long, multinucleate cells with cross striations. We can consciously control the action of skeletal muscle so we call it voluntary muscle
What does cardiac muscle consist of?
It is found in the heart, has branched fibers with intercalated disks which mark the boundaries between cells. This muscle is involuntary.
What does smooth muscle consist of?
spindle shaped cells which surround tubes such as in the digestive system. These cells have one nucleus and are involuntary.
Skeletal Muscle
Muscle composed of cylindrical multinucleate cells with obvious striations; the muscles attached to the body's skeleton; voluntary muscle.
What are the functions of muscle?
Movement
Posture maintenance
Joint stabilization
Heat Generation
Movement
Muscle contraction provides movement as in walking or eye movement.
Posture Maintenance
Contraction of muscle allows us to remain upright!
Joint Stabilization
Tendons of muscles often extend across joints and keep them stable.
Heat Generation
Muscle contraction produces heat used to maintain body temperature.
What are some of the functional characteristics of muscle?
Excitability
Contractility
Extensibility
Elasticity
Muscle Excitability
refers to the ability to respond to stimuli which in muscle is usually a neurotransmitter released by a nerve cell. This chemical gives the muscle cell the “message to contract”.
Muscle Contractility
refers to the ability of a muscle cell or fiber to shorten producing movement. This property sets muscle apart from other tissues
Muscle Extensibility
refers to the ability of muscle fibers to be stretched or extended.
Muscle Elasticity
refers to the ability of muscle fibers to contract or extend and return to their original length.
What are the primary functions of muscle?
Producing movement
Maintaining posture
Stabilizing joints
Generating heat
What percentage of body mass is skeletal muscle?
40%
What are some additional functions of muscle?
Protection of the more fragile internal organs (viscera).
Smooth muscles form valves to regulate passage of substances through internal body openings
Dilates and contracts the pupils of the eye
Forms arrector pili muscles attached to hair follicles
What are some key words to remember for cardiac muscle?
cardiac
striated
involuntary
What are some key words to remember for skeletal muscle?
skeletal
striated
voluntary
What are striations?
Obvious stripes within the muscle cells.
What are some key words to remember for smooth muscle?
visceral
nonstriated
involuntary
Epimysium
Sheath of fibrous connective tissue surrounding a muscle. Means literally 'outside the muscle'.
Fascicle
Bundle of nerve or muscle fibers bound together by connective tissue. Resembles bundles of sticks. Means 'bundles'.
Perimysium
Connective tissue that bundles muscle fibers into fascicles. Means 'around the muscle [fascicles]'
Endomysium
Thin connective tissue surrounding each muscle cell. Means 'within the muscle'.
Insertion
Movable attachment of a muscle.
Origin
Attachment of a muscle that remains relatively fixed during muscular contraction.
Direct muscle attachment
Also known as fleshy attachments. Epimysium of the muscle is fused to the periosteum of a bone or perichondrium of a cartilage.
Indirect muscle attachment
Where the muscle's connective tissue wrappings extend beyond the muscle either as a ropelike tendon or as a sheetlike aponeurosis.
Aponeurosis
Fibrous or membranous sheet connecting a muscle and the part it moves.
Tendon
Cord of dense fibrous tissue attaching muscle to bone.
Which type of muscle attachment is more common?
Indirect muscle attachment is more common than direct muscle attachment.