ANT203Y1 Lecture Notes - Ulna, Biceps, Anatomical Terms Of Motion

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7 Oct 2012
of 4
November 22, 2011
From last lecture:
Primate forelimbs
o emphasis on lower limbs
o upper limbs not as much
o humerus:
proximal end has large joint surface
mobility at that joint or weight bearing joint
deltoid muscles: important for lifting arms, to 90 degrees
well developed attachment sites
o radius
proximal end very circular = rotation
distal end quite large, joins to wrist
biceps not as massive because not hanging by arms, not arm dependent
o ulna
not a lot of bone (olecranon process)
does not articulate with carpals (wrist) so gives more mobility
o humerus: longer, curvature, bone it robust (very strong and well made, can
stand a lot of strain)
proximal end made for mobility and weight bearing (both)
distal end: joint capable of full extension and hyperextension
good for knuckle walking/hanging selves in tree
o bones make selves stronger by curving
o radius
equal emphasis
very circular = rotation
distal end quite large joins to wrist
large surface area for motion at wrist joint
biceps well developed, noticeable bump on bone for attachment
o ulna
not a lot of bone (olecranon process)
long ulna
very curved for strength
does not articulate with carpals (wrist) so gives more mobility
o arboreal
o restricted shoulder joint
cannot reach arms above head
not as much mobility
o humerus
proximal end is restricted
distal end is arms cannot fully extend because has flexed forelimbs,
running on trees want to keep arms close to body as possible for balance
elbows cannot fully extend
o radius
proximal end not as circular, not as much movement
distal end very small
do not want a lot of motion at wrists when running through trees
want wrists to be stable
processive bone: is not only bone that articulates with wrist
articulate with both radius and ulna
gives stability through joint because stabilizes on both sides of
want hand to move in same direction
o ulna
has projection of bone
articulates with wrist to give more stability
Primate hands
o emphasis on precision, so not as large
o phalanges: not too long
gracile: not a lot of bone, not knuckle walking, no weight resting on them
o thumbs
huge emphasis
for precision
o designed for grasping
o very large
o bones are bigger, larger, longer, and more robust
o need to withstand their weight
o bones slightly curved
advantageous when they go in tree
o thumb
is reduced
some precision, not to same degree as humans
o scaled down of gorilla
o asian great ape
o phalanges very curved
natural hook for movement in trees
o not too big
o longer fingers
good for reaching around tree branches
do not need to exert a lot of muscle
o reduced thumb, not emphasis
in some lemurs and lorises, thumb is very reduced
Primate pelvic girdles
o basin shape
o very robust to distribute weight from upper body to lower limbs
o sacrum
very thick
weight bearing
to transmit weight to lower limbs
o taller
o narrower
o oriented
o designed to attach lower limbs
o not to bear weight
o sacrum
larger sacrum in terms of length
not robust
less bone
because not weight bearing function
Primate hind limbs
o femur
orientation: runs on an incline
puts balance over top of knee
o fovea (proximal)
slight groove for attachment of ligament
ligament teres
helps to reinforce stability
in many primates
o knee joint (distal)
o tibia
hind limb dominant so very long
proximal end
knee joint
a lot of bone
huge joint surface
to transmit weight to foot
o feet
pedestal, platform
block like bones for stability
large and robust
o femur
move upper body a lot for balance to compensate for femur