Human Anatomy as a Science 2024 PDF

HUMAN ANATOMY AS A SCIENCE and GENERAL OSTEOLOGY Department of Anatomy and Clinical anatomy Dr. Angela Babuci © Babuci Angela, updated 2023  Plan of the lecture  Anatomy as a science and its his...

HUMAN ANATOMY AS A SCIENCE and GENERAL OSTEOLOGY Department of Anatomy and Clinical anatomy Dr. Angela Babuci © Babuci Angela, updated 2023  Plan of the lecture  Anatomy as a science and its historical development  Branches of Anatomy and relationship with other disciplines  Levels and methods of Anatomical study  Anatomical terminology  The norm and abnormalities  Constitutional types © Babuci Angela, updated 2023  Human Anatomy as science  Human Anatomy studies the external shape and macro- microscopic structure of the human body, its origin and regularities of phylo- and ontogenetic development, changes of its shape and structure, conditioned by the external environment, taking into consideration the age, gender and individual specific features. © Babuci Angela, updated 2023  The term Anatomy “anatemno” derives from a Greek word that means “to cut up”.  In the past, the word anatomize was more commonly used than the word dissect.  Modern Anatomy is a complex discipline applying various high clinical significance methods of study. © Babuci Angela, updated 2023  Historical development of Human Anatomy  Human anatomy as a fundamental science is on the base of medicine.  A physician who does not know anatomy is not only useless, but even dangerous. Periods of Human anatomy development: a) Ancient period; b) Roman Era; c) Middle Ages, or medieval period; d) The Renaissance; e) Anatomy of the (XVIII-XIX centuries); f) Modern Anatomy. © Babuci Angela, updated 2023  Hippocrates (460-377 B.C.)  Hippocrates was a famous Greek physician who is regarded as the father of medicine.  He developed "The humoral theory", according to which for a good health it is necessary the blood, bile, black bile, and phlegm to be balanced in the human body. "The greatest medicine Types of personality of all is teaching people how not to need it". a) In sanguine personality – courageous and passionate – the Hippocrates predominant humor was blood. b) If there was too much bile, one was choleric – angry and mean. c) In overproduction of black bile – melancholic personality – moody and depressed. d) Too much phlegm – phlegmatic personality – sluggish and apathetic. © Babuci Angela, updated 2023  Plato (427 – 347 BC)  Plato – philosopher and mathematician.  Founder of the Academy in Athens – the first institution of higher education in the Western world.  Plato, Socrates and Aristotle – laid the very foundations of Western philosophy and science.  According to Plato, the organism was controlled by three types of soul, or “pneuma”, contained into the: brain, heart, and liver (Plato's tripod). © Babuci Angela, updated 2023  Aristotle (384-332 B.C.)  Aristotle was interested in development of animals, including humans.  He wrote the first known account of embryology, describing the development in a chicken embryo.  His best-known zoological works are History of Animals, Parts of Animals, and Generation of Animals.  According to Plato, the brain was the seat of feeling, but Aristotle considered the heart to be the seat of intelligence.  Aristotle thought that the function of the brain was to "We are what we repeatedly do. cool the blood, and thus to maintain the body Excellence then is not an act, but a habit". temperature. Aristotle © Babuci Angela, updated 2023  Erasistratus (304–250 B.C.)  The Greek scientist Erasistratus was interested more in body functions than in its structure, and he is considered the father of physiology.  Along with Herophilus, he founded a school of Anatomy in Alexandria.  Erasistratus had written a book on the causes of diseases, in which he included observations on the heart, vessels, brain and cranial nerves.  He was the first who had differentiated the motor and sensory nerves.  He was studying the contraction of muscles, and developed the theory of movement that was accepted until the XVII-th century.  He noted the toxic effects of snake venom on various organs and described changes in the liver resulting from certain metabolic diseases. © Babuci Angela, updated 2023  Herophilos (335-280 B.C.)  Herophilos was a court physician to Ptolemy II and he established anatomy as an independent science.  He was an early performer of public dissections on human cadavers, and often called the father of anatomy. “When health is absent, wisdom cannot reveal itself, art cannot become manifest, strength  "He developed the theory of using the pulse cannot be executed, as a form of diagnosis and introduced the wealth is useless and reason is powerless.” use of experimental method to medicine". Herophilos [Romero RR. Herophilos, the great anatomist of antiquity. Anatomy 2015;9(2):108–111]. https://www.researchgate.net/ publication/51855958_Heart_ Rate_Variability_- _A_Historical_Perspective/fig ures?lo=1 © Babuci Angela, updated 2023  Herophilos began dissecting human cadavers, thus giving rise to a term anatomy.  Herophilos described various anatomical structures: a) the brain and its meninges; b) the vascular network and venous sinuses with their confluence (torcular Herophili); c) he distinguished the nerves from muscle tendons; d) he differentiated the arteries from veins; e) the chyliferous vessels (though he did not appreciated their significance) and other vessels, including the pulmonary veins; f) he discovered the prostate and duodenum. © Babuci Angela, updated 2023  Claudius Galen (A.D. 129-220)  Eminent philosopher, biologist, anatomist, and physiologist, regarded as the “father of physiology“ of ancient Rome.  Anatomy and medical treatment, for nearly 1 500 years, were based on Galen‘s writings.  The most famous physician of that time – areas of expertise included physiology, neurology, logics, phylosophy and anatomy.  Galen believed that the human body is controlled by the humors of three organs: a) liver, in which physical pneuma was produced and than distributed along the veins. b) heart, in which vital pneuma originated and was transmitted along the arteries. c) brain, in which the psychic pneuma was concentrated and distributed along the nerves.  He also gave authoritative explanations for nearly all body functions. © Babuci Angela, updated 2023  Roman Era  In many respects, the Roman Empire stifled scientific advancements and set the stage for Dark Ages.  The interest and emphasis of science shifted from the oriental to the practical under Roman rule.  Few dissections of cadavers were performed other than at autopsies in attempts to determine the cause of death in criminal cases.  Medicine was not preventive but was limited, almost without exception, to the treatment of soldiers injured in battle. © Babuci Angela, updated 2023  Middle Ages  The Middle Ages (Dark Ages 5th -17th centuries) came with the fall of Roman Empire in A.D. 476 and lasted nearly 1000 years.  Dissections of cadavers were totally prohibited during this period, and molesting a corpse was a criminal act.  If mysterious death occurred, examination by inspection and palpation were allowed.  During the epidemic plague in the sixth century, however a few necropsies and dissections were performed in hopes of determining the cause of the disease. © Babuci Angela, updated 2023  Ibn Sina, or Avicena (980-1037)  Was a great scholar, physician, poet and statesman, the “Father of Science” and an encyclopaedist who wrote about all the major problems of the second half of the Middle Ages.  Ibn Sina believed that the organism is controlled not by three organs (Plato's tripod) but four, namely the heart, brain, liver and testis (Avecena's quadrangle).  Ibn Sina studied the structure of the eye.  He was the author of more than 100 works, the most prominent of which is the Canon of Medicine (c. 1000), that contains valuable anatomical and physiological information from Hippocrates, Aristotle, and Galen.  The Canon of Medicine was the best medical work produced in the feudal age and served as the source of knowledge for physicians of the East and West until the 17th century. © Babuci Angela, updated 2023 Ibn-al-Nafiz (1213 – 1288 A.D.)  Ibn-al-Nafiz from Damascus (12th century), discovered the pulmonary circulation. © Babuci Angela, updated 2023 Leonardo da Vinci (1452-1519)  The genius of Renaissance, Leonardo da Vinci was a painter, engineer, philosopher, and scientist in various fields of science, including anatomy.  He studied the external relief of the human body, and was one of the first scholars to dissect human cadavers, applying innovative methods.  He dissected human cadavers, sawed and analyzed bones.  Prepared models and three-dimensional drawings of various organs of the human body. © Babuci Angela, updated 2023  Andreas Vesalius (1514-1564)  Andreas Vesalius was an anatomist and physician, "father of anatomy".  When he was 28 years old, Vesalius has completed the masterpiece of his life, “De Humany Corporis Fabrica”, with illustrations and descriptions of organs and various body systems.  His book boldly challenged Galen's erroneous teaching (more than 200), and thus undermine the authority of Galen's anatomy.  Vesalius was one of the first who studied the structure of the human body systematically © Babuci Angela, updated 2023 William Harvey (1578-1657)  William Harvey was the first who provided a true picture of blood circulation.  In 1628, he published his pioneering work “Anatomical Treatise on the Movement of the Heart and Blood in Animals”.  This brilliant work proved the continuous circulation of blood within vessels.  The controversy over the circulation of the blood raged for 20 years until other anatomists finally repeated Harvey's experiments and confirmed his observations. © Babuci Angela, updated 2023  Branches of human anatomy  Systemic anatomy, based on functional relationships of various organs within a system and interaction between systems of organs.  The topographic anatomy describes relationships of organs towards each other, towards body cavities and skeleton.  The dynamic anatomy studies the dynamics of locomotor apparatus.  The sport anatomy studies the effect of various sport activities on human body.  Plastic anatomy for artists and sculptors studies only the external shape and proportions of the human body.  Normal anatomy studies the normal healthy organism.  Pathological or morbid anatomy studies the sick organism and the morbid changes in its organs.  Modern anatomy includes a branch named anatomy on alive person.  All these branches of anatomical science are different aspects of human anatomy. © Babuci Angela, updated 2023  Human anatomy and medical sciences related to it  Anatomy and physiology (studies the functions, through physical and chemical processes) are closely related to each other.  The external shape of organs cannot be separated from their internal structure: histology (science of tissues) and cytology (science of cell) – microscopic anatomy.  The invention of electron microscope, made possible to examine submicroscopic structures and molecules of living matter, and a new science – cytochemistry appeared.  Anatomy, histology, cytology and embryology constitute the general science of the form (shape), structure and development of the human body called morphology (GK. morphe- form, or shape). © Babuci Angela, updated 2023  Human anatomy and its modern content  The human organism changes continuously from the time of birth to the moment of death.  The human species is the product of prolonged evolution.  Modern anatomy attempts to explain not only how the body is built, but to find out, why it is so built, taking into consideration the regularities governing the structure and development of the human body under its historical evolution. © Babuci Angela, updated 2023  Historical development of the human organism  The development of the human genus in relations to the evolutionary process of the lower life forms is called phylogenesis (Gk phylon – genus, genesis – development). Thus appeared comparative anatomy, which compares the structure of various animals and man.  The formation and development of the human being in relations to the development of society is called anthropogenesis (Gk anthropos – human being).  The process of the development of individual organism throughout life is called ontogenesis (Gk onthos – being), including intrauterine and extrauterine periods of development. © Babuci Angela, updated 2023  Traditional and contemporary methods of examination There are two main methods of anatomical study: a) Examination of a cadaver b) Examination of a living person  Examination of a cadaver by opening the body cavities and dissecting the organs and tissues with surgical instruments. 1. Tubular systems (vessels, ducts etc.) are injected with various media (injection method) and then exposed to X-rays, clarification, or corrosion. 2. Nerves are treated by elective staining (for example silver impregnation). 3. The bones are prepared by maceration method. 4. Fragments of the body, or organs are frozen and after that are sectioned to study the relationship of anatomical formations (Pirogov's method).  Examination of a living human being. This method includes clinical and paraclinical methods. © Babuci Angela, updated 2023  Clinical examination  Inspection  Palpation  Percussion  Auscultation  Anthropometry (various measurement of the body) © Babuci Angela, updated 2023  Paraclinical methods of examination  X-rays provide the best possibility for studying “living anatomy”. X-rays are used for making X-rays photographs (radiography) and for visualization on a special screen (radioscopy).  X-rays examination give to a physician the possibility to examine the structure of an organ without pain and without opening the body cavities. © Babuci Angela, updated 2023  Paraclinical methods of examination  Electroradiography produces an X-rays image of the soft tissues (skin, subcutaneous fat tissue, the connective tissue framework of the parenchymatous organs, ligaments, cartilages etc.), which are invisible on ordinary radiographs because they are radiolucent.  Computer tomography produces an image of all the organs in a single plane of body tissue, much like sections of a frozen cadaver.  Magnetic Resonance Imaging, etc. © Babuci Angela, updated 2023  Anatomical terminology  The names of all the consisting parts and organs of the human body were established at three Congresses in Basel, Jena and Paris.  In 1895 the Basel Nomina Anatomica, or BNA was introduced.  In 1935 it was greatly changed at the Congress of Anatomists in Jena.  In 1955 the IV-th International Federal Congress of Anatomists in Paris established new universal anatomical terms, the so-called Paris Nomina Anatomica, or PNA.  Nomina Anatomica 2nd to 6th edition 1960–1989.  The last revision, named Terminologia Anatomica, (TA), along with Latin anatomical terminology includes a list of recommended English equivalents.  It was created by the Federative Committee on Anatomical Terminology and approved by the International Federation of Associations of Anatomists, published in 1998. © Babuci Angela, updated 2023  In anatomy description of structures are referred to anatomical position: a) the body is vertically; b) the feet are parallel to one another and flat on the floor; c) the arms are at the sides of the body with the palms turned forward.  Directional terms are used to locate the position of structures, surfaces, and regions of the body. © Babuci Angela, updated 2023 Body regions and body cavities  The human body is divided into regions and specific areas that are identified on the surface. The major body regions are: a) head, b) neck, c) trunk, d) upper limb e) lower limb.  The trunk is frequently divided into the thorax and abdomen. © Babuci Angela, updated 2023  Planes of reference  In order to visualize and study the structural arrangements of various organs, the body may be sectioned (cut) and diagrammed accordingly to planes of reference.  Three fundamental planes of reference are used: a) Sagittal plan divides the body into unequal right and left parts. b) Midsagittal plane passes lengthwise through the middle plan of the body, dividing it into equal right and left halves. c) Frontal plan passes lengthwise and divides the human body into anterior (front) and posterior (back) parts. d) Transverse plane, also called horizontal, or cross-sectional plane, divides the body into superior (upper) and inferior (lower) portions. © Babuci Angela, updated 2023  The axes of the human body  The sagittal axis pierces the body from front to back, or opposite.  The frontal axis passes from the right side to the left, or opposite.  The vertical axis passes along the body of a man having vertical position.  The longitudinal axis as well passes along the human body, but the position of the man does not matter; as well this axis passes along the limbs, organs etc.  NB: The axes do not divide the human body into parts. © Babuci Angela, updated 2023  Conventional vertical lines of the thorax  On the both sides of the thorax on its anterior, lateral and posterior walls can be traced some vertical conventional lines.  The anterior median line – passes through the middle side of the sternum.  The posterior median line passes along the spinous processes of the thoracic vertebrae.  The sternal line passes along the lateral border of the sternum (B).  The medioclavicular line passes through the middle of the clavicle (D).  The parasternal line passes on the middle distance between the sternal and medioclavicular lines (C). © Babuci Angela, updated 2023 Conventional vertical lines of the thorax  The anterior axillary line descends along the thorax from the anterior end of the anterior axillary fold (G).  The middle axillary line comes downwards from the highest point of the axillary fossa (F).  The posterior axillary line descends from the posterior end of the posterior axillary fold (E).  The scapular line passes through the inferior angle of the scapula.  The vertebral line comes downwards through the costo-transverse joints.  The paravertebral line passes on the middle distance between the vertebral and scapular lines. © Babuci Angela, updated 2023 General notions concerning norm, variations, and abnormalities  In the process of development the human organism became adapted to the environment.  As a result definite equilibrium was established between the organism and the environmental conditions.  The norm is range of deviations within certain limits of statistical indexes, which are not accompanied by functional disorders - the most common from statistical point of view.  The organism and its organs have many variations, or variants of norm but the function of the organ is not disturbed.  The variant of norm (varitas) is a particular (individual) way of manifestation of an anatomical structure that appeared as a result of deviations of development, but does not exeed the normal limits. © Babuci Angela, updated 2023  Abnormality  Abnormalities result from improper development.  Deviation from the specific structure or/and function inhereted in the respective biological species, which appeared due to disturbances of embryogenesis/morphogenesis, of one or another anatomical structure, leading to functional disorders.  Gross developmental anomalies are called monstrosities, or teratisms.  The branch of anatomy and embryology which studied the abnormalities and malformations is named teratology (Gk. teras-monster, logos-science). © Babuci Angela, updated 2023  Human body and constitutional types Constitutional types of the human body: 1. Hypersthenic type 2. Asthenic type 3. Normosthenic type  Hypersthenic type, marked by predominant growth in breadth, massive bulk, and good nourishment.  The trunk is relatively long, but the limbs are short.  The head, chest, and abdomen are very large because the corresponding body cavities are greatly developed.  There is relative predominance of the size of the abdomen over that of the chest and of the transverse dimensions over the longitudinal dimensions. © Babuci Angela, updated 2023  Asthenic type, characterized by predominant growth in length, just proportions, slenderness of body build, and poor general development. The limbs predominate over a relatively short trunk, the chest over the abdomen, and the longitudinal dimensions over the transverse dimensions. Normosthenic type, a constitutional type intermediate between the hypersthenic and asthenic. © Babuci Angela, updated 2023  According to another classification the following three types of body built can be distinguished:  Dolicomorphic type, marked by a body that is long, or of above average height, a relatively short trunk, a small chest circumference, narrow or moderately wide shoulders, long lower limbs, and slight tilting of the pelvis.  Brachymorphic type, characterized by moderate or shorter than average height, a relatively long trunk, a large chest circumference, relatively wide shoulders, short lower limbs, and marked inclination of the pelvis.  Mesomophic type, is an average body build, intermediate between the two described above. © Babuci Angela, updated 2023  Staff of the Human Anatomy Department Dr. Anastasia Bendelic, Professor Head of studies Tamara Hacina Professor Ilia Catereniuc, Dr. Angela Babuci Head of the Department Dr. Lilian Globa Dr. Doina Botnaru Dr. Tatiana Botnari Dr. Nadia Ostahi Dr. Nadejda Negarî Dr. Diana Pașa © Babuci Angela, updated 2023 General osteology © Babuci Angela, updated 2023  Plan of the lecture 1. General concepts about skeleton 2. Bone as an organ 3. Functions of the skeleton 4. Classification of bones 5. Types of bone ossification 6. Development of bones © Babuci Angela, updated 2023  The locomotor apparatus – its componenets and functional role  The skeleton is a complex of hard structures that is of mesenchymal origin and possesses a mechanical significance.  The term skeleton comes from a Greek word meaning “dried up”.  NB: All the bones and joints of the body make up the passive part of the locomotor apparatus. © Babuci Angela, updated 2023  The skeleton  The science concerned with the study of bones is termed osteology.  The skeletal system of an adult is composed of approximately 200 bones. Each bone is an organ of the skeletal system.  The skeleton is divided into axial and appendicular parts. https://www.google.com/search?q=human+skeleton&tbm=isch&s ource=univ&sa=X&ved=2ahUKEwia-Lrn- 53kAhXBKVAKHWjTAGkQsAR6BAgGEAE&biw=1707&bih=821#i mgrc=W6sZEJ2P7JcyoM: © Babuci Angela, updated 2023  The axial skeleton The axial skeleton consists of 80 bones that form the axis of the body, which supports and protects the organs of the head, neck, and trunk. Components of the axial skeleton:  Skull  Auditory ossicles  Hyoid bone  Vertebral column  Thoracic cage © Babuci Angela, updated 2023  The appendicular skeleton The appendicular skeleton is composed of 126 bones of the upper and lower limbs and the bony girdles, which anchor the appendages to the axial skeleton.  The shoulder girdle (the scapula and clavicle).  The upper limb (the humerus, ulna, radius and bones of the hand).  The pelvic girdle (the hip bone).  The lower limb (the femur, tibia, fibula and bones of the https://www.google.com/search?q=human+skeleton&tbm=isch foot). &source=univ&sa=X&ved=2ahUKEwia-Lrn- 53kAhXBKVAKHWjTAGkQsAR6BAgGEAE&biw=1707&bih=8 21#imgrc=W6sZEJ2P7JcyoM: © Babuci Angela, updated 2023 BONE AS AN ORGAN STRUCTURE OF A BONE AND STRUCTURE OF THE PERIOSTEUM  Bone (osis) is one of the hardest structures of the body.  It possesses also a certain degree of toughness and elasticity.  Its color, in a fresh state, is pinkish-white externally, and red within. © Babuci Angela, updated 2023  Types of bone tissue There are two types of bone tissue: a) Compact or cortical bony tissue – it is a hard and homogeneous tissue, formed by adjacent bone plates, connected to each other without delimitation of interlamellar cavities. b) Spongy bony tissue – it has an appearance of a sponge, formed by bone plates (trabeculae), oriented in different directions, which are intersecting at certain points and they delimit cavities of different sizes, named lacunae. Within the lacunae the bone marrow is located. There are three types of cells that contribute to bone homeostasis. a) osteoblasts are bone-forming cell b) osteoclasts resorb or break down the bone c) osteocytes are mature bone cells. An equilibrium between osteoblasts and osteoclasts maintains the bone tissue structure. © Babuci Angela, updated 2023  Structure of bone  On examining a cross section of any bone, it is composed of two kinds of bony tissue:  Compact tissue, it is dense in texture and it is always placed on the exterior of the bone.  Spongy or cancellous tissue consists of slender fibers and lamellae, which join to form a reticular structure and it is placed in the interior of the bone © Babuci Angela, updated 2023 Macromicroscopic structure of a bone  The morphofunctional unit of the bone is the osteon, or Haversian system.  The osteon consists of a system of bony lamellae arranged concentrically around a canal, which is called Haversian canal and this canal contains nerves and blood vessels.  The bone lamellae consist of osteocytes, their lacunae, and interconnecting canaliculi and matrix. © Babuci Angela, updated 2023  Types of osteons  Developing osteons  Mature osteons  Osteons in stage of resorption © Babuci Angela, updated 2023  From the periosteum into the bone matter, in special canals called Volkmann's canals, pass blood vessels and nerves.  The blood vessels conveyed in the Volkmann‘s and Haversian canals provide for metabolism in the bone.  The canaliculi permit substances to pass from one cell to another and from the blood vessels in the Haversian canals.  In this way the living cells get rid of their waste products and receive the nourishment they must have to maintain normal function. © Babuci Angela, updated 2023 © Babuci Angela, updated 2023 The spongy bone tissue  Spongy (cancellous) bone is lighter and less dense than compact bone.  Spongy bone consists of plates (trabeculae) and bars of bone adjacent to small, irregular cavities that contain red bone marrow.  The canaliculi connect to the adjacent cavities, instead of a central haversian canal, to receive their blood supply. © Babuci Angela, updated 2023 The spongy bone tissue  It may appear that the trabeculae are arranged in a haphazard manner, but they are organized to provide maximum strength similar to braces that are used to support a building. The trabeculae of spongy bone follow the lines of stress and can realign if the direction of stress changes. © Babuci Angela, updated 2023  The periosteum  Externally bone is covered by periosteum (except articular surfaces). The periosteum adheres to the surface of the bones.  It consists of two layers closely united together: a) The outer layer fibrous layer b) The inner layer or bone- forming layer (cambial) © Babuci Angela, updated 2023  Structure of the periosteum  The periosteum is rich in vessels and nerves, and it contributes to the nutrition and growth of the bone in thickness.  Nutrients are conveyed by blood vessels penetrating in great number the outer (cortical) layer of the bone from the periosteum through numerous vascular openings (foramina nutricia). © Babuci Angela, updated 2023  The interior of each long tubular bone of the limbs presents a cylindrical cavity named marrow cavity and it is lined with the medullary membrane called endosteum. © Babuci Angela, updated 2023  CHEMICAL COMPOSITION AND PHYSICAL PROPERTIES OF BONE Bone matter consists of two types of chemical material:  Organic – 1/3, mainly ossein (it provides elasticity to the bone).  Inorganic – 2/3, mainly calcium phosphate in particular 51.04% (provides hardness to the bone).  The bone contains vitamins A, D and C.  A lack of salts or vitamin D in the period of growth reduces the bone hardness and causes deformities of bones (rickets) in children.  Vitamin A deficiency leads to abnormal thickness of bones, and the bone cavities and canals become empty. © Babuci Angela, updated 2023 Functions of the skeleton  Biological functions  Mechanical functions © Babuci Angela, updated 2023  Biological functions of the skeleton a) Haematopoiesis b) Mineral storage © Babuci Angela, updated 2023  The bone marrow  The bony compartments contain bony marrow, medulla ossium. Two types of bone marrow can be distinguished:  red bone marrow  white bone marrow  The white, or yellow marrow fills up the medullary cavities of the shafts of the long tubular bones.  The red marrow is located within the cancellous tissue and extends into the larger bony canals (Haversian canals) that contain blood vessels. © Babuci Angela, updated 2023  Haematopoiesis The bone marrow provides NB:The haematopoiesis function and bones of the biological protection of the organism. embryo and It takes part in nutrition, development new-born and growth of the bone. contain only red marrow. The red marrow concerned with haematopoiesis and bone formation, has an active role in the healing of fractures. Red marrow predominates in infants and in children, with growth of child the red marrow is gradually replaced by yellow marrow. © Babuci Angela, updated 2023  Mineral storage  The inorganic matrix of bone is composed primarily of minerals calcium and phosphorus. These minerals give bone rigidity and account for approximately two-thirds of the weight of bone.  About 95% of the calcium and 90% of the phosphorus, within the body, are stored in the bones and teeth.  In addition to calcium and phosphorus, lesser amounts of magnesium and sodium salts are stored in bones. © Babuci Angela, updated 2023 Mechanical functions of the skeleton a) Support b) Protection c) Body movement © Babuci Angela, updated 2023 Support (weight bearing)  The skeleton forms a rigid framework to which are attached the soft tissues and organs of the body. © Babuci Angela, updated 2023  Protection Protection is assured by the property of the bones to form body cavities which protects the vital important organs.  The skull and vertebral column enclose the central nervous system.  The thoracic cage protects the heart, lungs, great vessels, liver and spleen.  The pelvic cavity supports and protects the pelvic organs.  Even the site where blood cells are produced is protected within the central portion of certain bones. © Babuci Angela, updated 2023 Body movement  Bones serve as anchoring attachments for most skeletal muscles. In this capacity, the bones act as levers, with the joints functioning as pivots, when muscles, which are regulated by the nervous system, contract to cause the movement. © Babuci Angela, updated 2023 Classification of bones © Babuci Angela, updated 2023 Classification of bones © Babuci Angela, updated 2023 Classification of bones © Babuci Angela, updated 2023 Classification of bones according to shape Long bones  Humerus, radius, ulna,  Femur, tibia, fibula  Metacarpal and metatarsal bones  Phalanges  Sternum and ribs © Babuci Angela, updated 2023  Classification of bones according to shape Short bones  Carpal and tarsal bones Sesamoid bones  Knee-cap  Pisiform bone, etc. © Babuci Angela, updated 2023 Classification of bones according to shape Flat bones a) Bones of the vault of the skull:  the parietal bone  the frontal and the occipital squamous parts b) Bones of the girdles:  the scapula  the hip bone © Babuci Angela, updated 2023 Classification of bones according to shape Irregular bones – the vertebrae. © Babuci Angela, updated 2023 Classification of bones according to shape  Pneumatised bones a) The ethmoid bone b) The sphenoid bone c) The frontal bone d) The maxilla e) The mastoid process of the temporal bone © Babuci Angela, updated 2023 GENERAL NOTIONS CONCERNING DEVELOPMENT OF BONESnAND THEIR ABNORMALITIES  The sclerotome derives from the paraxial mesoderm.  At the end of the 4th week the sclerotome give rise to the mesenchyme, or embryonic connective tissue.  The mesenchymal cells migrate and differentiate in many ways.  They may become fibroblasts, chondroblasts, or osteoblasts (bone- forming cells). © Babuci Angela, updated 2023  Derivatives of the lateral plate mesoderm  Lateral plate mesoderm gives rise to the pelvic and shoulder girdles, and long bones of the upper and lower limbs. © Babuci Angela, updated 2023 Derivatives of the neural crests in the head region  Neural crests in the head region differentiate into mesenchyme and participate in formation of bones of the face and skull. © Babuci Angela, updated 2023  Derivatives of the occipital somites and somitomeres  Occipital somites and somitomeres contribute to formation of the cranial vault and base of the skull. © Babuci Angela, updated 2023 Stages of development of the human skeleton  Bone formation, or ossification, begins at about the 4th week of embryonic development, but ossification centers cannot be readily observed until about the tenth week.  Three stages of development of the human skeleton are encountered:  Connective-tissue (membranous)  Cartilaginous  Bony NB: Bones which do not go through the cartilaginous stage of development are named membrane, or primary bones. That bones which during their development undergo through all three stages of development are named secondary bones. © Babuci Angela, updated 2023 THE LOWS GOVERNING THE DEVELOPMENT OF THE BONES AND THEIR ABNORMALITIES  According to the three developmental stages of the skeleton bones may develop from connective or cartilaginous tissue. Four types of ossification (osteogenesis) are distinguished:  Desmal, or intramembranous  Perichondral  Periosteal  Enchondral, or endochondral © Babuci Angela, updated 2023 Intramembranous or endesmal ossification  Intramembranous or desmal ossification (Gk en in, into, desmos band) occurs in the connective tissue of the primary (membrane) bones.  The future bones are first formed as connective tissue membranes, that are replaced with bony tissue. Bones formed in this manner are called intramembranous bones. They include certain flat bones of the skull and some of the irregular bones.  The osteoblasts migrate to the membranes and deposit bony matrix around themselves.  As a result of osteoblastic activity appear points or nuclei of ossification. © Babuci Angela, updated 2023  Perichondral ossification (Gk peri around, chondros cartilage) takes place on the outer surface of the cartilaginous bone germs with the participation of the perichondrium.  The perichondral osteoblasts covering the cartilage replace the cartilaginous tissue gradually and form a compact bony substance. © Babuci Angela, updated 2023  With the conversion of the cartilaginous model to a bone model, the perichondrium becomes the periosteum, and further deposition of bone tissue is accomplished by the periosteum; this is periosteal ossification.  The perichondral and periosteal types of ossification are therefore connected and one follows the other chronologically. © Babuci Angela, updated 2023  Endochondral ossification Endochondral or enchondral ossification involves the replacement of hyaline cartilage with bony tissue. Most of the bones of the skeleton are formed in this manner. These bones are called endochondral bones. In this process, the future bones are first formed as hyaline cartilage models. © Babuci Angela, updated 2023  Endochondral ossification During the third month after conception, the perichondrium that surrounds the hyaline cartilage "models" becomes infiltrated with blood vessels and osteoblasts and changes into a periosteum. The osteoblasts form a collar of compact bone around the diaphysis. At the same time, the cartilage in the center of the diaphysis begins to disintegrate. © Babuci Angela, updated 2023  Endochondral ossification The osteoblasts penetrate the disintegrating cartilage and replace it with spongy bone. This forms a primary ossification center. Ossification continues from this center toward the ends of the bones. After spongy bone is formed in the diaphysis, osteoclasts break down the newly formed bone to open up the medullary cavity. © Babuci Angela, updated 2023 Primary centers of ossification  In the second month of the intrauterine life, the primary points of ossification appear first, in the shafts, or diaphyses of tubular bones, and in the metaphyses.  They ossify by perichondral and enchondral osteogenesis. © Babuci Angela, updated 2023  Secondary and accessory points of ossification  The secondary points of ossification appear shortly before birth or during the first years after birth and they develop by encondral osteogenesis.  The accessory points of ossification appear in children, adolescents, and even adults in the appophyses of bones (e.g. tubercles, trochanters, the accessory processes of the lumbar vertebrae). © Babuci Angela, updated 2023  Growth of bone When secondary ossification is complete, the hyaline cartilage is totally replaced by bone except in two areas. A region of hyaline cartilage remains over the surface of the epiphysis as the articular cartilage and another area of cartilage remains at the level of the metaphysis. © Babuci Angela, updated 2023 DEVELOPMENT OF THE VERTEBRAE  The mesenchyme (sclerotome) gives rise to the skeleton around the notochord. The vertebral column in its primitive form is made up of upper and lower cartilaginous arches, which are arranged in a metameric fashion on the ventral and dorsal aspects of the notochord.  The bodies of the vertebrae grow around the notochord and compress it.  As a result the notochord is replaced by the vertebral bodies and remains only between the vertebrae as pulpy nucleus (nucleus pulposus) in the center of the intervertebral discs.  The upper neural arches give rise to the spinous process, to the paired articular and transverse processes.  The lower ventral arches give rise to the ribs.  After going through the cartilaginous stage, the vertebral column becomes bony, except the intervertebral discs connecting them. © Babuci Angela, updated 2023  Abnormality is a deviation from the norm and it can be of different degrees.  Abnormalities of bones are the result of improper development of bony system.  Different abnormalities of bones are distinguished: e.g. subdevelopment of bone, absence of bone, abnormal location of bone, bones can vary in number (to be more or less that usually), additional bones can form etc. © Babuci Angela, updated 2023 VARIANTS AND DEVELOPMENTAL ABNORMALITIES OF THE VERTEBRAE  Assimilation of the atlas by the cranium, when the first cervical vertebra fusses with the occipital bone.  Lumbalization when the first sacral vertebra does not fuse with the sacrum and there are 6 lumbar vertebrae instead of five; or when the last thoracic vertebra is not joined with a rib and transforms into a lumbar vertebra.  Sacralization when there are 6-7 sacral vertebrae, because the last lumbar vertebrae fuse with the sacral bone and in this case the number of the lumbar vertebrae decreases.  Spina bifida – results from a failure of the vertebral arches to fuse. This abnormality is more commonly for the lumbar and sacral vertebrae.  Intervertebral disc herniation involves the prolapse of the nucleus pulposus through the defective annulus fibrosus into the vertebral canal.  Spondylolistesis occurs when the pedicles of the vertebral arches fail to fuse with the vertebral body. Congenital spondylolistesis usually occurs at the level of L5-S1vertebrae.  Asomia is the absence of the vertebral body.  Hemisomia is the absence of a half of the vertebral body. © Babuci Angela, updated 2023 DEVELOPMENT OF THE STERNUM AND RIBS  The ribs develop from costal processes that form at all vertebral levels, but only in the thoracic region the costal processes grow into ribs.  The sternum develops from two sternal bars which form in the ventral body wall independent of the ribs and clavicle. The sternal bars fuse with each other in a craniocaudal direction to form the manubrium, the body and the xiphoid process by week of 8th. © Babuci Angela, updated 2023 VARIANTS AND DEVELOPMENTAL ABNORMALITIES OF THE STERNUM AND RIBS  The ribs can vary in number to be more or less than normal number (12 pairs).  Cervical ribs on one or on both sides, when the VIIth cervical vertebra joins with a rib.  In case of presence of the cervical ribs, then the VIIth cervical vertebra has appearances of a thoracic vertebra.  Lumbar ribs in case the Ist lumbar vertebrae joins with a rib.  In rare cases the XIIth rib can be absent from one or from both sides, and more rarely are cases when the XIth rib is absent.  If there are XIIIth pairs of ribs, then the number of thoracic vertebrae as well increases.  The anterior extremities of the ribs can fuse to each other, or on the contrary to bifurcate. © Babuci Angela, updated 2023 Abnormalities of the sternum  Sternal cleft occurs when the sternal bars do not fuse completely and the body of the sternum is split into two halves, it is a rare abnormality.  Sometimes in the body of the sternum is present an orifice.  In the xiphoid process can be present an orifice, or it can be bifurcated. © Babuci Angela, updated 2023