Table of ContentsView AllTable of ContentsFive SectionsInjuriesSymptomsDiagnosisTreatment
Table of ContentsView All
View All
Table of Contents
Five Sections
Injuries
Symptoms
Diagnosis
Treatment
Thebrachial plexusis a network of nerves that begins at the base of the neck, passes through the armpit (axilla), and extends into the arm. It originates from five spinal “roots”—C5, C6, C7, C8, and T1—which merge and then separate into five main nerve branches. These branches supply sensation and muscle control to the shoulders, arms, and hands.
The brachial plexus consists of five structural sections: roots, trunks, divisions, cords, and branches. This organization maps the pathway of nerve fibers from the spinal cord down through the arm. Injuries to the brachial plexus, such as from trauma or excessive stretching (like pulling the head away from the shoulder), can cause weakness, numbness, or even paralysis in parts of the arm.
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Five Brachial Plexus Sections
There are five distinct anatomic sections to the brachial plexus: roots, trunks, divisions, cords, and branches. A good mnemonic to remember these sections isReadThatDamnCadaverBook.
Each section has a unique role in guiding nerve signals from the spinal cord to the arm:
Roots
The nerves of the brachial plexus start as “roots” that extend from the spinal cord. These roots are labeled C5 through C8 for the neck (cervical) vertebrae, and T1 for the first vertebra in the upper back (thoracic):
After exiting the spine, these nerve roots (C5–T1) join together at the base of the neck to form the brachial plexus, which then extends to the arm and shoulder.
Trunks
Shortly after the five nerves exit the spinal cord, they combine to form three nerve trunks, each of which plays a role in arm movement and sensation:
The three nerve trunks travel across the lower portion of the posterior triangle of the neck. From here, they curve outward around thesubclavian artery, a major blood vessel, and pass over the first rib before branching further down into the arm.
Divisions
Each of the three trunks in the brachial plexus splits into two branches within the posterior triangle of the neck. One branch moves toward the front of the body (anterior division), while the other moves toward the back (posterior division). This results in a total of six divisions:
After dividing in the posterior triangle, the six divisions move into the axilla (armpit region), where they merge to form the cords of the brachial plexus.
Cords
The six divisions then merge into three cords. These cords lie near theaxillary arteryand are named according to their relationship with the artery, whether lateral, medial, or posterior:
The cords give rise to the major branches of the brachial plexus, which extend through the arm to supply muscles and skin with motor and sensory signals.
Terminal Branches
The three cords next give rise to five major nerves of the upper extremity:
Understanding the origin of these nerves (and their function) can be very helpful in identifying the possible site of an injury to the brachial plexus.
Associated Conditions
There are a number of medical conditions and injuries that can result in damage or dysfunction of the brachial plexus. These can include:
When damage to the brachial plexus occurs, healthcare providers use different terms to describe the degree of damage.
Symptoms of a brachial plexus injury depend on the severity. Severe injuries can result in complete loss of sensation and paralysis of the arm. Lesser injuries may result in some loss of sensation and weakness.
Injuries are sometimes separated and described as upper trunk or lower trunk injuries, depending on the spinal nerve roots affected:
Lower trunk injury (Klumpke’s palsy):Lower trunk injuries (C8 to T1) may occur with tumors (such as Pancoast tumors of the lung), childbirth, and other causes. With trauma, these often include abduction of the arm (movement away from the body) while holding an object and falling. A person with Klumpke’s palsy will be unable to flex or extend their forearm and all fingers will have a clawed appearance.
A number of different diagnostic studies may be done depending on symptoms and what type of injury is suspected. These may include:
Treatment options for brachial plexus injuries include:
Natural recovery:Brachial plexus can naturally regrow from the neck to the arm at a rate of about 1 mm per day. While approximately two-thirds of children with brachial plexus birth injuries improve on their own, some may continue to face challenges like limited movement, weakness, or reduced sensation, requiring additional treatment.
Surgery:The timing of surgical repair is crucial for recovery, as muscles that haven’t connected to nerves within 18 months may weaken beyond repair. Surgical options include neurolysis to remove scar tissue, neuroma excision and reattachment, nerve grafting for large gaps, and neurotization using donor nerves; additional procedures like tendon transfers and botox may also enhance limb function.
Occupational and/or physical therapy:Nonsurgical management, including occupational andphysical therapy, is essential in the treatment process and may involve various therapeutic approaches, includingkinesio tapingandneuromuscular electrical stimulation.
Studies suggest that treatment for brachial plexus injuries should be performed early on after an injury, or within three to six months to have the best outcome.
Summary
The brachial plexus is a network of nerves that controls motor and sensory functions in the shoulder, arm, and hand. It originates from the spinal cord, specifically the C5 to T1 nerve roots, and can be organized into roots, trunks, divisions, cords, and branches, with major nerves like the musculocutaneous, radial, median, and ulnar nerves emerging from it.
Injuries to the brachial plexus can occur due to trauma, childbirth, cancer, and medical treatments. These can lead to conditions like Erb’s palsy and Klumpke’s palsy, which can result in muscle weakness and altered hand function. Diagnosis of brachial plexus injuries involves various imaging and electrical studies to evaluate nerve function and identify the extent of injuries.
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