MUSCULAR SYSTEM

“the power system”

FACTS:

• Nearly half our weight comes from muscle tissue.

• There are 650 different muscles in the human body.

• Muscles give us form and shape.

• Muscles produce most of our body heat.

THREE MAIN FUNCTIONS

• Responsible for all body movement.• Responsible for body form and shape (posture)• Responsible for body heat and maintaining body temperature.

Types of muscles

•Skeletal•Smooth•Cardiac•Sphincter

Skeletal Muscle

• Attached to bone• Striated (striped)

appearance• VOLUNTARY• Contract quickly, fatigue

easily, can’t maintain contraction for long period of time

Skeletal Muscles

• Each skeletal muscle cell contains many nuclei

• Muscle cells are known as muscle fibers

• Cell membrane is call sarcolemma

• Cytoplasm is called sarcoplasm

Smooth Muscle

• Visceral (organ) muscle• Found in walls of

digestive system, uterus and blood vessels

• Cells small and spindle-shaped

• INVOLUNTARY• Controlled by

autonomic nervous system

• Act slowly, do not tire easily, can remain contracted for long time

Cardiac Muscle

• Found only in the heart

• Striated and branched

• Involuntary• Cells are

fused – when one contracts, they all contract

Sphincter• special

circular muscles in openings of esophagus and stomach, stomach and small intestine, anus, urethra and mouth.

CHARACTERISTICS OF MUSCLES

• CONTRACTIBILITY – the ability of a muscle to reduce the distance between the parts of its contents or the space it surrounds.

• EXCITEABILITY (IRRITABILITY) – the ability to respond to certain stimuli by producing impulses.

CHARACTERISTICS OF MUSCLES

• EXTENSIBILITY – the ability to be stretched.

• ELASTICITY – ability of muscle to return to its original length when relaxing.

Naming Muscles• Location:

– frontalis-forehead• Size:

– gluteus maximus• Direction of fibers:• external abdominal oblique• Number of origins:

– Biceps-two headed muscle in humerus• Location of origin and Insertion:

sternocleidomastoid- origin in sternum

Naming muscles• Action flexor:– flexor carpi ulnaris- flexes the wrist

• Extensor: – extensor carpi ulnaris- extends the

wrist• Levator and Depressor:– depressor anguli oris-depresses the

corner of the mouth, raises or lowers body parts

MOVEMENT• Muscles move bones by pulling on

them. •  As a muscle contracts, it pulls the

insertion bone closer to the origin bone. Movement occurs at the joint between the origin and the insertion. 

• Rule: A muscle’s insertion bone moves toward its origin bone.

• Groups of muscles usually contract to produce a single movement.

Muscle Contraction

• Sarcolemma: muscle cell membrane

• Synaptic Cleft: gap between the axon and the muscle cell.

Muscle Contraction

• MOTOR UNIT – a motor neuron plus all the muscle fibers it stimulates.

 • NEUROMUSCULAR JUNCTION – the

junction between the motor neuron’s fiber which transmits the impulse – and the muscle cell membrane.

• ACETYLCHOLINE – chemical neurotransmitter, diffuses across the synaptic cleft (carries impulse across synaptic cleft)

• MUSCLE FATIGUE – caused by the accumulation of lactic acid in the muscles.

• OXYGEN DEBT – after exercise, the amount of oxygen needed by the muscle to change lactic acid back to glucose.

 • MUSCLE TONE - When muscles

are slightly contracted and ready to pull.

Muscle Efficiency

• Improves:-Coordination of all muscles

involved-Respiratory and circulatory

system to supply needs of active muscular system

-Elimination of excess fat-Joint movement involved with

that muscle activity

Muscle Strength

• Strength (capacity to do work) is increased with training

• Muscle size increase due to change in the sarcoplasm (cytoplasm found in the individual skeletal muscle fibers) Not the increase in the number of muscle fiber cells

Muscle Attachments

• Tendons: non-elastic cords that attach muscles to bones

• Bones are connected at joints

DIAPHRAGM

• Dome-shaped muscle that separates the abdominal and thoracic cavities, aids in breathing

Disorders and Related Terminology

• ATROPHY – wasting away of muscle due to lack of use.

• If we fail to exercise our muscles weaken and become flaccid ex. Quadriplegics, elderly on bedrest, extremity in a cast, etc.

 

• Massage of these muscles is essential in providing the proper physiotherapy or a general sense of comfort and well-being to a patient, also prevents atrophy in debilitated patients

• HYPERTROPHY – an increase in the size of the muscle cell.

• when over exercise the size of the muscle fibers increase due to a change in the sarcoplasm (not due to an increase in number of muscle fiber cells)

 

• STRAIN – tear in the muscle resulting from excessive use. Bleeding inside the muscle can result in pain and swelling. Ice packs will help stop bleeding and reduce swelling.–  RICE : rest, ice, compression,

elevation

• Rehabilitation: retaining of injured or unused muscles • MYALGIA – muscle pain

• TENDONITIS – inflammation of a tendon

• MUSCLE SPASM (cramp) – sustained contraction of the muscle, usually because of overuse.

Torticolis

• Or wry neck, may be due to an inflammation of the trapezius and/or

• Sternocleidomastoid muscle

La belleza perece en la vida pero es inmortal en el arte.

Leonardo Da Vinci