Massage & Bodywork

MAY | JUNE 2016

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C h e c k o u t A B M P 's l a t e s t n e w s a n d b l o g p o s t s . Av a i l a b l e a t w w w. a b m p . c o m . 99 prominences as well as compression between the two heads of the FCU muscle. The anatomical path of the ulnar nerve is already quite narrow and limited as it traverses the posterior elbow. Yet, this small and narrow passage is not the only cause for nerve compression in this region. The ulnar nerve can also be compressed by anatomical anomalies such as ganglion cysts, bone spurs, fibrous bands within the flexor carpi ulnaris, or small accessory muscles that sometimes occur in the region. 1 The mechanics of the elbow joint also pose significant challenges for this nerve. During elbow flexion, there is movement between the ulna and humerus that actually decreases the size of the cubital tunnel. Space within the tunnel can decrease as much as 55 percent during elbow flexion, making nerve compression during elbow flexion movements much more likely. 2 If the individual has a small or shallow tunnel to begin with, this space decrease becomes even more important as a potential causative factor. Many of us have experienced ulnar nerve compression. The most common occurrence is by holding your elbow bent during sleep, which is a common position. Many people wake up and say their hand has gone to sleep, because prolonged elbow flexion and subsequent tunnel narrowing has caused ulnar nerve compression symptoms. There is another important biomechanical consideration occurring during elbow flexion. Not only is the space in the cubital tunnel decreased, but the ulnar nerve is pulled taut and strung like a bow across the posterior side of the elbow (Image 3). This position increases compressive forces on the nerve as its diameter is narrowed from stretching, in the same way the diameter of a rubber tube is decreased when you stretch it from both ends. So the nerve is both stretched and compressed during elbow flexion, and this combination can be a recipe for symptoms. There are other biomechanical challenges as well. Usually the nerve is secured in the tunnel by the bony borders. However, in some cases, due to a very narrow tunnel or missing structures that restrain its movement, the nerve can pop out of the cubital tunnel during certain elbow movements. This is referred to as a subluxing nerve and it is very likely to cause nerve pathology symptoms. THE CLINICAL PICTURE Cubital tunnel syndrome develops from either acute or chronic compression at the elbow. While it is possible to have acute trauma causing ulnar nerve Path of ulnar nerve 3 The path of the ulnar nerve is increased when the elbow is in flexion, causing the nerve to get bowstrung across the posterior side of the elbow. Image courtesy of Wikimedia Commons. 4 Cubital valgus angulation with a lateral deviation of the radius and ulna. Image courtesy Wikimedia Commons. compression, the more common cause is chronic nerve compression over time due to anatomical or biomechanical factors. It is also more common for cubital tunnel compression to occur in men, although the reason for this is unclear. Observe the client's upper extremity in a neutral standing position. In some cases, excessive cubital valgus can contribute to ulnar nerve pathology in the elbow. A valgus angulation is one in which the distal end of a bony segment angles in a lateral direction. In this instance, the distal radius and ulna deviate in a lateral direction, and this is called cubital valgus (Image 4). However, just because a person has cubital valgus, it doesn't mean they will develop ulnar nerve pathology. It is simply one piece of the puzzle to consider. Another factor to consider with upper extremity nerve pathology is double (or multiple) crush phenomenon with the nerves, which is defined as two or more locations where a nerve is compressed and signals are impaired. When more than one location is involved, the nerve becomes increasingly sensitive and more susceptible to symptom

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