Question

Name the type of joint between pubic bones in the pelvic girdle.

Answer 1

Hint: The joint between pubic bones in the pelvic girdle is similar to that between two vertebrae in the intervertebral disk. These are permanent and amphiarthrosis which means slightly movable joints.

Complete answer:
The type of joint present in between pubic bones is the cartilaginous joint. It is called the symphysis pubis. It is made of cartilage but may turn into fibrocartilaginous joints with age. The joint unites the superior rami of the left pubic bone with the one of the right. This slightly widens, approximately 2mm, when the legs are stretched apart. But excessive stretching may cause dislocation of bones.

Additional Information: The pubic symphysis or the cartilaginous joint between the pubic bones in the midline cartilaginous joint that unites the superior rami of the left and right pubic bones. It is non-synovial and connected by fibrocartilage. Sometimes it may contain a fluid-filled cavity. The ends of the two bones are covered by a layer of hyaline cartilage attached to the fibrocartilage.
The symphysis pubis is located above the penis in males and above the vulva in females. It is anterior to the urinary bladder and superior to the external genitalia. Normally it moves roughly two mm with $1^\circ$ rotation but in the case of a pregnant woman, it can increase its movement during childbirth. During this time, the pubic symphysis slightly relaxes and widens.

During sports, there's a high risk of dislocation of bones, as the movement is frequent and the risk of blockage of the pubic symphysis is high. When the bones at the symphysis don't realign correctly the dislocation occurs. With age, the surface becomes worn at a predictable rate. This allows estimating the person's age during forensic anthropology.

Note: The symphysis is also found in between two vertebrae in the intervertebral disk. The symphysis is permanent joints, unlike synchondroses. In vertebral disks, each one of them forms a cartilaginous joint to allow slight movement of the vertebrae and also acts as a ligament for holding the vertebrae together. The disks are made of an outer annulus fibrosus, surrounding the inner nucleus pulposus. These two distribute pressure evenly across the disc.