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 A patient who is unable to adduct all the digits in the hand may have damage to the ulnar nerve, which innervates the muscles responsible for this action. The ulnar nerve supplies the adductor pollicis muscle, which adducts the thumb, and the palmar interossei muscles, which adduct the index, ring and little fingers⁹ [^10^]. The ulnar nerve also innervates the dorsal interossei muscles, which abduct the digits, but these muscles are antagonized by the median nerve, which innervates the lumbricals⁶. Therefore, if the ulnar nerve is damaged, the median nerve can still produce some abduction of the digits, but not adduction. The ulnar nerve can be injured at various levels, such as the elbow, wrist or hand, depending on the cause of the trauma. Some common causes of ulnar nerve injury include fracture or dislocation of the elbow, compression of the nerve in the cubital tunnel or Guyon's canal, or laceration of the nerve by a sharp object⁵. The symptoms of ulnar nerve injury may inclu...

 Atrial Fibrillation: Practice Essentials, Background, Pathophysiology 112 Feedback Practice Essentials Atrial fibrillation (AF) has strong associations with other cardiovascular diseases, such as heart failure, coronary artery disease (CAD), valvular heart disease, diabetes mellitus, and hypertension. It is characterized by an irregular and often rapid heartbeat (see the first image below). The exact mechanisms by which cardiovascular risk factors predispose to AF are not understood fully but are under intense investigation. Catecholamine excess, hemodynamic stress, atrial ischemia, atrial inflammation, metabolic stress, and neurohumoral cascade activation are all purported to promote AF. Ventricular rate varies from 130-168 beats per min Ventricular rate varies from 130-168 beats per minute. Rhythm is irregularly irregular. P waves are not discernible. The image on the right is a reconstructed 3-dimensional image of the right atrium in a patient undergoing atrial fibrillation abl...