The brachial plexus
Brachial plexus · plexus brachialis
A tangle of nerves in your neck and armpit that sorts signals into the nerves of the arm.
What it does
Five nerve roots from the lower neck and upper chest spinal cord join, split and rejoin in a network called the brachial plexus. Out of it come all the major nerves of the arm, each carrying fibres from several roots, so one damaged root rarely knocks out a whole muscle.
Surprising fact
It emerges between two neck muscles and passes under the collarbone, and anaesthetists can numb the whole arm by injecting local anaesthetic around it.
Why it matters
A hard fall onto the shoulder, as in motorcycle crashes, can stretch or tear the plexus. In newborns, a difficult delivery can cause a temporary weakness called Erb's palsy.
Nearby
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Sources
Drafted with AI help; awaiting a human fact-check against these sources.
Open in the 3D atlas · Suggest a correction · Not medical advice.
3D models: Z-Anatomy & BodyParts3D (CC BY-SA 4.0 / 2.1 JP). Card text CC BY 4.0.