Anatomy clinical correlates: Arm, elbow and forearm

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Anatomy clinical correlates: Arm, elbow and forearm

Prerequisite basic sciences

Prerequisite basic sciences

Prerequisite basic sciences

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Anatomy clinical correlates: Arm, elbow and forearm

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A 40-year-old man comes to the office to be evaluated for right-hand weakness. He works as a mechanic, which involves frequent screwdriver use. He does not report any trauma to his hand. Past medical history is unremarkable. Vitals are within normal limits. Physical examination demonstrates weakness with extension of the thumb and fingers of the right hand. There is no weakness with adduction and abduction of the fingers. The patient reports mild pain with resisted middle finger extension. The sensation is intact and reflexes are +2 and symmetrical bilaterally. This patient most likely has an injury to a nerve that courses through which of the following structures?  

Transcript

The majority of things we do every day require the use of our arms and forearms. Sometimes we forget how heavily we rely on our arms, and are quickly reminded how important they are when injury occurs. So, let's take a look at common injuries occurring to the arm and forearm.

Alright, let's begin by looking at fractures of the humerus, the main bone of the arm. The most common kind are fractures of the surgical neck of the humerus, which occur more frequently in elderly people with osteoporosis who have structurally weaker bones. The cause is usually indirect trauma, like falling on the hand with an extended arm.

Surgical neck fractures can result in damage to nearby structures, such as the axillary nerve causing cutaneous deficits in the proximal lateral arm, as well as damage to the anterior and posterior circumflex humeral arteries.

Next, there are humeral shaft fractures, which are usually caused by direct trauma. Now, remember that the radial nerve passes through the radial, or spiral, groove on the back of the humerus, so a common complication of midshaft humeral fractures is radial nerve injury.

Radial nerve injury results in damage to the extensors of the wrist and potential wrist drop, as well as cutaneous sensation dysfunction of the dorsal hand, forearm, and upper arm. Additionally, the deep brachial artery travels with the radial nerve in the spiral groove and can also be damaged. Finally, distal humeral fractures are a result of trauma to the elbow region, or hyperextension injuries.

In a supracondylar fracture, which is a fracture above the epicondyles, an anteriorly displaced portion of the fractured humerus on the medial supracondylar region could injure the median nerve, resulting in wrist flexion weakness and cutaneous deficits of the anterior 3 and a half digits, as well as the brachial vessels.

Sources

  1. "Interventions for treating proximal humeral fractures in adults" Cochrane Database of Systematic Reviews (2015)
  2. "Olecranon bursitis" Journal of Shoulder and Elbow Surgery (2016)
  3. "Treatment of olecranon bursitis: a systematic review" Archives of Orthopaedic and Trauma Surgery (2014)
  4. "The fate of missed atlanto-axial rotatory subluxation in children" Archives of Orthopaedic and Trauma Surgery (1998)
  5. "Low incidence of flexion-type supracondylar humerus fractures but high rate of complications" Acta Orthopaedica (2016)
  6. "Medial Epicondylitis" Journal of the American Academy of Orthopaedic Surgeons (2015)
  7. "Humerus fractures overview" StatPearls Publishing (2021)
  8. "Humeral shaft fractures" StatPearls Publishing (2021)
  9. "Fracture supracondylar humerus: a review" J Clin Diagn Res (2016)
  10. "Golfers elbow" StatPearls Publishing (2021)
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