1. Week 4: Skeletal System Part 04.D (#06-09) Osseous Tissue
A&P Lab
Week 4:
Skeletal System
Part 04.D (#06-09)
Osseous Tissue

2. Bone Surface Features/Markings
#6 SPO
Using specimens, models, and diagrams, describe and identify at least one instance of the following bone markings. When identifying landmarks, the bone MUST be identified as well:
Bone surface features/markings:
External and internal features related to functions
Elevations/projections for tendon and ligament attachment
Depressions/grooves/tunnels for blood vessels or nerves to lie alongside or penetrate

3. Bone Surface Features/Markings
Land Marks (cont.)
Tuberosity
Crest
Trochanter
Tubercle
Epicondyle
Spine

4. Bone Surface Features/Markings
Land Marks (cont.)
Process
Head
Facet
Condyle
Ramus

5. Bone Surface Features/Markings
Land Marks (cont.)
Sinus
Meatus
Fossa
Fissure
Foramen (plural – foramina)

6. Bone Surface Features/Markings
E.g. - Skull surface features:
Process (projection or bump)
Sinus (chamber within bone, usually filled with air)
Meatus or canal (large passageway)
Fissure (elongated cleft or gap)
Foramen (small rounded passageway)

7. Bone Surface Features/Markings
E.g. - Humerus surface features
Tuberosity (small, rough projection; may occupy broad area)
Tubercle (small, rounded projection)
Head (expanded proximal end that forms part of joint)
Condyle (smooth, rounded articular process)
Sulcus (deep, narrow groove)
Diaphysis (shaft; elongated body)
Trochlea (smooth, grooved articular process)

8. Bone Surface Features/Markings
E.g. - Femur surface features
Trochanter (large, rough projection)
Head
Facet (small, flat articular surface)
Condyle
Epicondyle (rounded eminence on a bone that lies upon a condyle)
Neck (narrow connection between head and diaphysis)
Diaphysis

9. Bone Surface Features/Markings
E.g. - Pelvis surface features
Crest (prominent ridge)
Spine (pointed or narrow process)
Ramus (extension making angle with rest of structure)
Fossa (shallow depression or recess)
Line (low ridge; more delicate than crest)

10. Basic Structures of a Long Bone
SPO #7
Using specimens, models, and diagrams and the sectioned bones, describe and identify the following long bone structures:
- Epiphysis - Diaphysis - Spongy bone
- Compact bone - Medullary cavity - Periosteum
- Articular cartilage - Red bone marrow
- Epiphyseal line - Yellow bone marrow

11. Basic Structures of a Long Bone (cont.)
Epiphysis (expanded ends)
Consist largely of spongy bone (trabecular bone)
Network of struts and plates
Resists forces from various directions and directs body weight to diaphysis and joints
Epiphyseal line
Has outer covering of compact bone
Strong, organized bone
Articular cartilage
Covers portions of epiphysis that form articulations
Avascular and receives resources from synovial fluid

12. The Epiphyseal Cartilage & Epiphyseal Line
Epiphyses & Epiphyseal Cartilage:
Epiphyses fill with spongy bone
Only articular cartilage (on epiphyses) and epiphyseal cartilage (in metaphysis) remain

13. The Epiphyseal Cartilage & Line
Hyaline cartilage
Epiphysis
Metaphysis
Periosteum
Compact
bone
Secondary
ossification
center
Formation of secondary
ossification centers
Formation of an epiphyseal
cartilage between epiphysis
and diaphysis
Articular cartilage
Spongy
Epiphyseal
cartilage
Diaphysis

14. The Epiphyseal cartilage & Bone Lengthening
Bone grows in length at epiphyseal cartilage:
Chondrocytes actively produce more cartilage on epiphysis side
Osteoblasts actively replace cartilage with bone on diaphysis side
As long as both processes are equally active, bone lengthening continues
At puberty, hormones increase bone growth and epiphyseal cartilage is replaced
Leaves epiphyseal line in adults

15. The ossifying surface of an epiphyseal cartilage
Cartilage cells undergoing
division and secreting
additional cartilage matrix
Epiphyseal
cartilage matrix
Articular cartilage
Spongy
bone
Epiphyseal
cartilage
Diaphysis
LM x 250
Medullary
cavity
Osteoblasts
Osteoid
Formation of an epiphyseal
cartilage between epiphysis
and diaphysis

16. Basic Structures of a Long Bone (cont.)
Diaphysis (shaft)
Contains medullary cavity (marrow cavity)
Filled with marrow:
Red bone marrow (red blood cell production)
Yellow bone marrow (adipose storage)

17. Coronal sections through a right femur, showing the boundaries of a long bone’s major regions, plus the bone’s internal organization and how it distributes the forces applied to the bone
Body weight
(applied force)
The epiphysis
(e-PIF-i-sis) is an
expanded area
found at each end
of the bone.
The epiphysis consists largely of spongy bone, also called trabecular bone. Spongy bone
consists of an open network
of struts and plates that
resembles latticework with
a thin covering, or cortex, of
compact bone.
The metaphysis
(me-TAF-i-sis; meta,
between) is a narrow
zone that connects
the epiphysis to the
shaft of the bone.
The wall of the diaphysis
consists of a layer of
compact bone.
Tension
on lateral
side of
shaft
The medullary cavity
(medulla, innermost part), or
marrow cavity, is a space
within the hollow shaft. In
life, it is filled with bone
marrow, a highly vascular
tissue. Red bone marrow
is highly vascular and
involved in the production
of blood cells. Yellow
bone marrow is adipose
tissue important in the
storage of energy reserves.
The diaphysis
(shaft) is long and
tubular.
Compression
on medial
side of shaft
Metaphysis
Epiphysis

18. A longitudinal section of the humerus, showing the extensive |network of blood vessels in long bones
An articular cartilage covers portions of the epiphysis that articulate with other bones. The cartilage is avascular, and it relies primarily on diffusion from the synovial fluid to obtain oxygen and nutrients and eliminate wastes.
Epiphyseal artery and vein
The metaphyseal artery (red) and metaphyseal vein (blue) carry blood to and from the area of the metaphysis and to the epiphysis through epiphyseal arteries and veins.
Metaphysis
Most bones have only one nutrient artery (shown in red) and one nutrient vein (shown in blue), but a few bones, including the femur, have more than one of each.
Periosteum
Compact bone
A nutrient foramen is a tunnel that penetrates the diaphysis and provides access for the nutrient artery and/or vein. Branches of these large vessels supply the osteons of the surrounding compact bone before entering and supplying the tissues of the medullary cavity.
Medullary cavity
Metaphyseal artery and vein
Metaphysis

19. Basic Structures of a Long Bone (cont.)
Periosteum features:
Smaller blood vessels (supply superficial osteons)
Lymphatic vessels (collect lymph from bone and osteons)
Sensory nerves (innervate diaphysis, medullary cavity, and epiphyses)

20. Histology of Bone Tissue
SPO #8.
Using microscope images, models and diagrams, describe and identify the following microscopic structures of compact bone:
Osteon
Central canal
Lamellae (plural), Lamella (singular)
Osteocyte
Canaliculi (plural), Canaliculus (singular)
Perforating canal
Blood vessels
Periosteum
Perforating fiber

21. Histology of a Long Bone (cont.)
Typical long bone organization:
Periosteum (outermost layer)
Perforating fibers
Compact bone (outer bone tissue layer)
Circumferential lamellae (circum-, around + ferre, to bear)
Outer and inner surfaces of compact bone layer
Interstitial lamellae
Fill spaces between osteons
Osteons
Contain central canals (parallel to bone surface)
Connected by perforating canals (perpendicular)
Spongy bone (innermost layer)
Endosteum (innermost lining cavities, lining central canal, & spongy tissue

22. Histology of a Long Bone (cont.)
Periosteum:
Two layers:
Fibrous outer layer
Cellular inner layer
Functions:
Isolate bone from surrounding tissues
Route for blood and nervous supply
Actively participate in bone growth and repair

23. Histology of Long Bone (cont.) Periosteum & Perforating Fibers:
Created by osteoblasts in periosteum cellular layer
Strongly connect tendons, ligaments, and joint capsules to bone through periosteum

24. Structure of the Periosteum
Circumferential
lamellae
Fibrous layer
of periosteum
Cellular layer
Canaliculi
Osteocyte
in lacuna
Perforating
fibers

25. Histology of Compact Bone (cont.)
Functional unit is osteon
Organized concentric lamellae around a central canal
Osteocytes (in lacunae) lie between lamellae
Central canal contains small blood vessels
Canaliculi connect lacunae with each other and central canal
Strong along its length

26. Histology of Compact Bone Tissue (cont.)
The structure of compact bone, as shown in
the shaft of a long bone
Capillary and venule (small vein)
Central canal
Concentric lamellae
Canaliculi radiating through the lamellae interconnect the lacunae of the osteons with one
another and with the central canal.
Endosteum
Central canal
Periosteum
Circumferential
lamellae
Osteon
Vein
Artery
Interstitial
lamellae
Compact bone
LM x 375
The osteocytes occupy lacunae that lie between the lamellae. In preparing this micrograph, a small piece of bone was ground down until it was thin enough to
transmit light. In this process, the lacunae and canaliculi are filled with bone dust, and thus appear black.
Central canal
Perforating canal

27. Histology of Compact Bone Tissue (cont.)
Osteocytes (osteo-, bone + cyte, cell)
Mature bone cells that cannot divide
Most numerous bone cell type
Maintain protein and mineral content of adjacent matrix
Dissolve matrix to release minerals
Rebuild matrix to deposit mineral crystals
Occupy lacunae (pocket)
Separated by layers of matrix (lamellae)
Connected with canaliculi
Osteoblasts become osteocytes once surrounded by bony matrix

28. Histology of Bone Tissue
The structures of osteocytes and osteoblasts within a
long bone
The layers of matrix
are called lamellae
(lah-MEL-lē; singular,
lamella, a thin plate).
Osteocytes account for most
of the cell population in bone.
Each osteocyte occupies a
lacuna, a pocket sandwiched
between layers of matrix.
Osteocytes cannot divide,
and a lacuna never contains more than one osteocyte.
Processes of the
osteocytes extend into
narrow passageways
called canaliculi that
penetrate the lamellae.
The canaliculi interconnect
the lacunae and reach
vascular passageways,
providing a route for
nutrient diffusion.
Osteoblast
Osteoid

29. Histology of Long Bone (cont.)
Endosteum:
Incomplete cellular layer lining medullary cavity
Covers spongy bone and lines central canals
Consists of simple layer of specialized osteoprogenitor cells
Where incomplete, osteoclasts and osteoblasts remodel matrix

30. Structure of the Endosteum
Osteoclast
Circumferential lamella
Osteocyte
Osteoprogenitor
cell
Osteoid
Osteoblast
Structure of the Endosteum

31. Histology of Compact Bone Tissue
Bone vasculature:
Growth and maintenance requires extensive blood supply
Vascular features:
Nutrient artery/vein (commonly one each/bone)
Nutrient foramen (tunnel providing access to marrow cavity)
Also supplies osteons of compact bone with blood
Metaphyseal artery/vein
Carry blood to/from metaphysis
Connects to epiphyseal arteries/veins

32. A longitudinal section of the humerus, showing the extensive |network of blood vessels in long bones
An articular cartilage covers portions of the epiphysis that articulate with other bones. The cartilage is avascular, and it relies primarily on diffusion from the synovial fluid to obtain oxygen and nutrients and eliminate wastes.
Epiphyseal artery and vein
Metaphysis
The metaphyseal artery (red) and metaphyseal vein (blue) carry blood to and from the area of the metaphysis and to the epiphysis through epiphyseal arteries and veins.
Most bones have only one nutrient artery (shown in red) and one nutrient vein (shown in blue), but a few bones, including the femur, have more than one of each.
Periosteum
Compact bone
Medullary cavity
A nutrient foramen is a tunnel that penetrates the diaphysis and provides access for the nutrient artery and/or vein. Branches of these large vessels supply the osteons of the surrounding compact bone before entering and supplying the tissues of the medullary cavity.
Metaphyseal artery and vein
Metaphysis

33. Histology of Spongy Bone Tissue
Located where bones not heavily stressed or in many directions
Lamellae form struts and plates (trabeculae) creating an open network
Reduces weight of skeleton
No blood vessels in matrix
Nutrients reach osteons through canaliculi open to trabeculae surfaces

34. Histology of Spongy Bone Tissue
The structure of spongy bone, as shown in the head of the femur
Trabeculae of
spongy bone
Canaliculi
opening on
surface
Endosteum
Lamellae

35. Bone Matrix Composition
SPO #9
Describe the appearance of bones soaked in acid with respect to color, flexibility, & hardness
Describe the appearance of bones that have been baked with respect to color, flexibility, & hardness
Identify the component of bone matrix responsible for the hardness of bone
Identify the component of bone matrix responsible for the flexibility of bone
Describe the impact of aging on the collagen content of bone in relation to the calcium-phosphate component.

36. Bone Tissue Matrix Composition
Bone matrix:
Collagen fibers account for ~1/3 bone weight
Provide flexibility
Calcium phosphate (Ca3(PO4)2) accounts for ~2/3 bone weight
Interacts with calcium hydroxide (Ca(OH)2) to form crystals of hydroxyapatite (Ca10(PO4)6(OH)2) salts
Incorporates other salts (calcium carbonate, CaCO3) and ions (Na+, Mg2+, F−)
Provides strength

37. Bone Tissue Matrix Composition
Composition of Bone
Bone Contains …
Calcium 39%
99% of the body’s calcium
Potassium 0.2%
4% of the body’s potassium
Sodium 0.7%
35% of the body’s sodium
Magnesium 0.5%
50% of the body’s magnesium
Organic
compounds
(mostly collagen)
33%
Carbonate 9.8%
80% of the body’s carbonate
Phosphate 17%
99% of the body’s phosphate
Total inorganic
components
67%

38. Bone Tissue Matrix Composition
Bones are important mineral reservoirs
Mostly calcium and phosphate, but other ions as well
Calcium
Most abundant mineral in body
1–2 kg (2–4 lb)
~99% deposited in skeleton
Variety of physiological functions
Concentration variation greater than 30–35% affects neuron and muscle function
Normal daily fluctuations are <10%

39. Bone Tissue Matrix Composition
The normal appearance, but great flexibility of bones lacking a calcified matrix (after being soaked in acid)

40. Bone Tissue Matrix Composition (cont.)
Burnt and blackened appearance; become very brittle with the loss of organic fibers from the calcified matrix (after being baked)

41. Bone Tissue Matrix Composition (cont.)
Locations of Calcium Homeostasis:
Levels controlled by activities of:
Intestines
Absorb calcium and phosphate under hormonal control
Bones
Remodeling by osteoblasts and osteoclasts
Kidneys
Calcium and phosphate loss in urine under hormonal control

42. Bone Tissue Changes With Age:
Appositional bone growth:
Increases bone diameter of existing bones
Does not form original bones
Specialized (osteoprogenitor) cells differentiate into osteoblasts that add bone matrix under periosteum
Adds successive layers of circumferential lamellae
Trapped osteoblasts become osteocytes
Deeper lamellae recycled and replaced by osteons
Osteoclasts remove matrix at inner surface to enlarge medullary cavity

43. Appositional bone growth
Increase in bone diameter resulting from appositional growth
Additional circumferential
lamellae are deposited, and
the bone continues to
increase in diameter.
Periosteum

44. Appositional bone growth
Enlargement of the medullary cavity with increased bone diameter resulting from appositional growth
Bone matrix is removed
by osteoclasts
Bone deposited by
superficial osteoblasts
Infant
Child
Young adult
Adult