The thoracodorsal nerve is a

nerve A nerve is an enclosed, cable-like bundle of nerve fibers (called axons) in the peripheral nervous system. A nerve transmits electrical impulses. It is the basic unit of the peripheral nervous system. A nerve provides a common pathway for the e ...

present in humans and other animals, also known as the middle subscapular nerve or the long subscapular nerve. It supplies the

latissimus dorsi muscle The latissimus dorsi () is a large, flat muscle on the back that stretches to the sides, behind the arm, and is partly covered by the trapezius on the back near the midline. The word latissimus dorsi (plural: ''latissimi dorsorum'') comes from L ...

Structure

The thoracodorsal nerve arises from 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 ...

. It derives its fibers from the sixth,

seventh Seventh is the ordinal form of the number seven. Seventh may refer to: * Seventh Amendment to the United States Constitution * A fraction (mathematics), , equal to one of seven equal parts Film and television *"The Seventh", a second-season e ...

, and eighth

cervical nerves 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 the ...

. It is derived from their

ventral 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 and the limbs. They are mainly larger than the dorsal rami. Shortly after a spinal n ...

, in spite of the fact that the latissimus dorsi is found in the

back The human back, also called the dorsum, is the large posterior area of the human body, rising from the top of the buttocks to the back of the neck. It is the surface of the body opposite from the chest and the abdomen. The vertebral column run ...

. The thoracodorsal nerve is a branch of the

posterior cord The posterior cord is a part of 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 ...

of the

, and is made up of fibres from the posterior divisions of all three trunks of the brachial plexus. It follows the course of the

subscapular artery The subscapular artery, the largest branch of the axillary artery, arises from the third part of the axillary artery at the lower border of the subscapularis muscle, which it follows to the inferior angle of the scapula, where it anastomoses w ...

, along the posterior wall of the

axilla The axilla (also, armpit, underarm or oxter) is the area on the human body directly under the shoulder joint. It includes the axillary space, an anatomical space within the shoulder girdle between the arm and the thoracic cage, bounded superior ...

to the

, in which it may be traced as far as the lower border of the muscle.

Function

The thoracodorsal nerve innervates the

on its deep surface.

Clinical Significance

The latissimus dorsi is occasionally used for transplantation, and for augmentation of

systole Systole ( ) is the part of the cardiac cycle during which some chambers of the heart contract after refilling with blood. The term originates, via New Latin, from Ancient Greek (''sustolē''), from (''sustéllein'' 'to contract'; from ''sun ...

cardiac failure Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome, a group of signs and symptoms caused by an impairment of the heart's blood pumping function. Symptoms typically include shortness of breath, excessive fatigue, an ...

. In these cases, the nerve supply is preserved, and transplanted with the muscle (for example, with facial reanimation). Posterior cord lesions can result in the loss of

adduction Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relative ...

of the

shoulder joint The shoulder joint (or glenohumeral joint from Greek ''glene'', eyeball, + -''oid'', 'form of', + Latin ''humerus'', shoulder) is structurally classified as a synovial ball-and-socket joint and functionally as a diarthrosis and multiaxial joint. ...

, as innervation to latissimus dorsi is lost.

Additional images

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

References

External links

Dissection Video of Superficial Back showing the Thoracodorsal Nerve
* - "The major subdivisions and terminal nerves of the brachial plexus."
Thoracodorsal Nerve
- BlueLink Anatomy - University of Michigan Medical School {{Authority control Nerves of the upper limb