Lesson 2: Types of Bones Flashcards
➢ is a rigid connective tissue
➢ the hardest tissue in the body
Bone
Bone Tissue is also called as …
Osseous Tissue
hardness of bones depends on…
▪ crystallized inorganic mineral salts
▪ organic collagen fibers
➢ initiated by osteoblasts (bone building cells)
➢ simply occurred when enough mineral salts were present to form crystals
➢ occurs only in the presence of collagen
Calcification
Types of Bone According to Distribution of Spaces
Compact Bone
Spongy Bone
➢ Dense, strong, with closely spaced lamellae (concentric layer of mineral deposits)
➢ Forms the external layer of all bones of the body and bulk of the diaphysis of long
bones
➢ Provides protection and support
➢ Helps the long bones resist the stress of weight placed on them
➢ Has many osteons/ Haversian system
Compact Bone
the basic functional unit of the compact bone
Osteons or Haversian System
➢ Porous, light and weaker
➢ With widely spaced lamellae
➢ Does not contain true osteons (incomplete Haversian system)
➢ Consists of lamellae arranged in an irregular lattice work of thin plates of bone
Cancellous/Spongy Bone
lamellae arranged in an irregular lattice work of thin plates of bone
Trabeculae
Types of Bone According to Shape
Long Bones
Short Bones
Flat Bones
Irregular Bones
Sesamoid Bones
Accessory Bones
➢ Classified as such when its length is greater than its width
➢ Located in the extremities
➢ E.g. femur (longest bone), humerus, radius
➢ Acts as levers that are pulled out by contracting muscles
Long Bones
➢ Have equal length, width and thickness but irregular in shape
➢ E.g. carpal, tarsal
Short Bones
➢ thin and flat
➢ has two thin layers of compact bone with spongy bone tissue between them
➢ RBC are manufactured
➢ protection of body organs
➢ translucent and thin
➢ e.g. ribs, scapulae, cranial bones, sternum
Flat Bones
➢ bones that do not fit in any category
➢ comes in different shapes
➢ e.g. facial bones, hip bone, mandible, vertebra
Irregular Bones
➢ resemble sesame seeds -small and round
➢ found adjacent to joints
➢ e.g. patella (knee cap)
➢ eliminates friction
➢ provides slight support and protection
Sesamoid Bones
➢ most commonly found in the feet
➢ usually occur when developing bones do not fuse completely
➢ may look like extra bores/broken bones in X-rays
➢ add some slight support and protection to the area of the skeleton where they are
found
Accessory Bones or Supernumerary Bones
Gross Anatomy of Long Bones
Diaphysis
Epiphyses
Metaphysis
Articular Cartilage
Endosteum
Periosteum
Medullary Cavity/ Marrow Cavity
➢ shaft or long main portion of the bone
➢ hollow cylinder which contains medullary yellow bone marrow in adult
➢ primarily a storage area for adipose tissue
Diaphysis
➢ distal and proximal extremities or ends of the bone
➢ composed of spongy bone covered by thin layer of compact zone
➢ contains red marrow (where some RBC’s are manufactured during childhood and
adolescence)
➢ erythropoietic activity in the adult mainly occurs in the flat bones and vertebrae
- wider than the shaft
Epiphyses (Proximal & Distal)
➢ region in a mature bone where the diaphysis joins the epiphysis
➢ made up of epiphyseal plate and the adjacent bony trabeculae
Metaphysis
➢ thin layer of hyaline cartilage covering the epiphysis; where the bone forms an
articulation with another bone
➢ provides a smooth, slippery surface that decreases friction at joint movement,
absorbs shock at freely movable joints
Articular Cartilage
➢ membrane that lines the internal cavities of bones
➢ covers the trabeculae of spongy bone tissue
➢ contains osteoprogenitor cells and osteoclasts
Endosteum
➢ strong fibrous membrane that covers and protects the diaphysis
➢ has the potential to form bone during growth periods and in fracture healing
➢ contains nerves, lymphatic vessels, blood vessels and bone cells necessary for
growth, repair and nutrition
➢ gives the distinctive pink color of living bone
Periosteum
layer of periosteum
composed of dense, irregular connective tissue containing blood vessels lymphatic vessels and nerves that pass into the bone
Outer Fibrous Layer
layer of periosteum
contains elastic fiber, blood vessels, and bone cells
Inner Osteogenic Layer
central part of the structure
space within the diaphysis that contains the fatty yellow bone marrow in adults
Medullary Cavity or Marrow Cavity
Two Kinds of Bone Marrow
Red Marrow & Yellow Marrow
➢ found at the epiphyses of long bones and at the center of other bones
➢ found in all cancellous bones of children
➢ forms RBCs, platelets and WBCs
➢ in adults, located in the cancellous bone of me vertebrae, hips, sternum, ribs,
cranial bones, and proximal ends of the femur and humerus
Red Marrow
➢ found chiefly in the medullary cavity of a long bone
➢ composed of adipose tissue
➢ fat storage
Yellow Marrow
Microscopic Anatomy of Bones
Osteon
Central/Haversian Canals
Lamellae
Lacunae
Canaliculi
Volkmann’s Canals/ Perforating Canals
➢ Haversian system
➢ basic functional unit of compact bone
➢ cylinders of calcified bone
➢ only seen in adult compact tissue
Osteon
➢ found in the center of the osteon
➢ enclosed by concentric lamellae
➢ usually run longitudinally thru the bone
➢ contains nerves, lymphatic vessels and blood vessels supplying the bone
Central Canal or Haversian Canal
➢ ring of hard, calcified matrix
➢ concentric cylindrical layer of calcified bone
➢ makes up cylinders of Osteons
Lamellae
➢ “little lakes”
➢ small spaces between the lamellae
➢ tiny cavities arranged in concentric circles where osteocytes are found
Lacunae
➢ tiny canals radiating from the lacunae to all directions
➢ filled with ECF and slender, fingerlike processes of osteocytes
➢ connect lacunae with one another and eventually with the central canals
➢ provides many routes for nutrients and 02 to each the osteocytes and wastes to
diffuse away
Canaliculi
➢ serves as communication pathway from the outside of the bone to is inferior
➢ where blood vessels, lymphatic vessels, and nerves from the periosteum penetrate
the compact bone
Volkmann’s Canals or Perforating Canals
Types of Bone Cells
Osteogenic/Osteoprogenitor Cells
Osteoblasts
Osteocytes
Osteoclasts
Bone Lining Cells
➢ unspecialized cells derived from mesenchyme (tissue from which all
connective tissues are derived)
➢ can undergo mitosis and develop into osteoblasts during time: of stress and
healing
➢ found in the inner portion of periosteum, in the endosteum and in the canals
of the bone that contain blood vessels
Osteogenic/
➢ unspecialized cells derived from mesenchyme (tissue from which all
connective tissues are derived)
➢ can undergo mitosis and develop into osteoblasts during time: of stress and
healing
➢ found in the inner portion of periosteum, in the endosteum and in the canals
of the bone that contain blood vessels
Osteogenic/Osteoprogenitor Cells
➢ “blast” – “sprouts/buds”
➢ Immature bone cells
➢ Bone forming, repairing, bone building cells
➢ Secretes matrix
➢ Cells responsible in bone formation
Osteoblasts
➢ “cytes” – maintain the tissue
➢ Mature bone cells derived from osteoblasts that had become entrapped in
matrix
➢ Principal cells of fully developed bone tissue
➢ Have no mitotic potential
➢ No longer secrete matrix material
found on the surfaces of bone but as they surround themselves with matrix materials they become trapped on their own secretion and become osteocytes
Function: maintain daily cellular activities of bone tissue, such as the exchange
of nutrients and wastes with the blood
Osteocytes
➢ “clasts” – to break
➢ Engulf necrotic cells
➢ Settle on the surfaces of bone
➢ Bone destroying cells- phagocytic function
➢ Prevents bone from breaking too thick
Osteoclasts
➢ Derived from the osteoblasts that cease their physiologic activity and flatten
out on the bone surface
➢ Found on the surface of most bones in the adult skeleton
Bone Lining Cells
Two Major Types of Surface Markings
Depression and Openings
Processes
➢ indentations in the grooves of bone
➢ allow the passage of soft tissues
➢ form joints
Depression and Openings / Cavities
➢ any prominent projections or outgrowths that form joints
➢ serve as attachments for ligaments and tendons
Processes
Six Types of Depression and Openings
Fissure
Foramen
Meatus
Paranasal Sinuses
Grooves / Sulcus
Fossa
➢ an opening thru which blood vessels, nerves or ligaments pass
Foramen
➢ e.g. Foramen Magnum, Obturator foramen
➢ a narrow cleft-like opening between adjacent parts of bones through which blood
vessels and nerves pass
Fissure
➢ e.g. Superior Orbital Fissure
➢ a tube like passageway running within a bone
Meatus
➢ e.g. External auditory meatus (ear canal)
➢ an air-filled cavity within a bone connected to the nasal cavity
➢ purpose: give resonance to the voice
Paranasal Sinuses
➢ e.g. Frontal sinus
➢ Furrow/depression that accommodates a soft structure such as blood vessels,
nerve or tendon
Grooves / Sulcus
➢ e.g. depression on the anterior surface of the humerus
➢ a depression in or on a bone
Fossa
➢ e.g. olecranon fossa; acetabulum
Three Types of Processes
Condyle
Head
Facet
Seven Types of Processes to which Tendons, Ligaments, and other Connective Tissue Attached
Tubercle
Tuberosity
Trochanter
Crest
Line
Spinous Process
Epicondyle
➢ small rounded process/ projection
Tubercle
➢ e.g. Upper end of the humerus, articular tubercle
➢ a large, usually rounded projection
Tuberosity
➢ e.g. tibial and radial tuberosity, sacral tuberosity
➢ a large, blunt projection found only on the femur
Trochanter
➢ e.g. greater and lesser trochanter of the femur
➢ a prominent border or ridge
Crest
➢ e.g. iliac crest
➢ a less prominent ridge than a crest
Line
➢ e.g. linea aspera -posterior femur
➢ sharp, slender process
Spinous Process
➢ e.g. spines of the vertebrae
➢ a prominence above a condyle
Epicondyle
➢ e.g. lateral and medial Epicondyle of humerus and femur
- a smooth, large rounded, articular projection
Condyle
- a smooth, large rounded, articular projection
Condyle
- a rounded articular projection supported on the constricted portion (neck) of a bone
Head
- a smooth, flat surface
Facet
