The document summarizes the anatomy of the lower extremities. It describes the bones and regions of the lower limb, including the pelvis, thigh, leg, and foot. It outlines the bones that make up the pelvis (hip bones, sacrum, coccyx), and provides details on the ilium, ischium, pubis, acetabulum, and other structures of the hip bone. It also describes the femur, including the head, neck, greater and lesser trochanters. The document emphasizes the anatomical landmarks and functional aspects of the lower extremity bones.

1. LOWER EXTREMITIES
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2. • The lower limb is directly anchored to the
axial skeleton by a sacroiliac joint and by
strong ligaments, which link the pelvic bone
to the sacrum.
• The lower limb is divided into the gluteal
region, thigh, leg, and foot on the basis of
major joints, component bones, and
superficial landmarks
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3. Inguinal ligament
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Sacroiliac ligament
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4. the gluteal region is posterolateral and between
the iliac crest and the fold of skin (gluteal fold)
that defines the lower limit of the buttocks;
anteriorly, the thigh is between the inguinal
ligament and the knee joint-the hip joint is just
inferior to the middle third of the inguinal
ligament and the posterior thigh is between the
gluteal fold and the knee;
the leg is between the knee and ankle joint;
the foot is distal to the ankle joint.
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5. • The femoral triangle and popliteal fossa, and the
posteromedial side of the ankle are important
areas of transition through which structures pass
between regions.
• The femoral triangle is a pyramid-shaped
depression formed by muscles in the proximal
regions of the thigh and by the inguinal ligament,
which forms the base of the triangle.
• The major blood supply and one of the nerves of
the limb (femoral nerve) enter into the thigh from
the abdomen by passing under the inguinal
ligament and into the femoral triangle.
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6. • The popliteal fossa is posterior to the knee joint
and is a diamond-shaped region formed by
muscles of the thigh and leg.
• Major vessels and nerves pass between the thigh
and leg through the popliteal fossa.
• Most nerves, vessels and flexor tendons that pass
between the leg and foot pass through a series of
canals (collectively termed the tarsal tunnel) on
the posteromedial side of the ankle. The canals
are formed by adjacent bones and a flexor
retinaculum, which holds the tendons in position.
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9. Bony Pelvis/ pelvic girdle
• Is formed by four bones in a mature individual.
• Hip bones, two large, irregularly shaped bones,
each of which develops from the fusion of three
bones-ilium, ischium, and pubis
• Sacrum, formed by the fusion of five originally
separate sacral vertebrae.
• Coccyx, formed by the fusion of four rudimentary
coccygeal vertebrae; sometimes the first sacral
vertebra is separated from the others and thus
participates in forming the skeleton of this
vestigial tail.
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10. • Hip bones;
• In infants and children, the hip bones consist of
three separate bones that are united by cartilage
at the acetabulum -the cuplike depression in the
lateral surface of the hip bone that articulates
with the head of the femur (thigh bone).
• At puberty the ilium, ischium, and pubis fuse to
form the hip bone.
• The hip bones are joined anteriorly by the pubic
symphysis and to the sacrum posteriorly to form
the pelvic girdle.
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11. The pelvic girdle performs this basic functions;
• Articulates with the sacrum at the sacroiliac
joints
• Is massively constructed for resistance to
stress
• Transmits the thrust between the vertebral
column and the lower limbs.
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12. • The pelvis is divided into a greater (false)
pelvis and a lesser (true) pelvis.
• These two components are divided by the
pelvic brim, a curved bony rim passing
inferiorly from the sacral promontory to the
upper margin of the symphysis pubis.
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13. • The greater pelvis is the expanded portion of
the pelvis, superior to the pelvic brim.
• The pelvic brim not only divides the two
portions but surrounds the pelvic inlet of the
lesser pelvis.
• The lower circumference of the lesser pelvis
bounds the pelvic outlet.
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14. Greater pelvis
Lesser pelvis
Pelvic Brim
Pubic symphysis
Pubic Arch
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Pubic Angle
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15. ILIUM
• The ilium is the uppermost and largest of the three pelvic
bones.
• It has a crest and four angles, or spines—important
surface landmarks that serve for muscle attachment.
• The prominence of the hip is formed by the iliac crest.
• This crest terminates anteriorly as the anterior superior
iliac spine.
• Just below this spine is the anterior inferior iliac spine.
• The posterior termination of the iliac crest is the
posterior superior iliac spine, and just below this is the
posterior inferior iliac spine.
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16. • Below the posterior inferior iliac spine is the
greater sciatic notch, through which the
sciatic nerve passes.
• On the medial surface of the ilium is the
roughened auricular surface, which
articulates with the sacrum.
• The iliac fossa is the smooth, concave surface
on the anterior portion of the ilium.
• The iliacus muscle originates from this fossa.
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17. Ilium
Iliac Crest
Anterior Gluteal line
Anterior superior iliac spine
Posterior Gluteal line
Inferior Gluteal line
Anterior Inferior iliac spine
Lesser Sciatic notch
Pubis
Ischium
Obturator Foramen
Acetabulum
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18. • The iliac tuberosity, for the attachment of the
sacroiliac ligament, is positioned posterior to
the iliac fossa.
• Three roughened ridges are present on the
gluteal surface of the posterior aspect of the
ilium.
• These ridges, which serve to attach the gluteal
muscles, are the inferior, anterior, and
posterior gluteal lines.
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20. Ischium
• The ischium (is'ke-um) is the posteroinferior bone
of the os coxae.
• This bone has several distinguishing features.
• The spine of the ischium is the projection
immediately posterior and inferior to the greater
sciatic notch of the ilium.
• Inferior to this spine is the lesser sciatic notch of
the ischium.
• The ischial tuberosity is the bony projection that
supports the weight of the body in the sitting
position.
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21. • A deep acetabular (as''e˘-tab'yu˘-lar) notch is
present on the inferior portion of the
acetabulum.
• The large obturator (ob'tu˘-ra''tor) foramen is
formed by the inferior ramus of the ischium,
together with the pubis.
• The obturator foramen is covered by the
obturator membrane, to which several
muscles attach.
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22. Obturator Foramen
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23. Pubis
• The pubis is the anterior bone of the os coxae.
• It consists of a superior ramus and an inferior
ramus that support the body of the pubis.
• The body contributes to the formation of the
symphysis pubis—the joint between the two
ossa coxae.
• At the lateral end of the anterior border of the
body is the pubic tubercle, one of the
attachments for the inguinal ligament.
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24. Obturator Foramen
• The obturator foramen is a large oval or
irregularly triangular aperture in the hip bone.
• It is bounded by the pubis and ischium and their
rami.
• Except for a small passageway for the obturator
nerve and vessels--the obturator canal--the
obturator foramen is closed by the thin, strong
obturator membrane covered on both sides by
attached muscles.
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25. Acetabulum
• The acetabulum is the large cup-shaped cavity or
socket on the lateral aspect of the hip bone,
which articulates with the head of the femur to
form the hip joint
• All three parts of the hip bone join to form the
acetabulum.
• The margin of the acetabulum is deficient
inferiorly at the acetabular notch, which makes
the fossa resemble a cup with a piece of its lip
missing.
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26. • The rough depression in the floor of the
acetabulum extending superiorly from the
acetabular notch is the acetabular fossa.
• The acetabular notch and fossa also comprise
a deficiency in the smooth articular lunate
surface of the acetabulum, which actually
articulates with the head of the femur.
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27. Anatomical Position of the Hip Bone
• Surfaces and borders of the hip bone are named
according to their anatomical position.
• To place the hip bone in this position, place it so that
the acetabulum faces laterally and slightly anteriorly.
• When the hip bone is in the anatomical position, the:
 Anterior superior iliac spine and the anterosuperior
aspect of the pubis lie in the same vertical plane
 Ischial spine and superior end of the pubic symphysis
are approximately in the same horizontal plane.
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28.  Symphyseal surface of the pubis is vertical,
parallel to the median plane.
Internal aspect of the body of the pubis faces
almost directly superiorly (it essentially forms
a floor on which the urinary bladder rests).
Acetabulum faces inferolaterally, with the
acetabular notch directed inferiorly.
Obturator foramen lies inferomedial to the
acetabulum.
Tip of the coccyx is typically on a level with
the superior half of the body of the pubis.
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30. FEMUR
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31. • The longest and heaviest bone in the bodytransmits body weight from the hip bone to
the tibia when a person is standing.
• Its length associated with a striding gait is
approximately a quarter of the person's height
(approximately 108 cm or 18 inches).
• It consists of a body (shaft) and two ends,
superior/proximal and inferior/distal.
• The superior end of the femur consists of a
head, neck, and two trochanters (greater and
lesser).
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33. • The head of the femur is spherical and articulates
with the acetabulum of the pelvic bone.
• It is characterized by a non articular pit (fovea) on
its medial surface for the attachment of the
ligament of the head.
• The neck of the femur is a cylindrical strut of
bone that connects the head to the shaft of the
femur.
• It projects superomedially from the shaft at an
angle of approximately 125°, and projects slightly
forward.
• The orientation of the neck relative to the shaft
increases the range of movement of the hip joint.
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34. • The upper part of the shaft of the femur bears
a greater and lesser trochanter, which are
attachment sites for the muscles that move
the hip joint.
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35. Greater and lesser trochanters
• The greater trochanter extends superiorly from
the shaft of the femur just lateral to the region
where the shaft joins the neck of the femur.
• It continues posteriorly where its medial surface
is deeply grooved to form the trochanteric fossa.
• The lateral wall of this fossa bears a distinct oval
depression for attachment of the obturator
externus muscle.
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36. • The greater trochanter has an elongated ridge
on its anterolateral surface for attachment of
the gluteus minimus and a similar ridge more
posteriorly on its lateral surface for
attachment of the gluteus medius.
• Between these two points, the greater
trochanter is palpable.
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37. • On the medial side of the superior aspect of
the greater trochanter and just above the
trochanteric fossa is a small impression for
attachment of the obturator internus and its
associated gemelli muscles.
• Immediately above and behind this feature is
an impression on the margin of the trochanter
for attachment of the piriformis muscle.
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39. • The lesser trochanter is smaller than the greater
trochanter and has a blunt conical shape.
• It projects posteromedially from the shaft of
femur just inferior to the junction with the neck.
• It is the attachment site for the combined
tendons of psoas major and iliacus muscles.
• Extending between the two trochanters and
separating the shaft from the neck of the femur
are the intertrochanteric line and
intertrochanteric crest.
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40. • Shaft of the femur
• The shaft of the femur descends from lateral
to medial in the coronal plane at an angle of
7° from the vertical axis.
• The distal end of the femur is therefore closer
to the midline than the upper end of the
shaft.
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42. The middle third of the shaft of the femur is
triangular in shape with smooth lateral and medial
margins between anterior, lateral and medial surfaces.
The posterior margin is broad and forms a
prominent raised crest (the linea aspera).
The linea aspera is a major site of muscle
attachment in the thigh.
In the proximal third of the femur, the medial and
lateral margins of the linea aspera diverge and
continue superiorly as the pectineal line and gluteal
tuberosity, respectively : the pectineal line curves
anteriorly under the lesser trochanter and joins the
intertrochanteric line; the gluteal tuberosity is a broad
linear roughening that curves laterally to the base of
the greater trochanter.
 The gluteus maximus muscle is attached to the
gluteal tuberosity.
 The triangular area enclosed by the pectineal line,
the gluteal tuberosity, and the intertrochanteric crest
is the posterior surface of the proximal end of the
femur.
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43.  lnferiorly, the linea aspera divides into
medial and lateral supracondylar lines that
lead to the spirally curved medial and lateral
condyles.
 The
condyles
are
separated
inferoposteriorly by an intercondylar fossa
/notch.
 Anteriorly, the femoral condyles merge at
a shallow depression the patellar surfacewhere they articulate with the patella.
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44.  The lateral surface of the lateral condyle has a
central projection--the lateral epicondyle.
 The medial surface of the medial condyle has a
larger and more prominent medial epicondyle,
superior to which is another elevation, the
adductor tubercle.
 The
trochanters, lines, tubercles, and
epicondyles are sites for muscular and
ligament attachements.
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GOODMORNIN
G
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