Download - Part 2 The Skeleton US-Mexico Border Fence Buenos Aires Wildlife Refuge The Skeletal System
Human Skeleton• 206 bones
• Axial skeleton—skull, vertebral column, sternum
• Appendicular skeleton—pectoral girdle, pelvic girdle, limbs
Figure 5.5
Axial skeleton
Cranium (skull)MaxillaMandible
Sternum
Vertebrae
Sacrum
Appendicular skeleton
Clavicle
Humerus
UlnaRadiusCarpals
Metacarpals
Phalanges
Coxal bone
PatellaTibiaFibula
TarsalsMetatarsalsPhalanges
Ribs
Scapula
Femur
Axial Skeleton This Side Appendicula
r Skeleton This Side
• 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
Types of Bone by Shape
• 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.
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
Figure 5.7
Cervical vertebrae (7)
Thoracicvertebrae (12)
Lumbar vertebrae(5)
Sacrum(5 fused)
Coccyx (4 fused)
12
34567
123
45
6
7
8
9
10
11
12
1
2
3
4
5
Figure 5.8
Spinal cord
Intervertebraldisk
Main bodiesof vertebrae
b) A herniated disk.
Articulations with another vertebra
Spinal nerve
Articulation with ribs
a) Healthy disks.
Herniated areapressing againsta nerve
Figure 5.9
Sternum (breastbone)
Ribs
Cartilage
Vertebral column
Floating ribs
T11
T12
L1
L2
12
11
C7
T1 1
2
3
4
5
6
7
8910
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
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)
Figure 5.11
Coxal bones and sacrum (pelvis)
Femur (upper leg)
Patella (knee cap)
Lower legTibia
Fibula
7 Tarsals (ankle)5 Metatarsals (foot)
14 Phalanges (toe bones)
Pubic symphysis
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
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
LigamentTibia
Fibula
Femur
Ligament
Meniscus
Hyaline cartilage
Posterior cruciate ligament
Anterior cruciate ligament
Meniscus
• 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