Chapter 11: Muscular System Flashcards
Muscles are attached to bones by tendons at which two locations?
origin - attachment to stationary bone
Insertion - attachment to moveable bone
The origin is usually located ________ and the insertion is usually pulled ____________ the origin
proximally; toward
Define belly (body)
Fleshy portion of the muscle between the tendons
Define actions of a muscle
The main movements that occur when a muscle contracts
Define reverse muscle action (RMA)
during specific movements of the body the actions are reversed; therefore the positions of the origin and insertion of a specific muscle are switched
Describe how during movements bones and joints act as levers and fulcrums
Lever is rigid structure that can move around a fixed point called a fulcrum
The lever is acted on at two points:
(E) Effort which causes movement and (L) Load which opposes movement
Motion occurs when effort applied to the bone at the insertion exceeds the load
Define mechanical advantage
Mechanical advantage - if the load is closer to the fulcrum and the effort father away, then only a relatively small effort is required to move a large load
Mechanical disadvantage - if the load is father and the effort is closer to the fulcrum, more effort is required to move a small load (but at greater speed)
Ex. chewing something with the front of your teeth (disadvantage) vs the back (advantage)
List the 3 categorizes of levers according to the positions of the fulcrum, the effort, and the load
First-class levers - fulcrum is between effort and load, they can produce either a mechanical advantage or disadvantage - very few in the body (seesaw)
Second-class levers - load is between fulcrum and effort and always produce a mechanical advantage because the load is always closer to fulcrum than the effort - uncommon in the body (wheelbarrow)
Third-class levers - effort is between fulcrum and load and always produce a mechanical disadvantage before effort is always closer to fulcrum than load - most common in body (forceps) as it favours speed and range of motion over force
Muscles are arranged into fascicles, in which all muscles run parallel to one another. However, list and describe the 5 different types based on their patterns with respect to tendons
Parallel - fascicles parallel to longitudinal axis of muscle
Fusiform - fascicles nearly parallel, muscles taper toward tendons, diameter larger at belly
Circular - fascicles in concentric circular arrangements for sphincter muscles that uncouple and orifice
Triangular - fascicles spread over broad area converge at thick central tendon
Pennate - short fascicles in relation to muscle length, tendon extends nearly entire length of muscle
- unipennate: fascicles on only one side of tendon
- bipennate: fascicles on both sides on centrally positioned tendons
- multipennate: fascicles attach obliquely from many directions to several tendons
Describe how the prime mover, antagonist, synergist, and fixation in a muscle group work together to produce movements
Most skeletal muscles are arranged in opposing pairs at joints, within these pairs one muscle called the prime mover or agonist contracts to cause an action while the other muscle, the antagonist stretches and yields to the effects of the prime mover
To prevent unwanted movements at intermediate joints muscles called synergists contract and stabilize them
Some muscles in a group also act as fixators, stabilizing the origin of the prime mover to move more efficiently - steady the proximal end while movements occur at the distal end
In the limbs, a compartment is a group of skeletal muscles, their blood cells/nerves, all of which have a common function
Using the example of flexing and extending the forearm, describe the coordination among muscles (prime mover/antagonist)
Flexing: the biceps brachii is the prime mover and the triceps brachii is the antagonist
Extending: the triceps brachii becomes the primary mover and the biceps brachii become the antagonist
The following terms are characteristics used to name muscles based on their direction (orientation relatively to body’s midline). Describe their meaning
- Rectus
- Transverse
- Oblique
Rectus: parallel to midline
Transverse: perpendicular to midline
Oblique: diagonal to midline
The following terms are characteristics used to name muscles based on their size. Describe their meaning
- maximus
- minimus
- longus
- brevis
- latissimus
- longissimus
- magnus
- major
- minor
- vastus
- maximus: largest
- minimus: smallest
- longus: long
- brevis: short
- latissimus: widest
- longissimus: longest
- magnus: large
- major: larger
- minor: smaller
- vastus: huge
The following terms are characteristics used to name muscles based on their shape. Describe their meaning
- deltoid
- trapezius
- serratus
- rhomboid
- orbicularis
- pectinate
- piriformis
- platys
- quadratus
- gracillis
- deltoid: triangular
- trapezius: trapezoid
- serratus: saw-toothed
- rhomboid: diamond shaped
- orbicularis: circular
- pectinate: comblike
- piriformis: pear-shaped
- platys: flat
- quadratus: square
- gracillis: slender
The following terms are characteristics used to name muscles based on their action. Describe their meaning
- flexor
- extensor
- abudctor
- adductor
- levator
- depressor
- supinator
- pronator
- sphincter
- tensor
- rotator
- flexor: decreases joint angle
- extensor: increases joint angle
- abudctor: moves bone away from midline
- adductor: moves bone towards midline
- levator: raises or elevates body part
- depressor: lowers or depresses body part
- supinator: turns palm anteriorly
- pronator: turns palm posteriorly
- sphincter: decreases size of an opening
- tensor: makes body part rigid
- rotator: rotates bone around longitudinal axis
