1. Part 2 The Skeleton US-Mexico Border Fence Buenos Aires Wildlife Refuge The Skeletal System

2. Human Skeleton 206 bones Axial skeleton—skull, vertebral column, sternum Appendicular skeleton—pectoral girdle, pelvic girdle, limbs

3. Figure 5.5 Axial skeleton Cranium (skull) Maxilla Mandible Sternum Vertebrae Sacrum Appendicular skeleton Clavicle Humerus Ulna Radius Carpals Metacarpals Phalanges Coxal bone Patella Tibia Fibula Tarsals Metatarsals Phalanges Ribs Scapula Femur Axial Skeleton This Side Appendicular Skeleton This Side

4. Long bones Associated with large movement Long and cylindrical with growth heads (epiphyses) Examples—femur, radius, and ulna Short bones Associated with small, complex movement Somewhat cube-shaped and associated with smaller, more complex movements. Examples—carpals (small bones in the base of the hand) and tarsals (in the feet) Flat bones Protect the internal organs Two thin layers of compact bone with spongy sandwiched between Examples—skull (cranium), ribs, scapula (shoulder blade), sternum (breast bone) and the pelvic girdle Types of Bone by Shape

5. Irregular bones Irregular in shape Examples—vertebrae and some facial bones Sesamoid bones Small bones held within tendon Example—patella. Cartilage separates the femur and the patella and acts as a shock absorber.

6. Axial Skeleton Vertebral column Regions—cervical, thoracic, lumbar, sacral, coccygeal Bones alternating with Intervertebral disks Intervertebral disks Cushion vertebrae Assist in movement and flexibility Are composed of fibrocartilage Ribs Twelve pairs Two pairs are “floating,” not attached to sternum Sternum Three bones fused together

7. Figure 5.7 Cervical vertebrae (7) Thoracic vertebrae (12) Lumbar vertebrae (5) Sacrum (5 fused) Coccyx (4 fused) 1 2 3 4 5 6 7 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5

8. Figure 5.8 Spinal cord Intervertebral disk Main bodies of vertebrae b) A herniated disk. Articulations with another vertebra Spinal nerve Articulation with ribs a) Healthy disks. Herniated area pressing against a nerve

9. Figure 5.9 Sternum (breastbone) Ribs Cartilage Vertebral column Floating ribs T 11 T 12 L1L1 L2L2 12 11 C7C7 T1T1 1 2 3 4 5 6 7 8 9 10

10. Appendicular Skeleton Pectoral girdle (shoulder) Clavicles Scapulas Pelvic girdles (hip areas) Coxal bones Sacrum Pubic symphysis Limbs Arms—humerus, radius, ulna, wrist, hand bones Legs—femur, tibia, fibula, ankle, foot bones

11. Figure 5.10 Pectoral girdle Clavicle (collar bone) Scapula (shoulder blade) Humerus (upper arm) Ulna Forearm Radius 8 Carpals (wrist) 5 Metacarpals (hand) 14 Phalanges (finger bones)

12. Figure 5.11 Coxal bones and sacrum (pelvis) Femur (upper leg) Patella (knee cap) Lower leg Tibia Fibula 7 Tarsals (ankle) 5 Metatarsals (foot) 14 Phalanges (toe bones) Pubic symphysis

13. Joints (Articulations) Classified by degree of movement Fibrous joint Relatively immovable Example—fontanels Cartilaginous joint Slightly movable cartilage connection Example—intervertebral connections Synovial joint Freely movable Composed of Tendons—join bone to muscle Joint capsule—synovial membrane (secretes lubricant) + hyaline cartilage (provides smooth surface and cushions) Example—shoulder

14. Figure 5.12 b) A view of the knee with muscles, tendons, and ligaments in their normal position surrounding the intact joint capsule. The combination of ligaments, tendons, and muscles holds the knee tightly together. Ligaments Joint capsule Tendon Thigh muscles Patella Ligaments a) A cutaway anterior view of the right knee with muscles, tendons, and the joint capsule removed and the bones pulled slightly apart so that the two menisci are visible. Tendon Patella Ligament Tibia Fibula Femur Ligament Meniscus Hyaline cartilage Posterior cruciate ligament Anterior cruciate ligament Meniscus

15. Hinge joint—elbow Ball and socket joint—hip Gliding joints—the carpals of the wrist Pivot joint▬atlas-axial joint Condyloid (ellipsoid) joint— radiocarpal joint Saddle joints—joint of thumb (between the metacarpal and carpal) Types of Synovial Joints