[Lab 4G] [Home] Lab 5: Thoracic Limb [ Lab 5,6H ] [Gross-page] [Lab 6G]
As
you learned in Lab 4, the extrinsic muscles are those
which have their origin on the axial skeleton and their insertion on the
proximal portion of the appendicular skeleton of the forelimb (either the scapula or the
humerus). The intrinsic muscles of the limb are those which have both
their origin and insertion on the appendicular skeleton (i.e., the limb). Extrinsic
muscles may abduct, adduct, advance or retract the whole limb, but the intrinsic muscle
more specifically have their actions across joints (i.e., such
as flex or extend the elbow, not flex or extend the
forearm). The muscles which extend or flex the digits are extending or flexing the
multiple joints of the digits, so that is considered acceptable terminology.
At the end of the notes for Lab 5, I have included a general review of muscle innervation and function. It would do you well to become familiar with that section in the notes.
Click on the [Lab 5,6H] link above for review of muscle histology.