On the dorsum of the wrist, clean and identify the extensor retinaculum, a thickening of the deep antebrachial fascia. The extensor retinaculum is attached medially to the styloid process of the ulna and laterally to the distal end of the radius. The tendons of the extensor muscles pass deep to the extensor retinaculum in six osteofibrous compartments, or canals [pipe cleaner is located in the compartment for the tendons of the extensor digitorum muscle]. As the tendons pass through these compartments, they are surrounded by synovial sheaths which allow the tendons to move freely, as their positions are fixed by the extensor retinaculum. The individual compartments of the extensor retinaculum will be studied later in this laboratory exercise.
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