Which of the following has a sigmoid notch?

Options

A. Radius-ulna
B. Humerus
C. Tibia-fibula
D. Femur

Explanation

To determine which of the following bones has a sigmoid notch, we can analyze each option provided:

1. **Radius**: The radius does not have a sigmoid notch. It is primarily involved in the forearm's rotation and articulation with the wrist.

2. **Ulna**: The ulna does have a sigmoid notch, also known as the radial notch. This notch is located at the proximal end of the ulna and allows for the articulation with the head of the radius.

3. **Humerus**: The humerus does not have a sigmoid notch; instead, it features a trochlear notch, which is involved in the elbow joint.

4. **Tibia**: The tibia does not have a sigmoid notch; it has a fibular notch, which is where the fibula articulates with the tibia.

5. **Fibula**: The fibula also does not have a sigmoid notch. It primarily serves as a support structure for the tibia.

6. **Femur**: The femur does not have a sigmoid notch; it has an intercondylar notch, which is located between the condyles of the femur.

After analyzing all the options, we conclude that the correct answer is:

**The ulna has a sigmoid notch.**