Labs 3 + 4

Lab 3 and 4: Integumentary
and Muscular Systems
Skeletal Muscle
origin - what muscle attaches to for leverage,
usually larger and more stationary bone than
insertion - what muscle attaches to for
movement, usually a smaller bone than the
origin and not stationary; the insertion is
what the muscle acts upon and causes to move
action - this is the type of movement that
Triceps Brachii – origin = proximal humerus, insertion =
proximal ulna, action = elbow extention
Biceps Brachii – origin = lateral scapula, insertion=
proximal radius, action = flexes forarm
Helpful hints for identification of skeletal muscles:
Relative to direction of muscle fibers:
rectus -fibers running
parallel to the midline of the
body or
longitudinal axis of a bone
transverse - fibers running
at right angles or
perpendicular to the midline
or longitudinal axis of a bone
oblique - fibers running
obliquely (slanted or at a
diagonal) to the midline of
the body or longitudinal axis
of a bone
Relative to size:
maximus – largest
minimus – smallest
longus – long
brevis - short
Relative to the number of origins:
Biceps – 2
Triceps – 3
Quadriceps – 4
Relative to location of origin and insertion
sternohyoid - sterno refers to the origin, which is the
manubrium of the sternum and hyoid refers to the
insertion, which is the hyoid bone.
Relative to location of
muscle example:
brachioradialis - brachio refers
to arm and radialis refers to the
radius. This muscle runs along
the radius of the forearm
Relative to shape of the muscle
deltoid - the muscle is
triangular like the name
Muscle Movements
Movements that occur in the saggital plane:
flexion/extension - waist (bend/extend)
plantarflexion/dorsiflexion - ankle (point/
Movements that occur in the frontal plane:
abduction/adduction - arm/hip (movement
away from midline/movement toward midline)
inversion/eversion - foot (turn or roll foot in/
turn or roll foot out)
Movements that occur in the transverse plane:
rotation - neck
pronation/supination - wrist (turn hand palm
down/palm up
antagonist muscle groups - one muscle works
against the other (ex: biceps brachii and
triceps brachii - when one muscle flexes the other
elevation/depression - upward movement/
downward movement (shrugging your shoulders)
protraction/retraction - moving a part of the body
away from the axis /opposite
action (you protract your jaw when you grasp
your upper lip with your lower teeth)
tensor - makes more rigid
sphincter - closes hole
Abdominal Wall Muscles:
External obliques
Internal obliques
Transverse Abdominus
Rectus Abdominus "6-pack")
Rotator Cuff Muscles ("SITS")
** ALL rotator cuff muscles: origin=scapula,
Teres Minor
Quadriceps Femoris ("Quads")
** ALL quad muscles: insertion=tibial
tuberosity via patellar ligament,
action=knee extension
Vastus Lateralis
Vastus Medialis
Vastus Intermedius
Rectus Femoris
** ALL hamstring muscles:
origin=ischium (the ischial
tuberosities you "sit on"),
action=knee flexion
Biceps femoris