S is the richest letter of all for body parts. It includes the skin, your largest organ; the skull and spine that protect your nervous system; the stomach and small intestine that digest your food; and the stapes, the smallest bone you have.
Here are more than 30 human body parts that start with S, grouped by body system, each with a short and accurate explanation.
Quick List: Body Parts That Start With S
| Sacrum | Shin | Spleen |
| Salivary glands | Shoulder | Stapes |
| Sartorius | Sinoatrial node | Sternum |
| Scalp | Sinuses | Stomach |
| Scapula | Skin | Subclavian artery |
| Sciatic nerve | Skull | Superior vena cava |
| Sclera | Small intestine | Sweat glands |
| Sebaceous glands | Soft palate | Synovial fluid |
| Semicircular canals | Soleus | Spinal cord |
| Septum (heart) | Sphenoid bone | Spine |
| Sternocleidomastoid |
Brain, Nerves and Senses
Spinal cord: A long bundle of nerve tissue running from the brainstem down through the spine. It carries messages between the brain and the body and controls many reflexes on its own.
Sciatic nerve: The longest and thickest nerve in the body, running from the lower back through the buttock and down each leg. Pressure on it causes pain known as sciatica.
Sclera: The tough, white outer coat of the eye. It protects the eye and gives it its shape.
Semicircular canals: Three fluid-filled loops in the inner ear, set at right angles to each other. They sense rotation of the head and help you keep your balance.
Stapes: The third of the tiny middle-ear bones, shaped like a stirrup. At about 3 mm long, it is the smallest bone in the human body.
Sinuses: Air-filled spaces in the bones around the nose. They make the skull lighter, help warm and moisten the air you breathe, and add resonance to your voice.
Heart and Blood Vessels
Sinoatrial node: A small group of cells in the wall of the right atrium. It is the heart’s natural pacemaker, sending out the electrical signal that starts each heartbeat.
Septum (heart): The wall that divides the left side of the heart from the right, keeping oxygen-rich and oxygen-poor blood apart.
Superior vena cava: A large vein that carries oxygen-poor blood from the head, neck, arms and chest into the right atrium.
Subclavian artery: A major artery running beneath each collarbone. It supplies blood to the arms and also to parts of the neck and brain.
Digestive and Immune System
Stomach: A J-shaped, muscular organ in the upper left abdomen. It stores food, mixes it with acid and enzymes, and begins breaking down proteins before passing it to the small intestine.
Small intestine: A coiled tube about 6 to 7 metres long, between the stomach and the large intestine. It is where most digestion and nutrient absorption happen. It has three parts: the duodenum, jejunum and ileum.
Salivary glands: Glands around the mouth that produce saliva, which moistens food and starts breaking down starches. The three main pairs are the parotid, submandibular and sublingual glands.
Soft palate: The soft, muscular back part of the roof of the mouth. It lifts when you swallow to stop food entering the nose.
Spleen: A fist-sized organ in the upper left abdomen, behind the stomach. It filters the blood, removes old red blood cells and helps fight infection. People can live without it, but are then more vulnerable to some infections.
Skin and Glands
Skin: The largest organ of the body, covering about 2 square metres in adults. It protects against germs and injury, controls body temperature, and senses touch, heat, cold and pain.
Scalp: The skin and tissue covering the top of the head, where most head hair grows.
Sweat glands: Tiny glands in the skin that release sweat. As sweat evaporates, it cools the body. Most people have two to four million of them.
Sebaceous glands: Small glands attached to hair follicles that release an oily substance called sebum, which keeps skin and hair from drying out.
Bones and Joints
Skull: The bony structure of the head. It protects the brain and supports the face. In adults it is made of 22 bones, most of them joined by fixed joints called sutures.
Sphenoid bone: A butterfly-shaped bone at the base of the skull. It touches many other skull bones and contains a small hollow that holds the pituitary gland.
Spine: The column of vertebrae running from the skull to the pelvis. It supports the body, allows bending and twisting, and protects the spinal cord.
Sacrum: A large, triangular bone at the base of the spine, made of five fused vertebrae. It connects the spine to the pelvis.
Sternum: The breastbone, a flat bone in the centre of the chest. Most ribs attach to it through cartilage.
Scapula: The shoulder blade, a flat, triangular bone on the upper back. It connects the arm to the collarbone and anchors many shoulder muscles.
Shoulder: The joint where the upper arm meets the shoulder blade. It is the most mobile joint in the body, which also makes it the most often dislocated.
Shin: The front of the lower leg. The bone you can feel there is the tibia, the main weight-bearing bone below the knee.
Synovial fluid: A thick, slippery fluid inside movable joints. It lubricates the joint and nourishes the cartilage.
Muscles
Sartorius: The longest muscle in the body. It runs in a strap from the outer hip across the front of the thigh to the inner knee, helping you sit cross-legged.
Soleus: A broad, flat calf muscle lying beneath the gastrocnemius. It lifts the heel and helps keep you upright when standing.
Sternocleidomastoid: A long muscle on each side of the neck, running from behind the ear to the breastbone and collarbone. It turns and tilts the head.
Common Mix-Ups to Avoid
- Spine vs. spinal cord: The spine is the column of bones; the spinal cord is the nerve tissue inside it.
- Sternum vs. scapula: The sternum is the breastbone at the front; the scapula is the shoulder blade at the back.
- Sweat glands vs. sebaceous glands: Sweat glands release water to cool you; sebaceous glands release oil to protect skin and hair.
Frequently Asked Questions
What is the largest organ that starts with S?
The skin. It is the largest organ in the entire human body.
Which organs start with S?
The skin, stomach, small intestine and spleen are organs that start with S.
What are easy S body parts for kids?
Skin, skull, shoulder, shin, stomach and spine are simple words that children can learn and point to.
Conclusion
From the skin that covers you to the stapes deep in your ear, the letter S includes the largest organ and the smallest bone in the body. Learning these words by system makes a long list much easier to remember.
Continue the series with body parts that start with R and body parts that start with T.
This article is for general education only and is not medical advice. If you have a health concern, please talk to a doctor.
