The long thoracic nerve (external respiratory nerve of Bell; posterior thoracic nerve) innervates the

serratus anterior muscle The serratus anterior is a muscle that originates on the surface of the 1st to 8th ribs at the side of the chest and inserts along the entire anterior length of the medial border of the scapula. The serratus anterior acts to pull the scapula fo ...

Structure

The long thoracic nerve arises from the

anterior rami The ventral ramus (pl. ''rami'') (Latin for ''branch'') is the anterior division of a spinal nerve. The ventral rami supply the antero-lateral parts of the trunk (anatomy), trunk and the limbs. They are mainly larger than the dorsal ramus of spinal ...

of the C5, C6, and C7 cervical

spinal nerve A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each side of the vertebral column. These are grouped into th ...

. The root from C7 may occasionally be absent. The roots from C5 and C6 pierce through the

scalenus medius The scalene muscles are a group of three pairs of muscles in the lateral neck, namely the anterior scalene, middle scalene, and posterior scalene. They are innervated by the third to the eight cervical spinal nerves (C3-C8). The anterior and ...

, while the C7 root passes in front of the muscle. The long thoracic nerve descends through the cervicoaxillary canal. It is posterior to the

brachial plexus The brachial plexus is a network () of nerves formed by the anterior rami of the lower four cervical nerves and first thoracic nerve ( C5, C6, C7, C8, and T1). This plexus extends from the spinal cord, through the cervicoaxillary canal in th ...

, and the

axillary artery In human anatomy, the axillary artery is a large blood vessel that conveys oxygenated blood to the lateral aspect of the thorax, the axilla (armpit) and the upper limb. Its origin is at the lateral margin of the first rib, before which it is c ...

and

vein Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated b ...

. This takes it deep to the

clavicle The clavicle, or collarbone, is a slender, S-shaped long bone approximately 6 inches (15 cm) long that serves as a strut between the shoulder blade and the sternum (breastbone). There are two clavicles, one on the left and one on the rig ...

. It rests on the outer surface of the

. It extends along the side of the thorax to the lower border of the serratus anterior muscle. It supplies filaments to each of its digitations (finger-like projections).Fischer, J. (2012). Anatomy of the Axilla. Fischer's Mastery of Surgery, 2 Volume Set. Retrieved September 20, 2015 from http://www.r2library.com/Resource/Title/1608317404/ch0046s1193

Function

The long thoracic nerve innervates the

. Serratis anterior is responsible for protraction of the scapula, a movement that occurs when throwing a punch. Furthermore, the serratus anterior acts with the upper and lower fibers of the

trapezius The trapezius is a large paired trapezoid-shaped surface muscle that extends longitudinally from the occipital bone to the lower thoracic vertebrae of the spine and laterally to the spine of the scapula. It moves the scapula and supports the ...

muscle to sustain upward rotation of the scapula, which allows for overhead lifting.

Clinical significance

Due to its long, relatively

superficial Superficial may refer to: * Superficial anatomy, is the study of the external features of the body *Superficiality, the discourses in philosophy regarding social relation * Superficial charm, the tendency to be smooth, engaging, charming, slick an ...

course, the long thoracic nerve is susceptible to injury, either through direct

trauma Trauma most often refers to: * Major trauma, in physical medicine, severe physical injury caused by an external source * Psychological trauma, a type of damage to the psyche that occurs as a result of a severely distressing event *Traumatic i ...

or stretch. Mechanisms of injury include: * nerve

lesion A lesion is any damage or abnormal change in the tissue of an organism, usually caused by disease or trauma. ''Lesion'' is derived from the Latin "injury". Lesions may occur in plants as well as animals. Types There is no designated classifi ...

s. * various

sports Sport pertains to any form of competitive physical activity or game that aims to use, maintain, or improve physical ability and skills while providing enjoyment to participants and, in some cases, entertainment to spectators. Sports can, th ...

injuries, typically occurring from a blow to the

ribs The rib cage, as an enclosure that comprises the ribs, vertebral column and sternum in the thorax of most vertebrates, protects vital organs such as the heart, lungs and great vessels. The sternum, together known as the thoracic cage, is a semi- ...

underneath an outstretched arm. *

surgery Surgery ''cheirourgikē'' (composed of χείρ, "hand", and ἔργον, "work"), via la, chirurgiae, meaning "hand work". is a medical specialty that uses operative manual and instrumental techniques on a person to investigate or treat a pat ...

for shoulder and thorax. Treating

breast cancer Breast cancer is cancer that develops from breast tissue. Signs of breast cancer may include a lump in the breast, a change in breast shape, dimpling of the skin, milk rejection, fluid coming from the nipple, a newly inverted nipple, or a re ...

with removal of

axillary lymph nodes The axillary lymph nodes or armpit lymph nodes are lymph nodes in the human armpit. Between 20 and 49 in number, they drain lymph vessels from the lateral quadrants of the breast, the superficial lymph vessels from thin walls of the chest and th ...

. * carrying weight, such as heavy bags, over the shoulder for a prolonged time. * Parsonage Turner Syndrome, an

autoimmune In immunology, autoimmunity is the system of immune responses of an organism against its own healthy cells, tissues and other normal body constituents. Any disease resulting from this type of immune response is termed an "autoimmune disease". P ...

disease. * trauma or

infection An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dise ...

. Symptoms are often minimal – if symptomatic, a posterior shoulder or scapular burning type of

pain Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, ...

may be reported. Some injuries, particularly lesions, can paralyse the

to produce a

winged scapula A winged scapula (scapula alata) is a skeletal medical condition in which the shoulder blade protrudes from a person's back in an abnormal position. In rare conditions it has the potential to lead to limited functional activity in the upper ex ...

. This is most prominent when the arm is lifted forward or when the patient pushes the outstretched arm against a wall. However, even winging may not be evident until the

stretches enough to reveal an injury several weeks later.

References

Additional images

File:Gray809.png, The right brachial plexus (infraclavicular portion) in the axillary fossa; viewed from below and in front. File:Brachial plexus.svg, Brachial plexus File:Brachial_plexus_color.svg, Brachial plexus with courses of spinal nerves shown

External links

* * * - "The major subdivisions and terminal nerves of the