Download C. Bones of the Pelvic Girdle

C. Bones of the Pelvic Girdle
1. 2 coxal bones (a.k.a hip bones):
-bony pelvis is made up of hip bones, sacrum, & coccyx
-pelvic bones are large & heavy & attach to
the axial skeleton via sacrum/coccyx
-The total weight of the upper body rests on the pelvis
-Protects reproductive organs, urinary bladder, &
part of large intestine
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The Pelvis
Figure 5.23a
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
C. Bones of Pelvic Girdle
2. Fusion of 3 bones to form each coxae
a. ilium: large, flaring bone that forms most
of hip bone; it is the most superior of hip
bones
*sacroiliac joint—where ilium connects
with sacrum posteriorly
*iliac crest—upper edge of ilium (along
superior margin); “hands on hips” indicates
placing hands on iliac crest
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C. Bones of Pelvic Girdle
b. ischium: forms the most inferior part of the coxal
bone; known as the “sit-down bone”
c. pubis (pubic bone): the most anterior part of a coxal
bone
*obturator foramen—an opening that allows blood
vessels & nerves to pass into anterior part of thigh
*pubic symphysis—pubic bones of each hip bone
fuse anteriorly to form this cartilaginous joint
*acetabulum—receives the head of the thigh bone;
location where ilium, ischium, & pubis fuse at deep
socket
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The Pelvis: Right Coxal Bone
Figure 5.23b
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
C. Bones of Pelvic Girdle
3. False & True pelvis: the
true pelvis is surrounded
by bone, lies inferior to
flaring parts of ilia and
pelvic brim
*Woman’s true pelvis
must be large enough to
allow infant’s head
(largest part of infant) to
pass during childbirth
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Male
Male
Female
C. Bones of Pelvic Girdle
4. 6 differences between male & female pelvis
1. female inlet is LARGER & more circular
2. female pelvis as whole is shallower, and bones are
lighter and thinner
3. female ilia flare more laterally
4. female sacrum is shorter & less curved
5. female ischial spines are shorter & farther apart;
thus outlet is LARGER
6. female pubic arch is more rounded b/c angle of
pubic arch is greater
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D. Bones of the Lower Limbs
 Lower limbs carry our total body weight when
we are erect
 Lower limb bones therefore are much thicker &
stronger than upper limb bones
 Lower limbs have 3 segments—thigh, leg, foot
Figure 5.24a–b
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D. Bones of Lower Limbs
1. Thigh – has only one bone
a.
femur: the thigh bone is
the heaviest, strongest
bone in body
-on proximal end, has a
ball-like head, a neck,
and greater/lesser
trochanters
-head of femur fits into
acetabulum of hip bone
to form hip joint
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
D. Bones of Lower Limbs
(a. femur continued)
*lateral/medial condyles—projections
that articulate with tibia bone below; located
on distal end of femur
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D. Bones of Lower Limbs
2. Leg: 2 bones form the skeleton of the leg
a. tibia: shinbone
-larger & more medial
*lateral/medial condyles—located at proximal
end of tibia; articulate with distal end of femur to
form knee joint
*medial malleolus—located at distal end of
tibia, forms the inner bulge of ankle
*anterior border—sharp ridge on anterior
surface of tibia, unprotected by muscles so is felt
easily beneath the skin
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D. Bones of Lower Limb
b. fibula: lies alongside
tibia and is think and
sticklike
-has NO part in
forming knee joint
*lateral
malleolus—at distal
end of fibula & forms
outer part of ankle
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
D. Bones of Lower Limb
3. Foot—composed of tarsals,
metatarsals, & phalanges.
-2 important functions:
supports body weight &
serves as lever that allows us
to propel our bodies forward
when we walk/run
a. tarsals: 7 ankle bones (see
fig. 5.25)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
D. Bones of Lower Limb
(a. tarsal bones continued)
**body weight is mostly carried by the 2 largest
tarsals—calcaneous & talus
i. calcaneous—heelbone
ii. talus—lies between tibia & calcaneous
b. 5 metatarsals: form the sole of foot
c. phalanges: 14 bones that form the toes
* toes—each toe has 3 phalanges (proximal, middle,
distal) except the “great toe”
* “great toe”—has only 2 phalanges (proximal &
distal)
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D. Bones of Lower Limbs
d. 3 arches of foot:
 Bones of the foot are
arranged to form three
strong arches
 Two longitudinal
 One transverse
 Ligaments & tendons
help to hold bones
firmly in arched
position
Figure 5.26
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings