Muscular System:
MUSCLE:
Muscle consists predominantly of contractile cells, produces the movements of various parts of the body by contraction.
And it occur by three types of muscles in muscular system:
A. Skeletal Muscle:
It is voluntary also striate; makes up approximately 40% of the total body mass; additionally functions to produce movement of the body, generate body heat, also maintain body posture.
In detail, it has two attachments, an origin (which is usually the more fixed and proximal attachment) also an insertion (which is the more movable and distal attachment).
Besides this, Skeletal muscle enclose by epimysium, a thin layer of connective tissue. Smaller bundles of muscle fibers surround by perimysium. Lastly, Each muscle fiber enclose by endomysium.
CLINICAL ANATOMY
Lou Gehrig disease
Lou Gehrig disease (in other words, amyotrophic lateral sclerosis) is a fatal neurologic disease that attacks the neurons responsible for controlling voluntary muscles. Moreover, The muscles gradually weaken and atrophy; the brain is unable to control voluntary movement of the arms, legs, also body; and patients lose the ability to breath, swallow, and speak. All in all, The earliest symptoms may include cramping, twitching, also muscle weakness.
B. Cardiac Muscle:
It is involuntary and striated and forms the myocardium, the middle layer of the heart.
This muscle is innervated by the autonomic nervous system (ANS) but contracts spontaneously without any nerve supply.
Includes specialized myocardial fibers that form the cardiac conducting system.
C. Smooth Muscle
■ In general, It is involuntary and nonstriated and generally arranged in two layers, circular and longitudinal, in the walls of many visceral organs.
■ This Muscle innervate by the ANS, additionally regulating the size of the lumen of a tubular structure.
■Undergoes rhythmic contractions called peristaltic waves in the walls of the gastrointestinal (GI) tract, uterine tubes, ureters, also other organs.
STRUCTURES ASSOCIATED WITH MUSCLE:
In Muscular System some structures associate with muscles, they are given as follow i.e.:
A. Tendons
■ In detail, Tendons are fibrous bands of dense connective tissue that connect muscles to either bones or cartilage.
■ Tendons supply by sensory fibers extending from muscle nerves.
B. Ligaments
■ Basically, Ligaments are fibrous bands that connect bones to bones or cartilage or are folds of peritoneum serving to support visceral structures.
C. Raphe
■ In brief, Raphe is the line of union of symmetrical structures by a fibrous or tendinous band such as the pterygomandibular, pharyngeal, also scrotal raphes.
D. Aponeuroses
■ In general, Aponeuroses are flat fibrous sheets or expanded broad tendons that attach to muscles and serve as the means of origin or insertion of a flat muscle.
E. Retinaculum
■ Retinaculum is a fibrous band that holds a structure in place in the region of joints.
F. Bursae
■ In brief, Bursae fluid-fill flattened sacs of synovial membrane that facilitate movement by minimizing friction.
G. Synovial Tendon Sheaths
■ Synovial Tendon Sheaths synovial fluid-fill tubular sacs around muscle tendons that facilitate movement by reducing friction.
H. Fascia
■ Fascia is a fibrous sheet that envelops the body under the skin also invests the muscles and may limit the spread of pus and extravasated fluids such as urine also blood.
1. Superficial Fascia
■ Is a loose connective tissue between the dermis and the deep (investing) fascia and has a fatty superficial layer (for example; fat, cutaneous vessels, nerves, lymphatics, also glands) and a membranous deep layer.
2. Deep Fascia
■ Is a sheet of fibrous tissue that invests the muscles also helps support them by serving as an either elastic sheath or stocking.
■ Provides origins or insertions for muscles, forms fibrous sheaths or retinacula for tendons, also forms potential pathways for infection or extravasation of fluids.
