Chapter 7

Pelvic Girdle and Lower Limbs

Pelvic Girdle

• Consists of two coxae (hipbones) that articulate with each other anteriorly and with the sacrum posteriorly

Pelvic Girdle

• Functions:– Supports the trunk of the body (weight is

transmitted through the girdle to the lower limbs and then the ground)

– Provides attachments for the lower limbs– Protects the bladder, the distal end of the large

intestine, and the internal reproductive organs

Coxae

• Each coxa develops from three parts: ilium, ischium, and pubis

• The three parts fuse to form a depression called the acetabulum on the lateral surface of the hipbone– The acetabulum that

receives the head of the femur

Coxae• Ilium– Largest and most superior of

the coxa– Forms the prominence of the

hip

Coxae• Ilium– Special features:• Iliac crest–Margin of the prominence

• Iliac fossa– Smooth, concave surface on

the anterior side

Coxae

• Ilium– Special features:• Sacroiliac joint–Where the iliac joins the sacrum

Coxae

• Ilium– Special features:• Anterior superior iliac

spine– Spine the provides

attachments for ligaments and muscles

• Posterior superior iliac spine– Spine on the posterior

border

Coxae

• Ilium– Special features:• Greater sciatic notch– Indentation below the

posterior superior iliac spine through which nerves and blood vessels pass

Coxae• Ischium– Forms the lowest portion of

the coxa– L-shaped

Coxae• Ischium– Special features• Ischial tuberosity– Angle of the ischium– Points downward and

posteriorly– Provides attachments for

ligaments and lower limb muscles– Supports the weight of

the body during sitting

Coxae• Ischium– Special features• Ischial spine– Sharp projection located

above the ischial tuberosity, near the junction of the iliam and ischium

Coxae• Pubis– Anterior portion of the coxa

Coxae• Pubis– Special features:• Symphysis pubis– Joint between the 2 pubic bones

• Pubic arch– Formed by the angle of the pubic bones beneath the

symphysis pubis

Coxae• Pubis– Special features:• Obturator foramen– Largest foramen in the skeleton– Located between the pubis and ischium bones– Covered by an obturator membrane

Greater and Lesser Pelves

• Greater pelvis (false pelvis)– Upper part of the pelvis– Bounded posteriorly by the lumbar vertebrae,

laterally by the flared parts of the iliac, and anteriorly by the abdominal wall

– Helps support the abdominal organs

Greater and Lesser Pelves

• Lesser pelvis (true pelvis)– Bounded posteriorly by the sacrum and coccyx

and laterally and anteriorly by the lower ilium, ischium, and pubis bones

– Surrounds the cavity through which an infant passes during the birthing process

Differences between Male and Female Pelves

• Iliac bones in females are usually more flared, creating broader hips

• Pelvic cavity in females is usually wider in all diameters than that of males

• Bones in female pelvis are usually lighter and show less evidence of muscle attachments than those of males

• http://www.innerbody.com/image_skel20/skel35.html

Lower Limbs

• Include femur, tibia, fibula, tarsals, metatarsals, and phalanges

Femur• Longest bone in the body• Extends from the hip to the

knee

Femur• Special features:– Head• Located at the proximal end• Projects medially into the

acetabulum of the coxa– Fovea capitis• Pit on the head that marks the

attachment of a ligament– Neck• Constriction located just below

the head

Femur• Special features– Greater trochanter• Large process below the head• Provide attachments for muscles

of the lower limbs– Lesser trochanter• Large process below the head• Provide attachments for muscles

of the lower limbs

Femur• Special features– Linea aspera• Longitudinal crest in the middle

of the femur that serves as an attachment for muscles

– Lateral and medial condyles• Rounded processes at the distal

end that articulate with the tibia– Medial and lateral epicondyles• Projections on the distal surface

that provide attachments for muscles

Patella

• Flat sesamoid (round) bone• Located in a tendon that passes anteriorly

over the knee

Tibia• Larger of the two leg bones• Located on the medial side• Articulates with the talus in

the ankle

Tibia• Special features:– Medial and lateral condyles• Expanded proximal end• Have concave surfaces that

articulate with the condyles of the femur

– Tibial tuberosity• Process on the anterior surface

that provides an attachment for the patellar ligament

Tibia• Special features:– Anterior crest• Extends downward from the

tuberosity and attaches connective tissues in the leg

– Medial malleolus• Expanded prominence on the

inner ankle that forms an attachment for ligaments

Fibula

• Long, slender bone located on the lateral side of the tibia

Fibula

• Special features:– Head• Enlarged proximal end• Articulates with the tibia• Doesn’t enter into the knee

joint or bear any body weight– Lateral malleolus• Enlarged distal end• Articulates with the ankle• Protrudes on the lateral side

Foot• Ankle (tarsus)– Composed of 7 tarsal bones– The talus (your ankle bone) articulates with the

tibia and fibula and can move freely– The calcaneus (your heel bone) helps support the

body weight and serves as an attachment for the muscles that move the foot

Foot• Instep (metatarsus)– Composed of 5 metatarsal bones (numbered 2 to

5 beginning on the medial side)– Articulates with the tarsus– The heads of the metatarsals at the distal end

form the ball of the foot

Foot• The tarsals and metatarsals are bound by

ligaments to form 2 arches (longitudinal arch and a transverse arch)

Foot

• Phalanges– Each toe (except the big toe – which has two) has

three phalanges (a proximal, middle, and distal phalanx)

– Align and articulate with the metatarsals