L3&L4 Skeletal System PDF

L3&L4- Skeletal System Dr.Pugazhandhi Bakthavatchalam Assistant Professor of Anatomy and Physiology, AUACAS, American University of Antigua LEARNING OUTCOMES At the end of this session the student would be able to List the components, classification and their major bony landmarks of...

L3&L4- Skeletal System Dr.Pugazhandhi Bakthavatchalam Assistant Professor of Anatomy and Physiology, AUACAS, American University of Antigua LEARNING OUTCOMES At the end of this session the student would be able to List the components, classification and their major bony landmarks of axial and appendicular skeleton Macroscopic and microscopic structure of the long bone Ossification of bones and blood supply to the long bones 02-Dec-22 2  INTRODUCTION Bone forms the major part of the body skeleton. Matrix is calcified by the deposition of calcium & phosphate. Human skeleton consist of 206 bones. It is a living, vascular form of connective tissue, the intercellular substance consists of dense, white fibrous tissue embedded in a hard calcium phosphate complex. Shows characteristic pattern of growth. Has greater regenerative power. 18-Aug-24 3  DEFINITION Bone is a hard calcified, highly vascular dynamic connective tissue. Total no.206 FUNCTIONS Shape and support Muscular attachment Act as levers Protection of organs Erythropoiesis Storage of minerals 18-Aug-24 4 CLASSIFICATION OF BONES A. According to shape B. According to development C. Regional classification D. Structural classification E. Microscopic classification 18-Aug-24 5 A. ACCORDING TO SHAPE 1. Long bones 2. Short bones 3. Flat bones 4. Irregular bones 5. Pneumatic bones 6. Sesamoid bones 7. Accessory bones 18-Aug-24 6  A. ACCORDING TO SHAPE 1.Long Bones Upper end It has an elongated shaft Two expanded ends Shaft has surfaces & borders, a central medullary cavity. Nutrient A nutrient foramen directed artery away from the growing end. Shaft Examples- femur, humerus Metacarpals(miniature long Lower end bones),Clavicle(modified long bone) 18-Aug-24 7  NETTER ATLAS 2. Short bones Plate No. 506A They are smaller in size. Shape is usually cuboid, Scaphoid or trapezoid. Examples- Carpal and tarsal bones. 3. Flat bones Resemble shallow plates. Form boundaries for certain body cavities. Examples- Ribs, Sternum, Scapula & bones in the vault of Skull. https://www.studyblue.co m/notes/note/n/bones/de ck/5435841 18-Aug-24 8  4. Irregular bones  Irregular in shapes.  Examples- Vertebrae, Hip bone & bones of the base of skull 5. Pneumatic bones  Certain irregular bones containing http://medical-dictionary.thefreedictionary.com/ large air spaces.  Lined with epithelium.  Examples- Maxilla, Sphenoid, Ethmoid etc  Function: make the skull lighter in weight help in resonance of voice act as air conditioning chambers for inspired air https://faithanatomy.wikispaces.com/Irregular+Bone 18-Aug-24 9  http://classes.midlandstech.edu/carterp/Cour 18-Aug-24 ses/bio210/chap06/lecture1.html 10  6. Sesamoid bones  Bony nodules found embedded in the tendons  No periosteum.  No medullary cavity. No Haversian system. http://forum.thefreedictionary.com/postst58033_Ole- Worm--1588-.aspx  Examples- Patella (QF), Pisiform (FCU) 7. Accessory (Supernumerary) bones  Occur as ununited epiphyses developed from extra centres of ossification.  Not always present.  Examples- Sutural bones http://corewalking.com/the-sesamoid-bones/ 18-Aug-24 11  B. ACCORDING TO DEVELOPMENT 1. Membranous (dermal) bones Derived from mesenchymal condensation. Intramembranous or mesenchymal ossification. Examples- Bones of the vault of skull, Facial bones. 2. Cartilagenous bones Derived from preformed cartilagenous models Intracartilaagenous or endochondral ossification. Examples- Bones of limbs, vertebral column & thoracic cage. 3. Membrano-cartilagenous bones Ossify partly in membrane & partly in cartilage. Example- Clavicle, Mandible, Temporal etc. 18-Aug-24 12  C. REGIONAL CLASSIFICATION 1. Axial skeleton Includes skull, vertebral column and thoracic cage 2. Appendicular skeleton Includes bones of limbs http://galleryhip.com/axial-and-appendicular- skeleton-unlabeled.html 18-Aug-24 13  DIVISION OF SKELETAL SYSTEM Total number of bones in an human body = 206 Axial Skeleton Appendicular Skeleton  Skull- Cranium- 8  Pectoral girdles- Clavicle - 2 Face - 14 Scapula - 2  Hyoid bone - 1  Upper extremities-60, Humerus, Ulna, Radius, Carpals,  Auditory ossicles - 3 in each ear Metacarpals and Phalanges  Vertebral column - 26  Pelvic girdles- Hip bones - 2  Sternum - 1  Lower extremities- 60 Femur, Fibula, Tibia, Patella, Tarsals, Metatarsals and  Ribs - 24 Phalanges 18-Aug-24 14  D. STRUCTURAL CLASSIFICATION I. Macroscopical a. Compact bone – -dense in texture -extremely porous, -best developed in cortex of long bone, -its an adaptation to bending & twisting forces b. Cancellous bones (spongy or trabecular bone) - Open in texture - made up of meshwork of trabeculae with marrow containing spaces in between. - Its an adaptation to compressive forces. 18-Aug-24 Cancellous bone 15 Compact Bone & Spongy Bone:  II. Microscopical a. Lamellar bone Composed of thin plates of bony lamellae. Each lamellus is made up of collagen fibres and mineral salts. Examples- most of matured human bones (compact & cancellous bones) Lamellae are arranged in piles in cancellous bones & in concentric cylinders (Haversian system) in compact bones. b. Fibrous bone Found in young fetal bones. Common in reptiles and amphibians. c. Dentine – occur in teeth. d. Cement – occur in teeth. 18-Aug-24 17  GROSS STRUCTURE OF AN ADULT LONG BONE Naked eye examination of L.S & T.S of a long bone shows the following features; 1. Shaft – from without inwards, it is composed of periosteum, cortex and medullary cavity. Periosteum : thick fibrous membrane covering the bone. Made up of an outer fibrous layer & an inner cellular layer (osteogenic in nature). It has rich blood supply. Pain receptors are present. Cortex: Made up of compact bone. 18-Aug-24 18  Medullary cavity: Filled with red or yellow bone marrow. Red marrow is present at birth due to active haemopoiesis. As age advances, red marrow is replaced by Yellow marrow, fatty marrow with no power of haemopoiesis. Red marrow persists in cancellous ends of long bones. Red marrow is found throughout life in sternum, ribs, vertebrae and skull bones. 2. Two ends ( Epiphysis) Made up of cancellous bone covered with hyaline cartilage. 18-Aug-24 19 Structure – Shaft of an adult long bone Periosteum Cortex Medullary cavity  FUNCTIONS OF PERIOSTEUM Provides a medium – attachment of muscles, tendons and ligaments. Richly supplied with blood – nutritive. Osteogenic inner cellular layer – formation of bone when required. Fibrous layer – limiting membrane- prevents spilling out of bone tissue into neighbouring tissues. 18-Aug-24 21 BONY LANDMARKS OF THE AXIAL AND APPENDICULAR SKELETON  Protuberance  Sutures  Notches  Margins  Foramina  Processes  Fossa  Tuberosity  Tubercles  Grooves  Sulcus  Crest https://www.studyblue.com 18-Aug-24 22 JOINTS Definition: It is the junction between 2 or more bones or cartilages, A device to permit movement Functions of joints : Give the skeleton mobility Hold the skeleton together Related terms: Arthron(G), Articulatio(L), Junctura(L), Syndesmology(G) 18-Aug-24 23 CLASSIFICATION OF JOINTS FIBROUS STRUCTURALY CARTILAGINOUS SYNOVIAL JOINTS SYNARTHROSIS FUNCTIONAL AMPHIARTHROSIS DIARTHROSIS  FUNCTIONAL CLASSIFICATION OF JOINTS According to the degree of mobility: Synarthrosis : Immovable (suture, gomphosis, synchondrosis) Amphiarthrosis : Slightly movable (syndesmosis, symphysis) Diarthrosis : Freely movable (synovial) 18-Aug-24 25 STRUCTURAL CLASSIFICATION OF JOINTS Based on the material binding them and presence or absence of a joint cavity Fibrous Cartilagenous Synovial 18-Aug-24 26 FIBROUS JOINTS The bones are joined by fibrous tissues There is no joint cavity Most are immovable There are three types : 1. Sutures 2. Syndesmoses 3. Gomphoses 18-Aug-24 27  SUTURES  Only between bones of skull  Fibrous tissue continuous with periosteum Serrate  Ossify and fuse in middle age: now Squamous suture suture technically called “synostoses”= bony junctions  VARIOUS TYPES OF SUTURES: Sutura SUTURA SERRATA, Eg: Saggital suture plana SUTURA DENTICULATA, Eg: occipitomastoid suture SUTURA SQUAMOSA, Eg: Temporoparietal suture SUTURA PLANA, Eg: Frontonasal suture SCHINDYLESIS, Eg: Vomer & SphenoidSutura denticulata 18-Aug-24 28  CARTILAGINOUS JOINTS Immovable and strong Cartilage replaced by bone. Synarthrotic Eg: costochondral joint, 18-Aug-24 29 SYNOVIAL JOINTS Include most of the body’s joints All are diarthroses (freely movable) All contain fluid-filled joint cavity Eg. intercarpal, intertarsal, elbow joint, knee joint, ankle joint, interphalangeal joints 18-Aug-24 30 GENERAL STRUCTURE OF SYNOVIAL JOINTS Synovial fluid Filtrate of blood Contains special glycoproteins Nourishes cartilage and functions as slippery lubricant “Weeping” lubrication 18-Aug-24 31 Osteogenesis- the formation of bone Bones are formed in two ways Intramembranous Endochondral Both involve replacing existing connective tissue Types of bone cells osteoblast - “budding” building cells, secrete matrix osteocyte - “cell” mature cell, maintenance activities osteoclast - “broken” cells that erode or destroy bone tissue Bone Formation and Remodeling Ossification (Bone Formation) and Growth - There are two major phases of ossification in long bones 1. Osteoblasts (builder cells)  osteoblasts multiply (through mitosis)  cartilage calcifies- it is replaced with bone by the osteoblasts 2. Cartilage inside the diaphysis is digested away  This opens up the medullary cavity Bone Formation and Growth By birth, most cartilage is converted to bone except: 1. Articular cartilages (the epiphyseal surfaces) 2. Epiphyseal plates New cartilage is continuously formed by chondrocytes © 2015 Pearson Education, Inc. Bone Formation and Growth Bones grow in two ways: length (longitudinal) width (appositional) Growth in diameter Controlled by growth hormones Epiphyseal plates are converted from cartilage to bone during adolescence Fused by the age of 18 (W), 21 (M) © 2015 Pearson Education, Inc. Bone Remodeling Bones are lengthened until growth stops Bones are remodeled throughout life (every 7-10 years) in response to two factors: 1. Blood calcium levels Negative feedback mechanisms to provide calcium to the nervous and muscular systems 2. Pull of gravity and muscles on the skeleton © 2015 Pearson Education, Inc. Bone Remodeling Calcium Levels are LOW (hypocalcemia) Release of Parathyroid Hormone by the Parathyroid glands Activates osteoclasts (bone-destroying cells) Osteoclasts break down bone and release calcium ions into the blood stream Calcium Levels are HIGH (hypercalcemia) Release of Calcitonin Hormone by the Thyroid gland Activates osteoblasts (bone-building cells) Osteoblasts use calcium and phosphorus to build bone © 2015 Pearson Education, Inc. Bone Fractures- a break in a bone Bone fractures are treated by reduction and immobilization Closed reduction: bones are manually coaxed into position by physician’s hands Open reduction: bones are secured with pins, screws, or wires during surgery © 2015 Pearson Education, Inc. Steps of Fracture Repair 1. Hematoma (blood-filled swelling) is formed 2. Fibrocartilage callus forms 1. A soft mixture of cartilage matrix, bony matrix, and collagen fibers splint the broken bone 3. Bony callus (hard) replaces the fibrocartilage callus 1. Osteoblasts and osteoclasts migrate in 4. Bone remodeling- compact bone replaces cartilage © 2015 Pearson Education, Inc. Figure 5.7 Stages in the healing of a bone fracture. Hematoma External Bony callus callus of spongy bone New Internal blood callus Healed vessels (fibrous fracture tissue and Spongy cartilage) bone trabecula 1 Hematoma 2 Fibrocartilage 3 Bony callus 4 Bone forms. callus forms. forms. remodeling occurs.  REFERENCES Drake R.L., Gray’s Anatomy for Students, 2nd Edition, 2009, Churchill Livingstone Moore, Clinically Oriented Anatomy, 6th Edition, 2009, Lippincott Williams & Wilkins Standring, Gray’s Anatomy: The Anatomical Basis of Clinical Practice, 40thEdition, 2008 Ellis H, Human Sectional Anatomy: Atlas of body sections, CT and MRI images, 3rd Edition, 2007, CRC Press Johannes W Rohen, Color Atlas of Anatomy: A photographic study of the human body, 7th Edition, Lippincott Williams & Wilkins Sadler T W, Langman's Medical Embryology, 12th Edition, 2011, Lippincott Williams & Wilkins Kenneth S Saladin, Human Anatomy, 2nd Edition, 2008, McGraw-Hill Companies 02-Dec-22 42 02-Dec-22 43