lecture 11 Flashcards
functions of the muscular system
supporting body movement
generating heat
origin
end of muscle attached to stabilized or stationary bone
usually proximal
insertion
end of muscle attached to moving bone
usually distal
muscle belly
thickened portion of the muscle between tendons
muscle actions
movements that are possible when the muscle contracts
Reverse muscle actions (RMAs)
result when the origin and insertion are reversed
NOT when the muscle relaxes
most muscles do not have RMAs
lever
an object that moves around a fulcrum
load
resistance against effort
effort
force required to move a load
first class levers
fulcrum is between effort and load
- like a see saw
eg. looking up
- posterior neck muscles (effort) contract to lift the head(load) at the atlanto-occipital joint (fulcrum)
second class lever
load is between effort and fulcrum
- like a wheelbarrow
eg. gastrocnemius (effort) lifts the body weight (load) at the toes (fulcrum)
third class levers
effort between fulcrum and load
most common in the body
eg. biceps (effort) life the hand (load) at the elbow joint (fulcrum)
why use third class levers if second class produced an advantage?
third class levers allow faster movement, but take more effort
muscles usually work in ______
opposing pairs
eg. biceps and triceps brachii
agonist
muscle that exerts effort to move lever
antagonist
muscle that opposes the agonist
must relax for the agonist to move
synergists
muscles that stabilize intermediate. joints when contracted
hold other joints stable while one moves
fixators
muscles that stabilize one end of bone so that the other can move
eg. muscles that stabilize the scapula during abduction of the arm (trapezius, serratus anterior, etc)
compartments
groups of skeletal muscles, their nerves, and blood vessels
- have specific functions
eg. flexor compartments of upper limb are the anterior sets of muscles
muscle function vs action
action - movement
function - what they do
eg. action - contract to close the mandibe
function - to chew
functions of the facial muscles (general)
to express emotions
- speech / vocalization
orbicularis oculi action
closes the eyelids
orbicularis oris action
close the lips / purses the lips (duckface)
occipitofronalis actions
frontal - raise eyebrows wrinkle forehead
occipital - raise hair (pulls on scalp)
epicranial aponeurosis
aponeurosis that connects the frontal and occipital bellies of the occipitofrontalis
aponeurosis
sheet like tendons
platysma action
pulls corners of mouth laterally and inferiorly
depresses mandible
masseter / temporalis actions
elevate the mandible
sternocleidomastoid actions
rotate the head
extend the head at atlanto-occipital joint
has RMA (elevation of sternum)
what happens if you only contract one sternocleidomastoid?
the head will rotate
function of abdomen muscles
protect abdominal viscera
move vertebral column
why do all the abdominal muscle fascicles run different ways
mainly stabilization, protection as well
tendinous intersections of rectus abdominis connection tissu
fibrous
The rectus abdominis originates at the pubic symphysis and inserts on the costal cartilages. If RMA of this muscle were possible, what movement would be permitted?
flexion of the vertebral column
a muscle cannot move a bone to which it is not ____
attached
central tendon
aponeurosis where the diaphragm inserts
serratus anterior action
abducts the scapula
assists in pushing
trapezius permits:
rotation, adduction, depression, stabilization of the scapula
pectoralis major permits:
adduction, medial rotation, flexion or the arm
deltoid permits:
abduction, medial/lateral rotation, flexion/extension of the arm
latissimus dorsi permits
extension, adduction, medial rotation of the arm
latissimus dorsi RMA
elevation of the vertebral column and torso
biceps brachii permits
flexion of the arm at the elbow joint
supination of the hand
triceps brachii permits
extension of the forearm at the elbow joint
brachioradialis function
controls speed of movement of the arm
brachioradialis permits
supination and pronation of the hand
gluteus maximus permits
flexion of the leg at the hip joint
lateral rotation of the femur at hip
gluteus maximus RMA
extension of the torso
gluteus medius permits
abduction and
medial rotation of the femur
flexor compartment of the thigh permits
flexion of the lower limb at the knee joint
extension of the leg at the hip joint
extensor compartment of the thigh permits
extension of the lower limb at the knee joint
flexion of the leg at the hip joint
all three “vastus” heads of the quadriceps originate on the ____
femur
gracilis permits
adduction of the thigh at the hip joint
medial rotation of the thigh
soleus permis
plantar flexion of the foot at the ankle joint
gastrocnemius permits
plantar flexion of the foot at the ankle
flexion of the lower limb at the knee
tibialis anterior permits
dorsiflexion of the foot at the ankle
inversion of the foot at the intertarsal joints
ways to prevent muscle injuries
regular, moderate exercise
stretching
nutrition
sleep
spasm
involuntary contraction of a muscle or muscle group
when painful - called cramps
main and other cause of spasms/cramps
dehydration
injury, overuse, prolonged periods in one position, inadequate bloodflow
muscle soreness
due to microscopic damage to muscles
(torn sarcolemmas, etc)
may be delayed
PRICE
Protection, rest, ice, compression, elevation
remedy for minor injuries
plantar fasciitis
chronic inflammation of the plantar aponeurosis
causes:excess weight, ill fitting shoes
treatments: PRICE, stretching, orthotics, surgery, weight loss
compartment syndrome
excess fluid causing swelling in the fascia
causes: pressure that restricts blood flow to a compartment
treatments: fasciotomy is severe
3 facts about muscles
they work in groups
theres organized in compartments
their structure determines their function
