The Skeletal System Parts of the skeletal system

The Skeletal System

Parts of the skeletal system

Two subdivisions of the skeleton Axial skeleton Appendicular skeleton

Two subdivisions of the skeleton

Adult skeleton approximately 206 bones Axial: 80 bones Appendicular: 126 bones

Two basic types of bone tissue Compact bone Homogeneous Spongy bone Many open spaces

Classification of Bones based on Shape

Classification of Bones based on Shape

Classification of Bones based on Shape

Classification of Bones based on Shape

Classification of Bones based on Shape

Anatomy of a Long Bone Epiphysis

Anatomy of a Long Bone

Anatomy of a Long Bone Diaphysis

Anatomy of a Long Bone Periosteum Sharpey’s fibers Arteries

Anatomy of a Long Bone

Anatomy of a Long Bone

Anatomy of a Long Bone Articular cartilage Covers surface of the epiphyses

Anatomy of a Long Bone Epiphyseal plate Epiphyseal line

Anatomy of a Long Bone

Anatomy of a Long Bone Medullary cavity Cavity inside of the shaft

Bone Markings Are bones smooth surfaces? Femur

Are bones smooth surfaces? Tibia

Bone Markings Are bones smooth surfaces? Mandible

Bone Markings Are bones smooth surfaces? Optical canal

Compact vs. Spongy bone

Microscopic Anatomy of Compact Bone Osteocytes: mature bone cells Lacunae:

Microscopic Anatomy of Compact Bone Lamella:

Microscopic Anatomy of Compact Bone Central (Haverersian) Canals:

Microscopic Anatomy of Compact Bone Osteon (Haversian System):

Microscopic Anatomy of Compact Bone

Microscopic Anatomy of Compact Bone Canaliculi: Hint: which way do central canals run?

Microscopic Anatomy of Compact Bone

Microscopic Anatomy of Compact Bone This eleaborate network of canals ensures bone cells are well nourished What significance does this have?

Perforating (Volkmann’s) canals:

Microscopic Anatomy of Compact Bone

Bone Formation, Growth, & Remodeling Mostly hyaline cartilage Replaced by bone

Bone Formation, Growth, & Remodeling Articular cartilage Hyaline cartilage Spongy bone New center of bone growth New bone forming Epiphyseal plate cartilage Growth in bone width Medullary cavity Bone starting to replace cartilage Growth in bone length Bone collar (a) New bone forming Epiphyseal plate cartilage Hyaline cartilage model In an embryo Blood vessels In a fetus In a child

Bone Formation, Growth, & Remodeling Osteocytes—mature bone cells Osteoblasts—bone-forming cells Osteoclasts—bone-destroying cells

Growth & Remodeling New cartilage is continuously formed Older cartilage becomes ossified

Growth & Remodeling Osteocytes can sense areas of stress Enhances the process Balance of calcium levels

Fractures

Fractures

Fractures

Fractures

Fractures

Fractures

Fractures Treated by Reduction: Closed Open