Skeletal system pt 3

Question 1

Lower limb

Answer 1

• carries entire weight of erect body
• subjected to exceptional forces if jump/run
• 3 segments of lower limb (thigh, leg, foot)

Question 2

Bones of thigh

Answer 2

1. Femur
   - largest, strongest bone in body
   - length 1/4 of person’s height
   - articulates proximally w/ acetabulum of hip + distally with tibia + patella
   - comparison to humerous
2. Patella
   - sesamoid bone in quadriceps tendon

Question 3

Bones of leg

Answer 3

1. Tibia (tough tibia)
   - medial leg bone
   - receives weight of body from femur, transmit to foot
2. Fibula (fragile fibula)
   - not weight bearing; no articulation with femur
   - several muscles originate from fibula
   - articulates proximally + distally with tibia

• tibia + fibula connected by interosseous membrane

Question 4

Foot (3 parts)

Answer 4

1. Tarsus
   - 7 tarsal bones
   - body weight carried primarily by talus + calcaneus
   - other tarsal bones: cuboid, navicular, and medial, intermediate, and lateral cueiform bones
   - several joints in ankle + foot to accomodate uneven ground surfaces
2. Metatarsals (foot)
   - metatarsal head
3. Phalanges (toes)

Question 5

Arches of foot

Answer 5

• maintained by interlocking foot bones, ligaments, and tendons
• allow foot to bear weight
• 3 arches (lateral + medial longitudinal, transverse)

Question 6

Fetal skull

Answer 6

infant skull has more bones than adult skull
- skull bones such as mandible + frontal bones unfused

skull bones connected by fontanelles
- unossified remnants of fibrous membranes
- ease brith + allow brain growht
- 4 fontanelles (soft spots) –> anterior, posterior, mastoid, sphenoidal

Question 7

Development of spinal curves

Answer 7

• at brith, only thoracic + sacral (primary) curves are present (convex posteriorly)
• cervical + lumbar (secondary) curvatures develop in childhood (convex anteriorly)
• cervical curve: when baby starts lifting head
• lumbar curve: baby begins to walk (12 months)

Question 8

Old age

Answer 8

• intervertebral discs thin, less hydrated, less elastic (risk of disc herniation increases)
• several cm height loss by 55
• costal cartilages ossify (rigid thorax causes shallow breathing and less efficient gasses exchange)
• all bones lose mass, so fracture risk increases, spontaneous fractures