It’s considered that there are above 650 named skeletal muscles in the body. Smooth muscle occurs on a cellular level, to have billions of smooth muscle cells. Skeletal muscles can be controlled, while cardiac & smooth muscles work involuntarily.
Types of muscles
The body has three distinct kinds of muscles. They include:
1. Skeletal muscle
- Attached to your bones via tendons
- Comprised of thousands of muscle fibres
- All are bundled together.
- The organized arrangement of fibres leads to a striped pattern.
- Referred to as striated muscle.
- Predominantly involved in the movement.
- Enables movement of a specific area of the body
- These are voluntary.
- You can control their movement.
2. Smooth muscle
- Found in different organ systems of the body, including:
- Digestive System
- Respiratory System
- Cardiovascular System
- Renal System
- Reproductive System
- Smooth muscle cells are rounded at the centre and tapered off at the sides.
- They aren’t striated & involuntary.
- Forms a mesh-like network.
3. Cardiac muscle
- Found only in the heart.
- Allows heart to beat.
- Referred to as the myocardium.
- Three layers of tissue in the heart.
- Located within the inner lining of the heart (endocardium)
- The protective sac that surrounds the heart (pericardium)
- Organized into fibres and has a striated appearance.
4. Skeletal muscle functions
- Enabling movement of the body
- Providing structural support
- Maintaining posture
- Generating heat, which helps maintain body temperature
Division of Skeletal muscles
1. Muscles of the head and neck
Controls movement of the face, head, and neck.
- Zygomaticus: Involved in facial expression and lifts the corners of mouth while smiling.
- Masseter: Found in the jaw and is used to close the mouth and to chew food.
- Eye (extraocular) muscles: Movements of eyes and opening-closing of eyelids.
- Powers of the tongue: Help to elevate & lower the tongue and help it move in-out.
- Sternocleidomastoid: Rotate or tilt head to the side & front.
2. Muscles of the trunk: Located in torso and abdomen
- Erector spinae: Supports spine and enabling movements like bending, arching, and twisting of the spine.
- Oblique muscles: Helps to bend to the side or twist the body at the waist.
- Intercostal muscles: Located around ribs to help facilitate inhaling & exhaling.
- Diaphragm: Separates torso from the abdomen & involved in breathing, contracting while inhaling, relaxing while exhaling.
- Levator ani: Supports the organs and tissues around your pelvis. Important for urination and bowel movements.
3. Muscles of the upper extremities: Move shoulders, arms, wrists, hands.
- Trapezius: Used for several movements, tilting head back, raising shoulders, and moving shoulder blades.
- Pectoralis major: Located in the upper chest, Utilized in rotational, vertical, & lateral movements of the arm.
- Deltoid: Lift or rotate the arm at the shoulder.
- Biceps brachii: Flexes the forearm.
- Triceps brachii: Extends the forearm, aligning the elbow.
4. Muscles of the lower extremities: Move legs and feet.
- Gluteus maximus: movement of hips and thighs for maintaining posture, standing up.
- Quadriceps: Positioned at the front of the thigh to straighten the leg at the knee.
- Hamstrings: Located in the back part of the leg. Extend thigh and bend leg at the knee.
- Tibialis anterior: Raises the sole from the ground
- Soleus: Lowers the sole of foot to the ground, maintains posture while walking.
5. Smooth muscle
- Digestive system: push food through the digestive tract.
- Respiratory system: Cause airways to widen or narrow
- Cardiovascular system: Aids in the flow of blood and regulate blood pressure.
- Renal system: Regulate the flow of urine from the bladder.
- Reproductive system: In the female reproductive system helps in contractions during pregnancy. In the male reproductive system, it propels sperm.
- Smooth muscle is involved in sensory processes.
6. Cardiac muscle
- Allows heart to beat with an electrical impulse.
- Contracts on receiving an electrical signal
- Closely connected
- Contract in a coordinated wave-like
The Bottom Line
Muscle tissue is found everywhere in the body, and its composition and function can be very different. You have three distinct types of muscle: skeletal, smooth, and cardiac. Skeletal muscle solely accounts for over 650 muscles.