1G Flashcards
Muscular System
System composed of all the muscles of the body and concerned with movements of the total body as well as movements within the body.
Properties of Muscle Tissue
Contractility, extensibility, elasticity, irritability, tonus
Contractility
Ability of muscle tissue to shorten or contract.
Extensibility
Ability of muscle tissue to be extended or stretched within limits.
Elasticity
Ability of muscle tissue to return to its original state after being stretched.
Irritability
The susceptibility of muscle tissue to react to external stimuli.
Tonus
State in which muscle is partially contracted allowing it to react instantly when stimulated.
Involuntary Muscle (based on nervous control)
Muscle not subject to the control of the will.
Cardiac and smooth muscle are of this type.
Voluntary Muscle (based on nervous control)
Muscle subject to control of the will.
Skeletal muscle is of this type.
Smooth Muscle
It is located compromising the walls of the internal organs as well as the blood vessels of the body.
Long spindles thick in center and pointed at the ends.
1 nuclei per cell.
May be circularly arranged; when muscles contract, obliterate cavity or lumen of organ.
Cardiac Muscle
Located in the heart and appears striated with 1 nuclei per cell.
Skeletal Muscle
Composed of very long cells (up to 4 cm in length); due to length, more than 1 nucleus is needed to carry out cellular functions, and thus the cells are multinucleated.
It is attached to the skeleton and affords movement of skeletal elements when they contract.
Have special terms for cellular parts:
- Sarco- refers to “muscle”
- Sarcolemma: cell membrane
- Sarcoplasm: cytoplasm
Myofilament
Special type of organelle found within skeletal muscle cells.
2 different types found within the myofibril:
Actin and Myosin: Arranged in patterns that appear as alternating light and dark bands.
Fascia
Connective tissue layer located surrounding muscles and between adjacent muscles.
Functions of Fascia
- Permits gliding of 1 muscle over another.
- Provides pathways for passage of vessels and nerves.
Nomenclature of muscles: 5 criteria for classification
Function
ex. flexor digitorum profunds
Shape
ex. rhomboid major
Location
ex. tibialis anterior
Number of heads of origin
ex. biceps brachii
Structure (direction of fibers)
ex. external oblique
Individual muscle can only be properly described by indicating its 4 criteria.
origin, insertion, action, innervation
Origin
Nonmovable point of attachment.
Insertion
Movable point of attachment.
Action
Movement a particular muscle produces.
Innervation
Nerve supply to a muscle.
Muscle Attachments
Bone, cartilage, skin, fascia, tendons (attach muscle to bone), Aponeurosis (flattened tendon), and ligaments
Blood supply of muscle
Skeletal muscles are involved in movement and are very active organs, thus they require a substantial amount of blood.
Nerve supply of muscle
Skeletal muscles are innervated by 2 types of nerve fibers.
Sensory or Afferent
Motor or Efferent
Sensory or Afferent
Nerve fibers carry nerve impulses from receptors (muscle spindles) in the muscle to the central nervous system (brain and spinal cord).
Motor or Efferent
Nerve fibers carry nerve impulses from the central nervous system to muscle.
Functional classification of muscles
Keep in mind that muscles work in opposing pairs.
Prime mover, antagonist, synergist, fixator
Prime Mover
A muscle that directly produces the desired movement.
ex. when the extensor digitorum muscle extenders the digits, it is acting as the prime mover.
Antagonist
A muscle that produces a movement opposite to that of a prime mover,
ex. the flexor digitorum profundus, which flexes the digits, is antagonist to the extensor digitorum.
Synergist
A muscle that adds a little extra force to help the prime mover perform the desirable movements.
ex. the flexor digitorum profundus muscle, which is assisted by the flexor digitorum superficial is when flexing the digits.
Fixator
Muscles that maintain body position while a part is moving.
This occurs in the shoulder, when a muscle (serratus anterior) holds the scapula at an angle, so that the humorous can move.
The muscle that fixes the scapula is acting as fixator.
Choose the correct properties of muscle tissue.
A. flexibility B. tonus C. strength D. irritability E. tenacity
B,D
Sensory nerve fibers carry nerve impulses from ______.
A. the CNS to muscle B. blood vessels to other nerve fibers C. afferent fibers to efferent fibers D. nerve fibers to blood vessels E. receptors in the muscle to the CNS
E
Choose the correct characteristic(s) of cardiac muscle.
A. It is located in the arteries. B. It does not appear striated. C. It appears striated. Correct D. 1 nuclei per cell E. composed of very long cells
C,D
A function of fascia would be to provide a pathway for passage of vessels and nerves.
A. True
B. False
A
Choose the incorrect pairing.
A. Prime Mover : Extensor Digitorum
B. Fixator : a muscle that maintains body position while a part is moving
C. Synergist : a muscle that produces a movement opposite to that of a prime mover
D. Antagonist : Flexor Digitorum Profundus (to Extensor Digitorum)
C
All of the following are properties of muscle tissue EXCEPT:
a. Elasticity
b. Tonus
c. flexibility
d. extensibility
e. none of the above
C
1 nucleus per cell
(match the muscle type)
A. Cardiac muscle B. skeletal Muscle C. smooth muscle
a. A
b. B
c. C
d. A & B
e. A & C
f. B & C
E
found in walls of internal organs
(match the muscle type)
A. Cardiac muscle B. skeletal Muscle C. smooth muscle
a. A
b. B
c. C
d. A & B
e. A & C
f. B & C
C
The combination of _____ and _____ overlapping one another cause a muscle to contract.
a. myosin and myofilaments
b. acetate and myosin
c. actin and myosin
d. myofibrils and actin
e. myofibrils and myofilaments
C
____ and _____ nerve fibers carry impulses from receptors in muscle to the CNS.
a. Afferent and Sympathetic
b. afferent and efferent
c. motor and sensory
d. efferent and sympathetic
e. afferent and sensory
E
Striated
(match the muscle type)
A. Cardiac muscle B. skeletal Muscle C. smooth muscle
a. A
b. B
c. C
d. A & B
e. A & C
f. B& C
D
