M covers a wide range of body parts, from the mouth where digestion begins to the medulla oblongata that keeps you breathing without a thought. It also includes the muscles that move you and the meninges that protect your brain.
Here are more than 20 human body parts that start with M, grouped by body system, each with a short and accurate explanation.
Quick List: Body Parts That Start With M
| Malleus | Maxilla | Mitral valve |
| Mammary glands | Medial malleolus | Molars |
| Mandible | Median nerve | Mouth |
| Masseter | Medulla oblongata | Mucous membranes |
| Mastoid process | Meninges | Muscles |
| Metacarpals | Menisci | Myocardium |
| Metatarsals | Midbrain |
Brain and Nervous System
Medulla oblongata: The lowest part of the brainstem, joining the brain to the spinal cord. It controls automatic functions essential for life, including breathing, heart rate, blood pressure, swallowing and vomiting.
Midbrain: The top section of the brainstem. It helps control eye movements, reflexes to sudden sights and sounds, and movement, and it contains cells that produce dopamine.
Meninges: The three protective membranes that cover the brain and spinal cord: the dura mater, arachnoid mater and pia mater. Infection of these layers is called meningitis.
Median nerve: A major nerve that runs down the middle of the arm into the hand. It controls many thumb muscles and carries feeling from the thumb and first fingers. Pressure on it at the wrist causes carpal tunnel syndrome.
Head, Mouth and Ears
Mouth: The opening where food enters the body and digestion begins. The teeth chew, the tongue mixes and tastes, and saliva starts breaking down starches. The mouth is also used for speaking and breathing.
Molars: The broad, flat teeth at the back of the mouth, used for grinding food. Adults usually have 12, including the four wisdom teeth.
Mandible: The lower jawbone, the largest and strongest bone of the face and the only skull bone that moves freely.
Maxilla: The upper jawbone. It holds the upper teeth and forms part of the eye sockets, the nose and the roof of the mouth.
Masseter: The thick chewing muscle at the side of the jaw. You can feel it tighten when you clench your teeth.
Mastoid process: The bony bump just behind the ear, part of the temporal bone. Several neck muscles attach to it.
Malleus: The first of the three tiny bones of the middle ear, also called the hammer. It is attached to the eardrum and passes its vibrations to the incus.
Heart
Myocardium: The thick, muscular middle layer of the heart wall. Its contractions pump blood around the body. A heart attack damages part of the myocardium by cutting off its blood supply.
Mitral valve: The valve between the left atrium and left ventricle. It has two flaps and is also called the bicuspid valve.
Bones, Joints and Muscles
Muscles: Tissues that contract to produce movement. There are three types: skeletal muscle, which moves the skeleton under your control; smooth muscle, in organs like the stomach and blood vessels; and cardiac muscle, found only in the heart.
Metacarpals: The five long bones in the palm of the hand, connecting the wrist to the fingers. Their ends form the knuckles.
Metatarsals: The five long bones in the middle of the foot, connecting the ankle to the toes. They help form the arch and are a common site of stress fractures in runners.
Medial malleolus: The bony bump on the inner side of the ankle, formed by the lower end of the tibia.
Menisci: Two C-shaped pads of cartilage inside each knee, between the thigh bone and shin bone. They cushion the joint and help keep it stable. A torn meniscus is a common sports injury.
Glands and Tissues
Mammary glands: The milk-producing glands in the breasts. They develop fully in females and produce milk after childbirth.
Mucous membranes: Moist linings found in the nose, mouth, throat, airways, gut and other passages. They make mucus, which traps germs and dust and keeps the surfaces from drying out.
Common Mix-Ups to Avoid
- Mandible vs. maxilla: The mandible is the movable lower jaw; the maxilla is the fixed upper jaw.
- Metacarpals vs. metatarsals: Metacarpals are in the hand; metatarsals are in the foot.
- Medial vs. lateral malleolus: The medial malleolus is the inner ankle bump (tibia); the lateral malleolus is the outer one (fibula).
Frequently Asked Questions
Which organ starts with M?
The mouth is the most familiar. The medulla oblongata and midbrain are vital parts of the brain, and the myocardium is the muscle of the heart.
How many muscles are in the human body?
There are more than 600 skeletal muscles in the human body. The exact number varies depending on how small muscles are counted.
What are easy M body parts for kids?
Mouth, muscles and molars are simple words children can learn, and they can feel their muscles work and their molars when they chew.
Conclusion
From the mouth that starts digestion to the medulla that keeps you breathing, the letter M covers parts of every major body system. Learning them in groups makes them easier to remember.
Continue the series with body parts that start with L and body parts that start with N.
Where to Learn More
For a clear overview of how the body’s systems fit together, see the Britannica guide to the human body. For trusted health information about body parts and conditions, visit MedlinePlus from the US National Library of Medicine. To check the meaning and pronunciation of tricky words, use the Cambridge Dictionary. You can also jump to the end of the alphabet with body parts that start with Z.
This article is for general education only and is not medical advice. If you have a health concern, please talk to a doctor.
