The Skeletal System

Course Overview, Syllabus, and Medical Terminology Fundamentals

• Course Details & Expectations

  • Textbook Requirement: Medical Terminology for Health Professions, 7th Edition by Ann Ehrlich and Carol L. Schroeder.

  • Course Goal: Understand and correctly apply the medical language used by healthcare professionals to describe the human body in health and disease, including methods of diagnosis and treatment.

  • Learning Outcomes: Develop the ability to use, spell, define, and pronounce primary medical terms related to anatomy, physiology, diagnosis, pathology, and treatment across all major body systems.

  • Course Format: Flipped Classroom approach.

    • Watch pre-recorded lectures prior to class sessions.

    • Review lecture slides and take notes.

    • Engage in active learning during class (case studies, group activities, practice questions).

  • Grading Criteria:

    • 4 Online Non-Cumulative Exams = $80\%$ of total grade ($50$ multiple-choice questions per exam, $80$ minutes allowed, $1$ attempt).

    • Assignments = $10\%$ of total grade.

    • Attendance and Participation = $10\%$ of total grade (mandatory attendance; zero-tolerance policy for cheating; no extra credit assignments).

  • Learning Strategies: Use multi-sensory reinforcement (reading, writing, speaking aloud, and listening via online audio glossaries). Create flashcards to memorize definitions.

• Course Schedule

• Purpose of Medical Terminology

  • Provides standard, precise, and consistent communication for healthcare professionals worldwide.

  • Eliminates ambiguity present in everyday language.

  • Derived predominantly from classical Greek and Latin word roots.

Word Parts and Building Medical Terms

• Four Primary Types of Word Parts

  • Word Root: The core or main part of the word that establishes its basic meaning. Usually describes the involved body part or organ. Cannot stand alone as a complete term. Multiple roots can share the same meaning (e.g., nephr and ren both mean kidney).

  • Combining Form: A word root combined with a combining vowel (usually o, occasionally i or e) separated by a slash (e.g., cardi/o, gastr/o). Facilitates pronunciation when joining word parts.

  • Prefix: A short word part placed at the beginning of a medical term to modify its meaning. Typically indicates location, time, number, direction, or degree. Spelled with a trailing hyphen (e.g., pre-, hyper-). Not present in all medical terms.

  • Suffix: A word part placed at the end of a word root to modify its meaning. Typically indicates a procedure, condition, disorder, specialty, or disease. Spelled with a leading hyphen (e.g., -itis, -ectomy). Present in every medical word.

• Compound Words

  • Medical terms containing more than one word root (e.g., cardiovascular = pertaining to heart and blood vessels; urogenital = pertaining to urinary and reproductive systems; lymphocyte = white blood cell found in the lymphatic system).

• Rules for Using Combining Vowels and Forms

  • Insert a combining vowel (usually o) before a suffix that begins with a consonant (e.g., neur/o + -logy = neurology).

  • Omit the combining vowel if the suffix begins with a vowel (e.g., neur/o + -itis = neuritis; tonsill + -itis = tonsillitis; arthr/o + -itis = arthritis).

  • If a suffix begins with the same vowel that ends a combining form, do not repeat the vowel (e.g., cardi/o + -itis = carditis).

  • Always keep the combining vowel between two word roots in a compound word, regardless of whether the second root starts with a vowel (e.g., my/o + cardi/o + -al = myocardial; oste/o + arthr/o + -itis = osteoarthritis).

• Rules for Words Ending in 'x'

  • When adding a suffix to a word root ending in x, change x to g or c:

    • If a consonant precedes x, change x to g (e.g., pharynx becomes pharyngeal).

    • If a vowel precedes x, change x to c (e.g., thorax becomes thoracotomy).

• Special "Double R" Suffixes

  • Suffixes derived from Greek beginning with rh: when attached to a root, the r is doubled (rh becomes rrh).

    • -rhage / -rhagia: Bursting forth or profuse flow (e.g., hem/o + -rhage = hemorrhage, a profuse flow of blood).

    • -rrhaphy: Surgical suturing (e.g., my/o + -rrhaphy = myorrhaphy, surgical suturing of a muscle wound).

    • -rrhea: Flow or discharge of body fluids (e.g., dia- + -rrhea = diarrhea, frequent flow of loose or watery stools).

    • -rrhexis: Rupture (e.g., my/o + -rrhexis = myorrhexis, rupture of a muscle).

• Steps for Dissecting and Defining Medical Terms

  1. Identify the suffix first and define it.

  2. Identify the prefix (if present) and define it second.

  3. Identify the word root(s) and define them last.

  4. Read from right to left across the components (e.g., intracardiac: -ac = pertaining to, intra- = within, cardi = heart \n\n\rightarrow \n pertaining to within the heart).

  5. When identifying body systems or organs in compound terms, define the suffix first, then define the organs in the order they are studied in the body system (e.g., cardiopulmonary: -ary = pertaining to, cardi = heart, pulmon = lungs \n\n\rightarrow \n pertaining to the heart and lungs).

Medical Language Rules, Pronunciation, Spelling, and Practice Questions

• Phonetic Pronunciation Rules

  • Primary emphasis is indicated in UPPERCASE BOLDFACE letters (e.g., eh-DEE-mah).

  • Secondary emphasis is indicated in lowercase boldface letters (e.g., ah-pen-dih-SIGH-tis).

  • Silent Letters & Initial Sounds:

    • ps at the beginning of a word is pronounced like s (e.g., psychology, Pseudomonas).

    • pn at the beginning of a word is pronounced like n (e.g., pneumonia).

    • kn at the beginning of a word is pronounced like n (e.g., knee).

    • ph sounds like f (e.g., physiology, phlegm).

    • x at the beginning of a word sounds like z (e.g., xanthoma, zygomatic).

    • ch sounds like k (e.g., chemistry, chorion).

  • Hard vs. Soft Consonants:

    • g sounds soft like j, and c sounds soft like s when preceding e, i, or y (e.g., gene, pharyngitis, cycle, cervix, cyst).

    • g has a hard "guh" sound, and c has a hard "k" sound when preceding a, o, or u (e.g., gangrene, meningocele, cornea, cancer, cuticle, collagen).

  • Diphthongs & Endings:

    • ae and oe are pronounced as ee (e.g., fasciae).

    • i at the end of a word is pronounced eye and usually indicates a plural form (e.g., fasciculi).

    • es at the end of a word is pronounced as a separate syllable (e.g., nares).

• Plural Endings & Rules

• Plural Exceptions: The plural of sinus is sinuses; the plural of virus is viruses; the plural of serum can be sera or serums.

• Spelling Precautions & Look-Alike/Sound-Alike Terms

  • Accurate spelling is critical to prevent fatal clinical errors.

  • arteri/o (artery) vs. ather/o (plaque, fatty substance) vs. arthr/o (joint).

  • -ectomy (surgical removal) vs. -ostomy (surgical creation of an artificial opening) vs. -otomy (cutting/surgical incision).

  • ileum (ILL-ee-um): the last and longest portion of the small intestine (remember e as in intestine).

  • ilium (ILL-ee-um): part of the hip bone (remember i as in hip).

Anatomic Reference Systems, Planes, Directions, and Cavities

• Anatomic Reference Systems

  • Used to describe the location of structural units of the body using planes, directions, cavities, and structural organs.

• Anatomy vs. Physiology

  • Anatomy: The study of the structures of the body.

  • Physiology: The study of the functions of the structures of the body (physi: nature or physical; -ology: study of).

• Anatomic Position

  • Standard baseline reference point for all spatial descriptions:

    • Body standing erect and upright.

    • Facing directly forward.

    • Arms resting at the sides with palms facing forward.

    • Feet parallel and flat on the floor.

• Body Planes

  • Imaginary vertical and horizontal lines used to divide the body into sections.

  • Midsagittal Plane (Midline): Vertical plane that divides the body into equal left and right halves.

  • Sagittal Plane: Vertical plane parallel to the midline dividing the body into unequal left and right portions.

  • Frontal (Coronal) Plane: Vertical plane that divides the body into anterior (front) and posterior (back) portions.

  • Transverse (Horizontal) Plane: Horizontal plane that divides the body into superior (upper) and inferior (lower) portions.

• Directional Terms

• Major Body Cavities

  • Hollow spaces within the body that enclose and protect internal organs.

  • Dorsal Cavity (Back of body and head; contains nervous system organs):

    • Cranial Cavity: Located within the skull; surrounds and protects the brain.

    • Spinal Cavity (Canal): Located within the spinal column; surrounds and protects the spinal cord.

  • Ventral Cavity (Front of body; contains organs sustaining homeostasis):

    • Thoracic Cavity (Chest Cavity): Located above the diaphragm; surrounds and protects the heart and lungs.

    • Abdominal Cavity: Located below the diaphragm and above the pelvic cavity; contains major digestive organs.

    • Pelvic Cavity: Located below the abdominal cavity, bounded by hip bones; contains excretory and reproductive organs.

    • Abdominopelvic Cavity: The combined continuous ventral space between the diaphragm and pelvis.

Abdominal Regions, Quadrants, and Membranes

• Nine Abdominal Regions

  • Used to precisely locate abdominal organs and clinical symptoms (ordered top to bottom, left to right):

    1. Right Hypochondriac Region: Upper right region below the ribs (hypo- = below; chondr/i = cartilage).

    2. Epigastric Region: Upper middle region located above the stomach (epi- = above; gastr = stomach).

    3. Left Hypochondriac Region: Upper left region below the ribs.

    4. Right Lumbar Region: Middle right region near the inward curve of the spine (lumb = lower back).

    5. Umbilical Region: Center middle region surrounding the umbilicus (navel).

    6. Left Lumbar Region: Middle left region near the spine.

    7. Right Iliac Region: Lower right region located over the hip bone (ili = hip bone).

    8. Hypogastric Region: Lower middle region located below the stomach (hypo- = below; gastr = stomach).

    9. Left Iliac Region: Lower left region located over the hip bone.

• Four Abdominal Quadrants

  • Divided by vertical and horizontal lines intersecting at the umbilicus:

    • Right Upper Quadrant (RUQ)

    • Left Upper Quadrant (LUQ)

    • Right Lower Quadrant (RLQ)

    • Left Lower Quadrant (LLQ)

• Peritoneum

  • Multilayered serous membrane lining the abdominopelvic cavity and holding organs in place.

  • Parietal Peritoneum: The outer layer that lines the interior of the abdominal wall.

  • Mesentery: A double layer of peritoneum that attaches parts of the intestine to the interior abdominal wall.

  • Visceral Peritoneum: The inner layer that directly coats and surrounds the organs of the abdominal cavity.

Structural Organization of the Body: Cells and Genetics

• Levels of Structural Organization

  • Chemicals $\rightarrow$ Cells $\rightarrow$ Tissues $\rightarrow$ Organs $\rightarrow$ Organ Systems $\rightarrow$ Whole Body.

• The Cell

  • Basic structural and functional unit of living organisms.

  • Performs metabolism: the sum of all physical and chemical activities occurring within the body.

  • Generates energy in the form of ATP (adenosine triphosphate).

  • cytology: Study of cells; cytologist: Specialist in the study and analysis of cells.

• Organic Compounds in Cells

  • Proteins: Structural materials, enzymes (speed up metabolic reactions), and hormones.

  • Carbohydrates: Sugars and starches; primary energy source is the simple sugar glucose (gluc/o, glyc/o).

  • Lipids: Fats (lip/o, adip/o, steat/o).

• Structure and Function of Cell Organelles

• Genetics and DNA

  • Gene: The fundamental physical/functional unit of heredity occupying a specific locus on a chromosome. Composed of DNA sequences controlling protein/enzyme synthesis. RNA aids in assembling proteins.

  • Inheritance: Each individual receives $2$ genes for every trait ($1$ from the father, $1$ from the mother).

    • Dominant Gene: Inherited from either parent; condition/trait will be expressed.

    • Recessive Gene: Trait expressed only if inherited from both parents ($2$ copies). If paired with a normal dominant gene, the individual is a carrier (does not express trait, but can pass it to offspring).

  • Chromosomes: Nuclear structures made of coiled DNA molecules.

    • Somatic Cells: All body cells except sex cells. Contain $46$ chromosomes ($23$ pairs: $22$ autosome pairs, $1$ sex pair—XX for female, XY for male).

    • Gametes: Sex cells (sperm or egg). Contain $23$ single chromosomes.

  • Genetic Mutations: Changes in DNA sequences.

    • Somatic Cell Mutation: Cannot be passed to offspring.

    • Gametic Cell Mutation: Occurs in sex cells; can be transmitted to future generations.

  • Genetic Disorders:

    • Cystic Fibrosis (CF): Genetic disorder affecting respiratory and digestive systems.

    • Down Syndrome (Trisomy 21): Presence of $3$ copies of chromosome $21$; causes characteristic facial features, learning disabilities, and physical defects.

    • Hemophilia: Group of hereditary bleeding disorders caused by missing clotting factors.

Tissues, Tissue Pathology, and Glands

• Histology

  • Microscopic study of tissues (hist/o = tissue; histologist = non-physician specialist in microscopic tissue structures).

• Four Primary Tissue Types

  • Epithelial Tissue: Covers internal and external body surfaces.

    • Epithelium: Specialized tissue forming skin epidermis and mucous membrane surface layers.

    • Endothelium: Lines blood and lymph vessels, body cavities, glands, and organs.

    • Simple Epithelium: Single layer; absorbs substances (e.g., respiratory and digestive tracts).

    • Stratified Epithelium: Multiple layers; protects underlying tissues (e.g., mouth, vagina).

  • Connective Tissue: Supports and binds body structures.

    • Dense Connective Tissue: Forms joints, bones, and cartilage.

    • Adipose Tissue: Provides padding, insulation, and fat storage (adip = fat; -ose = pertaining to).

    • Loose Connective Tissue: Surrounds organs, supporting nerves and blood vessels.

    • Liquid Connective Tissue: Blood and lymph; transports nutrients and wastes.

  • Muscle Tissue (my/o):

    • Skeletal Muscle: Attached to bones; striated; under voluntary (conscious) control.

    • Cardiac Muscle: Forms heart walls; striated; under involuntary (unconscious) control.

    • Smooth Muscle: Lines walls of hollow visceral organs; non-striated; involuntary control.

  • Nervous Tissue (neur/o): Contains neurons that conduct electrical impulses to coordinate body functions (brain, spinal cord, nerves).

• Pathology of Tissue Formation

  • Aplasia: Complete lack of development or congenital absence of an organ/tissue (a- = without; -plasia = formation).

  • Hypoplasia: Deficient cell numbers leading to incomplete tissue development (hypo- = deficient).

  • Anaplasia: Loss of cell structural differentiation and orientation (ana- = backward).

  • Dysplasia: Abnormal development or growth of cells, tissues, or organs (dys- = bad/abnormal).

  • Hyperplasia: Increase in the number of cells, increasing tissue size.

  • Hypertrophy: Increase in the bulk/size of individual cells, not overall cell number (hyper- = excessive; -trophy = development).

• Glands

  • Specialized epithelial cells that synthesize and secrete chemical substances.

  • Exocrine Glands: Secrete products through ducts directly to external surfaces or internal organs (e.g., sweat glands, salivary glands).

  • Endocrine Glands: Ductless glands that secrete hormones directly into the bloodstream (e.g., thyroid gland, pituitary gland).

• Pathology of Glands

  • adenitis: Inflammation of a gland.

  • adenocarcinoma: Malignant tumor arising in glandular epithelial tissue.

  • adenoma: Benign tumor of glandular origin.

  • adenosis: Any disease condition of a gland.

  • adenosclerosis: Abnormal hardening of a gland.

  • adenectomy: Surgical removal of a gland.

Organ Systems Overview

• Summary of 10 Major Organ Systems

  1. Immune System: Protects body against foreign pathogens (lymphatic vessels, lymph nodes, blood cells).

  2. Nervous & Sensory System: Processes information and regulates response (brain, spinal cord, nerves, eyes, ears).

  3. Urinary System: Filters blood, forms urine, excretes soluble waste, regulates fluid/electrolyte balance (kidneys, ureters, bladder, urethra).

  4. Gastrointestinal System: Digestion, nutrient absorption, waste elimination (mouth, esophagus, stomach, intestines, liver, gallbladder, pancreas).

  5. Cardiovascular System: Circulates oxygenated blood and nutrients (heart, blood vessels, blood).

  6. Respiratory System: Gas exchange ($O_2$ intake, $CO_2$ release), maintains acid-base balance (nose, pharynx, larynx, trachea, lungs, alveoli).

  7. Integumentary System: Exterior barrier protection, temperature regulation (skin, hair, nails, sweat/sebaceous glands).

  8. Muscular System: Produces skeletal movement, generates body heat, moves internal materials.

  9. Skeletal System: Structural support, organ protection, blood cell creation, mineral storage.

  10. Endocrine System: Secretes regulatory hormones directly into blood (pituitary, thyroid, adrenals, pancreas, gonads).

  11. Reproductive System: Sex cell production, hormone secretion, childbearing.

Pathology, Disease Categories, and Etiology

• Definitions in Pathology

  • Disease: Any condition disrupting normal bodily structure or physiological function.

  • Pathology: The study of disease, including its origin, nature, structural changes, and functional consequences (path/o = disease, suffering).

  • Etiology: The study of the causes of diseases (eti- = cause).

  • Acute Disease: Rapid onset, severe symptoms, short duration.

  • Chronic Disease: Slow progression, long duration.

  • Pathologist: Physician specializing in laboratory analysis of diseased tissue samples.

• Classifications of Diseases

  • Organic Disorder: Observable, physical, structural changes in organs/tissues (e.g., chickenpox rash).

  • Functional Disorder: Symptoms present without measurable physiological or structural changes (e.g., panic attacks, chronic fatigue syndrome).

  • Idiopathic Disease: Disease originating spontaneously without a known cause (idi/o = peculiar to the individual).

  • Iatrogenic Illness: Adverse condition caused inadvertently by medical treatment or physician action (e.g., radiation burn during cancer treatment).

  • Nosocomial Infection: Hospital-acquired infection occurring during clinical care (e.g., MRSA, VRSA).

  • Degenerative Disease: Progressive tissue deterioration due to aging, wear-and-tear, or injury (e.g., osteoarthritis, emphysema).

  • Congenital Disorder: Condition present at birth (e.g., developmental malformation, atresia—congenital absence of a normal tubular opening).

    • Prenatal Influences: Maternal infection (e.g., Rubella), maternal alcohol consumption (Fetal Alcohol Syndrome / FAS), or lack of care leading to premature delivery ($< 37$ weeks).

Disease Transmission, Outbreaks, and Epidemiology

• Modes of Transmission

  • Pathogen: Disease-causing microorganism.

  • Direct / Communicable Transmission: Spread directly from person to person via contact.

  • Indirect Contact: Infection via contact with a contaminated inanimate surface (fomite).

  • Bloodborne Transmission: Infection via contact with contaminated blood or body fluids (e.g., HIV, Hepatitis B, STDs).

  • Droplet Transmission: Spread through large respiratory droplets exhaled, coughed, or sneezed over short distances (e.g., flu, colds, measles, TB).

  • Airborne Transmission: Infection by microscopic germ nuclei floating in air currents over long periods.

  • Foodborne / Waterborne (Fecal-Oral): Ingestion of contaminated food or untreated water.

  • Vector-Borne Transmission: Transmission via animal/insect bite (e.g., mosquitoes, ticks, fleas, rats).

• Epidemiological Terminology

  • Epidemiologist: Specialist studying disease outbreaks and patterns in populations (epi- = above; dem/i = population).

  • Endemic: Ongoing, continuous presence of a disease within a specific population/region (e.g., common cold).

  • Epidemic: Sudden, widespread outbreak affecting many individuals in a specific population simultaneously.

  • Pandemic: An outbreak occurring over an extensive geographical area, multiple countries, or worldwide (e.g., AIDS).

Infectious Organisms and Immune Responses

• Common Infectious Organisms

• Gram Stain Laboratory Technique: Differentiates bacteria into Gram-positive (stain blue/purple) and Gram-negative (stain red/pink).

• Responses to Infection & Injury

  • Inflammation: Localized protective response triggered by cellular injury, characterized by chemical release and fluid shifts.

    • Four Cardinal Signs: Heat, Pain, Redness, Swelling (Edema—excess fluid accumulation in tissues).

    • Suffix -itis denotes inflammation.

  • Phagocytosis: Ingestion and destruction of foreign microorganisms, damaged cells, and debris by white blood cells (phagocytes, e.g., macrophages).

    • Accumulated liquid mixture of dead phagocytes, tissue fluid, and debris forms Pus (py/o).

  • Immunity: Total protective defense mechanism against pathogens.

    • Innate (Inborn) Immunity: Genetic, non-specific physical/mechanical barriers (intact skin, mucous membranes, stomach acid, tears, phagocytosis, inflammation).

    • Adaptive (Acquired) Immunity: Specific response developed over lifetime through exposure or vaccination; produces specialized lymphocytes and circulating antibodies.

Neoplasia, Aging, and Healthcare Professionals

• Neoplasia and Tumors

  • Neoplasm: Uncontrolled, abnormal tissue mass/growth (neo- = new; -plasm = formation; onc/o and -oma refer to neoplasms).

  • Benign Neoplasm: Non-invasive, non-spreading (does not metastasize); localized; generally favorable recovery.

  • Malignant Neoplasm: Harmful, invasive growth that invades surrounding tissue and spreads (metastasizes) to distant sites; cancer.

    • Carcinoma: Malignant neoplasm derived from epithelial tissue (carcin/o = cancer, crab).

    • Adenocarcinoma: Malignant neoplasm derived from glandular epithelium.

    • Sarcoma: Malignant tumor originating from connective tissue or muscle (sarc/o = flesh).

    • Carcinoma in situ (CIS): Malignant tumor strictly localized at original site without invading surrounding tissue.

• Aging, Death, and Healthcare Fields

  • Geriatrics: Branch of medicine caring for health problems of elderly individuals.

  • Autopsy: Postmortem examination of a body to determine cause of death.

  • Healthcare Professional Roles:

    • General Practitioner (GP): Offers ongoing primary care for all age groups.

    • Internist: Focuses on diagnosing/treating internal organ diseases in adults.

    • Pediatrician: Treats infants, children, and adolescents.

    • Geriatrician / Gerontologist: Focuses on elderly care.

    • Hospitalist: Physician caring specifically for hospitalized patients.

    • Intensivist: Physician specializing in the care of critically ill ICU patients.

    • Nurse Practitioner (NP) / Physician Assistant (PA): Mid-level providers practicing under physician supervision.

    • Medical Coder: Translates clinical care records into standardized codes.

Diagnostic, Surgical, and Clinical Medical Terminology

• Diagnostic & Clinical Terminology Manifestations

  • abscess: Localized cavity containing pus.

  • adhesion: Abnormal band of tissue holding internal surfaces together.

  • ascites: Pathological fluid accumulation in the peritoneal cavity.

  • cellulitis: Acute, spreading bacterial inflammation of dermal/subcutaneous tissues.

  • effusion: Escape of fluid into a body cavity.

  • exudate: Fluid, cells, or proteins escaping blood vessels due to injury/inflammation.

  • fistula: Abnormal passageway between two organs or from an organ to the surface.

  • gangrene: Tissue necrosis resulting from loss of blood supply, often followed by bacterial decay.

  • induration: Pathological hardening of soft tissues.

  • polyp: Smooth tumor extending outward from a mucous membrane, often attached by a thin stalk.

  • purulent / suppuration: Containing/forming pus.

  • septicemia: Blood poisoning; system-wide presence of pathogenic bacteria/toxins in blood.

Comprehensive Anatomical and Pathological Word Parts Reference Tables

• Roots for Cells, Tissues, and Chemistry

• Prefixes for Numbers, Colors, Negation, Direction, Degree, and Size

• Roots, Prefixes, and Suffixes for Diseases and Symptoms

Structure and Functions of the Skeletal System

• Components of the Skeletal System

  • Bones (oss/e, oss/i, oste/o, ost/o)

  • Bone Marrow (myel/o)

  • Cartilage (chondr/o)

  • Joints (arthr/o)

  • Ligaments (ligament/o)

  • Synovial Membranes & Fluids (synovi/o, synov/o)

  • Bursae (burs/o)

• Functions of the Skeletal System

  1. Protects internal vital organs and delicate tissues.

  2. Provides body support, structural framework, and stabilization.

  3. Serves as attachment surface for skeletal muscles, tendons, and ligaments.

  4. Enables mechanical movement via system of levers.

  5. Performs hematopoiesis: production of red blood cells, white blood cells, and platelets within red bone marrow.

  6. Stores essential mineral salts (contains $99\%$ of the body's total calcium reserves).

• Bone Formation and Development

  • Ossification: Process where cartilage is progressively converted into hard bone tissue during skeletal growth.

    • Begins at $3$ months gestation and continues through adolescence.

  • Bone Cell Types:

    • Osteoblasts: Immature bone cells that synthesize and build new bone tissue.

    • Osteocytes: Fully mature, functioning bone cells.

    • Osteoclasts: Specialized cells that break down, crush, and reabsorb bone tissue.

  • Resorption: The enzymatic destruction of bone matrix by osteoclasts to release minerals into circulation.

• Anatomical Tissues of Bones

  • Compact Bone: Dense, outer layer forming protective shell.

  • Spongy Bone (Cancellous Bone): Porous, mesh-like tissue containing red bone marrow inside epiphyses.

  • Periosteum: Tough, fibrous vascular membrane covering the external surface of bones (peri- = surrounding; oste = bone; -um = noun ending).

  • Medullary Cavity: Hollow central canal in long bone shafts storing yellow bone marrow.

  • Endosteum: Membrane lining the inner medullary cavity walls.

  • Red Bone Marrow: Hemopoietic tissue located in spongy bone; forms RBCs, hemoglobin, WBCs, and thrombocytes (platelets).

  • Yellow Bone Marrow: Fatty connective tissue located in medullary cavities serving as fat storage.

  • Cartilage: Smooth, resilient, rubbery connective tissue covering joint surfaces; acts as shock absorber.

• Long Bone Structural Regions

  • Diaphysis: Long tubular central shaft of a bone.

  • Epiphysis: Expanded ends of a long bone.

    • Proximal Epiphysis: End nearest the body midline.

    • Distal Epiphysis: End farthest from the body midline.

  • Metaphysis: Growing region located between diaphysis and epiphysis.

    • Contains the Epiphyseal Plate (Growth Plate) allowing longitudinal elongation.

• Bone Markings

  • Surface features providing passage for vessels/nerves or attachment for muscles.

  • Sulcus: Deep groove or depression along a bone surface (e.g., fissure).

  • Sinus: Air-filled cavity or hollow space within a bone (e.g., frontal sinus).

  • Fossa: Shallow, concave basin or depression in bone (e.g., iliac fossa).

  • Foramen: Hole or opening through bone for nervous/vascular passage (e.g., foramen magnum).

  • Process: Prominent bony projection providing attachment for tendons/muscles (e.g., spinous process).

Bones of the Axial Skeleton

• Division of the Skeleton

  • Total count = $206$ bones.

  • Axial Skeleton: Protects nervous, respiratory, and circulatory organs ($80$ bones: skull, ribs, sternum, spine).

  • Appendicular Skeleton: Protects digestive, excretory, and reproductive organs ($126$ bones: upper/lower extremities, shoulder, pelvis).

• Bones of the Cranium (Skull)

  • Frontal Bone: Forms forehead and anterior skull roof.

  • Parietal Bones (Paired): Form roof and upper lateral sides of the cranium.

  • Occipital Bone: Forms back and inferior base of skull; contains Foramen Magnum.

  • Temporal Bones (Paired): Form lower sides/base of skull; contain External Auditory Meatus.

  • Sphenoid Bone: Wedge-shaped bone at skull base articulating with all other cranial bones.

  • Ethmoid Bone: Light spongy bone at nasal roof separating nasal cavity from brain; forms orbital walls.

• Bones of the Face

  • Nasal Bones ($2$): Form upper structural bridge of nose.

  • Zygomatic Bones ($2$): Prominent cheekbones.

  • Maxillary Bones ($2$): Form upper jaw and hard palate.

  • Palatine Bones ($2$): Form posterior hard palate and nasal floor.

  • Mandible: Lower jaw bone; only freely moveable skull bone.

• Thoracic Cavity (Rib Cage)

  • Encloses heart and lungs.

  • Ribs (Costals): $12$ pairs attached posteriorly to thoracic vertebrae.

    • True Ribs: First $7$ pairs (Ribs $1-7$); connect directly anteriorly to sternum via costal cartilage.

    • False Ribs: Next $3$ pairs (Ribs $8-10$); connect indirectly anteriorly to cartilage of rib above.

    • Floating Ribs: Last $2$ pairs (Ribs $11-12$); unattached anteriorly.

  • Sternum (Breastbone): Flat anterior midline bone consisting of $3$ parts:

    • Manubrium: Superior part articulating with clavicles.

    • Body: Large middle portion.

    • Xiphoid Process: Cartilaginous inferior projection.

• Vertebral Column (Spine)

  • Consists of $26$ individual articulating bones enclosing spinal cord.

  • Structure of Vertebra: Anterior solid Body; posterior Lamina; central Vertebral Foramen (spinal cord pathway).

  • Spinal Regions:

    • Cervical Vertebrae: $7$ vertebrae (C1–C7) forming neck region (C1 = Atlas, C2 = Axis).

    • Thoracic Vertebrae: $12$ vertebrae (T1–T12); each articulates with pair of ribs.

    • Lumbar Vertebrae: $5$ massive vertebrae (L1–L5); weight-bearing lower back region.

    • Sacrum: Triangular bone composed of $5$ fused sacral segments at birth.

    • Coccyx (Tailbone): Terminal segment composed of $4$ small fused coccygeal bones.

Bones of the Appendicular Skeleton

• Pectoral Girdle & Upper Extremity

  • Clavicle (Collar Bone): Connects manubrium to scapula.

  • Scapula (Shoulder Blade): Flat triangular posterior shoulder bone; features the Acromion (high tip of shoulder).

  • Humerus: Upper arm bone.

  • Radius: Lateral, shorter forearm bone (thumb side).

  • Ulna: Medial, longer forearm bone (pinky side); features the Olecranon Process (elbow projection).

  • Carpals: $8$ wrist bones.

  • Metacarpals: $5$ palm bones.

  • Phalanges: $14$ finger bones ($3$ in each of the $4$ fingers: proximal, middle, distal; $2$ in thumb: proximal, distal).

• Pelvic Girdle

  • Consists of fused pelvic bones articulating with sacrum at Sacroiliac Joint.

  • Ilium: Superior blade-like pelvic bone.

  • Ischium: Inferior posterior pelvic bone.

  • Pubis: Anterior pelvic bone; left and right join at Pubic Symphysis (cartilaginous joint).

  • Acetabulum: Large lateral circular socket articulating with head of femur to form hip joint.

• Lower Extremity

  • Femur: Longest, heaviest, strongest bone in body.

    • Lesser Trochanter: Medial muscle attachment site.

    • Greater Trochanter: Landmark for locating ventrogluteal intramuscular (IM) injection sites.

  • Patella: Kneecap (sesamoid bone); posterior region is Popliteal area.

  • Tibia (Shinbone): Larger anterior weight-bearing lower leg bone.

  • Fibula: Smaller, non-weight-bearing lateral lower leg bone.

  • Malleolus: Prominent bony projections forming ankle bulges (medial malleolus on tibia, lateral malleolus on fibula).

  • Tarsals: $7$ ankle/heel bones.

    • Talus: Articulates superiorly with tibia/fibula.

    • Calcaneus: Heel bone (largest tarsal).

  • Metatarsals: $5$ midfoot bones.

  • Phalanges: $14$ toe bones.

Joints and Joint Movements

• Classification of Joints (Articulations)

  • Fibrous Joints (Sutures): Immovable joints held by fibrous tissue (e.g., skull sutures).

  • Cartilaginous Joints (Symphysis): Slightly movable joints connected by cartilage (e.g., pubic symphysis, intervertebral disks).

  • Synovial Joints: Freely movable joints.

    • Ball-and-Socket Joints: Wide range of movement in all planes (e.g., hip, shoulder).

    • Hinge Joints: Movement limited to one plane (e.g., elbow, knee).

• Structures of Synovial Joints

  • Synovial Capsule: Sleeve-like outer fibrous envelope.

  • Synovial Membrane: Inner lining secreting lubricating Synovial Fluid.

  • Ligaments: Fibrous bands connecting bone to bone.

  • Tendons: Fibrous cords attaching muscle to bone.

  • Bursae: Fluid-filled sacs reducing friction between moving parts.

• Types of Joint Movements

  • Abduction: Movement away from midline.

  • Adduction: Movement toward midline.

  • Flexion: Movement decreasing joint angle.

  • Extension: Movement increasing joint angle.

  • Rotation: Turning a bone around its axis (medial or lateral).

  • Circumduction: Circular movement combining flexion, extension, abduction, adduction.

  • Inversion: Turning sole of foot inward.

  • Eversion: Turning sole of foot outward.

  • Dorsiflexion: Bending foot upward toward shin.

  • Plantar Flexion: Pointing foot downward.

  • Pronation: Rotating forearm so palm faces downward/backward.

  • Supination: Rotating forearm so palm faces upward/forward.

Pathology, Disorders, and Fractures of the Skeletal System

• Pathology of Bones and Joints

  • Osteomyelitis: Bacterial bone and bone marrow inflammation with pus.

  • Pott Disease: Tuberculosis spreading specifically to the spine.

  • Arthrosclerosis: Pathological stiffness/hardening of joints (arthr/o = joint; -sclerosis = hardening).

  • Bursitis: Inflammation of a bursa sac.

  • Chondromalacia: Softening of articular cartilage (chondr/o = cartilage; malacia = softening).

  • Costochondritis: Inflammation of rib costal cartilages.

  • Hallux Valgus: Abnormal lateral deviation/enlargement of joint at base of great toe (bunion).

  • Hemarthrosis: Blood accumulation inside a joint cavity (hem = blood; arthr = joint).

  • Sprain: Ligament damage due to wrenching/tearing.

• Forms of Arthritis

  • Osteoarthritis (OA): Most common wear-and-tear degenerative joint disease associated with aging; cartilage wears down, joint space narrows, bone thickens, forming bony spurs (Osteophytes).

  • Rheumatoid Arthritis (RA): Chronic autoimmune disorder where immune cells attack synovial membranes, forming thickened, inflamed, painful, immobile joints.

  • Gout: Metabolic arthritis characterized by uric acid crystal deposition in joint spaces, causing extreme heat, redness, and pain (commonly in great toe).

• Spinal Disorders

  • Ankylosing Spondylitis: Inflammatory spinal disease primarily in males causing cartilage destruction, intervertebral disk calcification, and vertebral fusion ("bamboo spine").

  • Herniated Disk: Protrusion of nucleus pulposus through annulus fibrosus compressing spinal nerve roots (common in lumbar and cervical regions).

  • Spinal Curvatures:

    • Kyphosis: Exaggerated outward thoracic curve ("hunchback").

    • Lordosis: Exaggerated inward lumbar curve ("swayback").

    • Scoliosis: Abnormal lateral S-shaped/C-shaped spine curvature.

• Metabolic & Neoplastic Bone Diseases

  • Osteoporosis (OP): Loss of bone density and increase in porosity, rendering bones fragile; most common in postmenopausal women ($> 50$ years).

  • Osteomalacia: Adult bone softening due to Vitamin D deficiency, liver/kidney disease.

  • Rickets: Pediatric bone growth defect due to Vitamin D / Calcium deficiency.

  • Paget's Disease (Osteitis Deformans): Bone disease marked by excessive bone breakdown followed by unorganized, chaotic bone rebuilding, resulting in thick, weak bones.

  • Bone Neoplasms:

    • Osteochondroma: Benign bony projection covered with cartilage.

    • Osteogenic Sarcoma: Highly malignant primary bone tumor in growing bone regions.

    • Chondrosarcoma: Malignant cartilage tumor.

• Fractures & Complications

  • Closed Fracture: Simple break with intact skin.

  • Open Fracture: Compound break with open skin wound.

  • Complications: Fat Embolus (yellow marrow fat droplets entering blood from long bone break); Crepitation (grating sound of broken bone ends rubbing together); Callus (bulging vascular repair tissue turning to bone).

  • Treatment: Closed Reduction (CR) (manual realignment); Open Reduction (surgical realignment); Traction (distal pulling force); Internal Fixation (permanent internal pins/plates); External Fixation (external frame holding pins).

Medical Specialties, Diagnostic Tests, and Procedures of the Skeletal System

• Skeletal Medical Specialties

  • Chiropractor: Focuses on spinal manipulative alignment.

  • Orthopedic Surgeon: Diagnoses/treats surgical musculoskeletal diseases.

  • Osteopath: Combines standard medicine with spinal manipulation (oste/o = bone; -path = disease).

  • Podiatrist: Foot disorder specialist (pod = foot; -iatrist = specialist).

  • Rheumatologist: Inflammatory joint and connective tissue disease specialist.

• Diagnostic Tests & Surgical Procedures

  • Radiograph (X-Ray): Visualization of fractures.

  • Arthroscopy: Internal visual examination of joint with endoscope.

  • Bone Marrow Biopsy / Aspiration: Removal of marrow tissue/fluid via needle.

  • Arthrocentesis: Needle fluid removal from joint space.

  • Arthrodesis: Surgical fusion of $2$ bones (-desis = bind, tie).

  • Arthroplasty: Surgical joint replacement/reconstruction (e.g., THA, TKA).

  • Chondroplasty: Surgical repair of damaged cartilage.

  • Laminectomy: Surgical removal of posterior vertebral lamina.

  • Craniectomy / Craniotomy / Cranioplasty: Removal of skull piece / Incision into skull / Surgical repair of skull.

• Abbreviations Related to the Skeletal System

Questions and Discussion

• Question: What passes through the foramen magnum on the underside of the skull?

  • (a) Neck muscles

  • (b) Spinal cord

  • (c) Ball-and-socket joint

  • (d) Aorta

  • Answer: (b) The brain connects via the medulla oblongata to the spinal cord, which passes through the foramen magnum.

• Question: The main part of a word is called the:

  • (a) origin

  • (b) prefix

  • (c) root

  • (d) extension

  • Answer: (c) root.

• Question: A word part at the beginning of a word is a:

  • (a) prefix

  • (b) combining form

  • (c) preview

  • (d) root

  • Answer: (a) prefix.

• Question: A word part at the end of a word is the:

  • (a) vowel

  • (b) adjective

  • (c) insertion

  • (d) suffix

  • Answer: (d) suffix.

• Question: The adjective form of cervix, meaning "neck," is:

  • (a) cervical

  • (b) cervixal

  • (c) cervous

  • (d) cerviral

  • Answer: (a) cervical.

• Question: The ch in the word chemistry is pronounced like the letter:

  • (a) s

  • (b) h

  • (c) k

  • (d) f

  • Answer: (c) k.

• Question: The ps in the word psychology is pronounced like the letter:

  • (a) p

  • (b) s

  • (c) j

  • (d) k

  • Answer: (b) s.

• Question: The pn in the word pneumonia is pronounced like the letter:

  • (a) p

  • (b) u

  • (c) m

  • (d) n

  • Answer: (d) n.

• Question: To combine the word root lith (stone) and suffix -tripsy (crushing), is "lithtripsy" a valid medical term?

  • (a) No. The suffix begins with a consonant and needs a combining vowel.

  • (b) Yes. Every term needs a word root and an ending, and this has both.

  • (c) No. Every term needs a prefix as well.

  • (d) Yes. The suffix begins with a consonant and does not need a combining vowel.

  • Answer: (a) A combining vowel is required when the suffix begins with a consonant (lithotripsy).

• Question: The suffix in the word microscopic is:

  • (a) -ic

  • (b) scop-

  • (c) micro-

  • (d) -ros

  • Answer: (a) -ic.

• Question: The prefix in the word microscopic is:

  • (a) mic-

  • (b) scop-

  • (c) micro-

  • (d) pic-

  • Answer: (c) micro-.

• Question: The prefixes uni-, tri-, and poly- all refer to:

  • (a) size

  • (b) number

  • (c) location

  • (d) shape

  • Answer: (b) number.

• Question: The prefixes leuk/o-, cyan/o-, and erythr/o- all refer to:

  • (a) dimensions

  • (b) area

  • (c) abnormalities

  • (d) color

  • Answer: (d) color.

• Question: The opposite of hypoglycemia (low blood sugar) is:

  • (a) hypoglucemia

  • (b) hyperglycemia

  • (c) hypocalcemia

  • (d) hyperglycemic

  • Answer: (b) hyperglycemia.

• Question: Identify the prefix in the term premenstrual and give its meaning.

  • Answer: pre- meaning before.

• Question: Prefixes come at the ______________ of a term.

  • Answer: beginning.

• Question: Quadriplegia involves how many parts?

  • Answer: four.

• Question: The plural for bronchus is:

  • Answer: bronchi.

• Question: The term gastrointestinal is a(n):

  • (a) abbreviation

  • (b) word root

  • (c) combining form

  • (d) compound word

  • Answer: (d) compound word.

• Question: What usually needs to happen when a term has more than one word root?

  • Answer: A combining vowel (usually o, occasionally i) is needed between the word roots.

• Question: True or False: The meaning of prefixes and suffixes never changes, but both change the meaning of the word root.

  • Answer: True.

• Question: In the term hypodermic, why is there no combining vowel before the suffix?

  • Answer: The suffix -ic begins with a vowel, so no combining vowel is required.

• Question: When you have all three components of a term, what is the order in which you read them?

  • Answer: Read the suffix first, prefix second, and word root last.

• Question: If intra- = within, cardi = heart, and -ac = pertaining to, define intracardiac:

  • Answer: Pertaining to within the heart.