Chapter 6 Bones and Skeletal Tissues Part B
Chapter 6 Bones and Skeletal Tissues Part B Bone Structure
Bones • Bones are organs! – Contains various types of tissues • Osseous tissue (dominates) • Nervous tissue • Cartilage • Fibrous connective tissue (lining cavities) • Muscle and epithelial tissues in blood vessels
Bones • We will look at bone structure on three levels • Gross • Microscopic • Chemical
Bone Structure Gross Anatomy Bone Markings, Bone Textures, Bone Structures
Bone Markings • Surface features of bones – Sites for attachments for muscles, tendons and ligaments – Joint surfaces – Passages for nerves and blood vessels
Bone Markings • Categories of bone markings – Projections • Bulges that grow outward from the bone surface – Depressions and openings • Indentations, holes, and cavities
Projections That Are Sites of Muscle and Ligament Attachment • Tuberosity – rounded projection • Crest – narrow, prominent ridge of bone • Trochanter – large, blunt, irregular surface • Line – narrow ridge of bone • Tubercle – small rounded projection • Epicondyle – raised area above a condyle • Spine – sharp, slender projection • Process – any bony prominence
Projections That help to Form Joints • Head – bony expansion carried on a narrow neck • Facet – smooth, nearly flat articular surface • Condyle – rounded articular projection • Ramus – armlike bar of bone
Depressions and Openings Allowing Blood Vessels & Nerves to Pass • • • Meatus – canal-like passageway Sinus – cavity within a bone Fossa – shallow, basinlike depression Groove – furrow Fissure – narrow, slitlike opening Foramen – round or oval opening through a bone
Bone Textures • Compact bone – dense outer layer – Looks solid to the eye • Spongy bone – honeycomb or spongy appearance – Has small needle-like or flat pieces called trabeculae • filled with red or yellow bone marrow
Structure of Long Bone • General structure of Long Bones –Diaphysis –Epiphyses –Membranes
Structure of Long Bone • Diaphysis – Shaft constructed of a thick collar of compact bone that surrounds the medullary cavity
Structure of Long Bone • Medullary Cavity – Cavity of the shaft – Contains yellow marrow (mostly fat) in adults – Contains red marrow (for blood cell formation) in infants
Structure of Long Bone • Epiphyses – Expanded ends of long bones – Exterior is compact bone, interior is spongy bone – Joint surface is covered with articular cartilage – Epiphyseal line separates the diaphysis from the epiphyses
Structure of Long Bone • Articular cartilage – Covers the external surface of the epiphyses – Made of hyaline cartilage – Decreases friction at joint surfaces
Structure of Long Bone • Epiphyseal Line – Remnant of epiphyseal plate • Disc of hyaline cartilage that grows during childhood to lengthen the bone
Structure of Long Bone • Membranes of long bones – Periosteum – Endosteum
Structure of Long Bone • Periosteum – Outside covering of the bone • Except joint surfaces – Glistening white, doublelayered membrane
Structure of Long Bone • Periosteum – Outer Fibrous layer is dense connective tissue – Inner osteogenic layer (next to bone surface) is mostly osteoblasts (bone germinators) and osteoclasts (bone breakers)
Structure of Long Bone • Periosteum – Richly supplied with nerve fibers, lymphatic vessels, blood vessels which enter the diaphysis by a nutrient foramen (opening)
Structure of Long Bone • Sharpey’s fibers – Secures periosteum to underlying bone – Made of collagen fibers – Extends into bone matrix
Structure of Long Bone • Arteries – Supplies bone cells with nutrients
Structure of Long Bone • Endosteum – Delicate connective tissue – Contains osteoblasts & osteoclasts
Structure of Long Bone • Endosteum – Covers internal surfaces of bone • Medullary cavity • Trabeculae (spongy) • Canals through compact bone
Structure of Long Bone Figure 6. 3
Structure of Short, Irregular, and Flat Bones
Structure of Short, Irregular, and Flat Bones • Thin plates of periosteum-covered compact bone on the outside with endosteum-covered diploë on the inside • Spongy bone in flat bone is called diploë
Structure of Short, Irregular, and Flat Bones • Have no diaphysis or epiphyses • Contain bone marrow between the trabeculae
Red Bone Marrow Hematopoietic Tissue
Location of Hematopoietic Tissue (Red Marrow) • In infants – Found in the medullary cavity and all areas of spongy bone
Location of Hematopoietic Tissue (Red Marrow) • In adults – Found in the diploë of flat bones, and the head of the femur and humerus – Remember, the diploë is the spongy bone of flat bones
Yellow Bone Marrow • Yellow marrow is found in the medullary cavities • Yellow marrow can revert back to red marrow if a person becomes very anemic and needs enhanced red blood cell production
Bone Structure Microscopic Anatomy
Microscopic Structure of Compact Bone • Haversian system, or osteon – the structural unit of compact bone
Microscopic Structure of Compact Bone • Each osteon is a group of hollow tubes of bone matrix, called lamella, each one placed outside the next
Microscopic Structure of Compact Bone • Each osteon is oriented parallel to the long axis of the bone
Microscopic Structure of Compact Bone • Osteons are like tiny weightbearing pillars
Microscopic Structure of Compact Bone • Lamella – The weightbearing, column—like matrix tubes composed mainly of collagen
Microscopic Structure of Compact Bone • Haversian, or central canal – channel in the center of the osteon – containing blood vessels and nerves
• Volkmann’s canals – channels lying at right angles to the central canal, connecting blood and nerve supply of the periosteum to that of the central canal Microscopic Structure of Compact Bone
Microscopic Structure of Bone: Compact Bone • Osteocytes – Mature bone cells – Spider-shaped • Lacunae – small cavities in bone that contain osteocytes
Microscopic Structure of Bone: Compact Bone • Canaliculi – Tiny, hair-like canals – connect lacunae to each other and the central canal – Forms a transport system
Microscopic Structure of Compact Bone Figure 6. 6 a, b
Chemical Composition of Bone Organic components and inorganic components
Chemical Composition of Bone: Organic • Osteoblasts – bone-forming cells • Osteocytes – mature bone cells • Osteoclasts – large cells that resorb or break down bone matrix • Osteoid – unmineralized bone matrix composed of proteoglycans, glycoproteins, and collagen
Chemical Composition of Bone: Inorganic • Hydroxyapatites, or mineral salts – Sixty-five percent of bone by mass – Mainly calcium phosphates – Responsible for bone hardness and its resistance to compression
Chemical Composition of Bone: Inorganic • Hydroxyapatites, or mineral salts – Bone is half as strong as steel in resisting compression and fully as strong as steel in resisting tension – Bones last long after death, sometimes many centuries
Paris catacombs
Study Guide Pages 123 to top of 126 Quiz Next Time!
- Slides: 49