Carpal Tunnel: Basic Anatomy and Definition

Carpal tunnel syndrome is a nerve problem categorized as compressive neuropathy or simply a pinched nerve. Nerves can experience pressure or pinching injury anywhere along the path between exiting the spinal canal and arriving at their final destination.

In the case of carpal tunnel syndrome, the pressure or pinching injury occurs in the wrist through the pathway known as the carpal tunnel. The carpal tunnel is actually an anatomic tunnel or conduit through which the flexor tendons of the fingers and the thumb pass from the forearm to the hand and fingers. The median nerve also passes through this tunnel with these flexor tendons. The median nerve provides sensation nerve endings to the thumb, index finger, middle finger, and usually half of the ring finger.

It also provides muscle nerve endings to several important fine muscles in the hand. The most important of these muscles controlled by the median nerve is at the palmar base of the thumb and is responsible for positioning the thumb out away from the plane of the palm to allow for grasping objects. Carpal tunnel syndrome refers specifically to the pinching of the median nerve within the carpal tunnel to the degree that symptoms are produced. 

Symptoms of Carpal Tunnel

When the median nerve gets pinched in the carpal tunnel people most often initially experience sensation changes in the thumb, index finger, and middle finger which can occur in any combination. It may be experienced in only one of those fingers to begin with or all of them. These sensory changes are often described as tingling, pins, and needles, “going to sleep”, numbness, etc. People can also experience pain that can radiate from the palm side of the wrist into the fingers or less commonly into the palm side of the forearm.

These symptoms usually are intermittent at first and are often present at night or noticed upon awakening in the morning. As the condition worsens the symptoms occur more frequently being experienced on a daily or nightly basis. People can also experience early fatigue and cramping-type pain in the hand muscles.

In advanced stages of severe carpal tunnel syndrome symptoms are present most of the time or even continually. Also, the muscles controlled by the median nerve can become weak and eventually shrink or atrophy. This can make it difficult or impossible to bring the thumb out far enough to grasp objects.

Treatment – the goal of treatment is to relieve the pressure on the nerve 

Self-care:  Initially when symptoms are still intermittent, treatment can involve wearing a padded but rigid wrist brace while sleeping. This will prevent the wrist from being flexed when asleep; and places the nerve in a neutral position to relax pressure on it. 

The use of a nighttime brace can be combined with the use of anti-inflammatory medication such as ibuprofen or naproxen. Adding acetaminophen to either of these can augment their effectiveness. This type of brace and these medications can be purchased over the counter at many pharmacies without a prescription.

Professional care – seek professional medical attention for any of the following situations: 

  • If you are experiencing sensory changes for most or all of the day/night.
  • If you have any signs of muscle weakness in the hand – such as loss of dexterity, clumsiness, or easy fatigue of hand muscles.
  • If you have any loss in the size or bulk of the hand muscles. 
  • If nighttime bracing and anti-inflammatory medication are not successful.

In these situations, your medical professional can discuss further treatment options which may involve prescription or injection medications or possibly surgery to relieve the pressure from off of the nerve.  

Written by: Dirk Slade, MD