The three types of muscle tissue are skeletal, smooth, and cardiac.
The function of muscles is movement, but the types of movement elicited differ between skeletal, cardiac, and smooth muscle.
Skeletal muscle contains different fibers which allow for both rapid short-term contractions and slower, repeatable long-term contractions.
The force a muscle generates is dependent on its length and shortening velocity.
The shortening velocity affects the amount of force generated by a muscle.
The motor unit is the functional unit of muscle contraction and includes the motor nerve fiber and the muscle fibers it innervates.
Muscle tone is a measure of a muscle's resistance to stretching while in a passive resting state.
Muscle contractions are defined by changes in the length of the muscle during contraction.
Muscle contraction occurs via metabolism of adenosine triphosphate (ATP) derived primarily from the simple sugar glucose.
Muscle fatigue occurs following a period of sustained activity.
Sustained, repeated overload of a muscle group leads to hypertrophy and strengthening of those muscles.
Muscle atrophy is a decrease in muscle mass; muscle hypertrophy is an increase in muscle mass due to an increase in muscle cell size.
Exercise damages muscles due to eccentric and concentric muscle loading and often results in delayed onset muscle soreness (DOMS).
Rigor mortis is the stiffening of all muscles of the body following death.
The muscular system controls numerous functions, which is possible with the significant differentiation of muscle tissue morphology and ability.
Creatine supplements may increase anaerobic exercise performance by augmenting phosphocreatine levels and ATP availability.
Aerobic activity relies on the availability of oxygen for energy production, whereas anaerobic activity utilizes primarily glycolysis.
Hypertonia is the reduced ability of muscles to stretch due to increased muscle tension; hypotonia, due to chronic reduced muscle tension.
Anabolic steroids mimic natural hormones and can stimulate muscle hypertrophy.
Autoimmune diseases are an inappropriate immune response against tissues in the body.
Muscular dystrophy (MD) is a group of muscle diseases characterized by non-functional muscle proteins that impair proper function.
Fibromyalgia is a medical disorder characterized by chronic widespread pain and a heightened and painful response to pressure.
Involuntary muscle contractions are referred to as spasms, and can be due to abnormal activity of the nerve or the muscle.
Myogenesis is the formation of muscle tissue during embryonic development from stem cells in the mesoderm.
The musculoskeletal system provides form, support, stability, and movement to the body.
The hydrostatic skeleton, exoskeleton, and endoskeleton support, protect, and provide movement to the bodies of different types of animals.
The axial skeleton forms the central axis of the human body and consists of the skull, vertebral column, and thoracic cage.
The appendicular skeleton supports the attachment and functions of the upper and lower limbs of the human body.
Bones are made of a combination of compact bone tissue for strength and spongy bone tissue for compression in response to stresses.
The osteoblast, osteoclast, osteocyte, and osteoprogenitor bone cells are responsible for the growing, shaping, and maintenance of bones.
Intramembranous ossification stems from fibrous membranes in flat bones, while endochondral ossification stems from long bone cartilage.
Long bones lengthen at the epiphyseal plate with the addition of bone tissue and increase in width by a process called appositional growth.
Bone is remodeled through the continual replacement of old bone tissue, as well as repaired when fractured.
Joints, responsible for movement and stability of the skeleton, can be classified based on structure or function.
Synovial joints allow for many types of movement including gliding, angular, rotational, and special movements.
Synovial joints include planar, hinge, pivot, condyloid, saddle, and ball-and-socket joints, which allow varying types of movement.
Tropomyosin and troponin prevent myosin from binding to actin while the muscle is in a resting state.
Excitation–contraction coupling is the connection between the electrical action potential and the mechanical muscle contraction.
Skeletal muscles interact to produce movements by way of anatomical positioning and the coordinated summation of innervation signals.
The anatomical arrangement of skeletal muscle fascicles can be described as parallel, convergent, pennate, or sphincter.
Muscles are arranged in groupings of agonist, antagonist, and synergists that produce and modulate movement.
Tendons are composed of connective tissue that attaches muscle to bone.
Skeletal muscles are grouped into fascicles, which are bunches of muscle fibers surrounded by a perimysium.
Arrangement of muscles allows them to move relative to one another, while the insertion joint acts as the pivot point for a lever system.
The human face is composed of multiple muscles that control the fine movements that produce facial expressions.
Mastication, or chewing, involves the adduction and lateral motions of the jaw bone. It is controlled by four muscles of the face.
Cervical muscles are those associated with the front of the neck; vertebral muscles are associated with the vertebral column.
The anterior muscles of the torso (trunk) are those on the front of the body, including the muscles of the chest, abdomen, and pelvis.
Muscles of the posterior portion of the trunk include muscles of the back, suboccipital region, and perineum region.
Humerus that act on the forearm are primarily involved in flexion and extension.
Muscles in the forearm move the wrists, and hand movement is caused by both forearm and hand muscles.
Muscles of the shoulder include those that attach to the bones of the shoulder to move and stabilize the joint.
The four main groups of hip muscles are gluteal, adductor, iliopsoas, and lateral rotator, defined by the type of movement they mediate.
Three sets of muscles (popliteus, quadriceps and hamstrings) allow for movement, balance, and stability at the knee joint.
Muscles of the leg insert into ankle and foot bones to facilitate ankle movement.
Movement of the foot and toes requires the action of many muscles.
Tenosynovitis is the inflammation of the fluid-filled sheath (called the synovium) that surrounds a tendon.
Intramuscular (or IM) injection is the injection of a substance directly into a muscle.
Stretching is a form of physical exercise, where specific skeletal muscles are stretched, improving elasticity and muscle tone.
Bell's palsy is a form of facial paralysis resulting from a dysfunction of cranial nerve VII (the facial nerve).
Strabismus also known as heterotropia is a condition in which the eyes are not properly aligned with each other.
Tracheal intubation is the placement of a flexible tube into the trachea to maintain an open airway or to facilitate drug administration.
An inguinal hernia is a protrusion of abdominal-cavity contents through the inguinal canal.
Levator ani syndrome, episodic rectal pain, is caused by spasm of the levator ani muscle; urinary incontinence is involuntary urine leakage.
Shoulder impingement syndrome occurs when the tendons of the rotator cuff muscles become irritated and inflamed.
Carpal tunnel syndrome is an entrapment median neuropathy of the median nerve due to its compression at the wrist in the carpal tunnel.
Back injuries result from damage, wear, or trauma to the bones, muscles, or other tissues of the back.
A pulled groin muscle usually refers to a painful injury sustained by straining the hip adductor muscles.
A strained hamstring, also known as a pulled hamstring, is defined as an excessive stretch or tear of muscle fibers and related tissue.
Shin splints is a common injury that affects athletes who engage in running sports or basic athletic activities.
Plantar fasciitis is a painful inflammatory process of the plantar fascia, the connective tissue on the sole (bottom surface) of the foot.
Running injuries can be debilitating and include "runner's knee," shin splints, pulled muscles, and iliotibial band syndrome.
Compartment syndrome is caused by the compression of tissues within a limb from swelling following an injury, resulting in tissue necrosis.
Muscle atrophy can occur from disuse (decreated activity) or disease, resulting in power loss or immobility.
Dermatomyositis and polymyositis cause inflammation of the muscles.