Ch. 11 - The Muscular System Flashcards
How do skeletal muscles produce movement?
muscles PULL on tendons, which pull o bones, skin, etc
What is the origin and insertion?
origin: attachment to the bone that does NOT move when the muscle shortens; usually proximal
insertion: attachment to moveable bone; usually distal
What are 2 muscle attachment sites?
muscle belly - fleshy part of muscle in bt attachment sites
tendons - attach muscles to bones
What is a lever and fulcrum?
lever - rigid structure moves around the fulcrum (fixed point)
What are the 2 forces the lever is acted on?
LOAD - opposes movement
EFFORT - causes movement
What must exceed what to allow movement?
effort must exceed load
What do bones, joints, and muscle contraction serve as in lever systems?
bones - lever
joints - fulcrum
force of musc contraction - effort
What is a mechanical advantage?
distance bt fulcrum and effort > distance bt fulcrum and load
What is a mechanical disadvantage?
distance bt fulcrum and effort < distance bt fulcrum and load
What is a first class lever?
fulcrum is in bt effort and load (EFL)
- can produce mech adv/disadv
What is a second class lever?
load is in bt fulcrum and effort (FLE)
- always produce mech adv; resistance is always closer to fulcrum than effort is
What is a third class lever?
effort in bt fulcrum and load (FEL)
- always produce mech disadv; effort is always closer to fulcrum than resistance is
What are adv and disadv of third class levers?
adv: increase range, control, and speed of movement
disadv: requires more effort to move load
What happens to a muscle’s length when it contracts?
shortens to about 70% of its length
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What are agonists and antagonists in muscle contraction?
agonist - main contracting muscle/prime mover
antagonist - performs opposite movement
*one contracts, the other relaxes (e.g. flexion vs. extension)
What is the difference between synergists and fixators?
S - muscles that assist prime mover or prevent unwanted movements
F - stabilize origin of prime mover
What are the 7 facial muscles? (2 - mandible, 1 - head)
occipitofrontalis, orbicularis oculi, orbicularis oris, platysma, masseter, temporalis, sternocleidomastoid
What are the 6 eye muscles?
inferior oblique, inferior rectus, lateral rectus, medial rectus, superior oblique, superior rectus
10 chest and abdominal muscles
diaphragm, external/internal intercostals, external/internal obliques, pectoralis minor, rectus abdominis, serratus anterior, transversus abdominis, trapezius
6 arm muscles
biceps brachii, brachioradialis, deltoid, latissimus dorsi, pectoralis major, triceps brachii
9 leg muscles
gastrocnemius, gluteus maximus, gluteus medius, gracilis, hamstrings (3), quadriceps (4), sartorius, soleus, tibialis anterior
Identify and describe occipitofrontalis
frontal and occipital belly, draws scalp ant/post, raises brows
Identify and describe orbicularis oculi
closes eye
Identify and describe orbicularis oris
closes lips (kiss!), compresses lips against teeth, shapes lip during speech
Identify and describe platysma
depresses mandible, raws outer part of lower lip inf/post (pouting)
Identify and describe masseter
elevates mandible, closes mouth
Identify and describe temporalis
elevates and retracts mandible
Identify and describe sternocladimastoid
unilaterally - laterally flexes & rotates head
bilaterally - flexes head + cervical portion of vert column
Identify and describe external and internal obliques
unilaterally - flex vert column (esp lumbar portion), rotate vertebral column
bilaterally - compress abdomen, flex vert column
- ext - superior muscle
- int - intermediate muscle
Identify and describe diaphragm
contractions during inhalation (expands thoracic cavity)
relaxes during exhalation (decreases vert dimension thoracic cavity)
Identify and describe external/internal intercostals
spaces b/t ribs
E - contraction-inhalation, elevates ribs; relaxation-exhalation, depresses ribs
I - contraction draws adj ribs tgt during forced exhalation
Identify and describe pectoralis minor
abducts scapula and rotates downward; rotates ribs 3-5 during forced inhalation when scapula is fixed
Identify and describe rectus abdominis
compresses abdomen to aid in defecation, urination, forced exhalation, childbirth
Identify and describe serratus anterior
abducts scapula and rotates upward; important in horizontal arm movements (pushing, punching)
Identify and describe transversus abdominis
compresses abdomen
Identify and describe trapezius
upwardly rotate, adduct, depress, stabilize scapula
Identify and describe biceps brachii
flexes forearm at elbow joint; supinates forearm at radioulnar joints; flexes arm at shoulder jount
Identify and describe brachioradialis
flexes forearm at elbow joint; supinates and pronates forearm at radioulnar joint to neutral pos
Identify and describe deltoids
lat - abduct arm at shoulder joint
anterior - flex, medially rotate arm at shoulder joint
posterior - extend and laterally rotate arm at shoulder joint
Identify and describe latissimus dorsi
extends, adducts, medially rotates arm at shoulder joint; draws arm inferiorly and posteriorly
Identify and describe pectoralis major
whole - adducts, medially rotates arm at shoulder joint
clavicular head - flexes arm
sternocostal head - extends flexed arm to side of trunk
Identify and describe triceps brachii
extends forearm at elbow joint and extends arm at shoulder joint
Identify and describe gastrocnemius
plantar flexes foot at ankle joint and flexes leg at knee joint
Identify and describe gluteus maximus and gluteus medius
max - extends thigh at hip joint and laterally rotates thigh; helps lock knee in extension
med - abducts thigh at hip joint and medially rotates thigh
Identify and describe hamstrings (3)
biceps femoris, semitendinosus, semimembranosus
- flexes leg at knee joint and extends thigh at hip joint
Identify and describe quadriceps (4)
vastus lateralis/medialis/intermedius, rectus femoris
- extend leg at knee joint; rectus femoris flexes thigh at hip joint
Identify and describe sartorius
- weakly flexes leg at knee joint
- weakly flexes, abducts, laterally rotates thigh at hip joint
Identify and describe soleus
plantar flexes foot at ankle joint
Identify and describe tibialis anterior
dorsiflexes foot at ankle joint and inverts foot at intertarsal joints
Identify and describe gracilis
adducts thigh at hip joint, medially rotates thigh, flexes leg at knee joint
