The term "sigmoid notch" is often used in anatomy to describe a deep indentation at the top of the ulna bone in the forearm. The word "sigmoid" originates from the Greek word "sigmoeides," meaning "shaped like the letter sigma (Σ)." It is pronounced /sɪɡˈmɔɪd/ in IPA, indicating the "s" sound followed by the "ig" vowel sound and ending with an "m" sound. The word "notch" is pronounced /nɒtʃ/, with a long "o" sound, and an "ch" sound at the end. Together, the spelling of "sigmoid notch" accurately conveys its shape and location in the forearm.
The sigmoid notch is a term commonly used in anatomy to refer to a specific anatomical feature within the human skeleton. More specifically, it is a notch present at the superior end of the ulna bone, which is one of the two forearm bones, the other being the radius. The sigmoid notch is located on the distal end of the ulna, forming a concave surface that articulate with the trochlea of the humerus bone at the elbow joint.
This particular notch is named due to its resemblance to the letter "S" or sigma in the Greek alphabet, hence the term "sigmoid." It is a crucial part of the elbow joint structure as it contributes to the ulnar articulation with the humerus, allowing for forearm rotation and flexion/extension movements of the elbow joint.
The sigmoid notch provides stability and support to the elbow joint, helping to distribute the forces exerted during various arm movements. Additionally, it serves as an attachment point for several ligaments, tendons, and muscles involved in forearm and elbow joint function.
Understanding the anatomy and function of the sigmoid notch is important for healthcare professionals, such as orthopedic surgeons, radiologists, and anatomists, as it plays a key role in the diagnostic, surgical, and therapeutic management of injuries and abnormalities affecting the elbow joint.
Incisura mandibulae.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.
The word "sigmoid" in "sigmoid notch" comes from the Greek word "σῖγμα" (sigma), which means the Greek letter "S". This is because the sigmoid notch, a concave feature in the ulna bone of the forearm, resembles the shape of the letter "S" when viewed from certain angles. The term "notch" refers to a narrow indentation or cut in the bone. So, "sigmoid notch" is a descriptive term referring to the "S-shaped" indentation in the ulna bone.