Transcript Chapter 7
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 • 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) that fuse in a depression (called the acetabulum) on the lateral surface of the hipbone that receives the head of the femur 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 • Ischium Coxae – Forms the lowest portion of the coxa – L-shaped – 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 • Ischial spine – Sharp projection located above the ischial tuberosity, near the junction of the iliam and ischium 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 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 Lower Limbs • Include femur, tibia, fibula, tarsals, metatarsals, and phalanges 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 • Special features (cont) Femur – 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 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 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 – 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 • 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 • Ankle (tarsus) Foot – 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) 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