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)