[+][+]
- superior vena cava (SVC)
- inferior vena cava (IVC)
-
coronary veins
-
cardiac veins which drain into the coronary sinus
- great cardiac vein
- middle cardiac vein
- small cardiac vein
- posterior vein of the left ventricle
- vein of Marshall (oblique vein of the left atrium)
- anterior cardiac veins
- venae cordis minimae (smallest cardiac veins or thebesian veins)
-
cardiac veins which drain into the coronary sinus
- pulmonary veins
- bronchial veins
- thoracoepigastric vein
- lymphatics of the thorax[+][+]
- innervation of the thorax[+][+]
Related articles: Anatomy: Head and neck
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-
cranial vault
- scalp (mnemonic)
- fontanelle
-
sutures
- calvarial
- facial
- frontozygomatic suture
- frontomaxillary suture
- frontolacrimal suture
- frontonasal suture
- temporozygomatic suture
- zygomaticomaxillary suture
- parietotemporal suture (parietomastoid suture)
- occipitotemporal suture (occipitomastoid suture)
- sphenofrontal suture
- sphenozygomatic suture
- spheno-occipital suture (not a true suture)
- lacrimomaxillary suture
- nasomaxillary suture
- internasal suture
- basal/internal
- skull landmarks
- frontal bone
- temporal bone
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- occipital bone
- skull base (foramina)
-
facial bones
- midline single bones
- paired bilateral bones
- cervical spine
- hyoid bone
- laryngeal cartilages
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cranial vault
- muscles of the head and neck
- muscles of the tongue (mnemonic)
- muscles of mastication
-
facial muscles
- epicranius muscle
- circumorbital and palpebral muscles
- nasal muscles
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buccolabial muscles
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- levator labii superioris alaeque nasalis muscle
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- zygomaticus major muscle
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- depressor labii inferioris muscle
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- mentalis muscle
- compound sphincter
-
orbicularis oris muscle
- incisivus labii superioris muscle
- incisivus labii inferioris muscle
-
orbicularis oris muscle
- muscle of mastication
- modiolus
- elevators, retractors and evertors of the upper lip
- muscles of the middle ear
- orbital muscles
- muscles of the soft palate
- pharyngeal muscles
- suprahyoid muscles
- infrahyoid muscles
- intrinsic muscles of the larynx
- muscles of the neck
- platysma muscle
- longus colli muscle
- longus capitis muscle
- scalenus anterior muscle
- scalenus medius muscle
- scalenus posterior muscle
- scalenus pleuralis muscle
- sternocleidomastoid muscle
-
suboccipital muscles
- rectus capitis posterior major muscle
- rectus capitis posterior minor muscle
- obliquus capitis superior muscle
- obliquus capitis inferior muscle
- accessory muscles of the neck
- deep cervical fascia
-
deep spaces of the neck
- anterior cervical space
- buccal space
- carotid space
- danger space
- deep cervical fascia
- infratemporal fossa
- masticator space
- parapharyngeal space
- stylomandibular tunnel
- parotid space
- pharyngeal (superficial) mucosal space
- perivertebral space
- posterior cervical space
- pterygopalatine fossa
- retropharyngeal space
- suprasternal space (of Burns)
- visceral space
- surgical triangles of the neck
- orbit
- ear
- paranasal sinuses
- upper respiratory tract
- viscera of the neck
- blood supply of the head and neck
-
arterial supply
-
common carotid artery
- carotid body
- carotid bifurcation
- subclavian artery
- variants
-
common carotid artery
- venous drainage
-
arterial supply
- innervation of the head and neck
-
cranial nerves
- olfactory nerve (CN I)
- optic nerve (CN II)
- oculomotor nerve (CN III)
- trochlear nerve (CN IV)
-
trigeminal nerve (CN V) (mnemonic)
- trigeminal ganglion
- ophthalmic division
- maxillary division
- mandibular division
- abducens nerve (CN VI)
- facial nerve (CN VII)
-
vestibulocochlear nerve (CN VIII)
- vestibular ganglion (Scarpa's ganglion)
- glossopharyngeal nerve (CN IX)
- vagus nerve (CN X)
- (spinal) accessory nerve (CN XI)
- hypoglossal nerve (CN XII)
- parasympathetic ganglia of the head and neck
- cervical sympathetic ganglia
- greater occipital nerve
- third occipital nerve
-
cervical plexus
- muscular branches
- longus capitis
- longus colli
- scalenes
- geniohyoid
- thyrohyoid
-
ansa cervicalis
- omohyoid (superior and inferior bellies separately)
- sternothyroid
- sternohyoid
- phrenic nerve
- contribution to the accessory nerve (CN XI)
- cutaneous branches
- muscular branches
- brachial plexus
- pharyngeal plexus
-
cranial nerves
- lymphatic drainage of the head and neck
- embryological development of the head and neck
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