Chapter 7

1. Chapter 7 Pelvic Girdle and Lower Limbs

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

3. Coxae • Each coxa develops from three parts (ilium, ischium, and pubis) that fuse in a depression (called the acetabulum) on the lateral surface of the hipbone that receives the head of the femur

4. Coxae • Ilium • Largest and most superior of the coxa • Forms the prominence of the hip • Special features: • Iliac crest • Margin of the prominence • Iliac fossa • Smooth, concave surface on the anterior side • Sacroiliac joint • Where the iliac joins the sacrum • Anterior superior iliac spine • Spine the provides attachments for ligaments and muscles • Posterior superior iliac spine • Spine on the poster border • Greater sciatic notch • Indentation below the posterior superior iliac spine through which nerves and blood vessels pass

5. Coxae • Ischium • Forms the lowest portion of the coxa • L-shaped • Special features • Ischialtuberosity • Angle of the ischium • Points downward and posteriorly • Provides attachments for ligaments and lower limb muscles • Supports the weight of the body during sitting • Ischial spine • Sharp projection located above the ischialtuberosity, near the junction of the iliam and ischium

6. Coxae • Pubis • Anterior portion of the coxa • Special features: • Symphysis pubis • Joint between the 2 pubic bones • Pubic arch • Formed by the angle of the pubic bones beneath the symphysis pubis • Obturator foramen • Largest foramen in the skeleton • Located between the pubis and ischium bones • Covered a nearly closed by an obturator membrane

7. 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

8. 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

9. 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

10. Lower Limbs • Include femur, tibia, fibula, tarsals, metatarsals, and phalanges

11. Femur • Longest bone in the body • Extends from the hip to the knee • 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

12. Femur • Special features (cont) • 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 • 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

13. Patella • Flat sesamoid (round) bone • Located in a tendon that passes anteriorly over the knee

14. Tibia • Larger of the two leg bones • Located on the medial side • Articulates with the talus in the ankle • Special features: • Medial and lateral condyles • Expanded proximal end • Have concave surfaces that articulate with the condyles of the femur • Tibialtuberosity • Process on the anterior surface that provides an attachment for the patellar ligament • 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

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

16. 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 • 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 • The tarsals and metatarsals are bound by ligaments to form 2 arches (longitudinal arch and a transverse arch)

17. Foot • Phalanges • Each toe (except the big two – which has two) has three phalanges (a proximal, middle, and distal phalanx) • Align and articulate with the metatarsals