What is Muscular System Anatomy?

Muscular System

The muscular system gives mobility to the human body. Muscles move your bones and your internal organs like your heart, stomach, and diaphragm. We have more than 600 muscles in our body. About 40% of your body weight is from muscles. Muscles can't push. They only pull. Your muscles work in pairs to move your bones. To move bones, they pull in opposite directions. The eye muscles are the busiest ones.They can move more than 100,000 times a day.

Muscle Structure

A muscle fiber is a single, multinucleated muscle cell. Although muscle fiber makes up most of the muscle tissue, a large amount of connective tissue, blood vessels, and nerves are also present. Connective tissue covers and supports each muscle fiber and reinforces the muscle as a whole. Active use a lot of energy and require a continuous supply of oxygen and nutrients, which are supplied by arteries. Muscles produce large amounts of Metabolic waste

that must be removed by Veins. Muscle fibers consist of bundles of thread-like structures called myofibrils. 

Each myofibril is made up of two types of protein filaments (thick ones and thin ones). The thick

Filaments are made up of a protein called myosin. The thin filaments are made of a protein called actin Myosin and actin filaments are arranged to form overlapping patterns, which are responsible for the light and dark   that can be seen in skeletal (stiated appearance) muscle. Thin Actin Filaments are anchored at their Midpoints to a structure called the Z-LINE

The Region From one Z line to the next is called a SARCOMERE, the Functional Unit of Muscle Contractions.

Also read: Anatomy Clinical Questions For NEET PG/FMGE 2025

Muscles of the Body

Types of Muscles 

There are three types of muscles that make up the muscular system:

• Smooth Muscle
• Skeletal Muscle
• Cardiac muscles

Functions of Muscular System

• Movement of body parts
• Propel body fluids and food
• Circulation/Heartbeat
• Distribute heat
• Protects body

Also read: Ulnar Nerve Injuries Anatomy & Functions Explained

Features of Muscle

Origin: The head of the muscle, usually superior, relatively immobile.

Insertion: The end of the muscle, usually inferior, relatively mobile.

When a muscle contracts, the insertion is moved towards the origin.

Muscle Interactions

Agonist: A muscle that causes an action. Ex. Deltoid is the agonist for abduction of arms. Antagonist: A muscle that opposes an action. Ex. Pectoralis Major is the antagonist for abduction of arms. Synergist: muscles that work together. Prime Mover: The muscle that does most of the work in synergistic relationships

Types of Movements

Flexion: moving parts at a joint, angle decreases. Extension: moving parts at a joint, angle

Increases. Hyperextension: Extension beyond anatomical position

Dorsiflexion: moving the ankle closer to the shin. Plantar Flexion: Moving ankle further from shin

Abduction: moving a body part away from the midline of the body. Adduction: Moving a body part towards the midline of the body, think. ADDuction= ADDing to body

Medial Rotation: turning a limb on its axis towards the midline of the body. Lateral Rotation: Turning a limb on its axis away from the midline of the body

Also read: Flexor Retinaculum: Tarsal Tunnel Syndrome

Circumduction: moving a body part so that it follows a circular path

Pronation: Rotation of forearm so that the palm is facing downward

Supination: Rotation of forearm so that the palm is facing upward, think "holds soup"

Eversion: Turning the foot so the bottom faces laterally

Inversion: Turning the foot so the bottom faces medially

Protraction: Moving a body part forward

Retraction: moving a body part backward

Elevation Raising a part of the body

Depression: Lowering a part of the body

Also read: Extravasation of Urine : Causes, Cases

Important Questions to Ask

Q. How many muscles are there in the human body?

Ans. 640 muscles. The muscles make up about 40% of the body mass.

Q. What is the longest muscle in the body?

Ans. Sartorius.

Q. What is the smallest muscle in the body?

Ans. Stapedius. It is located deep in the ear. It is only 5 mm long and thinner than cotton thread. It is involved in hearing.

Q. What is the biggest muscle in the body?

Ans. Gluteus maximus. It is located in the buttock. It pulls the leg backwards powerfully for walking and running.

Download the PrepLadder app now and unlock a 24-hour FREE trial of premium high-yield content. Access Video Lectures, digital notes, QBank, and Mock Tests for FREE. And if you need any assistance in NEET PG preparation, you can always seek our assistance. Our best neet pg coaching online is all you need to ace the exam like never before.