Phrenic nerve
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At the time the article was created Henry Knipe had no recorded disclosures.
View Henry Knipe's current disclosuresAt the time the article was last revised Yoshi Yu had no financial relationships to ineligible companies to disclose.
View Yoshi Yu's current disclosures- Phrenic nerves
- Left phrenic nerve
- Right phrenic nerve
The phrenic nerve is a mixed motor/sensory nerve that courses through the neck and thorax to innervate the diaphragm.
On this page:
Gross anatomy
Origin
Arises from the ventral rami of the C3, C4 and C5 nerve roots, part of the cervical plexus.
Course
In the neck, the phrenic nerve lies on the anterior surface of the anterior scalene muscle, passes over the dome of the pleura and enters the thorax posterior to the subclavian vein. The right and left phrenic nerves have a different course in the thorax but as a general rule they descend as lateral as possible whilst keeping in contact with the mediastinal pleura. Both travel anterior to the hilum/bronchus on their respective side.
Left phrenic nerve
After entering the thorax posterior to the subclavian vein it descends lateral to origin of the left subclavian artery, arch of the aorta, left auricle and left ventricle (in contact with pericardium) before piercing the dome of the left hemidiaphragm to enter the abdominal cavity.
Right phrenic nerve
In contrast to the left phrenic nerve, the right is in contact with venous structures and descends lateral to the superior vena cava, right atrium and ventricle, and inferior vena cava before passing through the vena caval foramen to enter the abdominal cavity.
Within the abdominal cavity both the left and right phrenic nerves divide into three main branches - anterior, lateral and posterior. These course peripherally in a radial pattern.
Supply
The phrenic nerve is the sole motor supply to each hemidiaphragm. It also provides sensory supply to:
diaphragm (except the most peripheral diaphragm, which is supplied by intercostal nerves)
mediastinal pleura
central parts of diaphragmatic pleura and peritoneum
Blood supply
arterial supply: pericardiophrenic artery (branch of the internal thoracic artery)
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Variant anatomy
course anterior to the subclavian vein
course along the lateral border of the anterior scalene muscle
may pierce the anterior scalene muscle
accessory phrenic nerve (usually arising from the ansa cervicalis or subclavian nerve)
may receive additional branches from the cervical or brachial plexuses
may supply a branch to the subclavius muscle
Relations
Posterior: Scalenus anterior, 2nd part of subclavian artery (at root of neck)
Anterior: Sternocleidomastoid, inferior belly of omohyoid, internal jugular vein, transverse cervical artery, suprascapular artery, thoracic duct (for left phrenic only) subclavian vein (at base of neck)
Related pathology
Quiz questions
References
- 1. McMINN. Lasts Anatomy Regional and Applied. CHURCHILL LIVINGSTONE. (2003) ISBN:B0084AQDG8. Read it at Google Books - Find it at Amazon
- 2. Bigeleisen PE. Anatomical variations of the phrenic nerve and its clinical implication for supraclavicular block. Br J Anaesth. 2003;91 (6): 916-7. doi:10.1093/bja/aeg254 - Pubmed citation
- 3. In Standring, S. (2016). Gray's anatomy: The anatomical basis of clinical practice.
Incoming Links
- Central tendon of diaphragm
- Accessory phrenic nerve
- Peritoneum
- Pericardiophrenic artery
- Thoracic duct
- Middle mediastinum
- Mediastinum
- Longus colli muscle
- Perivertebral space
- Brachial plexus
- Lesser diaphragmatic apertures
- Thyrocervical trunk
- Diaphragmatic apertures (mnemonic)
- Diaphragm
- Right atrium
- Pericardiophrenic vein
- Diaphragmatic apertures
- Sniff test
- Phrenic nerve paralysis
- Central control of respiration
Related articles: Anatomy: Thoracic
- thoracic skeleton[+][+]
- thoracic cage
- thoracic spine
- articulations
- muscles of the thorax[+][+]
- diaphragm
- intercostal space
- intercostal muscles
- variant anatomy
- spaces of the thorax[+][+]
- thoracic viscera[+][+]
- lower respiratory tract
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heart
- cardiac chambers
- heart valves
- cardiac fibrous skeleton
- innervation of the heart
- development of the heart
- cardiac wall
-
pericardium
- epicardium
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- pericardial space
- oblique pericardial sinus
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pericardial recesses
- aortic recesses
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- postcaval recess
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- pericardial ligaments
- myocardium
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pericardium
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-
thoracic aorta (development)
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ascending aorta
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aortic root
- aortic annulus
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coronary arteries
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- myocardial segments
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left main coronary artery (LMCA)
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circumflex artery (LCx)
- obtuse marginal branches (OM1, OM2, etc))
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left anterior descending artery (LAD)
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right coronary artery (RCA)
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- congenital anomalies
- sinotubular junction
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aortic root
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- aortic isthmus
- descending aorta
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ascending aorta
- pulmonary trunk
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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
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cranial vault
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sutures
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facial bones
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facial muscles
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orbicularis oris muscle
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orbicularis oris muscle
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deep spaces of the neck
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arterial supply
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common carotid artery
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common carotid artery
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arterial supply
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cranial nerves
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trigeminal nerve (CN V) (mnemonic)
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vestibulocochlear nerve (CN VIII)
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