The carpal tunnel is a small space bounded by the wrist bones and a tough ligament called the transverse carpal ligament. Through this tunnel pass nine flexor tendons and the median nerve. When the tendons swell or the tunnel narrows, pressure rises on the nerve and symptoms appear.
Repetitive gripping, prolonged keyboard or tool use, vibration exposure, pregnancy-related fluid retention, thyroid disease, diabetes, rheumatoid arthritis, and prior wrist fracture can all contribute. Sleeping with the wrist curled often triggers night symptoms because flexion further raises tunnel pressure. Genetics also play a role, as some patients are simply born with a smaller carpal tunnel.
