Muscular joint actions
Spine
Concentric contraction Passively lengthening
To maintain extension against pressure of
arm:
Spinal extensors
To rotate spine toward leg:
Internal oblique, erector spinae, splenius capi-
tis (top leg side); external oblique, rotatores,
multifidi (bottom leg side)
To turn head:
Sternocleidomastoid (bottom leg side)
External oblique, rotatores, multifidi, ster-
nocleidomastoid (top leg side); internal
oblique, erector spinae, splenius capitis,
latissimus dorsi (bottom leg side)
Upper limbs
Front arm (contralateral to top leg)Back arm
Concentric contraction Concentric contraction
To stabilize humeral head:
Rotator cuff
To maintain placement of scapula on rib
cage:
Rhomboids
To extend arm against leg:
Posterior deltoid
To flex elbow:
Biceps brachii
To stabilize humeral head:
Rotator cuff
To keep scapula placed on rib cage and resist
adduction of this scapula:
Serratus anterior
To extend shoulder and elbow:
Triceps brachii
Lower limbs
Top leg Bottom leg
Concentric
contraction
Passively
lengthening
Concentric
contraction
Passively
lengthening
To flex and adduct
leg:
Adductor longus
and brevis,
pectineus
Piriformis; superior
and inferior gemel-
lus; obturator inter-
nus and externus;
quadratus femoris;
gluteus maximus,
medius, and mini-
mus
To externally rotate
hip:
Obturator internus
and externus,
quadratus femoris,
piriformis, superior
and inferior gemel-
lus
To externally rotate
and flex hip and
knee:
Sartorius
To flex knee:
Hamstrings
To flex and adduct
leg:
Adductor longus
and brevis
Gluteus medius
and minimus
(continued)