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The major muscle groups Axial muscles- position head and spinal column; move rib cage (about 60% of muscles) Appendicular muscles stabilize or move the bones of the appendicular skeleton. Muscle movement. Which joint? How is muscle attached? Origin- immovable part
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The major muscle groups Axial muscles- position head and spinal column; move rib cage (about 60% of muscles) Appendicular muscles stabilize or move the bones of the appendicular skeleton
Muscle movement • Which joint? • How is muscle attached? • Origin- immovable part • Insertion-movable end (insertion will move toward origin) • Flexion decreases angle, and extension increases it
Muscle names are descriptive Location (e.g., temporalis attaches to temporal bone in skull) Action (flexor causes muscle flexion) Shape (deltoid is shaped by the Greek letter delta)
Groups of axial muscles Head and neck- facial expressions, chewing, swallowing Muscles of the spine- flexors and extensors of the spinal column Muscles of the trunk- walls of the thoracic and abdominopelvic cavities; floor of the pelvic cavity
Originate on skull Insert into the dermis
Largest group of muscles associated with mouth Orbicularis oris- opening Buccinator- compresses cheeks Masseter and temporalis- chewing Other, smaller groups control movements of eyes, scalp, ears, movements of jaw, etc.
Muscles of spine Covered by superficial muscles erector spinae- extensors quadratus lumborum- flexors Muscles of trunk- intercostals, obliques, transversus abdominalis, diaphragm, rectus abdominalis
Muscles associated with pelvic floor Broad sheet of support muscles (levator ani) Muscles associated with urination and defecation
Appendicular muscles shoulders and upper limbs pelvic girdle and lower limbs Trapezius; movements of scapula, clavicle, extension of head and neck Flexors, rotators, abductors (raise) adductor (lower) of arm Extensors of wrist Flexors and extensors of fingers
Muscles of hip and lower limb Movement of the thigh flexors, extensors, abductors, adductors Movement of the leg flexors, extensors Movement of ankles and feet dorsiflexor, eversion, plantar flexion
Effects of aging on the muscular system skeletal muscle fibers become smaller in diameter muscles become smaller and less elastic tolerance for exercise decreases ability to recover from injury decreases You can’t start exercising too early!
Disorders of the muscular system (often due to nervous disorders) Trauma (tears, bruises, damage to connective tissue). Pain may arise from damage to skeleton Infection, inflammation Weakness, atrophy (disease, infection) Tremors, paralysis (nervous system)
Summary • There are over 700 skeletal muscles • They are named according to shape, size, location, and function • Arrangement of muscles and motor nerves gives an enormous range of voluntary movement • Learning the names requires brute force!