Function of Bones • Protection- of soft tissues and organs. • Movement – muscles attached to bones= function as levers. • Storage – of minerals (Calcium and Phosphorous) and lipids ( yellow marrow) • Blood Cell Formation- hematopoiesis- occurs within the marrow of the bone. • Support- for the entire body; Individual bones provide a framework for attachment of soft tissues and organs.
Bones of the Human Body • The adult skeleton has 206 bones • Two basic types of bone tissue • Compact bone • Homogeneous • Spongy bone • Small needle-like pieces of bone • Many open spaces Figure 5.2b
Gross Anatomy of a Long Bone • Diaphysis • Shaft • Composed of compact bone • Epiphysis • Ends of the bone • Composed mostly of spongy bone Figure 5.2a
Classification of Bones • Long Bones- Relatively long and slender; occurs in the forearm, thigh and leg (A shaft w/ 2 heads) Mostly compact. • Short Bones- Short and Boxy: carpal bones, tarsal bones.( mostly spongy) • Flat Bones-thin, flattened, usually curved. ; Most bones of Skull, ribs, sternum. have 2 layers of compact bones sandwiched w/ one layerof spongy. • Irregular Bones- the vertebrae. ( Misc.)
The Skeletal System • Parts of the skeletal system • Bones (skeleton) • Joints • Cartilages • Ligaments • Divided into two divisions • Axial skeleton • Appendicular skeleton
Long Bones • Longer than • wide • Shaft is Composed of • compact bone • Ends are composed • spongy bone • Found: bones of • limbs & digits
Structures of a Long Bone • Periosteum • Outside covering of the diaphysis • Fibrous connective tissue membrane • Sharpey’s fibers • Secure periosteum to underlying bone • Arteries • Supply bone cells with nutrients Figure 5.2c
Long Bone Formation and Growth Figure 5.4a
Cartilage locations in the skeletal system
Gross Anatomy: Proof of Growth • Epiphyseal Line- Remnant of epiphyseal plate. • Epiphyseal Plates- Here hyaline cartilage is replaced w/ bone ( ossification) Hence bones grow longer here. • Hormones influence the growth of bones. • Epiphseal lines are left to mark previous location of plates. • Growth stops during late adolescence.
Microscopic Anatomy of Bone • Osteon (Haversian System) • A unit of bone • Central (Haversian) canal • Opening in the center of an osteon • Carries blood vessels and nerves • Perforating (Volkman’s) canal • Canal perpendicular to the central canal • Carries blood vessels and nerves
Microscopic Anatomy of Bone Figure 5.3
Microscopic Anatomy of Bone • Canaliculi • Tiny canals • Radiate from the central canal to lacunae • Form a transport system Detail of Figure 5.3
Microscopic Anatomy of Bone • Lacunae • Cavities containing bone cells (osteocytes) • Arranged in concentric rings • Lamellae • Rings around the central canal • Sites of lacunae Detail of Figure 5.3
Types of Bone Cells • Osteocytes • Mature bone cells • Osteoblasts • Bone-forming cells • Osteoclasts • Bone-destroying cells • Break down bone matrix for remodeling and release of calcium • Bone remodeling is a process by both osteoblasts and osteoclasts
Bone Homeostasis Parathyroids regulate the homeostasis of blood calcium When blood calcium is low Osteoclasts tap into reserves and Bone is “demineralized” Calcium ions is released into blood Too much calcium in the blood? This hormone causes the deposition of Calcium into the bone matrix by osteoblasts
The Skull • Your skull has many different bones, with different functions: • Protect your brain. • Housing sensory organs (eyes, ears, etc.). • Help you to chew your food. • All of these bones are either fused together, or are hinged (your jaw).
Basic Cranial Bones • Frontal, parietal, occipital, and temporal. • These make up the basic brain case. • Nasal, zygomatic, maxilla, and mandible. • The make up the front of your face, and your jaw.
Lets look at the skeleton Again. Your axial skeleton provides basic support Your appendicular skeleton allows your body to do all of its movements.
Your Axial SkeletonYour backbone gives you flexibility. • Your backbone has several functions: • Supports the head. • Attachment of ribs. • Allows movement side to side. • Houses the spinal cord. • Your backbones, made of many vertebrae all working together, are extremely important. • Vertebrae are irregular bones.
You need to know the basic bone types of the backbone. • Cervical vertebrae (7) • Your neck. • Thoracic vertebrae (12) • Attaches to your ribs. • Lumbar vertebrae (5) • Your lower back. • Sacrum and coccyx • Part of your hip and tail bone. • Know the numbers and function of the basic vertebrae.
About Spinal Curvature • At birth your spinal Column is shaped like a C • When baby is about to crawl the cervical region curves towards posterior. • As toddler begins to walk, another curve sets in the lumber area in the same direction…resulting in its characteristic S shape.
Spinal Maladies • Kyphosis or Hunchback- When too much thoracic curvature (usually a result of osteoporosis) • Lordosis- Exaggerated Lumbar curvature ( may result from too much weight in pregnancy or obesity) • Scolliosis- A developmental abnormality in thoracic region (abnormal lateral curvature): can be corrected w/ a back brace. • Herniated Disk (see board)
This is one of your vertebrae. • This picture is taken from directly above the vertebrae. • Your spine, nerves, and other structures move through the holes (foramen) • As you stack vertebrae on top of one another, and connect these with tissue, this gives your back flexibility.
Here are three vertebrae stacked upon one another. • Cartilage (blue) • Vertebrae (orange) • Notice that the vertebrae are surrounded and cushioned by the cartilage. • This gives you the flexibility in your back. • Side to side. • Front to back. • Twisting.
What do you think happens if you have a “blown disc”? • Your cartilage is located between your vertebrae. • When the tissue surrounding your disc ruptures, it allows your cartilage to move. • “Herniated disc” • This movement can pinch surrounding nerves, causing back pain.
How does a broken bone heal? 1. Blood flow increases to the area of the break. This allows nutrients and oxygen to help the healing process. 2. As bone becomes deposited, it grows stronger, and eventually remodels itself.
Clinical Forms of Arthritis • Osteoarthritis • Most common chronic arthritis • Probably related to normal aging processes • Rheumatoid arthritis • An autoimmune disease – the immune system attacks the joints • Symptoms begin with bilateral inflammation of certain joints • Often leads to deformities
Gouty Arthritis (GOUT) • Inflammation of joints is caused by a deposition of urate (URIC ACID) crystals from the blood • Can usually be controlled with diet • Hereditary as it runs in families. • This is very painful!!
Cartilaginous Joints • Bones connected by cartilage • Examples • Pubic symphysis • Intervertebral joints Figure 5.27d–e