The Skeletal System......Bones......Joints.....Joints Types......Bone Structure.

1. By
Muhammad Iqbal Khan
SS Biology
Email ID: mikhan1313@yahoo.com
0923135448175
The Skeletal System

2. Function
 Support
 Internal framework of body
 Ex: Legs support body trunk, rib cage supports chest wall
 Protection
 Protects soft body organs (skull protects brain, ribs protect heart and lungs, etc)
 Movement*
 Muscles use bones as levers to move body
 NOT a function skeletal system can do on it’s own
 Storage
 Fat storage
 In yellow marrow
 Mineral storage
 Calcium, phosphorus, and others.
 Blood cell formation
 Hematopoeisis
 Occurs in bone marrow of long bones

3. Bones
206 bones in the adult skeleton
Two types of bone
Compact bone
Homogeneous appearance
Dense, looks smooth
Spongy bone
Small needle-like pieces
Lots of open spaces
(Looks like a sponge, hence the name)

4. Bone Classification
Long Bones
Longer than wide
Contain shaft with head at
each end
Mostly compact bone
Limbs (not ankle or wrist
bones)
Short Bones
Cube-shaped
Mostly spongy bone
Wrist and ankle bones
Patella (kneecap)
Flat Bones
Thin, flat, usually curved
Two layers of compact bone
with spongy bone in between
Skull, ribs, breastbone
Irregular Bones
Don’t fit into the other
categories
Vertebrae, hip bones

5. Bone Classification

6. Long Bone Anatomy
Diaphysis
Shaft
Made of compact bone
Epiphyses
Ends of long bone
Made of compact bone
surrounding spongy bone
Covered with articular
cartilage
Smooth, glassy, decreases
friction at joints

7. Long Bone Anatomy
Epiphyseal Line
Line of bone tissue that
looks different from rest of
bone
Remnant of epiphyseal
plate
Hyaline cartilage
Causes long bones to grow
lengthwise

8. Long Bone Anatomy
Periosteum
Outer covering of shaft
Like “skin” on chicken
bone
Sharpey’s fibers
Attach periosteum to bone
Arteries
Supply nutrients to bone
cells

9. Long Bone Anatomy
Medullary Cavity
In shaft
Contains yellow marrow
(adipose) in adults
Contains red marrow in
infants (for blood cell
formation)

10. Microscopic Anatomy of Bone
Osteon (Haversian system)
A “unit” of bone
Central (Haversian) canal
Opening in center of osteon
Contains blood vessels
Perforating (Volkman’s) canal
Perpendicular to central canal
Contains blood vessels and nerves

11. Microscopic Anatomy of Bone

12. Microscopic Anatomy of Bone
Lacunae
Cavities that contain
osteocytes (bone cells)
Arranged in concentric
rings (like tree rings)
Lamellae
Rings around the central
canal
Where the lacunae can be
found

13. Microscopic Anatomy of Bone
Canaliculi
Tiny canals
Radiate from central canal
to lacunae
Transport nutrients to
bone cells

14. Other Facts
Bone is one of the hardest parts of the body
Very lightweight
Can resist tension
Calcium salts make it hard
Collagen fibers make it strong and flexible

15. Bone Formation
In embryos…
Skeleton made of hyaline cartilage
Gets replaced by bone with age
Cartilage remains in a few places…
Bridge of nose
Parts of ribs
Joints

16. Bone Growth
Epiphyseal plates allow for growth of long bone
during childhood
New cartilage is continuously formed
Older cartilage becomes ossified
Cartilage is broken down
Bone replaces cartilage
Bones remodeled, lengthened until growth stops
Bones change shape somewhat
Bones grow in width

17. Long Bone Growth

18. Long Bone Growth

19. Types of Bone Cells
Osteocyte
Mature bone cell
Osteoblast
“Bone builders”
Osteoclast
“Bone destroyers”
Break down bone matrix to remodel and/or release calcium

20. Bone Remodeling
Bone remodeling is done by osteoblasts and osteoclasts
Essential for bones to keep normal proportions and strength
Bones get larger/thicker when…
Large muscles are attached to them
Need more bone to attach the large muscle to
Bones get smaller/weaker when…
Physical inactivity
Non-use of musclesatrophy
Small muscles don’t need large bones to attach to
 Bones remodeled to become smaller

21. Fractures
A break in a bone
Types of Fractures
Simple (closed) fracture
Bone breaks cleanly, does not penetrate skin
Compound (open) Fracture
When bone ends penetrate through skin
Treated by reduction and immobilization
Realignment of bone ends

22. Common Fractures

23. Bone Repair
Hematoma forms
Blood vessels rupture when
bone breaks
Blood filled swelling
Cells without nutrients die
Fibrocartilage callus forms
Made of connective tissue
Splints the break
Phagocytes dispose of dead
tissue
Bony callus forms
Osteoblasts/clasts move in,
create callus of spongy bone
Remodeling
Osteoblasts/clasts remodel in
response to stress on the bone
Helps strengthen bone
Creates a permanent “patch” at
the site
Often, a healed fracture can be
stronger than the rest of the
bone

24. Bone Repair

25. Axial Skeleton
Makes up longitudinal part of the body
Three parts
Skull
Vertebral column
Bony thorax
**Note: notes on specific bones are not included. Make sure you
are using your textbook to help identify shapes/functions of
bones!!

26. Axial Skeleton **Shown in green

27. Skull
Formed by two sets of bones
Cranium
Encloses/protects brain
Facial bones
Holds eyes forward (anterior position)
Allow facial muscles to show feelings
Sutures
Interlocking, immovable joints holding most skullbones
together
Mandible-only freely movable bone in skull

28. Skull

29. Skull

30. Paranasal Sinuses
Hollow portions of bone around nasal cavity
Named for bones they are found in
Lighten skull
Amplify sounds when speaking/ give resonance

31. Fetal Skull
Large in comparison to
body length of infant
Contains fontanelles
Soft fibrous membranes
connecting cranial bones
“Soft Spots”
Usually convert to bone
around 24 months after birth

32. The Vertebral Column
Vertebrae named for their
location
7 cervical vertebrae
 C1 = Atlas
 C2 = Axis
12 thoracic vertebrae
5 lumbar vertebrae
Sacrum
 5 fused vertebrae
Coccyx
 4 fused vertebrae
Vertebrae separated by
fibrocartilage discs
Cushions/absorbs shock

33. Vertebrae Structure

34. Regional Characteristics

35. Regional Characteristics

36. Bony Thorax Forms a cage to protect
organs
Three parts
Sternum
 Flat bone
 3 fused bones
 Manubrium
 Body
 Xyphoid process
 Attached to first 7 pr of ribs
Rib Cage
 12 pairs
 True Ribs= 7 pr
 False Ribs = 5 pr
 Floating Ribs = 2 pr
Thoracic vertebrae

37. Appendicular Skeleton
Limbs (appendages)
Pectoral girdle
Pelvic girdle
**shown in yellow

38. Pectoral Girdle (shoulder)
Two bones
Clavicle-collarbone
Scapula-shoulder blade

39. Upper Limb (arm)
Arm bone- humerus
Forearm bones-
Radius (thumb side)
Ulna
Hand bones
Carpals-wrist
Metacarpals-palm
Phalanges-fingers

40. Pelvic Girdle (hip bones)
Three pairs of fused bones
Ilium
Ischium
Pubic bone
Carries total weight of
upper body
Protects
Reproductive organs
Bladder
Part of large intestine

41. Gender Differences in Pelvis
Female inlet larger/more
circular
Female pelvis is shallower,
bones lighter/thinner
Female hip bones flare wider
Female sacrum is shorter/less
curved
Female pubic arch is more
rounded/angle is greater

42. Lower Limb (leg)
Thigh bone-femur
Two leg bones
Tibia (larger, medial bone)
Fibula (smaller, lateral
bone)
Foot
Tarsals-ankle
Metatarsals-sole
Phalanges-toes

43. Joints
Articulations of bones
Functions
Hold bones together
Mobility
Classified by
structure/function
**we’ll use structural classification
Fibrous joints
Immovable
EX: sutures of skull
Cartilaginous joints
Immovable OR slightly
movable
EX:Pubic symphysis and
Vertebrae
Synovial joints
Freely movable
**Be familiar with types of synovial
joints (illustrations to follow)

44. Synovial Joints
Articulating bones separated
by joint cavity
Articular cartilage covers bone
ends
Joint surfaces enclosed by
fibrous capsule
Cavity contains synovial fluid
Ligaments help reinforce the
joint
Associated Joint Structures
Bursae
 Flat fibrous sacs
 Lined with synovial membrane
 Contains synovial fluid
 Common where ligaments,
muscles, skin, tendons rub
together
Tendon sheath
 Elongated bursa wrapping
around a tendon that deals with
lots of friction
 Like a bun around hot dog

45. Synovial Joints

46. Types of Synovial Joints by Shape

47. Types of Synovial Joints by Shape