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 tendonsComprised of thousands of muscle fibresAll 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 bodyThese are voluntary.You can control their movement.
2. Smooth muscle
Found in different organ systems of the body, including:Digestive SystemRespiratory SystemCardiovascular SystemRenal SystemReproductive SystemSmooth 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 bodyProviding structural supportMaintaining postureGenerating 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 groundSoleus: 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 narrowCardiovascular 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 signalClosely connectedContract 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.