UNIT 2 (OSTEOLOGY).pdf

School of Nursing and Allied Health Diploma in Physiotherapy Program FUNCTIONAL ANATOMY OF UPPER EXTREMITY...

School of Nursing and Allied Health Diploma in Physiotherapy Program FUNCTIONAL ANATOMY OF UPPER EXTREMITY (PTUL 4113) UNIT 2 : OSTEOLOGY Prepared by, Vaneeyshaa Chandran M.PT(MY),B.PT(MY/UK), D.PT(MY) 16/08/2024  Lesson Learning Outcome At the end of this chapter, student will be able to: to classify skeletal system, bone tissues, structure and functions of bone to draw and label part of bones  Topic Outlines Classification of skeletal system, bone tissues, structure and function of bone Ossification of bone  Introduction OSTEOLOGY Osteo Bone Logy Study “scientific study of bone structure and the treatment of bone disorders” Often used by scientists with identifying human remains with regards to age, death, sex and growth. The entire framework of bones and their cartilages, along with ligaments and tendons, constitutes the “skeletal system”. The human skeleton consists of both fused and individual bones. Skeletal System  Introduction In an adult, the skeleton comprises around 13% of the total body weight, and half of this weight is water. At birth, a newborn baby has approximately 270 bones. Whereas on average an adult human has 206 bones (these numbers can vary slightly from individual to individual). The longest and heaviest bone in the body is the femur and the smallest is the stapes bone in the middle ear.  Introduction The difference comes from several small bones that fuse together during growth, such as the sacrum and coccyx of the vertebral column. The sacrum (the bone at the base of the spine) consists of five bones which are separate at birth but fuse together into a solid structure in later years.  Classification of Skeleton System Axial Appendicular Skeleton Skeleton Consists of Consists of 80 bones. 126 bones. Includes: Includes: Skull Upper and lower limbs Vertebral Pectoral column (shoulder) Rib cage girdle Pelvic girdle  Functions of Bone and The Skeletal System Mechanical Protection - to protect internal organs from injuries. For example, cranial bones (skull) protects the brain, vertebrae (backbones) protects the spinal cord, and or the rib cage protects the heart and lungs. Support – skeleton serves as foundation of the body by supporting soft tissues and providing attachment points for the tendons of most skeletal muscles. Movement – most skeletal muscles attach to bones, when they contract, they pull on bones to produce movement. The interaction between bone and muscle is studied in biomechanics. Sound transduction - bones are important in the mechanical aspect of hearing.  Functions of Bone and The Skeletal System Metabolic Mineral storage - Bones act as reserves of minerals important for the body, most notably calcium and phosphorus. Fat storage - The yellow bone marrow acts as a storage reserve of fatty acids. Acid-base balance - Bone buffers the blood against excessive pH changes by absorbing or releasing alkaline salts. Detoxification - Bone tissues can also store heavy metals and other foreign elements, removing them from the blood and reducing their effects on other tissues. These can later be gradually released for excretion.  Structure of Bone Macroscopic structure of a typical bone shows the following parts: Long bone : Example: humerus (the arm bone) Has greater length than width Consists of the following parts: 1. Diaphysis (growing between) is the bone’s shaft or body – the long, cylindrical, main portion of the bone. 2. Epiphyses (growing over; singular is epiphysis) – the proximal and distal ends of the bone.  Structure of Bone 3. Metaphyses (between; singular is metaphysis) are the regions between the diaphysis and epiphysis. → Each metaphysis contains an epiphyseal (growth) plate, a layer of hyaline cartilage that allows the diaphysis of the bone to grow in length. → When bone starts to grow in length (18-21 age), the cartilage in the epiphyseal plate is replaced by bone; resulting in bony structure known as the epiphyseal line. 4. Articular cartilage – thin layer of hyaline cartilage covering part of epiphysis where bone forms an articulations with another bone. →Reduces friction and absorbs shock at freely movable joints.  Structure of Bone 5. Periosteum (peri – around) is a tough connective tissue sheath and associated blood supply surrounds the bone surface wherever it is not covered by articular cartilage. → Composed of an outer fibrous layer of dense irregular connective tissue and an inner osteogenic layer that consists of cells. → Function: - protects the bone, assists in fracture repair, helps nourish bone tissue, and serves as an attachment point of ligaments and tendons.  Structure of Bone 6. Medullary cavity (medulla – marrow) or marrow cavity, is a hollow, cylindrical space within the diaphysis that contains fatty yellow bone marrow and numerous blood vessels in adults. → This cavity minimizes the weight of bone by reducing the dense bony material where it is needed. 7. Endosteum (endo – within) is a thin membrane that lines the medullary cavity. → Contains a single layer of bone-forming cells and a small amount of connective tissue.  Histology of Bone Tissue Like other connective tissues, bone and osseous tissue contains an abundant extracellular matrix that surrounds widely separated cells. These extracellular matrix : → 15% water → 30% collagen fibers → 55% crystallized mineral salts Calcium phosphate, combines with; Calcium Hydroxide To form crystals of hydroxyapatite As the crystals form, they combine with other mineral salt like calcium carbonate, ions such as magnesium, potassium, fluoride and sulfate. They then crystallize and the tissue hardens. This process is called as “calcification” which is initiated by bone-building cells called osteoblasts.  Types of Bone Tissue Osteogenic cells Osteoblasts Osteocytes (blasts – buds or sprouts) (genic – producing) Bone-building cells. (cytes – cells) Unspecialized bone stem cells Synthesize and secrete Mature bone cells derived from connective tissue. collagen fibers and other Main cells in bone tissue The only bone cells to undergo organic components needed to Maintain its daily metabolism cell division; resulting cells build the extra cellular matrix such as exchange of nutrients develop into osteoblasts. of bone tissue. and wastes with the blood. Found at inner portion of Also initiate calcification Like osteoblasts, it does not periosteum, in the endosteum Surrounds themselves with undergo cell division. and in the canals within bone extracellular matrix and that contains blood vessels. becomes osteocytes.  Types of Bone Tissue Osteoclasts (clast – break) Huge cells derived from fusion of as many as 50 monocytes (a type of white blood cells) and concentrated into endosteum. Ruffled border (plasma membrane that is deeply folded) found on the side of the cell that faces the bone surface. Here, the cell releases powerful lysosomal enzymes and acids that digest the protein and mineral components of the underlying extracellular bone matrix. This breakdown of extracellular bone matrix term as “resorption”, part of the normal development, maintenance and repair of bone. Types of Bone Tissue Histology of Bone Tissue  Types of Bone Tissue Bone tissue is not completely solid but has many small spaces between the cells and the extracellular matrix. Some of these surfaces provide channels for blood vessels that supply the bone with nutrients while some spaces act as storage areas for the bone marrow. Depending on the size and distribution of these spaces we have 2 main types of bone tissue: Compact bone (80%) Spongy bone (20%)  Types of Bone Tissue Compact Bone Contains fewer spaces and is the strongest form of bone tissue. provides protection, support and resists the stresses produced by weight and movement. made up of structural units called Haversian system or osteons. The areas between the osteons is called interstitial lamellae.  Types of Bone Tissue Compact Bone Structure of Haversian system It has a central canal Around the canal are concentric rings of calcified extracellular matrix - concentric lamellae Between the lamellae are small spaces called lacunae which contain the osteocytes Radiating in all directions from the lacunae are tiny canaliculi.  Type of Bone Tissue Bone tissue (a microscopic view)  Types of Bone Tissue Spongy Bone Contains more number of spaces. Does not contain Haversian system It consists of lamellae arranged in an irregular manner of thin columns called trabeculae Within each trabeculae are concentric lamellae, osteocytes and canaliculi. The trabeculae are arranged based on the stress on the bone. Types of Bone Tissue Trabeculae pattern  Types of Bone Tissue Spongy Bone Spongy bone is located where the bones are not heavily stressed Spongy bone is lighter than the compact bone It allows more room for blood vessels; hence it is found in the center (medullary cavity) of long bones. Spongy bone is always covered with compact bone for protection. Types of Bone Tissue  Development of Bone 1. Bone begins as a model of hyaline cartilage in an embryo 2. Then a collar forms around the midsection.  Development of Bone 3. Primary ossification center as cartilage is replaced by spongy bone 4. Spongy bone expands as more blood vessels penetrate  Development of Bone 5. Central cavity is formed and secondary ossification centers develop 6. Ossification continues until spongy bone fills epiphyses and compact bone surrounds the entire structure  Development of Bone 7. Hyaline cartilage remains in the epiphyseal plates and articular cartilages Development of Bone Development of Bone  Types of Bone Long bones these are bones which have their length greater than the width. The bones consist of a shaft and a variable number of extremities and are slightly curved for strength. Consist mainly of compact bone tissue in their diaphysis but have considerable amounts of spongy bone tissue in their epiphyses.  Types of Bone Short bones the bones are somewhat cube shaped with length and width almost equal. Consist of spongy bone except at the surface where there is a thin layer of compact bone.  Types of Bone Flat bones generally thin and plate like. Consists of two nearly parallel plates of compact bone tissue with a layer of spongy bone in the center. Give protection and provide a larger area for attachment of muscles.  Types of Bone Irregular bones Generally, they have complex shapes They vary in the amount of spongy and compact bone that they contain.  Types of Bone Sesamoid bones develop inside the muscle (tendons of the muscles) Number of sesamoid bones can vary from person to person. They protect the tendons from injury during repeated muscle action.  References Tortora, G.J. & Grabowski, K.S.R. 2006. Principles of Anatomy and Physiology. New York: Harper Collins Saladin, K.S. 2006. Anatomy and Physiology: The unity of form and function. New York: McGraw Hill Guyton, A.C. 2006. Textbook of Medical Physiology. Philadelphia: W.B. Saunders.