Anatomy clinical correlates: Arm, elbow and forearm

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.