Intrinsic Finger Musculature Flashcards
intrinsic musculature of the fingers
dorsal interossei
volar (palmar) interossei
lumbricals
hypothenar group
dorsal interossei
ABDs of the MCPs
volar (palmar) interossei
ADDs of the MCPs
how do the interossei pass the MCPs for flex/ext
all interossei pass volar (anterior) to the MCP joint axis
interossei are flexors of the MCPs to varying degrees
interossei MCP flexion when MCPs are extended
poor flexors in this position
too short of a movement arm
interossei MCP ABD/ADD when MCPs are extended
good in this position
dorsal –> ABDs
volar –> ADDs
role of interossei when MCP in flexion (as flexors)
as MCP flexion increases, interossei have improves ability to flex MCPS
become better flexors w/ the more flexion we are in
role of interossei when MCP in flexion (as ABD/ADDs)
as the amount of MCP flexion increases, interossei have less ability to ABD or ADD the fingers
in full MCP flexion, MCP ABD/ADD is completely restricted
3 reasons
3 reasons for no ABD/ADD in full flexion
MCP collateral ligaments are tight in flexion
shape of the condyles of the metacarpal heads
inability of the interossei to shorten enough to produce both MCP flexion and MCP ABD/ADD
role of interossei at IP joint
interossei via distal insertions will extend the IP joints
tension to the extensor hood
when is most consistent activity of interossei found
when the MCPs are being flexed and the IPs are being simultaneously extended
lumbricals
origin and insertion on tendons of other muscles
4 of them –> all innervated differently
lumbricals are effective in
IP extension (despite MCP position)
lumbricals are relatively weak
MCP flexors
how do the lumbricals and interossei work together
support the arches of the hand
