CRT04101 Anatomy, Physiology and Pathology

DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Anatomy of reproductive Organs CRT04101 · Anatomy, Physiology and Pathology START READING NOTES Study Anatomy of reproductive Organs using the sections below. Use the topic navigation to continue through Anatomy, Physiology and Pathology. Contents of This Topic Female Reproductive System …… Ovaries Anatomy of reproductive Organs Uterus Vagina External genitals (Vulva) Labia majora and minora Male reproductive organs Testes The testes are surrounded by three layers of tissues which are (outer-inner layer) Cells of testis Epididymis Ejaculatory ducts Seminal vesicles Their secretion contains fructose to provide an energy source for sperm and is alkaline to enhance sperm motility. Prostate gland Bulbourethral (Cowper‘s) glands Urethra Anatomy of reproductive Organs Female Reproductive System Is made up of the internal and external sex organs The female reproductive system consists of the: Internal genitalia which include: Paired ovaries Fallopian tubes Single uterus Vagina AND External genital structures (vulva) which include: Clitoris Labia majora and minora …… Bartholin‘s glands Ovaries The ovaries are a pair of oval structures on either side of the uterus in the pelvic cavity (with size approx. 3.5 cm in length, 2 cm wide, and 1 cm thick) Within an ovary are several hundred thousand primary follicles, which are present at birth and later matures to become ova Fallopian /uterine tubes or oviduct There are two fallopian tubes(oviducts) The lateral end of a fallopian tube encloses an ovary, and the medial end opens into the uterus. They are line by ciliated columnar Epithelium. Parts of Oviduct include isthmus,Ampulla and Infindubilum (contains fimbriae) !!Fertilization takes place in oviduct (ampulla) Anatomy of reproductive Organs Isthmus=narrowed part of a structure. There are two isthmuses. The one is between the body of uterus and cervix and the other is the first medial part of fallopian tube. Uterus The uterus is shaped like an upside-down pear, superior to the urinary bladder and between the two ovaries in the pelvic cavity …… Uterus…. It is divided in to fundus (upper part), body/corpus (central part),Isthmus and cervix (lower part) Layers of uterus (from innermost-outermost): Endometrium- inner lining and consists of glandular cells (simple columnar epithelium) that make secretions and undergoes cyclic shedding during menstruation It forms the maternal portion of the placenta during pregnancy Anatomy of reproductive Organs The myometrium is the smooth muscle layer during pregnancy these cells increase in size to accommodate the growing foetus and contract for labour and delivery at the end of pregnancy. Perimetrium: consists of Subserosa tissue Vagina The vagina is a muscular tube that extends from the cervix to the vaginal orifice The vaginal opening is usually partially covered by a thin membrane called the hymen which ruptures after sexual intercourse The functions of the vagina are to receive sperm from the penis during sexual intercourse, To provide the exit for menstrual blood flow, and To become the birth canal at the end of pregnancy. External genitals (Vulva) Clitoris Is a small mass of erectile tissue anterior to the urethral orifice. The only function of the clitoris is sensory. It responds to sexual stimulation. Labia majora and minora Are paired folds of skin which covers the urethra and vagina openings and prevent drying of their mucous membranes Bartholin‘s glands They secrete lubricant which keep the vagina moist during sexual intercourse. Male reproductive organs They include: Testes Epididymis Dactus deferens (vas deferens) Ejaculatory ducts ….. Seminal vesicles Prostate gland Bulbourethral (Cowper‘s) glands Urethra-penis Testes The testes are located in the scrotum, a sac of skin between the upper thighs. Internally is divided in to lobes Each lobe contains several seminiferous tubules where spermatogenesis takes place. The testes are surrounded by three layers of tissues which are (outer-inner layer) Tunica vaginalis Tunica albuginea Tunica vasculosa Cells of testis sertoli cells which produce inhibin hormone when stimulated by testosterone Leydig cells: produce Testosterone is responsible for maturation of sperm and secondary male characteristics Epididymis It is a tube about 6m long that is coiled in the posterior surface of each testis. Within it the sperm complete the maturation and their flagella become functional. … Smooth muscle of the wall of epididymis propels the sperm to dactus deferens Dactus deferens (vas deferens) Extends from the epididymis in the scrotum on its own side into the abdominal cavity through the inguinal canal … Spermatic cord is a connective tissue sheath that contains the ductus deferens, testicular blood vessels(Cremasteric artery,Testicular artery, artery to vas deferens & pampinifom venous plexus), and nerves, [well discussed in inguinal canal session] Ejaculatory ducts Each of the two ejaculatory ducts receives sperm from the ductus deferens and the secretion of the seminal vesicle on its own side. Both ejaculatory ducts empty into the single urethra Seminal vesicles The paired seminal vesicles are posterior to the urinary bladder Their secretion contains fructose to provide an energy source for sperm and is alkaline to enhance sperm motility. The duct of each seminal vesicle joins the ductus deferens on that side to form the ejaculation duct Prostate gland A muscular ,walnut-shaped gland just below the urinary bladder It surrounds the first inch of the urethra as it emerges from the bladder The glandular tissue of the prostate secretes an alkaline fluid that helps maintain sperm motility. The smooth muscle of the prostate gland contracts during ejaculation to contribute to the expulsion of semen from the urethra Bulbourethral (Cowper‘s) glands They are located below the prostate gland and empties to the urethra Their alkaline secretion coats the interior of the urethra just before ejaculation, which neutralizes any acidic urine that might be present. Urethra The urethra is the last of the ducts through which semen travels, and its longest portion is enclosed within the penis. Anatomy of reproductive Organs The penis is an external genital organ; its distal end is called the glans penis and is covered with a fold of skin called the prepuce or foreskin which is removed by surgical procedure of circumcision Within the penis are three masses of cavernous (erectile) tissue by

DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Accessory organs of digestive systems CRT04101 · Anatomy, Physiology and Pathology START READING NOTES Study Accessory organs of digestive systems using the sections below. Use the topic navigation to continue through Anatomy, Physiology and Pathology. Contents of This Topic By the end of this session, students are expected to be able to: Overview of Accessory Organs of Digestive System Accessory organs of digestive systems Structure and Functions of the Liver The Quadrate lobe Structures related to Liver The connective tissue septa divide the liver into hexagon-shaped lobules with a portal triad at each corner Functions of hepatocytes Hepatocytes have six major functions, which are: Main Functions of the Liver Breakdown of erythrocytes and defence against microbes Vascular Supply and Lymphatic Drainage Structure and functions of the Gallbladder Organisation of the Biliary System This completes the formation of the bile duct Bile Production, Circulation and Functions Bile circulation. Composition of Bile Structure and Functions of Pancreas In the lower part of the head of pancreas, the pancreatic duct joins the bile duct The main and accessory pancreatic ducts usually communicate with each other Key points evaluation Accessory Organs of Digestive System By the end of this session, students are expected to be able to: Describe the Accessory Organs of Digestive System Describe the Structure and Functions of the Liver Describe the Structure and Functions of Gallbladder Explain Organization of the Biliary System Explain Bile Production, Circulation and Functions Identify Structure of Pancreas Overview of Accessory Organs of Digestive System What are the accessory organs of the digestive system? Accessory organs of digestive systems Accessory organs of gastrointestinal tract: The organs which are not directly part of gastrointestinal tract but their products are essential for the digestive system to accomplish its primary function These organs include: The liver Gallbladder and bile duct Pancreas These are essential for the digestive system as they either produce or store secretions essential the digestion to take place Structure and Functions of the Liver Liver is the largest gland in the body, weighing between 1 and 2.3Kg In adults the liver weighs 2% of body mass Occupying the greater part the right hypochondriac, part of the epigastric and frequently extending into the left hypochondriac regions as far as the left lateral line The liver is divided into right and left lobes by fossae for the gallbladder and the inferior vena cava The right lobe of liver is the largest lobe, whereas the left lobe of liver is smaller wedge shaped The quadrate and caudate lobes are described as arising from the right lobe of liver, but functionally are distinct these are seen on the posterior side of the liver making it to have four lobes: The Quadrate lobe It is visible on the upper part of the visceral surface of the liver It is bounded on the left by the fissure for ligamentum teres and on the right by the fossa for the gallbladder Functionally it is related to the left lobe of the liver The caudate lobe It is visible on the lower part of the visceral surface of the liver It is bounded on the left by the fissure for the ligamentum venosum and on the right by the groove for the inferior vena cava Functionally, it is separate from the right and the left lobes of the liver Structures related to Liver The right anterior part of the stomach The superior part of the duodenum The lesser omentum The gallbladder The right colic flexure The right transverse colon The right kidney The right suprarenal gland Accessory organs of digestive systems The porta hepatis serves as the point of entry into the liver for the hepatic arteries and the portal vein, and the exit point for the hepatic ducts The liver is attached to the anterior abdominal wall by the falciform ligament and, except for a small area of the liver against the diaphragm (the bare area), the liver is almost completely surrounded by visceral peritoneum Additional folds of peritoneum connect the liver to the stomach (hepatogastric ligament), the duodenum (hepatoduodenal ligament), and the diaphragm (right and left triangular ligaments and anterior and posterior coronary ligaments) The connective tissue septa divide the liver into hexagon-shaped lobules with a portal triad at each corner *The triad are so named because three vessels – the hepatic portal vein, hepatic artery and hepatic duct are commonly located in them Hepatic nerves and lymphatic vessels often too small to be easily seen in light microscope are also located in these areas Liver lobules are hexagonal in outline and are formed by cubical-shaped cells; the hepatocytes arranged in pair, between them are columns of cells called sinusoids Hepatic macrophages (Kupffer cells) are also present which function in destroy and ingest worn out cells and foreign particles in the liver A central vein is in the centre of each lobule Accessory organs of digestive systems Central veins unite to form hepatic veins, which exit the liver on its posterior and superior surface and empty into the inferior vena cava Hepatic cord radiate out from the central vein of each lobule like the spokes of a wheel The hepatic cords are composed of hepatocytes, the functional cells of the liver The spaces between the hepatic cords are blood channels called hepatic sinusoids The sinusoids are lined with a very thin, irregular squamous epithelium consisting of two cell populations; endothelial cells and Hepatic phagocytic cells (kupffer cells) A cleft-like lumen, the bile canaliculus lie between the cells within each cord Functions of hepatocytes What are the function of hepatocyte Hepatocytes have six major functions, which are: o Bile production o Storage o Interconversion of nutrients o Detoxication o Phagocytosis (kuppfer cells) o Synthesis of blood components Main Functions of the Liver Nutrient and vitamin metabolism and storage o Glucose and other sugars o Amino acids (Deamination of amino acids),the end product is urea which is then excreted in the urine) o Lipids o

DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE A Cell CRT04101 · Anatomy, Physiology and Pathology START READING NOTES Study A Cell using the sections below. Use the topic navigation to continue through Anatomy, Physiology and Pathology. Contents of This Topic CELL Other organisms are multicellular(consist of many cells) e.g. humans There are two types of cells: Most eukaryotic cells also contain other membrane-bound organelles such a mitochondria, and the Golgi apparatus Prokaryotic Cells Instead processes such as oxidative phosphorylation and photosynthesis take place across the prokaryotic plasma membrane. Structure of a generalized animal cell The cytosol is the liquid portion containing water and dissolved solutes. Characteristics of the Cell Growth- is the increase in the size and number of the existing cells. . Functions of the Human Cell Mitochondria Vacuole Endoplasmic Reticulum Golgi apparatus Ribosomes Lysosomes Assignment CELL Is the smallest living structural and functional unit of life It is the smallest unit of an organism that is classified as living, and is often called building block of life All cells come from pre-existing cells Most cells are microscopic and can replicate independently Some organisms are unicellular (consist of a single cell) e.g. some bacteria. Other organisms are multicellular(consist of many cells) e.g. humans Vital functions of an organism occur within cells, and all cells contain the hereditary information necessary for regulating cell functions and for transmitting information to the next generation of cells Cells of the body perform specific functions, and therefore their structures vary greatly There are two types of cells: 1.Eukaryotic 2.Prokaryotic Eukaryotic Cells Cells in higher animals (mammals) are eukaryotic, that is they have membrane bound nucleus, which is well protected, inside the cell Eukaryotic cells are often found in multicellular organisms Eukaryote is an organism whose cells contain complex structures inside the membranes Most eukaryotic cells also contain other membrane-bound organelles such a mitochondria, and the Golgi apparatus Eukaryotes do have "true" nuclei containing DNA Eukaryotic organisms may be unicellular, as in amoebae, or multicellular, as in humans Cell division in eukaryotes is different from that in organisms without a nucleus (prokaryotes) Prokaryotic Cells Do not contain membrane bound organelles and genetic material is scattered in the cytoplasm The simple forms of life like bacteria are made up entirely of single cell are prokaryotic, the nucleus is not membrane bound it is scattered in the protoplasm and is vulnerable Prokaryotic cells are usually independent Prokaryotes generally lack membrane-bound cell compartments: such as mitochondria and chloroplasts. Instead processes such as oxidative phosphorylation and photosynthesis take place across the prokaryotic plasma membrane. However, prokaryotes do possess some internal structures, such as cytoskeletons. Prokaryotes also differ from eukaryotes in that they contain only a single loop of stable chromosomal DNA stored in an area named the nucleoid, while eukaryote DNA is found on tightly bound and organized chromosomes Structure of a generalized animal cell The cell is divided into three main parts namely: plasma membrane, cytoplasm and nucleus The plasma membrane: Forms the cell’s outer surface separating the cell’s internal environment from the external environment. It regulates the flow of material into and out of the cell The cytoplasm: It is the fluid-filled cell interior. It has two components: cytosol and organelles. The cytosol is the liquid portion containing water and dissolved solutes. The organelles are small structures with highly specialized functions, many of which are contained within a membrane. They include nucleus, mitochondria, ribosomes, endoplasmic reticulum (ER), Golgi apparatus, cell membrane, microfilaments and microtubules. Characteristics of the Cell Metabolism-are the sum of all chemical processes that occur in the body including anabolism and catabolism. Responsiveness- ability to detect and respond to changes like temperature, pressure, sound etc. Movement- includes motion of the whole cell and tiny structures inside the cell. Growth- is the increase in the size and number of the existing cells. Differentiation- the development of a cell from unspecialized to specialized state Reproduction- the formation of new cells for tissue growth, repair and replacement or to the production of a new individual . Functions of the Human Cell The functions of animal cell are all carried out by the different cell organelles These cell organelles function as a unit and regulate the activities of the cell on the whole. Cell nucleus The nucleus is referred to as the heart of the cell The nucleus houses the genetic material of the organism which is the DNA. DNA replication and RNA synthesis occurs in the nucleus. Mitochondria The mitochondria is also referred to as the power house of the cell It is a double membrane organelle that helps in energy production for the cell. The energy is generated in the form of ATP from the glucose. This occurs in the process called cellular respiration Vacuole The vacuole is a large empty storage organelle. They store excess water or food. It is present in many numbers within the cell floating in the cytoplasm Endoplasmic Reticulum The endoplasmic reticulum is a network for transportation of certain critical substances in and out of the nucleus. There are two kinds of ER namely ; 1.Rough ER Smooth ER. Rough ER has ribosome molecules attached to its surface Smooth ER does not have ribosome molecules attached to its surface Golgi apparatus Is involved with processing and packaging of the molecules synthesized by the cell mainly the proteins ready for secretion The ER transports the proteins in their crude form to the golgi apparatus Ribosomes Is involved in protein synthesis. It consists of two sub units Protein synthesis primarily occurs in the ribosomes The ribosomes may be found freely floating in the cytoplasm or may be found attached to the ER Lysosomes Are referred to as suicide bags of the cell,they are involved in clearing the unwanted and waste materials from the cell The lysosomes contain hydrolytic enzymes that are destructive that they kill the toxic materials of the cell time to time. They engulf materials like damaged organelles, virus, bacteria and food particles Assignment Explain functions of cell organelles

DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Bones and Disorders of Connective Tissue CRT04101 · Anatomy, Physiology and Pathology START READING NOTES Study Bones and Disorders of Connective Tissue using the sections below. Use the topic navigation to continue through Anatomy, Physiology and Pathology. Contents of This Topic Structure and Functions of Bone Tissues Definition Of Bone Bones and Disorders of Connective Tissue Bone consists of: Bone Cells; The bone contains four types of cells namely the osteoprogenator cells, osteoblasts, osteocytes, and the osteoclasts Types of Bones Parts of the long bone Bones Formation Bones formation occurs in four main stages which are Functions of Bones Movement KEYPOINTS QUESTIONS Common Disorders of Common Disorders of Connective Tissues Common Types of Connective Tissue Diseases Acute pyrogenic arthritis Gout The disease is commonest in men over 40 years. Chronic joint disease Osteoarthritis Generalized bone disease Osteomalacia Structure and Functions of Bone Tissues PHARM. EMERENCIANA M. JAMES Definition Of Bone Bone is a hard and rigid tissue that forms the bony skeleton of the body. Bone supports the body weight, It provides attachment to muscles, Acts as lever for movements, and provides protection to organs Inside the bone there are spaces, which are filled with the bone marrow that produce red blood cells, platelets and cells of the immune system Bones and Disorders of Connective Tissue Cells of the immune system produced in bone marrow include monocytes, lymphocytes, mast cells, neutrophils, eosinophils and basophils The only difference with other connective tissues is that its ground substance is made up of inorganic salts, mostly calcium ions The bone is highly vascularized, and in living conditions the bone appears pinkish in colour Bone consists of: Cells Fibers Ground substances Bone Cells; The bone contains four types of cells namely the osteoprogenator cells, osteoblasts, osteocytes, and the osteoclasts Bone Matrix (Intercellular substance);It is made up of the collagen fibers (osteocollagenous fibers), amorphous ground substance and inorganic salts which constitute about 74% of bone mass Types of Bones Long bones e.g. femur, tibia and fibula Short bones e.g. carpals (wrist bones) Flat bones e.g. sternum, ribs and most skull bones (skull) Irregular bones e.g. vertebrae and some skull bones Sesamoid bones e.g. patella (kneecap) Parts of the long bone A long bone is one that has greater length than width. A typical long bone consists of the following parts: The diaphysis is the bone’s shaft or body—the long, cylindrical, main portion of the bone. The epiphyses (singular is epiphysis) are the proximal and distal ends of the bone. The metaphyses (singular is metaphysis) are the regions between the diaphysis and the epiphyses. Bones Formation Bones formation is commonly referred to as ossification and it occurs in two processes Intramembranous Ossification The bones that form by this process include most of skull bones such as frontal,parietal, maxilla, mandible, clavicle and parts of occipital and temporal bones. Endochondral Ossification In endochondral ossification bone is formed from the pre-existing hyaline cartilage that has the shape that closely resembles the bone to be formed. Bones and Disorders of Connective Tissue Most long and irregular bones form via endochondral ossification, such as the base of the skull, vertebral column, the pelvis and bones of the extremities (limbs). During this process the cartilage is gradually replaced by bone. Only a small amount of cartilage remains covering the articular surfaces of the joints. During endochondral ossification the bone also grows in length and width. Generally flat bones develop by intramembranous ossification while long bones develop by intra cartilaginous ossification Bones formation occurs in four main stages which are Development of the ossification canters (special membrane) Formation of bone matrix Deposition of minerals or calcification Formation of trabeculae and appearance of periosteum Functions of Bones Support The skeleton serves as the structural framework for the body by supporting soft tissues providing attachment points for the tendons of most skeletal muscles Protection The skeleton protects the most important internal organs from injury for example, cranial bones protect the brain, vertebrae (backbones) protect the spinal cord, and the ribcage protects the heart and lungs. Movement When muscles contract, they pull on bones to produce movement. Mineral homeostasis (storage and release); Bone tissue stores several minerals, especially calcium and phosphorus, which contribute to the strength of bone Blood cell production; bone marrow produces red blood cells, white blood cells, and platelets, a process called hemopoiesis KEYPOINTS Bone is a hard and rigid connective tissue that forms the bony skeleton of the body Functions of bones Bone supports the body weight, It provides attachment to muscles, Acts as lever for movements, and provides protection to organs. Inside the bone there are spaces, which are filled with the bone marrow that produce Red blood cells, platelets and cells of the immune system. Production of body cells: monocytes, lymphocytes, mast cells, neutrophils, eosinophils and basophils QUESTIONS What is bone tissue? What are the types of bones? What are the functions of bones? Common Disorders of Connective Tissues PHARM. EMERENCIANA M. JAMES Common Disorders of Connective Tissues A connective tissue diseases are diseases that affect the joints (parts of the body that connect the structures of the body together). It is presented by the inflammation of the joints (arthritis) It may be infective or non-infective. In most cases, all signs of inflammation are present (swollen joints, hot, tender and red) and there is limitation of movements Common Types of Connective Tissue Diseases Acute pyrogenic arthritis Gout Chronic joint disease Osteoarthritis Generalized bone disease Osteomalacia Osteoporosis Acute pyrogenic arthritis This is the infection of the joints by pus-producing bacteria It is caused by any pyrogenic bacteria like staphylococci. The infection may start suddenly without any obvious cause or may occur from other septic focus nearby like osteomyelitis The patients complain of pain, swelling and reduced movement of the joint Gout This is arthritis due to congenital abnormality of uric acid metabolism, leading to abnormal high uric acid in the blood. Uric acid is deposited in joints and also around the

DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Lymphatic system and its diseases CRT04101 · Anatomy, Physiology and Pathology START READING NOTES Study Lymphatic system and its diseases using the sections below. Use the topic navigation to continue through Anatomy, Physiology and Pathology. Contents of This Topic By the end of this session students are expected to be able to: Definition and Organization of Lymphatic System Composition of Lymphatic System Lymphatic system and its diseases Tonsils They are: Thymus Spleen The white pulp is lymphatic tissue consisting mainly of lymphocytes around arteries. Bone marrow Functions of Lymph System Plasma filters into the interstitial spaces from blood flowing through the capillaries. If this would continue over even a brief period of time, the increased interstitial fluid would cause massive oedema. Absorption and transport of dietary fat, Immunity Common Disorder of the Lymphatic System Lymphadenopathy Lymphedema This most commonly occurs in women who have had surgery to remove a breast cancer. Infectious causes of lymphangitis Lymphoma Key Points Evaluation Assignment Structure, Functions and Common Disorders of Lymphatic System By the end of this session students are expected to be able to: Define Lymphatic System Explain the Organization of Lymphatic System the Structures Lymphatic System Describe Functions of Lymph System List the Common Disorders of the Lymphatic System What is lymphatic system? Definition and Organization of Lymphatic System Lymphatic system: A network of tissue, organs, and vessels that help to maintain the body‘s fluid balance, cleanse the body fluid of foreign matter and provide immune cells (lymphocytes) for defence Composition of Lymphatic System Lymph, the fluid corrected by the system from the interstitial spaces of the tissue and returns to the bloodstream. Lymphatic plexuses, networks of small lymphatic vessels, lymphatic capillaries, that originate in the extracellular spaces of most tissues. Lymphatic system and its diseases Lymphatic vessels (lymphatics), a nearly body wide network of thin-walled vessels with valves, originating from lymphatic plexuses along which lymph nodes are located. Lymph nodes, small masses of lymphatic tissue through which lymph is filtered on its way to the venous system. Lymphocytes, circulating cells of the immune system that react against foreign materials/microbes. Lymphatic system and its diseases Lymphoid tissue, sites that produce lymphocytes, such as that found in the walls of the digestive tract; in the spleen, thymus, and lymph nodes; and in myeloid tissue in red bone marrow. Lymphatic system and its diseases The lymphoid tissue is primarily involved in immune responses, and consists of lymphocytes and other white blood cells enmeshed in connective tissue through which the lymph passes. Lymphatic system and its diseases The lymphatic system differs from the circulatory system in the way that, the lymphatic do not form a closed ring or circuit. Instead, it begins blindly in the intercellular spaces of the soft tissues of the body. The Specialized organs of the lymphatic system are tonsils, thymus, bone marrow and spleen. Tonsils Masses of lymphoid tissue located in a protective ring under mucous membranes in the mouth and back of the throat. Help protect against bacteria that may invade tissues in the area around the openings between the oral and nasal cavities. They are: Palatine tonsils; located on each side of the throat. Pharyngeal tonsils; are near the posterior openings of the nasal cavity. Lingual tonsils; located near the base of the tongue Lymphatic system and its diseases The tonsils serve as the first line of defence from the exterior and as such are subject to chronic infection (tonsillitis). Thymus The thymus is located inferior to the thyroid gland. In the foetus and infant, the thymus is large and extends under the sternum Lymphatic system and its diseases The thymus hormones are necessary for immunological competence by enabling the T-cells to participate in the recognition of foreign antigens and provide immunity. This capability of T cells is established early in life and then is perpetuated by the lymphocytes themselves. Lymphatic system and its diseases The new-born‘s immune system is not yet fully mature, and infants are more susceptible to certain infections than are older children and adults. Usually by the age of 2 years, the immune system matures and becomes fully functional Spleen A soft, elongated wedge shaped purple organ Spleen is located in the left hypochondrium directly below the diaphragm, above the left kidney and descending colon, and behind the fundus of the stomach … The white pulp is lymphatic tissue consisting mainly of lymphocytes around arteries. The red pulp consists of venous sinuses filled with blood and cords of lymphatic cells, such as lymphocytes and macrophages. Arteries leading into each compartment are surrounded by dense masses (nodules) of developing lymphocytes Lymphatic system and its diseases Near the outer regions of each compartment is tissue called red pulp made up of fine reticular fibres submerged in blood that comes from nearby arteries. Lymphatic system and its diseases After passing through the reticular meshwork, blood collects in venous sinuses and then returns to the heart through Subclavian veins. Bone marrow Bone marrow is responsible for the production of blood cells: red blood cells, white blood cells, and platelets. Bone marrow stem cells play an important role in immunity as they generate lymphocytes Functions of Lymph System Maintenance of fluid balance in the body It returns excess fluid and proteins from the tissues that cannot be returned through the blood vessels. Lymphatic system and its diseases The fluid is found in tissue spaces and cavities, in the tiny spaces surrounding cells, known as the interstitial spaces. These are reached by the smallest blood and lymph capillaries Proteins that accumulate in the interstitial spaces can return to the blood only via lymphatic vessels. Plasma filters into the interstitial spaces from blood flowing through the capillaries. Much of this interstitial fluid is absorbed by tissue cells or reabsorbed by the blood before it flows out of the tissue. A small amount of interstitial fluid is left behind. Lymphatic system and its diseases Loss of the lymphatic system would be fatal within

DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Overview Of Muscle Tissues CRT04101 · Anatomy, Physiology and Pathology START READING NOTES Study Overview Of Muscle Tissues using the sections below. Use the topic navigation to continue through Anatomy, Physiology and Pathology. Contents of This Topic The three types of muscle tissue are skeletal, cardiac, and smooth. SKELETAL MUSCLE Overview Of Muscle Tissues CONNECTIVE TISSUE SHEATHS Epimysium. An overcoat of dense irregular connective tissue surrounds the whole muscle. ATTACHMENTS Muscle attachments, whether origin or insertion, may be direct or indirect. SMOOTH MUSCLE Smooth muscle lacks the coarse connective tissue sheaths seen in skeletal muscle. CARDIAC MUSCLE NERVOUS TISSUE NEUROGLIA Neuroglia in the CNS include astrocytes, microglia, ependymal cells, and oligodendrocytes. NEURONS 1. They have extreme longevity. Given good nutrition, neurons can function optimally for a lifetime (over 100 years). OVERVIEW OF MUSCLE AND NERVOUS TISSUES The three types of muscle tissue are skeletal, cardiac, and smooth. First, skeletal and smooth muscle cells (but not cardiac muscle cells) are elongated and, for this reason, are called muscle fibers. Second, muscle contraction depends on two kinds of myofilaments, which are the muscle equivalents of the actin- or myosin-containing microfilaments. These two proteins play a role in motility and shape changes in virtually every cell in the body, but this property reaches its highest development in the contractile muscle fibers. Third, whenever you see the prefixes myo or mys or sarco (flesh), the reference is to muscle SKELETAL MUSCLE Each skeletal muscle is a discrete organ, made up of several kinds of tissues. Although skeletal muscle fibers predominate, blood vessels, nerve fibers, and substantial amounts of connective tissue are also present. A skeletal muscle’s shape and its attachments in the body can be examined easily without the help of a microscope. Overview Of Muscle Tissues In general, each muscle is served by one nerve, an artery, and by one or more veins, all of which enter or exit near the central part of the muscle and branch profusely through its connective tissue sheaths. Unlike cells of cardiac and smooth muscle tissues, which can contract in the absence of nerve stimulation, each skeletal muscle fiber is supplied with a nerve ending that controls its activity. Overview Of Muscle Tissues Contracting muscle fibers use huge amounts of energy, a situation that requires more or less continuous delivery of oxygen and nutrients via the arteries. Muscle cells also give off large amounts of metabolic wastes that must be removed through veins if contraction is to remain efficient. Muscle capillaries, the smallest of the body’s blood vessels, are long and winding and have numerous cross-links, features that accommodate changes in muscle length. CONNECTIVE TISSUE SHEATHS In an intact muscle, the individual muscle fibers are wrapped and held together by several different connective tissue sheaths. Together these connective tissue sheaths support each cell and reinforce the muscle as a whole, preventing the bulging muscles from bursting during exceptionally strong contractions. Overview Of Muscle Tissues Endomysium. Each individual muscle fiber is surrounded by a fine sheath of connective tissue consisting of areolar and reticular fibers. Perimysium and fascicles. Within each skeletal muscle, the endomysium-wrapped muscle fibers are grouped into fascicles that resemble bundles of sticks. Surrounding each fascicle is a layer of fibrous connective tissue called perimysium. Epimysium. An overcoat of dense irregular connective tissue surrounds the whole muscle. This coat is the epimysium, a name that means outside the muscle. Sometimes the epimysium blends with the deep fascia that lies between neighboring muscles or the superficial fascia deep to the skin ATTACHMENTS Most skeletal muscles span joints and are attached to bones (or other structures) in at least two places. When a muscle contracts, the movable bone, the muscle’s insertion, moves toward the immovable or less movable bone, the muscle’s origin. In the muscles of the limbs, the origin typically lies proximal to the insertion Muscle attachments, whether origin or insertion, may be direct or indirect. In direct, or fleshy, attachments, the epimysium of the muscle is fused to the periosteum of a bone or perichondrium of a cartilage. In indirect attachments, the muscle’s connective tissue wrappings extend beyond the muscle either as a ropelike tendon or as a sheetlike aponeurosis. The tendon or aponeurosis anchors the muscle to the connective tissue covering of a skeletal element (bone or cartilage) or to the fascia of other muscles SMOOTH MUSCLE Smooth muscle fibers are spindle-shaped cells, each with one centrally located nucleus. Typically, they have a diameter of 5–10 µm and are 30–200 µm long. Skeletal muscle fibers are some 10 times wider and thousands of times longer. Smooth muscle lacks the coarse connective tissue sheaths seen in skeletal muscle. However, a small amount of fine connective tissue, secreted by the smooth muscles themselves and containing blood vessels and nerves, is found between smooth muscle fibers. Most smooth muscle is organized into sheets of closely apposed fibers. These sheets occur in the walls of all but the smallest blood vessels and in the walls of hollow organs of the respiratory, digestive, urinary, and reproductive tracts CARDIAC MUSCLE like skeletal muscle, is striated, and it contracts by the sliding filament mechanism. However, in contrast to the long, cylindrical, multinucleate skeletal muscle fibers, cardiac cells are short, fat, branched, and interconnected. Each fiber contains one or at most two large, pale, centrally located nuclei. The intercellular spaces are filled with a loose connective tissue matrix (the endomysium) containing numerous capillaries. This delicate matrix is connected to the fibrous skeleton, which acts both as a tendon and as an insertion, giving the cardiac cells something to pull or exert their force against Overview Of Muscle Tissues Large mitochondria account for 25–35% of the volume of cardiac cells and give cardiac cells a high resistance to fatigue. Most of the remaining volume is occupied by myofibrils composed of fairly typical sarcomeres. The sarcomeres have Z discs, A bands, and I bands that reflect the arrangement of the thick (myosin) and thin (actin)

DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Nervous Tissue CRT04101 · Anatomy, Physiology and Pathology START READING NOTES Study Nervous Tissue using the sections below. Use the topic navigation to continue through Anatomy, Physiology and Pathology. Contents of This Topic Nervous tissue or nerve tissue: Components of Nervous Tissue A typical Neuron consist of: Types of Neurons Classification of Neurons according to their Functional Roles Neuroglia (Glial Cells) Microglia Glia Cells Found in the Peripheral Nervous System NERVOUS TISSUE Nervous tissue or nerve tissue: Is a complex network of cells that makes up the brain,spinal cord and nerves which are responsible for controlling and coordinating many of body’s activities. It creates two parts of the nervous system,which are; 1.The brain and spinal cord of the Central nervous system (CNS) and 2.The peripheral nerves of the Peripheral nervous system (PNS) Nervous tissue is distributed throughout the body as an integrated communications network. Components of Nervous Tissue Structurally, nerve tissue consists of two classes of cell types. 1.Neurons, Nervous tissue is made up of billions of cells called neurons that are specialized to respond to stimuli and to transmit a signal to activate other cells. 2.Glial cells or neuroglia (non-excitable supporting cells), They participate in neural activity, neural nutritional and defence processes of the central nervous system. A typical Neuron consist of: Cell body, which has many radiating processes called dendrites, which are specialized to receive signals from other neurons. Axon, a single long process, which is capable of generating a nerve impulse and conducting it over a long distance to stimulate other neurons in the CNS, or muscular or secretory cells elsewhere in the body. Neurons usually receive information through dendrites; the information is integrated in the cell body and transmitted onwards via axons. Types of Neurons 1.Unipolar neurons, These neurons have single processes, the axon arising from the cell body.Unipolar neurons have no dendrites. 2.Bipolar neurons, Have two processes (both axons) emerging directly and oppositely from the cell body. Bipolar neurons are found in the cochlear and vestibular ganglia as well as retina and olfactory mucosa. 3.Multipolar neurons, Has one axon and many dozens of dendrites.Most neurons in the CNS are multipolar. 4.Pseudo unipolar neurons, Has a single short process (an axon) with a T-shaped branching, one branch extending towards the CNS, and the other extending to a periphery ending.In typical pseudo unipolar neurons, both branches are axons on both structural and electrophysiological grounds. Classification of Neurons according to their Functional Roles Motor neurons, They are involved in stimulating muscles or glands (effector organs) in the periphery. Sensory neurons, Sensory neurons receive sensory stimuli from the environment or from tissues and organs of the body. Inter-neurons, They maintain connection between neurons in the CNS, forming complex functional chains or circuits Neuroglia (Glial Cells) These are supporting cells found in the central nervous system and peripheral nervous system.There are six types of supporting cells whereas four are found in the CNS and two are found in the PNS. Neuroglia found in central nervous system are; Astrocytes Star-shaped, abundant, and versatile cells which guide the migration of developing neurons, they are found in large numbers adjacent to blood vessels. They form a blood-brain barrier, i.e. the blood is separated from neurones by capillary wall and a layer of astrocytes foot process. Microglia Specialized immune cells that act as the macrophages of the CNS and they derived from monocytes. Ependymal Cells These cells form the epithelial lining of the ventricles of the brain and the central canal of the spinal cord. Oligodendrocytes These are found in clusters around cell bodies.They form and maintain the myelin, having the same functions as schwann cells in peripheral nerves. These cells have clinical importance as most tumours of the brain are arising from them. Glia Cells Found in the Peripheral Nervous System Satellite cells, surround clusters of neuronal cell bodies in the PNS, they are of unknown function Schwann cells, form myelin sheaths around the larger nerve fibers in the PNS, they are for neuronal regeneration ← PREVIOUS TOPICNEXT TOPIC →VIEW ALL MODULE NOTESVIEW SEMESTER NOTESVIEW ALL LEVEL NOTESALL DIAGNOSTIC RADIOLOGY NOTES Need These Notes as PDF? Need a clean, well-formatted PDF copy for offline study, revision or printing? Request the complete notes directly through WhatsApp. GET WELL-FORMATTED PDF NOTES

DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Nervous System CRT04101 · Anatomy, Physiology and Pathology START READING NOTES Study Nervous System using the sections below. Use the topic navigation to continue through Anatomy, Physiology and Pathology. Contents of This Topic Nervous System Division of nervous system: Present in the cranial cavity Don’t get confused about simple anatomy on parts of the brain- fore brain,mid brain and hind brain Brain and spinal cord composed of grey mater and white mater Brain The diencephalon is located at the center of the brain, and its name (Greek for “between-brain”) reflects that. The corpus callosum is the bridge between the left and right sides of the brain The Meninges Ventricular system Ventricles of the Brain lateral ventricles Fourth ventricle It is also found inside the subarachnoid space of the meninges which surrounds both the brain and the spinal chord. Ependymal cell, Composition of CSF PNS Cranial nerve spinal cord Spinal nerves T1–T6 Intercostals and trunk above the waist Brain Present in the cranial cavity. Diencephalon. Hypothalamus. Meninges of the Brain. Peripheral Nervous System. Nervous System Nervous System The nervous system is responsible for controlling much of the body, both through somatic (voluntary) and autonomic (involuntary) functions It is very important in helping to maintain balance of the body Made up of nerve tissue neurones and neuroglia Nervous system enables the body to react to continuous changes in its internal and external environment Division of nervous system: Nervous system is divided Structurally into Central nervous system Peripheral nervous system Functionally into Somatic Autonomic Present in the cranial cavity Surrounded by three layers of meninges Don’t get confused about simple anatomy on parts of the brain- fore brain,mid brain and hind brain brain has 2 hemispheres namely right and left hemisphere has 4 lobes namely occipital lobe,pariental lobe,frontal lobe and temporal lobe Brain and spinal cord composed of grey mater and white mater Grey mater formed by nerve cell bodies White mater formed by interconnecting fibre tract system Brain Forebrain (prosencephalon)-cerebrum,thalamus+hypothalamus form limbic system(regulation of thirst, hunger, mood) and basal ganglia (reward processing, habit formation, movement and learning Midbrain(mesencephalon)-tectum,tegmentum Hind brain (rhombencephalon)- cerebellum,pons,medulla oblangata Applied anatomy:degeneration of basal ganglia cells uncoordinated movements of skeletal muscles e.g in Parkinson’disease NB: midbrain, pons and medulla form the brain stem Development of brain Nervous System v vv The diencephalon is located at the center of the brain, and its name (Greek for “between-brain”) reflects that. It’s surrounded by the brain stem and cerebellum on the bottom and the cerebral cortex on top. The corpus callosum is the bridge between the left and right sides of the brain The corpus callosum (Latin for "tough body") The Meninges The central nervous system consists of the brain and spinal cord. The brain and spinal cord are completely covered by three membranes, the meninges lying between the skull and the brain, and between vertebrae and the spinal cord. o Dura mater o Arachnoid mater o Pia mater Ventricular system Ventricular system is a communicating system of cavities underlined by choroid plexus which produce cerebrospinal fluid and transport it around the cranial cavity. They are lined by ependymal cells. There are ventricles:- Lateral ventricles Third ventricle Fourth ventricle Central Canal. Ventricles of the Brain Within the brain there are four irregular shaped cavities containing cerebrospinal fluid. They are called ventricles, these are o Right and left lateral ventricles o third ventricle and fourth ventricle lateral ventricles lateral ventricles are the two largest cavities of the ventricular system of the human brain and contain cerebrospinal fluid (CSF). Each cerebral hemisphere contains a lateral ventricle, known as the left or right ventricle They open into the 3rd ventricle through the interventricular foramina (of monro). They are separated from each other by a thin membrane, the septum lucidium,and are lined by ciliated epithelium (ependymal cells). 3rd ventrical It is a cavity situated below the lateral ventricles between the two parts of the thalamus. Fourth ventricle It is situated below and behind the third ventricle, between the cerebellum and pons. It communicates with the subarachnoid space by 3 foramina in its roof, and continuous below with central canal of the spinal cord The fourth ventricle contains cerebrospinal fluid. It has a diamond shape and is located in the upper portion of the medulla CEREBRAL SPINAL FLUID It is also found inside the subarachnoid space of the meninges which surrounds both the brain and the spinal chord. In addition, a space inside the spinal chord called the central canal also contains cerebrospinal fluid CSF is produced mainly by a structure called the choroid plexus in the lateral, third and fourth ventricles. A small amount is also produced by ependymal cells. Ependymal cell, type of neuronal support cell (neuroglia) that forms the epithelial lining of the ventricles (cavities) in the brain and the central canal of the spinal cord. Composition of CSF It consists of Water Mineral salts Glucose Plasma proteins: small amount of albumin and globulin Small amount of creatinine, urea A few leukocytes It is slightly alkaline Functions of CSF Applied anatomy Hydrocephalus PNS 12 pairs of cranial nerves—leave the brain and pass through the foramina in the skull 31 pairs of spinal nerves—leave the spinal cord and pass through intervertebral foramina Cranial nerve any of the nerves that arise in pairs from the lower surface of the brain one on each side and pass through openings in the skull to the periphery of the body and that comprise 12 pairs. They can be classified as sensory nerves, motor nerves, or a combination of both, primarily responsible for the sensory and motor functions of the head and neck (one of these nerves targets organs in the thoracic and abdominal cavities as part of the parasympathetic nervous system). spinal cord cervical segments thorathic segments lumbar segments sacral segments coccygeal segements Origin of spinal nerves Spinal nerves Actions of the spinal nerves Level Motor Function C1–C6: Neck flexors C1–T1: Neck extensors C3, C4, C5=Phrenic nerve Supply diaphragm

DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Musculoskeletal System CRT04101 · Anatomy, Physiology and Pathology START READING NOTES Study Musculoskeletal System using the sections below. Use the topic navigation to continue through Anatomy, Physiology and Pathology. Contents of This Topic Musculoskeletal System Axial skeleton Outside the bony skull there is a layer with fascia and muscles known as scalp which covers the skull The spine Atlas Axis (C2) Thoracic spine Lumbar spine Sacrum MUSCULOSKELETAL SYSTEM Musculoskeletal System The musculoskeletal system is an interconnected structure of bone, muscle, cartilage, tendons, and other tissues that give our bodies form, support, movement, and the ability to do work. Skeleton is made up of 206 bones that articulates together to form joints that support balance and movement. It is classified into two forms,which are; 1.Axial skeleton 2.Appendicular skeleton Axial skeleton It consists of skull,spine and pelvis bones The Skull Skull is the most superior part of the bodily structure and has total of 22 bones which are divided in two categories,which are; 1.Cranial bones (8 bones) 2.Facial bones (14 bones) Outside the bony skull there is a layer with fascia and muscles known as scalp which covers the skull And inside the skull there is strong layer that protects the brain from trauma is called meninge Meninges has three layers,which are; 1.Dura matter 2.Arachnoid matter 3.Pia matter The space btn dura and arachnoid matter is called subdural space while a space btn arachnoid and pia matter is called subarachnoid space Cranial bones The spine It is fundamental structure in body balance,support,coordination and movement.It consists of 33 vertebral bodies that are divided into 5 categories depending on the position and function. Cervical spine The cervical spine is the first part of the spinal column, consisting of 7 cervical vertebrae, C1-C7. These vertebrae are ring-like bony structures supporting the weight of the head. The first two bones, C1 and C2, are highly specialized, known as the atlas and axis.It is found at the neck posteriorly surrounded by adjacent muscles that support neck movement i.e sternocleiodomastoid Atlas Located at the top of the spine,the atlas forms the articulation with the occipital bone, connecting the skull and spine. Its primary difference from the other vertebrae in the cervical region is the absence of a vertebral body and spinous process. Its lateral masses are connected by the anterior and posterior arches. Axis (C2) It forms the pivot upon which the Atlas rotates (atlanto-axial joint), letting us rotate our head independently of the body. The most identifiable landmark of this bone is the strong odontoid process or dens that rises perpendicularly from the upper surface of the body and articulates with the atlas’ anterior arch. There are also articulations between the axis’s superior articular facets and the atlas’ inferior articular facets. Between two vertebral bodies there is catilagenous roundish pad known as intervertebral disc. Thoracic spine It is below the cervical spine and it is made up of 12 vertebral bodies.Bends posteriorly creating thoracic kyphosis. Has articulating facets both superiorly and inferiorly for rib attachment thus involved in creating thoracic cage posteriorly Lumbar spine Has 5 vertebral bodies joined up by intervertebral discs.They are wide and tough as it creates the base of the spine.It is tightly hold up by psoas and iliopsoas muscles.It bend anteriorly resulting into lumnar lordosis. Sacrum It consist of 5 fused vertebra with 4 paired sacral foramens for passage of spinal nerves.It is involved in creating pelvic brim posteriorly and it is attached to iliac spine by sacroiliac joint in both left and right side Coccyx It consist of 4 fused small vertebral bodies and it is the last segment of the spine.It is known as the spine tail. Pelvis ← PREVIOUS TOPICNEXT TOPIC →VIEW ALL MODULE NOTESVIEW SEMESTER NOTESVIEW ALL LEVEL NOTESALL DIAGNOSTIC RADIOLOGY NOTES Need These Notes as PDF? Need a clean, well-formatted PDF copy for offline study, revision or printing? Request the complete notes directly through WhatsApp. GET WELL-FORMATTED PDF NOTES

DIAGNOSTIC RADIOGRAPHY · NTA LEVEL 4 · SEMESTER ONE Musculoskeletal CRT04101 · Anatomy, Physiology and Pathology START READING NOTES Study Musculoskeletal using the sections below. Use the topic navigation to continue through Anatomy, Physiology and Pathology. Contents of This Topic BONES AND CARTILAGES Musculoskeletal HYALINE CARTILAGES Skeletal hyaline cartilages include: ELASTIC CARTILAGES FIBROCARTILAGES CLASSIFICATION OF BONES Bones come in many sizes and shapes. 2. Short bones are roughly cube shaped. 3. Flat bones are thin, flattened, and usually a bit curved. FUNCTIONS OF BONES 2. PROTECTION. The fused bones of the skull protect the brain. 4. MINERAL AND GROWTH FACTOR STORAGE. Bone is a reservoir for minerals, most importantly calcium and phosphate. BONE STRUCTURE BONE MARKINGS These bone markings are named in different ways. BONE TEXTURES: COMPACT AND SPONGY BONE DIAPHYSIS EPIPHYSES MEMBRANES Internal bone surfaces are covered with a delicate connective tissue membrane called the endosteum . STRUCTURE OF SHORT, IRREGULAR, AND FLAT BONES LOCATION OF HEMATOPOIETIC TISSUE IN BONES BONE DEVELOPMENT FORMATION OF THE BONY SKELETON BONE HOMEOSTASIS: REMODELING AND REPAIR Spongy bone is replaced every three to four years; compact bone, every ten years. BONE REMODELING Bone deposit occurs wherever bone is injured or added bone strength is required. BONE REPAIR FRACTURES CLASSIFICATION 3. Orientation of the break relative to the long axis of the bone. 4. Whether the bone ends penetrate the skin. A fracture is treated by reduction, the realignment of the broken bone ends. Repair in a simple fracture involves four major stages Fibrocartilaginous callus formation. Bony callus formation. SKELETAL SYSTEM BONES AND CARTILAGES A skeletal cartilage is made of some variety of cartilage tissue, which consists primarily of water. The high water content of cartilage accounts for its resilience, that is, its ability to spring back to its original shape after being compressed. Musculoskeletal The cartilage, which contains no nerves or blood vessels, is surrounded by a layer of dense irregular connective tissue, the perichondrium. The perichondrium acts like a girdle to resist outward expansion when the cartilage is compressed. HYALINE CARTILAGES Which look like frosted glass when freshly exposed, provide support with flexibility and resilience. They are the most abundant skeletal cartilages. When viewed under the microscope, their chondrocytes appear spherical. The only fiber type in their matrix is fine collagen. Skeletal hyaline cartilages include: Articular cartilages, which cover the ends of most bones at movable joints. Costal cartilages, which connect the ribs to the sternum (breastbone) Respiratory cartilages, which form the skeleton of the larynx (voicebox), and reinforce other respiratory passageways. Nasal cartilages, which support the external nose. ELASTIC CARTILAGES Look very much like hyaline cartilages, but they contain more stretchy elastic fibers and so are better able to stand up to repeated bending. They are found in only two skeletal locations the external ear and the epiglottis (the flap that bends to cover the opening of the larynx each time we swallow). FIBROCARTILAGES Are highly compressible and have great tensile strength. The perfect intermediate between hyaline and elastic cartilages, fibrocartilages consist of roughly parallel rows of chondrocytes alternating with thick collagen fibers. Fibrocartilages occur in sites that are subjected to both heavy pressure and stretch, such as the padlike cartilages (menisci) of the knee and the discs between vertebrae CLASSIFICATION OF BONES The 206 named bones of the human skeleton are divided into two groups: axial and appendicular. The axial skeleton forms the long axis of the body and includes the bones of the skull, vertebral column, and rib cage. Generally speaking these bones are most involved in protecting, supporting, or carrying other body parts. Musculoskeletal The appendicular skeleton consists of the bones of the upper and lower limbs and the girdles (shoulder bones and hip bones) that attach the limbs to the axial skeleton. Bones of the limbs help to get from place to place (locomotion) and to manipulate our environment. Bones come in many sizes and shapes. For example, the pisiform bone of the wrist is the size and shape of a pea, whereas the femur (thigh bone) is nearly 2 feet long in some people and has a large ball-shaped head. The unique shape of each bone fulfills a particular need. Musculoskeletal For the most part, bones are classified by their shape as long, short, flat, and irregular . 1. Long bones, as their name suggests, are considerably longer than they are wide. A long bone has a shaft plus two ends. All limb bones except the patella (kneecap) and the wrist and ankle bones are long bones. Notice that these bones are named for their elongated shape, not their overall size. 2. Short bones are roughly cube shaped. The bones of the wrist and ankle are examples. Sesamoid bones are a special type of short bone that form in a tendon (for example, the patella). They vary in size and number in different individuals. 3. Flat bones are thin, flattened, and usually a bit curved. The sternum (breastbone), scapulae (shoulder blades), ribs, and most skull bones are flat bones. Irregular bones have complicated shapes that fit none of the preceding classes. Examples include the vertebrae and the hip bones. FUNCTIONS OF BONES Besides contributing to body shape and form, our bones perform several important functions: SUPPORT. Bones provide a framework that supports the body and cradles its soft organs. For example, bones of lower limbs act as pillars to support the body trunk when we stand, and the rib cage supports the thoracic wall. 2. PROTECTION. The fused bones of the skull protect the brain. The vertebrae surround the spinal cord, and the rib cage helps protect the vital organs of the thorax. Musculoskeletal MOVEMENT. Skeletal muscles, which attach to bones by tendons, use bones as levers to move the body and its parts. As a result, we can walk, grasp objects, and breathe. The design of joints determine the types of movement possible. 4. MINERAL AND GROWTH FACTOR STORAGE. Bone is a reservoir for minerals, most importantly calcium and phosphate. The stored minerals are