1. Skeletal muscles: 

Attached to bones, these muscles help move the body's skeleton.

2. Smooth muscles: 

Found in walls of hollow organs, these muscles help move substances through organs (e.g., digestive tract).

3.Cardiac muscles:

Found in the heart, these muscles pump blood throughout the body.

Muscles work by contracting and relaxing, using energy from ATP (adenosine triphosphate). They are essential for various bodily functions, such as:

Movement (walking, running, lifting)

Posture (standing, sitting)

 Balance

Regulation of body temperature

Support for organs and joints

Muscle health is crucial for overall well-being, and regular exercise helps maintain muscle strength and flexibility.

Muscles anatomy

Skeletal muscles

Skeletal muscles are attached to bones and help move the body's skeleton. There are over 600 skeletal muscles in the human body, making up about 40% of our body weight. They are voluntary muscles, meaning we can control their movements.

Here are some key characteristics of skeletal muscles:

1. Striated appearance: 

Skeletal muscles have a striated appearance under a microscope, with alternating light and dark bands.

2. Voluntary control:

We can consciously control skeletal muscle movements.

3. Attached to bones: 

Skeletal muscles are attached to bones via tendons.

4. Movement and support: 

Skeletal muscles help move the body's skeleton and support posture and balance.

5. Fast-twitch and slow-twitch fibers

 Skeletal muscles contain both fast-twitch (for rapid, powerful movements) and slow-twitch (for slower, more endurance-based movements) fibers.

Some examples of skeletal muscles include:

1. Biceps brachii(upper arm)

2. Quadriceps femoris(thigh)

3. Gastrocnemius (calf)

4. Deltoid (shoulder)

5. Gluteus maximus_ (buttock)

Skeletal muscles work together with bones and joints to provide movement, stability, and support for our bodies!

The biceps brachii

The biceps brachii is a skeletal muscle located in the upper arm, responsible for flexing the elbow and forearm. Its structure includes:

1. Origin: 

The biceps brachii originates from two heads:

    - Long head: originates from the supraglenoid tubercle of the scapula

    - Short head: originates from the coracoid process of the scapula

2. Belly:

The muscle belly is the main body of the muscle, containing muscle fibers that contract to produce movement

3. Insertion: The biceps brachii inserts into the radial tuberosity of the radius bone in the forearm

4. Tendons:

 The muscle has two tendons:

     Long head tendon: attaches to the scapula

    Short head tendon: attaches to the coracoid process

5. Muscle fibers: 

The biceps brachii contains both fast-twitch (FT) and slow-twitch (ST) muscle fibers

6. Nerve supply:

The muscle is innervated by the musculocutaneous nerve (C5-C7)

7. Blood supply: 

The biceps brachii receives blood from the brachial artery and its branches

When the biceps brachii contracts, it flexes the elbow and forearm, making it essential for movements like lifting, pulling, and bending.

The deltoid muscle

The deltoid muscle is a skeletal muscle located in the shoulder region, responsible for abduction, flexion, and extension of the arm. Its structure includes:

1. Origin:

  Anterior (front) fibers: originate from the anterior border of the clavicle (collarbone)

    Middle fibers: originate from the acromion process of the scapula (shoulder blade)

    Posterior (back) fibers: originate from the posterior border of the scapula

2. Muscle belly:

The main body of the muscle, containing muscle fibers that contract to produce movement

3. Insertion:

The deltoid muscle inserts into the deltoid tuberosity of the humerus (upper arm bone)

4. Tendons:

 The muscle has three tendons, corresponding to the three parts of the muscle:

     Anterior tendon

     Middle tendon

     Posterior tendon

5. Muscle fibers: 

The deltoid contains both fast-twitch (FT) and slow-twitch (ST) muscle fibers

6. Nerve supply: 

deltoid muscle is innervated by the axillary nerve (C5-C6)

7. Blood supply: 

The deltoid receives blood from the posterior circumflex humeral artery and the anterior circumflex humeral artery

The deltoid muscle has three parts, each with a specific function:

Anterior (front) fibers: flexion and medial rotation

Middle fibers: abduction

Posterior (back) fibers: extension and lateral rotation

Together, the deltoid muscle helps move the arm in various directions, making it essential for movements like lifting, throwing, and reaching.

Type of smooth muscles

There are several types of smooth muscles, including:

1. Single-unit smooth muscle: 

This type of smooth muscle is found in most hollow organs, such as the digestive tract, blood vessels, and airways. It contracts as a single unit, meaning that the entire muscle contracts simultaneously.

2. Multi-unit smooth muscle:

 This type of smooth muscle is found in some specialized organs, such as the iris, ciliary muscles, and some blood vessels. It consists of multiple units that can contract independently of each other.

3.Phasic smooth muscle: 

This type of smooth muscle contracts in a rapid, phasic manner, such as in the muscles that move food through the digestive tract.

4.Tonic smooth muscle:

This type of smooth muscle contracts slowly and maintains contraction for a longer period, such as in the muscles that regulate blood pressure.

5. Myoepithelial cells:

 These cells are found in some organs, such as the salivary glands, mammary glands, and sweat glands, and have both smooth muscle and epithelial properties.

6. Peristaltic smooth muscle: 

This type of smooth muscle is found in the digestive tract and contracts in a wave-like manner to move food through the tract.Each type of smooth muscle has unique properties and functions that allow it to perform specific tasks in the body.