Tuesday, 27 November 2012

Finger and Hand Anatomy, and Grip


Now, I thought I'd provide some information on the most commonly injured part of a climber - fingers! (As Logan et al 2004 report that of 545 climbers, 28% has sustained an injury to the wrist or hand - the highest percentage of injuries)

What I will discuss is the finger anatomy, grips commonly used in climbing and then I will follow it with a second post regarding injuries and their management.

So, to begin:

Anatomy

Now, not only am I going to discuss the anatomy of the fingers, but also the wrist and forearm, as some of the muscles involved in the movement of the fingers originate in the forearm.


The bones in the hand are shown here:



All relatively straight forward and not much to worry about there (apart from epiphyseal plates - but I will come onto that when I discuss injuries of fingers). The ligaments, on the other hand, are a bit more complex.
 
The finger flexor tendons are held in place by pulleys (A1-4 shown in the diagram). These pulleys ensure the action of the flexor muscle contracting bends the finger all the way to the tip across each different joint. This means that a lot of force and friction can be exerted on these tendons when a large load is put through the finger tips.

One thing worth noting is that the A2 pulley contains the tendons of both the flexor digitorum profundus (FDP) and the flexor digitorum superficialis (FDS), whereas the A4 pulley only contains the tendon of the FDP as the FDS splits and inserts to the lateral sides of the A4 pulley (see image below).
This means more force is exerted on the A2 pulley than the A4 (hence why climbers most commonly injure the A2 pulley)
 
The carpal tunnel is worth mentioning briefly. This is the area in which the tendons to the fingers, blood vessels and nerves pass through from the wrist to the palm of the hand, between the carpal bones and flexor retinaculum (a ligament). It is quite a compact area and so any increase in pressure in the area, such as dramatic increase in blood supply, or inflammation of tendons etc can cause tingling etc of the hand, from compression of the other structures in the carpal tunnel such as the nerves or vessels.
 
 Now, the muscles. The muscles that flex or extend the hand/fingers originate at the medial epicondyle (for flexing) and lateral epicondyle (for extension). The epicondyles are the corners of your elbow, if you like (see pictures).

 
 

There are a few other muscles within the hand to be aware of. Have a look at the palm of your hand. Notice the fleshy parts of your hand around the base of the thumb and little finger? Good (I hope you can see them!), these are the areas where the muscles that move your thumb and little finger are hidden away, and, as you can see, they have more movement than the other digits in the hand beause of these muscles. 


Finally, the last group of muscles in the hand are the lumbricals and interossei.


  • Lumbricals - (shown in the picture above) are responsible for flexion only at the metacarpophalangeal joint
  • Interossei - are responsible for abduction and adduction of your fingers (see below)
 

Now, all this hand anatomy will be useful when we discuss injuries to the fingers and hand (in a later post).
Next, I will briefly discuss the significance of grip. 
 
Grips

When gripping any object, the optimum gripping position is when your wrist is at approximately 10 degrees of extension. 



This applies even with the common climbing grips displayed below.


When a climber becomes tired, they tend to lose this 10 degrees of extension and rely on the passive structures of the upper limb. 
This creates strain on these passive structures and puts them at a higher risk of injury. 
This can often be seen when climbers start sticking their elbows out like chicken wings, as they are tiring and resorting to use of passive structures.


To prevent this passive gripping and chicken winging: pure and simple, train the active structures, and when tired, try and keep some control over your positioning, as otherwise you'll never change this. 

References

Logan AJ, Makwana N, Mason G, Dias J 2004 Acute hand and wrist injuries in experienced rock climbers. British Journal of Sports Medicine 38: 545-548 

Drake, Vogl, Mitchell 2009 Gray's Anatomy for Students. Elvesier, Philadelphia


 Coming soon: Finger Injuries: Symptoms and Treatment

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