The letter B gives us some of the most important words in the human body. The brain controls everything you do, blood carries oxygen to every cell, and your bones hold it all together. Alongside these big names are smaller parts with big jobs, like the bronchioles in your lungs and the bundle of His in your heart.
Below you will find more than 35 human body parts that start with B, grouped by body system, with a short and accurate explanation of each one. It is useful for students, teachers, quiz lovers and anyone building their vocabulary.
Quick List: Body Parts That Start With B
| Baby teeth | Blind spot | Brachioradialis |
| Back | Blood | Brain |
| Backbone | Blood vessels | Brainstem |
| Basal ganglia | Bone marrow | Breast |
| Basilar artery | Bones | Broca’s area |
| Belly button | Bowel | Bronchi |
| Biceps brachii | Bowman’s capsule | Bronchioles |
| Biceps femoris | Brachial artery | Buccinator |
| Bicuspid (mitral) valve | Brachial plexus | Bundle of His |
| Big toe | Brachialis | Buttocks |
| Bile duct | Bladder |
Brain and Nervous System
Brain: The control centre of the body. An adult brain weighs about 1.3 to 1.4 kg and contains tens of billions of nerve cells. It handles thinking, memory, emotion, movement, the senses and many automatic functions.
Brainstem: The stalk-like part that connects the brain to the spinal cord. It is made of the midbrain, pons and medulla oblongata, and it controls vital automatic functions such as breathing, heart rate, blood pressure and swallowing.
Basal ganglia: A group of structures deep inside the brain that help start and smooth out movement and form habits. Problems in this system are involved in conditions such as Parkinson’s disease.
Broca’s area: A region in the frontal lobe, usually on the left side, that is essential for producing speech. Damage to it can make it hard to form words, even when a person knows what they want to say.
Basilar artery: A large artery formed where the two vertebral arteries join at the base of the brainstem. It supplies blood to the brainstem, the cerebellum and the back of the brain.
Brachial plexus: A network of nerves that starts in the lower neck and upper chest spinal cord and runs into the armpit. Its branches control almost all the muscles and feeling in the shoulder, arm and hand.
Blind spot: A small area at the back of each eye where the optic nerve leaves. It has no light-sensing cells, so it cannot see. You do not normally notice it because the brain fills in the gap.
Heart, Blood and Circulation
Blood: The fluid that carries oxygen, nutrients, hormones and waste around the body. It is made of plasma (a yellowish liquid) plus red blood cells, white blood cells and platelets. An average adult has about 5 litres of blood.
Blood vessels: The tubes that carry blood. Arteries take blood away from the heart, veins bring it back, and tiny capillaries connect the two and let oxygen and nutrients pass into the tissues.
Bicuspid (mitral) valve: The heart valve between the left atrium and left ventricle. It has two flaps (cusps), which is why it is called bicuspid. It stops blood flowing backward into the atrium when the ventricle pumps.
Bundle of His: A band of special heart-muscle fibres that carries the electrical signal from the atrioventricular node down the wall between the ventricles, so both ventricles contract together.
Brachial artery: The main artery of the upper arm. It continues from the axillary artery and splits into the radial and ulnar arteries near the elbow. Doctors usually measure blood pressure over this artery.
Bone marrow: The soft tissue inside many bones. Red bone marrow makes red blood cells, white blood cells and platelets. Yellow bone marrow is mostly fat and becomes more common with age.
Lungs and Airways
Bronchi: The two main airways that branch off the windpipe (trachea), one into each lung. Inside the lungs they divide again and again into smaller tubes (singular: bronchus).
Bronchioles: The smallest airways in the lungs. They have no cartilage, can narrow or widen, and end in the tiny air sacs called alveoli. In asthma, the muscles around the bronchioles tighten and make breathing difficult.
Digestive and Urinary System
Bowel: Another word for the intestines. The small bowel absorbs most nutrients from food, and the large bowel absorbs water and forms stool.
Bile duct: A tube that carries bile from the liver and gallbladder into the first part of the small intestine (duodenum). Bile helps break down and absorb fats.
Bladder: A hollow, stretchy organ in the lower abdomen that stores urine from the kidneys until you go to the toilet. A healthy adult bladder can comfortably hold roughly 400 to 600 ml.
Bowman’s capsule: A tiny cup-shaped structure at the start of each nephron in the kidney. It surrounds a knot of capillaries and collects the fluid filtered out of the blood, which then becomes urine.
Bones and Skeleton
Bones: The hard, living organs that form the skeleton. An adult usually has 206 bones. They support and protect the body, store calcium and, through bone marrow, make blood cells.
Backbone: The everyday name for the spine or vertebral column. It is a stack of 33 vertebrae at birth; some later fuse to form the sacrum and coccyx. It protects the spinal cord and supports the head and upper body.
Big toe: The first and largest toe, known medically as the hallux. It has two bones (phalanges), while the other toes usually have three, and it carries much of your weight when you push off to walk.
Baby teeth: The first set of teeth, also called primary or milk teeth. Children have 20 of them, and they are gradually replaced by 32 permanent teeth (including wisdom teeth).
Muscles
Biceps brachii: The well-known muscle at the front of the upper arm. It has two heads (that is what “biceps” means). It bends the elbow and turns the palm to face upward.
Brachialis: A muscle lying underneath the biceps. Although less famous, it is actually the main muscle that bends the elbow.
Brachioradialis: A muscle on the thumb side of the forearm. It helps bend the elbow, especially when the hand is in a thumbs-up position, such as when lifting a mug.
Biceps femoris: One of the three hamstring muscles at the back of the thigh. It bends the knee and helps straighten the hip. Hamstring strains often affect this muscle.
Buccinator: The thin muscle of the cheek. It keeps food between the teeth when you chew and helps you blow out air, as when playing a trumpet or blowing up a balloon.
Body Regions
Back: The rear of the trunk, from the neck to the pelvis. It contains the spine and many layers of muscle that keep you upright and let you bend and twist.
Belly button: The small scar on the abdomen where the umbilical cord was attached before birth. Its medical name is the umbilicus or navel.
Breast: The front of the upper chest. In women, the breasts contain mammary glands that can produce milk; men have a small amount of breast tissue too.
Buttocks: The rounded area at the back of the hips. It is formed mainly by the gluteus maximus, the largest muscle in the body, which helps you stand up, climb stairs and run.
Common Mix-Ups to Avoid
- Biceps vs. bicep: “Biceps” is both singular and plural in anatomy, because the word means “two heads.”
- Bronchi vs. bronchioles: Bronchi are the larger airways with cartilage; bronchioles are the smaller ones without it.
- Biceps brachii vs. biceps femoris: The first is in the upper arm; the second is a hamstring in the thigh.
Frequently Asked Questions
Which organs start with B?
The brain, bladder and bowel are organs that start with B. Bones are also considered organs because they are living tissue with their own blood supply.
What is the largest muscle that starts with B?
The buttocks are formed by the gluteus maximus, the largest muscle in the body. Among muscles whose own names start with B, the biceps femoris and biceps brachii are the best known.
What are easy B body parts for kids?
Back, belly button, brain, bones, blood, big toe and baby teeth are simple words that young children can learn and point to.
Conclusion
From the brain that runs the whole body to the bronchioles that carry each breath, B covers some of the most essential parts of human anatomy. Grouping them by body system makes them easier to remember and shows how they work together.
Continue the series with body parts that start with A and body parts that start with C.
This article is for general education only and is not medical advice. If you have a health concern, please talk to a doctor.
