Muscular system - general knowledge Flashcards
What are the three types of muscle?
- skeletal striated muscle
- cardiac striated muscle
- smooth muscle
Describe skeletal striated muscle
- voluntary and somatic (controlled by SNS)
- makes up gross skeletal muscle
- function to move and stabilize bones and other structures
Describe cardiac striated muscle
- involuntary and visceral
- forms most of the walls of the heart and adjacent great vessels
- functions to pump blood
Describe smooth muscle
- involuntary and visceral
- forms part of the walls of vessels and hollow organs
- moves substances through using coordinated sequential contractions
What is peristalsis?
coordinated, sequential contractions that move substances through vessels and organs
What are the different parts of skeletal muscle?
- heads or bellies: fleshy, reddish, contractile portion
- tendons: white, non-contractile portions
Composition of tendons
mainly of organized collagen
What is aponeurosis?
flat sheet formed by some tendons that anchor muscle to skeleton, deep fascia and/or aponeurosis of another muscle
When referring to the length of a muscle, what is included
both belly/head and tendon
How are muscles classified?
by muscle fiber arrangement and shape
What are the 6 classifications of muscles?
- flat
- fusiform
- pennate
- quadrate
- circular
- multi-headed (multi-bellied)
Describe flat muscles
parallel fibers, often with aponeurosis
Describe fusiform muscle
spindle-shaped with a round, thick belly and tapered ends
Describe pennate muscles
- featherlike arrangement of fibers
- can be unipennate, bipennate or multipennate
Deltoid is an example of what type of muscle?
multipennate
Extensor digitorium and palmar interossei are examples of what type of muscle?
unipennate
Rectus femoris and dorsal interossei are an example of what type of muscle?
bipennate
Describe quadrate muscles
have four equal sides.
Biceps brachii is an example of what type of muscle?
fusiform
External oblique and sartorius are examples of what type of muscle?
flat
Rectus abdominis between its tendinous inscriptions is an example of what type of muscle?
quadrate
Orbicularis oculi is an example of what type of muscle?
circular
Describe circular muscles
surround body opening or orifice and constrict when contracted
Describe multi-headed muscles
have more than one head of attachment or contractile belly
Gastrocnemius, biceps brachii and triceps brachii are examples of what type of muscle?
multi headed
Describe origin of muscles
- proximal attachment
- usually remains fixed during contraction
Describe insertion of muscles
- distal attachment
- moves towards origin during contraction
What are the 3 types of skeletal muscle contraction?
- reflexive
- tonic
- phasic (isometric and isotonic)
Describe reflexive contraction?
-automatic aspect of skeletal muscle activity
Contraction of the thoracic diaphragm is an example of what type of muscle contraction?
reflexive
How is the contraction of the thoracic diaphragm controlled?
- oxygen and carbon dioxide levels in the blood
- can be controlled to an extent
The movement of a muscle after a stretch to tendon has been induced by tapping with a hammer is called what?
myotatic reflex
Describe tonic contraction
-the slight contraction present in muscles when relaxed creating muscle tone but not movement or active resistance
What is the function of tonic contraction?
- gives muscle firmness to stabilize joints and maintain posture
- keeps muscles ready to respond
- it is absent in deep sleep, under anesthesia and after paralysis
Describe isometric contraction
- type of phasic muscle contraction where muscle length remains the same while muscle tension increases above tonic levels
What is the function of isometric contraction?
to resist gravity or other antagonistic force
Describe isotonic contraction
-type of phasic contraction where muscle length changes in relationship to production of movement
The type of muscle contraction used to maintain upright posture is what?
isometric contraction
What are the two types of isotonic contractions?
- concentric
- eccentric
Describe how the movement occurs with a concentric isotonic contraction
the movement occurs as a result of muscle shortening such as when lifting a weight
Describe how the movement occurs with a eccentric isotonic contraction
- the movement occurs as a result of muscle lengthening such as when setting an object down
- the movement is controlled and gradual while exerting a diminishing force
What are the 4 functions of muscles?
- prime mover (agonist)
- fixator
- synergist
- antagonist
Describe the agonist function of muscles
- concentric contraction that produces a specific movement
- usually performed by a single muscle but sometimes by gravity
Describe the fixator function of muscles
-isometric contraction that steadies the proximal parts of the limb
Describe the synergist function of muscles
- concentric contraction that compliments actions of agonist/prime mover
- usually there are several synergists helping one prime mover
Describe the antagonist function of muscles
- eccentric contraction that opposes action of another muscle
- prime antagonists oppose prime movers
- secondary antagonists oppose synergists
Describe flexion/extension movement
occurs in the saggital plane around a transverse axis to decrease (F) or increase (E) angle between bones or body
Describe abduction/adduction
occurs in frontal plane around an anteroposterior axis to produce movement away (abd) or towards median plane (add)
Describe circumduction
occurs at distal joint to produce sequential flexion, abduction, extension and adduction to make a circle
Describe medial/lateral rotation
occurs around longitudinal axis of a bone anterior surface closer (MR) or farther away (LR) from median plane
Describe supination/pronation
movement where radius rotates around ulna in forearm
-radius rotates medially (P) or laterally (S) so palm faces posteriorly (P) or anteriorly (S) in anatomical position or inferiorly (P) or superior (S) if elbow is flexed
Describe dorsiflexion/plantarflexion
movement of foot at the ankle where toes point up (DF) or down (PF)
Describe inversion/eversion
movement of sole of foot away from median plane (Ev) or towards median plane (In)
Describe protraction/retraction
anterior displacement (PT) or posterior displacement (R) as in moving mandible or scapula forward and backward
Describe elevation/depression
movement superiorly (EL) or inferiorly (D) as in a shoulder shrug
Describe upward/downward rotation
rotational movement of the scapula where glenoid fossa tilts superiorly (UR) and inferiorly (DR)
Describe radial/ulnar deviation
abduction or adduction of the wrist when in anatomical position
What kind of nerves supply skeletal muscle?
motor nerves
Characteristics of muscle innervation
- muscles of similar action share innervations, usually
- nerve supplies a muscle that it pierces or passes between its 2 head, usually
