Muscles Flashcards
Patterns of muscular imbalance (tightness/weakness) can impact…
joint motion, stability, posture, etc.
What is isometric contraction?
No movement takes place, load on the muscle exceeds the tension generated by the contracting muscle
What is concentric contraction?
Muscle shortens against an opposing load
What is eccentric contraction?
Muscle lengthens as it resists a load
Initiation of movement involves what type of muscle contraction?
Concentric contraction; origin and insertion approximate during contraction
Control of movement involves what type of muscle contraction?
Eccentric contraction; origin and insertion separate during contraction
Which muscles initiate extension from upright position?
Erector spinae
Which muscle control extension from upright position?
Abdominals
What are the limitations of extension from upright position?
- Bony impaction (SPs, facets)
- Smaller contribution from ligaments (ALL, anterior annulus)
Which muscles initiate flexion from upright position?
Iliopsoas (when femur is fixed)
Abdominals (if pelvis is fixed, as in a sit up from supine)
Which muscles control flexion from upright position?
Mostly gluteus maximus and hamstrings early, then after 60 degrees, erector spinae primarily (until 90 degrees)
What are the limitations of flexion from upright position?
- Facet joints and capsule
- Disc and ligaments (LF, PLL, interspinous ligaments)
What muscle initiates lateral flexion from upright?
Ipsilateral quadratus lumborum
What muscles control lateral flexion from upright?
Contralateral quadratus lumborum and contralateral psoas major
What are the limitations of lateral flexion from upright?
- Ipsilateral facet impaction
- Contralateral facet capsule
- Lumbar facets
- Intertransverse ligaments
What muscles initiate rotation?
Concentric contraction of contralateral external abdominal obliques, multifidi, and rotatores
What muscles control rotation?
Eccentric contraction of ipsilateral multifidi and rotatores
What are the limitations of rotation?
- Shape and orientation of facets, facet capsules, and interspinous ligaments
- Disc (annulus)
What is an agonist?
Muscle that is the prime mover
What is an antagonist?
Stabilizer, allows extremity to return to normal position
What is a synergists?
Help agonists with desired motion
What is a stabilizer?
Maintain body position to allow motion to occur
What are four examples of agonist/antagonist pairs?
- Biceps/triceps
- Abdominals/spinal erectors
- Quadriceps/hamstrings
- Grastrocnemius/tibialis anterior
What is Sherrington’s law?
“Law of reciprocal inhibition”
When contraction of a muscle is stimulated there is simultaneous inhibition of its antagonist
How do agonist/antagonist pairs often present clinically?
Patterns of over/under activation create faulty movement patterns
Some muscles tend toward hyperactivity/hypertonicity, others toward…
inhibition/hypotonicity
Both hyperactivity/hypertonicity and inhibition/hypotonicity can be caused by…
repetitive use, stress, neurological coordination, postural strain, trauma, etc.
If muscle imbalance is not addressed, what is likely to happen?
Self-perpetuating, will continue to progress if not addressed
Muscle imbalance can in turn affect…
joint movement
Describe patterns of hypertonicity
Varies between patients
Patterns are common based on typical movement/positional stresses in most patient populations BUT may differ based on specific activities
How is muscle tone determined?
- Ability of the muscle to lengthen (movement based assessment)
- Deformation of the muscle at rest
What is normal muscle tone?
- Relative not absolute
- Compare side to side
- Compare agonist/antagonist
What is a myofascial trigger point?
A focus of hyperirritability in muscular or fascial tissue.
When compressed, it is locally tender, and gives rise to referred pain and tenderness.
