Long Thoracic Nerve: Difference between revisions

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== Description ==
== Description ==
The long thoracic nerve is also known as the external respiratory nerve of bell or posterior thoracic nerve, It arises from the superior trunk of the brachial plexus after which it descends posterior to the brachial plexus and anterior to the posterior scalene muscle, passes over the 1st rib, descends along the lateral aspect of the thoracic wall at the mid-axillary line for a distance of approximately 22-24 cm. This long and superficial course of the nerve makes is susceptible to various injuries. <sup>[1]</sup>
The long thoracic nerve is also known as the external respiratory nerve of Bell or the posterior thoracic nerve<ref name=":0">Lung K, Lui F. Anatomy, Thorax, Long Thoracic Nerve. [Updated 2020 Jul 31]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK535396/</ref>. It originates from the superior trunk of the brachial plexus after which it descends posterior to the brachial plexus and anterior to the posterior scalene muscle. It passes over the chest wall and lies on the superficial surface of the serratus anterior muscle<ref name=":0" /><ref name=":1">Bilfeld MF, Lapègue F, Cintas P, Acket B, Basselerie H, Bachour R, Nougarolis F, Ricard C, Gandois HC, Laumonerie P, Aprodoaei C. [https://www.sciencedirect.com/science/article/pii/S2211568420302187 Ultrasonographic anatomy of the long thoracic nerve: A reappraisal using high frequency (24-MHz) probe.] Diagnostic and Interventional Imaging. 2021 Apr 1;102(4):241-5.</ref>. The long (22-24cm) and superficial course of this nerve makes it susceptible to various injuries<ref name=":0" />. The long thoracic nerve has an upper (C5 and C6 ) and lower portion (C7) which fuse in the axilla<ref name=":0" /><ref name=":1" />.


== Root  ==
== Root  ==
Anterior Ramii of C<sub>5</sub>, C<sub>6</sub>, C<sub>7</sub>
The long thoracic nerve originates at the anterior ramii of C5, C6, C7<ref name=":0" /><ref name=":1" />.


In a small percentage of population (approximately 10%), the long thoracic nerve receives supply from C<sub>8</sub> nerve root as well.<sup>[1]</sup>
In a small percentage of population the long thoracic nerve receives contributions from C4 (5%) <ref name=":1" />and  C8 (10%)<ref name=":0" /><ref name=":1" /> nerve roots as well.


== Function  ==
== Function  ==
The long thoracic nerve is a motor nerve that supplies the [[Serratus Anterior|Serratus anterior muscle]] which is responsible for shoulder protraction (during punching) and upward rotation of scapula during lifting.
Motor function
 
The long thoracic nerves solely innervates the [[Serratus Anterior|serratus anterior muscle]] which is primarily responsible for shoulder protraction. It also works with [[trapezius]] to provide sustained upward rotation of scapula which is needed for overhead lifting<ref name=":0" />.


== Injury to the Long thoracic nerve  ==
== Injury to the Long thoracic nerve  ==
Injury to long thoracic nerve can cause paralysis of the serratus anterior muscle leading to a phenomenon called [[Winged scapula|Winging of scapula]].  
Injury to long thoracic nerve can cause weakness of the serratus anterior muscle and dynamic [[Winged scapula|winging of scapula]]<ref name=":0" /><ref name=":1" />.
 
There are various causes for injury to long thoracic nerve but they can be mainly divided into 3 categories i.e. non-traumatic, traumatic and iatrogenic.
 
Non-traumatic:
 
* viral illness (influenza)<ref name=":2">Martin RM, Fish DE. [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2684151/ Scapular winging: anatomical review, diagnosis, and treatments.] ''Curr Rev Musculoskelet Med''. 2008;1(1):1-11. doi:10.1007/s12178-007-9000-5</ref>
* tonsillitis-bronchitis<ref name=":2" />
* poliomyelitis<ref name=":2" />
* allergic drug reactions<ref name=":2" />
* muscular dystrophy (facio-scapulohumeral dystrophy)<ref name=":2" />
* Parsonage-Turner syndrome<ref name=":1" />
 
 
Traumatic:


There are various causes for injury to long thoracic nerve but they can be mainly divided into 3 categories i.e. Non-traumatic, traumatic and Iatrogenic.
* clavicle or upper rib fractures<ref name=":1" />
* sudden scapular depression<ref name=":2" />
* repetitive arm movements as seen in athletes<ref name=":2" />(especially in athletes where arm abduction and external rotation is combined with contralateral neck and neck movement e.g. javelin<ref name=":1" />)
* house-hold activities such as digging, car washing or prolonged lying in bed with arm abducted and propping up the head to read<ref name=":2" />


The causes of non-traumatic injury to long thoracic nerve include Viral illness (influenza), Tonsillitis-bronchitis, Poliomyelitis, allergic drug reactions and muscular dystrophy (facio-scapulohumeral dystrophy).<sup>[2]</sup>


The causes of traumatic injury include sudden scapular depression, repetitive arm movements as seen in athletes and house-hold activities such as digging, car washing or prolonged lying in bed with arm abducted and propping up head to read.<sup>[2]</sup>
Iatrogenic injury:


The causes of Iatrogenic injury include use of a single axillary crutch<sup>[3]</sup>, mastectomies with axillary node dissection and spontaneous pneumothorax.<sup>[2]</sup>
* use of a single axillary crutch<ref>Murphy MT, Journeaux SF. Case reports: long thoracic nerve palsy after using a single axillary crutch. ''Clin Orthop Relat Res''. 2006;447:267-269. [https://journals.lww.com/clinorthop/_layouts/15/oaks.journals/downloadpdf.aspx?trckng_src_pg=ArticleViewer&an=00003086-200606000-00043 doi:10.1097/01.blo.0000205880.27964.a3]</ref>  
* mastectomy<ref name=":1" /><ref name=":2" />
* axillary node dissection <ref name=":1" /><ref name=":2" />
* scalenectomy<ref name=":1" />


== References  ==
== References  ==

Revision as of 18:05, 19 March 2023

Original Editor - Ankit Shah

Top Contributors - Ankit Shah, Wendy Snyders and Rahma Ahmed Ahmed Bahbah

Description[edit | edit source]

The long thoracic nerve is also known as the external respiratory nerve of Bell or the posterior thoracic nerve[1]. It originates from the superior trunk of the brachial plexus after which it descends posterior to the brachial plexus and anterior to the posterior scalene muscle. It passes over the chest wall and lies on the superficial surface of the serratus anterior muscle[1][2]. The long (22-24cm) and superficial course of this nerve makes it susceptible to various injuries[1]. The long thoracic nerve has an upper (C5 and C6 ) and lower portion (C7) which fuse in the axilla[1][2].

Root[edit | edit source]

The long thoracic nerve originates at the anterior ramii of C5, C6, C7[1][2].

In a small percentage of population the long thoracic nerve receives contributions from C4 (5%) [2]and C8 (10%)[1][2] nerve roots as well.

Function[edit | edit source]

Motor function

The long thoracic nerves solely innervates the serratus anterior muscle which is primarily responsible for shoulder protraction. It also works with trapezius to provide sustained upward rotation of scapula which is needed for overhead lifting[1].

Injury to the Long thoracic nerve[edit | edit source]

Injury to long thoracic nerve can cause weakness of the serratus anterior muscle and dynamic winging of scapula[1][2].

There are various causes for injury to long thoracic nerve but they can be mainly divided into 3 categories i.e. non-traumatic, traumatic and iatrogenic.

Non-traumatic:

  • viral illness (influenza)[3]
  • tonsillitis-bronchitis[3]
  • poliomyelitis[3]
  • allergic drug reactions[3]
  • muscular dystrophy (facio-scapulohumeral dystrophy)[3]
  • Parsonage-Turner syndrome[2]


Traumatic:

  • clavicle or upper rib fractures[2]
  • sudden scapular depression[3]
  • repetitive arm movements as seen in athletes[3](especially in athletes where arm abduction and external rotation is combined with contralateral neck and neck movement e.g. javelin[2])
  • house-hold activities such as digging, car washing or prolonged lying in bed with arm abducted and propping up the head to read[3]


Iatrogenic injury:

  • use of a single axillary crutch[4]
  • mastectomy[2][3]
  • axillary node dissection [2][3]
  • scalenectomy[2]

References[edit | edit source]

[1] Lung K, Lui F. Anatomy, Thorax, Long Thoracic Nerve. [Updated 2020 Jul 31]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK535396/

[2] Martin RM, Fish DE. Scapular winging: anatomical review, diagnosis, and treatments. Curr Rev Musculoskelet Med. 2008;1(1):1-11. doi:10.1007/s12178-007-9000-5

[3] Murphy MT, Journeaux SF. Case reports: long thoracic nerve palsy after using a single axillary crutch. Clin Orthop Relat Res. 2006;447:267-269. doi:10.1097/01.blo.0000205880.27964.a3

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Lung K, Lui F. Anatomy, Thorax, Long Thoracic Nerve. [Updated 2020 Jul 31]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK535396/
  2. ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 Bilfeld MF, Lapègue F, Cintas P, Acket B, Basselerie H, Bachour R, Nougarolis F, Ricard C, Gandois HC, Laumonerie P, Aprodoaei C. Ultrasonographic anatomy of the long thoracic nerve: A reappraisal using high frequency (24-MHz) probe. Diagnostic and Interventional Imaging. 2021 Apr 1;102(4):241-5.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 Martin RM, Fish DE. Scapular winging: anatomical review, diagnosis, and treatments. Curr Rev Musculoskelet Med. 2008;1(1):1-11. doi:10.1007/s12178-007-9000-5
  4. ↑ Murphy MT, Journeaux SF. Case reports: long thoracic nerve palsy after using a single axillary crutch. Clin Orthop Relat Res. 2006;447:267-269. doi:10.1097/01.blo.0000205880.27964.a3
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