Structure of Bone Gross Anatomy of a Long Bone Microscopic Anatomy Bone Markings Pages 137-140

Anatomy of a Long Bone Three major sections: Diaphysis Proximal Epiphysis Distal Epiphysis

Anatomy of a Long Bone Diaphysis (a.k.a. shaft) Periosteum most of bone’s length Composed of compact bone Periosteum Covers the outside of the diaphysis Fibrous connective tissue membrane Provides insertion site for tendons & ligaments Perforating (Sharpey’s) fibers secure periosteum to underlying bone These are made up of thick bundles of collagen © 2015 Pearson Education, Inc.

Figure 5.3a The structure of a long bone (humerus of arm). Articular cartilage Proximal epiphysis Spongy bone Epiphyseal line Periosteum Compact bone Medullary cavity (lined by endosteum) Diaphysis Distal epiphysis (a)

Figure 5.3c The structure of a long bone (humerus of arm). Endosteum Yellow bone marrow Compact bone Periosteum Perforating (Sharpey’s) fibers Nutrient arteries (c)

Anatomy of a Long Bone Epiphysis Articular cartilage Ends of the bone Composed mostly of spongy bone enclosed by thin layer of compact bone Line vs. plate depends on age Articular cartilage Covers the external surface of the epiphyses Made of hyaline cartilage Decreases friction at joint surfaces © 2015 Pearson Education, Inc.

Figure 5.3b The structure of a long bone (humerus of arm). Articular cartilage Compact bone Spongy bone (b)

Anatomy of a Long Bone Epiphyseal plate Epiphyseal line Flat plate of hyaline cartilage seen in young, growing bone Causes lengthwise growth of a long bone Think of a divergent plate boundary Epiphyseal line Remnant of the epiphyseal plate Seen in adult bones © 2015 Pearson Education, Inc.

Figure 5.3a The structure of a long bone (humerus of arm). Articular cartilage Proximal epiphysis Spongy bone Epiphyseal line Periosteum Compact bone Medullary cavity (lined by endosteum) Diaphysis Distal epiphysis (a)

Anatomy of a Long Bone Marrow (medullary) cavity Cavity inside the shaft Contains: yellow marrow (mostly fat) in adults red marrow for blood cell formation in infants Lined by the endosteum (thin connective tissue) In adults, red marrow is situated in cavities of spongy bone In flat bones In epiphyses of some long bones © 2015 Pearson Education, Inc.

Figure 5.3a The structure of a long bone (humerus of arm). Articular cartilage Proximal epiphysis Spongy bone Epiphyseal line Periosteum Compact bone Medullary cavity (lined by endosteum) Diaphysis Distal epiphysis (a)

Bone Markings Surface features of bones Categories of bone markings Attachments sites for muscles, tendons, and ligaments Passages for nerves and blood vessels Categories of bone markings Projections or processes Depressions or cavities © 2015 Pearson Education, Inc.

Table 5.1 Bone Markings (1 of 3).

Table 5.1 Bone Markings (2 of 3).

Table 5.1 Bone Markings (3 of 3).

Microscopic Anatomy of Compact Bone Osteocytes (mature bone cells) situated within cavities known as lacunae Lacunae arranged in concentric rings called lamellae Lamellae rings situated around the central (Haversian) canal © 2015 Pearson Education, Inc.

Figure 5.4b Microscopic structure of compact bone. Lamella Osteocyte Canaliculus Lacuna Central (Haversian) canal (b)

Microscopic Anatomy of Bone Central (Haversian) canal Opening in the center of an osteon Runs lengthwise through bone Carries blood vessels and nerves Osteon (Haversian system) A unit of bone containing central canal and matrix rings © 2015 Pearson Education, Inc.

Figure 5.4a Microscopic structure of compact bone. Spongy bone Perforating (Volkmann’s) canal Osteon (Haversian system) Blood vessel continues into medullary cavity containing marrow Lamellae Blood vessel Compact bone Central (Haversian) canal Perforating (Sharpey’s) fibers Periosteum Periosteal blood vessel (a)

Figure 5.4c Microscopic structure of compact bone. Osteon Interstitial lamellae Lacuna Central (Haversian) canal (c)

Haversian System summary From smallest to largest structure: 1. Osteocyte 2. Lacunae 3. Lamellae 4. Central (Haversian) canal 5. Osteon (Haversian system)

Microscopic Anatomy of Bone Canaliculi Tiny canals that radiate from the central (Haversian) canal to the lacunae a transport system that connects all bone cells to a nutrient supply Perforating (Volkmann’s) canal Canal perpendicular to the central canal Carries blood vessels and nerves © 2015 Pearson Education, Inc.

Figure 5.4b Microscopic structure of compact bone. Lamella Osteocyte Canaliculus Lacuna Central (Haversian) canal (b)

Chemical Composition of Bone Organic parts of the matrix make bone flexible Cells, fibers (collagen), ground substance salts of calcium phosphate deposited in the extracellular matrix make bone hard © 2015 Pearson Education, Inc.