The term "sigmoid cavity of the radius" refers to a feature on the underside of the radius bone in the forearm. The spelling of this term can be explained using the International Phonetic Alphabet (IPA) as /sɪɡˈmɔɪd ˈkævəti əv ðə ˈreɪdiəs/. The "s" is pronounced as a voiceless alveolar fricative, the "g" as a voiced velar stop, and the "m" as a bilabial nasal. The "oi" in "sigmoid" is a diphthong pronounced as an open-mid back rounded vowel followed by an off-glide. The stress falls on the second syllable of "sigmoid" and the first syllable of "cavity."
The sigmoid cavity of the radius is a specific anatomical term that refers to a depression or concave area located on the lateral side of the proximal end of the radius bone in the forearm. The term "sigmoid" comes from the Greek word "sigma," meaning 'S,' which describes the shape of the cavity, resembling the Greek letter sigma (∑). This cavity articulates with the ulna bone, specifically with its sigmoid notch, forming a pivotal joint known as the radioulnar joint.
The sigmoid cavity of the radius plays a crucial role in forearm movement and stability. It allows for rotational movements between the radius and the ulna bone, enabling supination (rotating the forearm palm-up) and pronation (rotating the forearm palm-down) movements. These movements are vital for various everyday activities such as writing, gripping objects, and turning doorknobs.
Understanding the anatomical structures, such as the sigmoid cavity of the radius, is essential for medical professionals, especially orthopedic surgeons, radiologists, and anatomists, to diagnose and treat conditions involving the forearm, such as fractures, dislocations, and joint diseases. Additionally, knowledge of this anatomical structure is beneficial for physical therapists and occupational therapists in designing targeted rehabilitation programs for patients recovering from injuries or surgeries involving the forearm or wrist.
Incisura ulnaris.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.