Homework Skeletal System Flexbook

Introduction Human skeleton is initially cartilages and fibrous membranes Hyaline cartilage is the most abundant cartilage By age 25 the skeleton is completely hardened 206 bones make up the adult skeleton (20% of body mass) 80 bones of the axial skeleton 126 bones of the appendicular skeleton

Bone Structure Bones of the skeletal system vary greatly in size and shape There is similarity in structure, development, and function

Bone Classification Bone Classification: Long Bones Short Bones Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Bone Classification: (b) Long Bones Short Bones Flat Bones Irregular Bones Sesamoid Bones (c) (d) (a) (e)

Bone Classification Bone Classification: Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Bone Classification: Long Bones: have long longitudinal axes and expanded ends Example: forearm, thigh

Bone Classification Bone Classification: Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Bone Classification: Short Bones: are cube-like, with roughly equal lengths and widths. Example: bones of wrists and ankles

Bone Classification Bone Classification: Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Bone Classification: Flat Bones: are plate-like structures with broad surfaces. Example: ribs, scapulae, some bones of the skull

Bone Classification Bone Classification: Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Bone Classification: Irregular Bones: have a variety of shapes and are usually connected to several other bones. Example: vertebrae and many facial bones

Bone Classification Bone Classification: Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Bone Classification: Sesamoid Bones: also called round bones; usually small and nodular and are embedded in tendons adjacent to joints, where the tendons are compressed. Example: patella

Bone Classification Bone’s shape makes possible its function Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Bone’s shape makes possible its function Bony projections called processes provide sites for attachment of ligaments and tendons Grooves and openings provide passageways for blood vessels and nerves

Read and Annotate 7.1-7.3 Bones Graphic Organizer Homework Read and Annotate 7.1-7.3 Bones Graphic Organizer

Parts of a Long Bone Epiphysis End of a long bone which articulates with another bone. Distal Proximal Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Epiphyseal plates Articular cartilage Proximal Spongy bone epiphysis Space containing red marrow Endosteum Compact bone Medullary cavity Diaphysis Shaft of a long bone between the epiphyses Y ellow marrow Periosteum Diaphysis Distal epiphysis Femur

Parts of a Long Bone Articular cartilage Layer of hyaline cartilage covering the outer surface of the articulating portion of the epiphysis. Periosteum Tough, vascular covering of fibrous tissue covering the bone except for the articular cartilage on ends Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Epiphyseal plates Articular cartilage Proximal Spongy bone epiphysis Space containing red marrow Endosteum Compact bone Medullary cavity Y ellow marrow Periosteum Diaphysis Distal epiphysis Femur

Parts of a Long Bone Compact bone Composes wall of diaphysis; continuous extracellular matrix with no gaps Spongy (Cancellous) bone Composes epiphyses Thin layers of compact bone Many branching bony plates called trabeculae Irregular connecting spaces between these plates help reduce bone’s weight Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Epiphyseal plates Articular cartilage Proximal Spongy bone epiphysis Space containing red marrow Endosteum Compact bone Medullary cavity Y ellow marrow Periosteum Diaphysis Distal epiphysis Femur

Parts of a Long Bone Medullary cavity Hollow chamber formed within a semirigid tube by the compact bone in the diaphysis of a long bone that is continuous with the spaces of the spongy bone. Endosteum Thin membrane containing bone-forming cells that lines the medullary cavity Marrow Specialized soft connective tissue fills medullary cavities; red and yellow Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Epiphyseal plates Articular cartilage Proximal Spongy bone epiphysis Space containing red marrow Endosteum Compact bone Medullary cavity Y ellow marrow Periosteum Diaphysis Distal epiphysis Femur

Parts of a Long Bone Epiphyseal Plate cartilaginous layer in the long bone epiphysis that grows. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Epiphyseal plates Articular cartilage Proximal Spongy bone epiphysis Space containing red marrow Endosteum Compact bone Medullary cavity Y ellow marrow Periosteum Diaphysis Distal epiphysis Femur

Fig. 7.4a Endosteum Nerve Blood vessels Compact bone Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Endosteum Nerve Blood vessels Compact bone

Homework Read and annotate Section 7.4-7.5

7.4: Bone Function Bones shape, support, and protect body structures

Support, Protection, and Movement Support, Movement & Protection Gives shape to head, etc. Supports body’s weight Protects lungs, etc. Bones and muscles interact When limbs or body parts move

Blood Cell Formation Blood Cell Formation Also known as hematopoiesis Occurs in the red bone marrow Inside the medullary cavity of a long bone In adults, red marrow is limited to the axial skeleton, pectoral girdle, pelvic girdle, and proximal heads of the humerus and the femur. In a child, the medullary cavity of nearly every bone is filled with red bone marrow

Yellow Bone Marrow In young to middle-aged adults, the shafts of the long bones are filled with fatty yellow bone marrow. Yellow marrow no longer produces blood, although in the event of severe or chronic anemia, it can transform back into red marrow

Inorganic Salt Storage Calcium Phosphate Magnesium Sodium Potassium

Microscopic Structure Mature bone cells are called osteocytes; transport nutrients and wastes Osteocytes in tiny bony chambers called lacunae Lacunae form concentric circles around central canals (Haversian canals) The extracellular matrix of bone is largely collagen and inorganic salts Collagen gives bone resilience Inorganic salts make bone hard

a: © Ed Reschke; b,c: Courtesy of John W. Hole, Jr. Spongy Bone Spongy bone is aka cancellous bone Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Composed of osteocytes and extracellular matrix Spongy bone Compact bone (a) Remnant of epiphyseal plate Spongy bone Compact bone (b) No central canals Cells lie in trabeculae (c) Spongy bone Compact bone a: © Ed Reschke; b,c: Courtesy of John W. Hole, Jr.

Compact Bone Osteon Haversian System Unit of bone Osteon Compact bone Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Osteon Compact bone Central canal containing blood vessels and nerves Endosteum Spongy bone Periosteum Nerve Blood vessels Pores Central canal Perforating canal Compact bone Nerve Blood vessels Nerve Trabeculae Bone matrix Canaliculus Osteocyte Lacuna (space)

Compact Bone Osteon Haversian System Central canal Opening in the center of an osteon Carries blood vessels and nerves Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Osteon Compact bone Central canal containing blood vessels and nerves Endosteum Spongy bone Periosteum Nerve Blood vessels Pores Central canal Perforating canal Compact bone Nerve Blood vessels Nerve Trabeculae Bone matrix Canaliculus Osteocyte Lacuna (space)

Compact Bone Each of the concentric matrix “tubes” that surrounds a Haversian canal is known as a lamella. All the collagen fibers in a particular lamella run in a single direction, while collagen fibers in adjacent lamellae will run in the opposite direction. This allows bone to better withstand twisting forces.

Compact Bone Osteon Haversian System Central canal Perforating canal Perpendicular to central canal Carries larger blood vessels and nerves Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Osteon Compact bone Central canal containing blood vessels and nerves Endosteum Spongy bone Periosteum Nerve Blood vessels Pores Central canal Perforating canal Compact bone Nerve Blood vessels Nerve Trabeculae Bone matrix Canaliculus Osteocyte Lacuna (space)

Running perpendicular to the haversian canals are Volkmann’s canals Running perpendicular to the haversian canals are Volkmann’s canals. They connect the blood and nerve supply in the periosteum to those in the haversian canals and the medullary cavity.

Compact Bone Osteon Haversian System Central canal Perforating canal Osteocytes Mature bone cells Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Osteon Compact bone Central canal containing blood vessels and nerves Endosteum Spongy bone Periosteum Nerve Blood vessels Pores Central canal Perforating canal Compact bone Nerve Blood vessels Nerve Trabeculae Bone matrix Canaliculus Osteocyte Lacuna (space)

Compact Bone Osteon Haversian System Central canal Perforating canal Osteocytes Lamellae Rings around the central canal Sites of lacunae Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Osteon Compact bone Central canal containing blood vessels and nerves Endosteum Spongy bone Periosteum Nerve Blood vessels Pores Central canal Perforating canal Compact bone Nerve Blood vessels Nerve Trabeculae Bone matrix Canaliculus Osteocyte Lacuna (space)

Compact Bone Osteon Haversian System Central canal Perforating canal Osteocytes Lamellae Lacunae Tiny, bony chambers housing osteocytes Form concentric circles around central Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Osteon Compact bone Central canal containing blood vessels and nerves Endosteum Spongy bone Periosteum Nerve Blood vessels Pores Central canal Perforating canal Compact bone Nerve Blood vessels Nerve Trabeculae Bone matrix Canaliculus Osteocyte Lacuna (space)

Compact Bone Osteon Haversian System Central canal Perforating canal Osteocytes Lamellae Lacunae Bone matrix Collagen Inorganic salts Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Osteon Compact bone Central canal containing blood vessels and nerves Endosteum Spongy bone Periosteum Nerve Blood vessels Pores Central canal Perforating canal Compact bone Nerve Blood vessels Nerve Trabeculae Bone matrix Canaliculus Osteocyte Lacuna (space)

Compact Bone Osteon Haversian System Central canal Perforating canal Osteocytes Lamellae Lacunae Bone matrix Canaliculi Cellular processes used to transport nutrients and wastes Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Osteon Compact bone Central canal containing blood vessels and nerves Endosteum Spongy bone Periosteum Nerve Blood vessels Pores Central canal Perforating canal Compact bone Nerve Blood vessels Nerve Trabeculae Bone matrix Canaliculus Osteocyte Lacuna (space)

Microscopic Anatomy of Bone Figure 5.3 Slide 5.10b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Compact Bone

Long Bone Cross-section Each yellow circle represents an osteon. The blue represents additional matrix filling in the space between osteons. The black in the middle is the marrow cavity. Imagine these osteons as weight-bearing pillars that are arranged parallel to one another along the long axis of a compact bone.

Homework Structure of a Long Bone – Gross Anatomy