Primary somatic dysfunction of which joint tends to present with superior/inferior shear stress?

Primary somatic dysfunction of which joint tends to present with superior/inferior shear stress?

• A. Pubic symphysis
• B. Sacroiliac joint
• C. Ischial tuberosity
• D. Iliac crest

Answer: (A)

The main idea is that vertical (superior/inferior) shear across the pelvis most often comes from dysfunction at the pubic symphysis. This midline joint between the two pubic bones has a fibrocartilaginous disc and permits only small movements, but those movements include limited vertical translation. When forces act on the pelvis—such as muscle pulls from the adductors and pelvic floor or asymmetries in loading—the two pubic bones can slide a bit up or down relative to each other. That creates the distinct superior or inferior shear stress felt at the pubic region. In contrast, the sacroiliac joints are more associated with rotary or nutation/counternutation movements and anterior/posterior shear patterns, not a primary vertical (superior/inferior) shear at the midline. The iliac crest and ischial tuberosity are prominent surfaces or landmarks rather than joints that transmit this vertical shear between pelvic halves.

The main idea is that vertical (superior/inferior) shear across the pelvis most often comes from dysfunction at the pubic symphysis. This midline joint between the two pubic bones has a fibrocartilaginous disc and permits only small movements, but those movements include limited vertical translation. When forces act on the pelvis—such as muscle pulls from the adductors and pelvic floor or asymmetries in loading—the two pubic bones can slide a bit up or down relative to each other. That creates the distinct superior or inferior shear stress felt at the pubic region.

In contrast, the sacroiliac joints are more associated with rotary or nutation/counternutation movements and anterior/posterior shear patterns, not a primary vertical (superior/inferior) shear at the midline. The iliac crest and ischial tuberosity are prominent surfaces or landmarks rather than joints that transmit this vertical shear between pelvic halves.