A&P Ch. 6 Bones
Structure of typical long bone
All of these have a shaft (diaphysis), bone ends (epiphyses), and membranes
Process (bone marking)
Any bony prominence
Spongy bone
Appears poorly organized but is organized along lines of stress to help bone resist stress.
Ramus (bone markings: projections that help to form joints)
Armlike bar of bone
Epiphyseal line
Between diaphysis and epiphysis (remnant of childhood epiphyseal plate where bone growth occurs)
Osteoblasts
Bone forming cells that secrete unmineralized bone matrix called osteoid
Appendicular skeleton
Bones of upper and lower limbs. Girdles attaching limbs to axial skeleton
Sesamoid bones
Bones that form within tendons
Head (bone markings: projections that help to form joints)
Bony expansion carried on a narrow neck
Depression (bone marking)
Bowl or groove like cut out that can serve as passageways for vessels and nerves, or plays a role in joints
Meatus (bone markings)
Canal like passageway
Perforating (Volkmann's) canal
Canals lined with endosteum that occur at right angles to central canal (connect blood vessels and nerves of periosteum, medullary cavity, and central canal).
Appositional growth
Cartilage-forming cells in perichondrium secrete matrix against external face of existing cartilage (new matrix laid down on surface of cartilage).
Sinus (bone markings)
Cavity within a bone, filled with air and lined with mucous membrane
Interstitial growth
Chondrocytes within lacunae divide and secrete new matrix, expanding cartilage from within (new matrix made within cartilage)
Structure of short, irregular, and flat bones
Consist of thin plates of spongy bone covered by compact bone. Compact bone sandwiched between connective tissue membranes. Bone marrow is scattered throughout spongy bone; no defined marrow cavity. Hyaline cartilage covers area of bone that's part of a movable joint.
Endosteum
Covers inside of compact bone
Periosteum
Covers outside of compact bone
Short bones
Cube-shaped bones in wrist and ankle. Sesamoid bones form within tendons (ex: patella).
Compact bone (lamellar bone)
Dense outer layer on every bone that appears smooth and solid. Consists of: Osteon (Haversian system), Canals & canaliculi, and Interstitial & circumferential lamellae
Resorption bays
Depressions that active osteoclasts are located in
Osteoclasts
Derived from same hematopoietic stem cells that become macrophages. Giant multinucleate cells function in bone resorption (breakdown of bone). When active cells are located in depressions called resorption bays. Cells have ruffled borders that serve to increase surface area for enzyme degradation of bone.
Epiphyses
Ends of long bones that consist of compact bone externally and spongy bone internally
Elastic cartilage
External ear and epiglottis
Bone lining cells
Flat cells on bone surfaces believed to also help maintain matrix (along with osteocytes).
Groove (bone markings: for passage of blood vessels and nerves)
Furrow
Canaliculi
Hairlike canals that connect lacunae to each other and to central canal
Opening (bone marking)
Hole or canal in bone that serves as passageways for blood vessels and nerves
Medullary cavities
In newborns, these and all spongy bone contain red marrow
Notch (bone markings: projections that help to form joints)
Indentation at end of a structure
Osteogenic layer of periosteum membrane
Inner layer abutting bone and contains primitive osteogenic stem cells that gives rise to most bone cells
Hyaline: articular
Joints
Circumferential lamellae
Just deep to periosteum, but superficial to endosteum, these layers extend around entire surface of diaphysis. Help long bone to resist twisting.
Interstitial lamellae
Lamellae that aren't part of osteon. Some fill gaps between forming osteons, others are remnants of osteons cut by bone remodeling
Tuberosity (bone marking)
Large rounded projection, may be roughened
Hyaline: respiratory
Larynx
Perichondrium
Layer of dense connective tissue surrounding cartilage like a girdle. Helps cartilage resist outward expansion. Contains blood vessels for nutrient delivery to cartilage.
Trabeculae
Like cables on a bridge confer strength to bone. No osteons are present, but these contain irregularly arranged lamellae and osteocytes interconnected by canaliculi.
Periosteal cells
Lining cells on external bone surface
Endosteal cells
Lining cells on internal bone surface
Axial skeleton
Long axis of body. Skull, vertebral column, rib cage
Skeletal cartilage
Made of resilient, molded cartilage tissue that consists primarily of water (contains no blood vessels or nerves)
Spongy bone (diploe)
Made up of a honeycomb of small, needle-like or flat pieces of bone called trabeculae
Osteoid
Makes up 1/3 of organic bone matrix, is secreted by osteoblasts
Hydroxyapatites (Mineral salts. Inorganic components)
Makeup 65% of bone by mass. Consist mainly of tiny calcium phosphate crystals in and around collagen fibers. Responsible for hardness and resistance to compression. Bone is 1/2 as strong as steel in resisting compression and as strong as steel in resisting tension.
Osteocytes
Mature bone cells in lacunae that no longer divide. Maintain bone matrix and act as stress or strain sensors.
Fibrocartilage
Menisci of knee. Vertebral discs.
Osteogenic cells (osteoprogenitor cells)
Mitotically active stem cells in periosteum and endosteum. When stimulated, differentiate into osteoblasts or bone lining cells. Some remain osteogenic stem cells.
Line (bone marking)
Narrow ridge of bone, less prominent than a crest
Crest (bone marking)
Narrow ridge of bone, usually prominent
Fissure (bone markings: projections that help to form joints)
Narrow, slitlike opening
Hyaline: nasal cartilage
Nose tip
Hematopoiesis
Occurs in red marrow cavities of certain bones
Organic components
Osteogenic cells, osteoblasts, osteocytes, bone-lining cells, osteoclasts, and osteoid
Fibrous layer of periosteum membrane
Outer layer consisting of dense irregular connective tissue consisting of Sharpey's fibers that secure to bone matrix
Projection (bone marking)
Outward bulge of bone (may be due to increased stress from muscle pull or is a modification for joints)
Why are bones organs?
They contain different types of tissues
Fibrocartilage
Thick collagen fibers: has great tensile strength.
Red marrow location
Trabecular cavities of spongy bone and diploe of flat bones, such as sternum
Diaphysis
Tubular shaft that forms long axis of bone (consists of compact bone surrounding central medullary cavity that's filled with yellow marrow in adults)
Hyaline, elastic, fibrocartilage
Types of cartilage
Osteoid
Unmineralized bone matrix. Made of collagen and calcium-binding proteins. Collagen makes up 90% of bone protein.
Irregular bone examples
Vertebrae and hip bones
Trochanter (bone marking)
Very large, blunt, irregularly shaped process (only examples on femur)
Chondrocytes
What cartilage is made out of. Cells encased in small cavities (lacunae) within jelly-like extracellular matrix.
When do canaliculi form?
When matrix hardens and cells are trapped
Periosteum membrane
White, double-layered membrane that covers external surfaces except joints (1. Fibrous layer 2. Osteogenic layer 3. contains nerve fibers & blood vessels that continue to shaft through nutrient foramen openings 4. anchoring points for tendons and ligaments)
Hyaline cartilage
Provides support, flexibility, and resilience. Contains collagen fibers only.
Epicondyle (bone marking)
Raised area on or above a condyle
Hematopoietic tissue in bones
Red marrow
What are open spaces between trabeculae filled with?
Red or yellow bone marrow
Sacrificial bonds
Resilience of bone is due to this in or between collagen molecules that stretch and break to dissipate energy and prevent fractures
Hyaline: costal
Ribs
Foramen (bone markings: projections that help to form joints)
Round or oval opening through a bone
Condyle (bone markings: projections that help to form joints)
Rounded articular projection
Central (Haversian) canal
Runs through core of osteon (contains blood vessels and nerve fibers)
Osteocalcin
Secreted by bones helps to regulate insulin secretion, glucose levels, and metabolism
Lamellae
Several rings of bone matrix. Contain collagen fibers that run in different directions in adjacent rings. Withstand stress and resist twisting. Bone salts are found between collagen fibers.
Fossa (bone markings)
Shallow, basinlike depression in a bone, often serving as an articular surface
Spine (bone marking)
Sharp, slender, often pointed projection
Elastic cartilage
Similar to hylaine but contains elastic fibers.
Bone markings
Sites of muscle, ligament, and tendon attachment on external surfaces. Areas involved in joint formation or conduits for blood vessels and nerves.
Lacunae
Small cavities that contain osteocytes
Tubercle (bone marking)
Small rounded projection or process
Facet (bone markings: projections that help to form joints)
Smooth, nearly flat articular surface
Flat bone examples
Sternum, scapulae, ribs, most skull bones
Osteon (Haversian system)
Structural unit of compact bone. Consists of elongated cylinder that runs parallel to long axis of bone. Consists of several rings of bone matrix called lamellae.
2 ways cartilage grows
1. Appositional 2. Interstitial
2 skeletal groups
1. Axial 2. Appendicular
Endosteum membrane
1. Delicate connective tissue membrane covering internal bone surface 2. Covers trabeculae of spongy bone 3. Lines canals that pass through compact bone 4. Contains osteogenic cells that can differentiate into other bone cells
3 levels of structure
1. Gross 2. Microscopic 3. Chemical
4 bone shapes
1. Long bones 2. Short bones 3. Flat bones 4. Irregular bones
5 cells of bone tissue
1. Osteogenic 2. Osteoblasts 3. Osteocytes 4. Bone-lining cells 5. Osteoclasts
2 types of membranes
1. Periosteum 2. Endosteum
3 types of bone markings
1. Projection 2. Depression 3. Opening
7 bone functions
1. Support (for body and soft organs) 2. Protection (brain, spinal cord, organs) 3. Movement (levers for muscle action) 4. Mineral and growth factor storage (calcium & phosphorus, growth factors reservoir) 5. Blood cell formation (hematopoiesis occurs in red marrow cavities of certain bones) 6. Triglyceride (fat) storage (fat used for energy is stored in bone cavities) 7. Hormone production (osteocalcin secreted by bones helps regulate insulin secretion, glucose levels, and metabolism)