What Human Body Parts Start With the Letter “R”?


Radius, rectum, retina, ribs, red blood cells, rotator cuff, ribcage, rectus abdominis, rhomboids, and rectus femoris are all body parts that start with the letter “R.” Two major body systems, reproductive and respiratory systems, also start with the letter R. Some body parts have informal names or nicknames that start with the letter, such as rump, roof of the mouth, or ring finger. Finally, when there are two of a body part, a person may use terms like right leg, right arm, right eye, right elbow, right ear, right ovary, right foot, right hand, or right kidney to describe them.


The radius is one of the two major bones that make up the forearm. The other is the ulna. The radius joins the wrist and hand together, and it’s one of the most frequently broken bones.  


The rectum is the end of the large intestine that occurs just before the anus. It holds feces until a person defecates.


Part of the eye, the retina is a thin layer of tissue that receives light and converts it so that the brain can see it. Damage to the retina may result in permanent blindness. 

Ribs and Rib Cage

The rib cage is a group of bones called ribs that protect the chest cavity and many vital organs. Most humans have 24 ribs. 

Red Blood Cells

Red blood cells are the part of the blood that carry oxygen from the lungs to the rest of the body. If a person does not have enough red blood cells, he or she may be described as anemic. This condition can make one feel tired, weak, dizzy, or lightheaded. It can also lead to shortness of breath, irregular heartbeat, headaches, chest pain, and cold extremities. 

Rotator Cuff

Made up of muscles and tendons, the rotator cuff is what keeps the upper arm bone in place in the shoulder’s socket. Without it, you couldn’t lift your arms, turn your arms, swim, or play many sports that require you to swing a racket or bat. A torn rotator cuff, which happens when the body part is overused, is a common injury. 

Rectus Abdominis

The rectus abdominis is an abdominal muscle that runs from the sternum down to the pubic bone. Anyone who has ever worked toward “six-pack abs” was working towards a strong rectus abdominis. The muscle is important for a number of activities, ranging from giving birth to simply coughing.

Rectus Femoris 

Located in the thigh, the rectus femoris crosses over the knee and hip. It helps with flexing the hip and the ability to move the knee 90 degrees. Some people have a shorter or longer rectus femoris, which may impact their ability to extend their hips and knees fully.


The rhomboids are the muscles in the upper back that are responsible for posture. They connect between the spine and shoulder blades, and when they’re contracted, the pull the shoulder blades together to support the back. When the muscles become overstretched, a person may develop kyphosis, or a hunched or curved spine