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LOWER EXTREMITIES

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• 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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Inguinal ligament

Sacroiliac ligament

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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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• 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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• 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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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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• 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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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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• 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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• 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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Greater pelvis

Lesser pelvis

Pubic symphysis

Pubic Arch

Pubic Angle

Pelvic Brim

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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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• 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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Iliac Crest

Ilium

Pubis

Ischium

Acetabulum

Obturator Foramen

Lesser Sciatic notch

Anterior superior iliac spine

Inferior Gluteal line

Anterior Inferior iliac spine

Anterior Gluteal line

Posterior Gluteal line

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• 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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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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• 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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Obturator Foramen

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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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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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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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• 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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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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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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FEMUR

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• The longest and heaviest bone in the body-transmits 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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• 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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• 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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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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• 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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• 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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• 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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• 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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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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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 surface-where they articulate with the patella.

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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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GOODMORNING