Transcript Skeletal_–_Part_7

Skeletal System – Part 7
Bones of the Pelvic Girdle
 Pelvic Girdle - Formed by two coxal bones,
commonly called the hip bones.
 Bony Pelvis – Hip bones + coccyx + sacrum
Bones of the Pelvic Girdle
 Large and heavy bones,
and they are attached to
the axial skeleton.
 The sockets, which
receive
the thigh bones, are
deep and heavily
reinforced by ligaments
that attach the limbs
firmly to the girdle.
Bones of the Pelvic Girdle
 Functions of the Girdle:
1. Bearing weight is the most important
function.
2. Protect the
reproductive organs,
urinary bladder, and
part of the large
intestine.
Structure of the Hip Bones
 Each hip bone is formed by the fusion of
three bones:
1. Ilium
2. Ischium
3. Pubis
Ilium
 Ilium – Large, flaring
bone that forms most of
the hip bone.
Connects posteriorly with
the sacrum at the
sacroiliac joint.
 When you put your hands
on your hips, they are
resting over the winglike
portion of the ilia.
 Iliac Crest – The upper
edge of the winglike
portion of the ilium.

Ischium and the Pubis
 Ischium –
“Sitdown bone”;
Forms the the
most inferior part
of the coxal bone.
 Pubis – Most
anterior part of a
coxal bone.
Acetabulum
 Acetabulum – Deep socket that receives the
head of the thigh bone.

Formed by the fusion of the ilium,
ischium, and pubis.
Regions of the Bony Pelvis
 False Pelvis – Superior to the true pelvis; The
area medial to the flaring portions of the ilia.
 True Pelvis - Surrounded by bone; Lies
inferior to the flaring parts of the ilia and the
pelvic brim.

Dimensions of the true pelvis
of a woman are very important
because they must be large
enough to allow the infant’s
head to pass during childbirth.
Differences Between a
Male and Female Pelvis
 The pelvis of a female tends
to be:
1.
2.
3.
4.
5.
6.
Inlet is larger and more
circular.
As a whole is shallower, and
the bones are lighter and
thinner.
Ilia flare more laterally.
Sacrum is shorter and less
curved.
Ischial spines are shorter and
farther apart; thus the outlet
is larger.
Pubic arch is more rounded
because the angle of the pubic
arch is greater.
Bones of the Lower Limbs
 The lower limbs carry our total body
weight when we are erect.
 Hence, it is not surprising that the
bones of the lower limbs are much
thicker and stronger than the
comparable bones of the upper limb.
 The 3 segments of the lower limbs:
1.
2.
3.
Thigh
Leg
Foot
Thigh
 Femur – Thigh bone.
 Only bone in the thigh.
 The heaviest, strongest
bone in the body.
 It slants medially as it runs
downward to join with the
leg bones.
This brings the knees in line
with the body’s center of
gravity.
 The medial course of the femur
is more noticeable in females
because of the wider female
pelvis.

Structure of the Femur Bone – Proximal End
 Its proximal end has a:
1. Ball-like head
 The head of the femur
articulates with the acetabulum
of the hip bone in a deep,
secure socket.
2. A neck
 Common site of fractures,
especially in old age.
Structure of the Femur Bone – Distal End

Anteriorly on the
distal femur is the
smooth patellar
surface, which forms
a joint with the
patella (kneecap).
Leg
 Two bones form the
skeleton of the leg:
1.
2.
Tibia
Fibula
 The tibia and fibula are
connected along their
length by an
interosseous
membrane.
Tibia and Fibula
 Tibia – Shinbone;
Larger and more
medial.
 At
the proximal end,
the tibia articulates
with the distal end of
the femur to form the
knee joint.
Tibia and Fibula
 Fibula – Lies
alongside the tibia;
Thin and sticklike.
 Forms
joints with the
tibia both proximally and
distally.
 Has no part in forming
the knee joint.
 The distal end of the
fibula forms the outer
part of the ankle.
Foot
 The foot is
composed of the:
1.
2.
3.
Tarsals
Metatarsals
Phalanges
Foot
 Two important
functions of the
foot:
1.
2.
Supports our
body weight
Serves as a lever
that allows us to
propel our
bodies forward
when we walk or
run.
Foot: Tarsals
 Tarsus – The
posterior half of the
foot.
Composed of 7 tarsal
bones.
 Body weight is mostly
carried by the two largest
tarsals:

1.
2.
Calcaneus - Heelbone
Talus – Tarsal that lies
between the tibia and the
calcaneus.
Foot: Metatarsals
and Phalanges
 The sole of the foot:
 Composed of 5
metatarsals.
 The toes of the foot:
 Composed of 14
phalanges.
 Like the fingers of the
hand, each toe has
three phalanges,
except the great toe
which has two.
Arches of the Foot
 The bones in the foot
are arranged to form
three strong arches:
1.
2.
Two longitudinal
(medial and lateral)
One Transverse
 Ligaments (bind the
foot bones together) and tendons:

Help to hold the bones firmly in the arched position but still
allow a certain amount of give or springiness.