1. HUMAN ANATOMY
ZOO 3733c
CHAPTER 1: THE ORGANIZATION OF THE HUMAN BODY
A. Introduction to Anatomy
1. Anatomy is the study of the human body, its structure and organization.
a) It is a consideration of human morphology.
b) Anatomy is divided into:
1) Gross Anatomy - a study of those body structures which are
visible to the “naked” (unaided) eye.
a] It involves the use of observation and dissection.
b] It can be further subdivided into:
1] Regional Anatomy - all structures in a region of the body
(ex; the abdomen).
2] Systemic Anatomy - a study of the organs which make up a
system; the organs which serve a particular function.
3] Surface Anatomy - a study of internal structures and how
they relate to the integument.
2) Histology / Microscopic Anatomy - a study of anatomy on the
cellular level. It is a study of structures which can not be
viewed with the naked eye.
a] It involves use of the microscope.
3) Embryological Anatomy - chronicles the changes which occur as
the body develops from a zygote to a neonate.
4) Developmental Anatomy - chronicles the changes which occur in
the body throughout an individual’s life; from birth to death.
5) Pathological Anatomy - studies the changes which occur in cells,
tissues, and organs due to the effects of disease.
6) Radiographic Anatomy - studies the internal anatomy via
radiation (ex; MRI, X-rays, CAT Scans).
7) Functional Morphology - studies the correlation between
anatomical structures and their functions.
2. The Hierarchy of Structural Organization {p3, Fig. 1.1}
a) Organism - the highest level of organization (for our purposes), a
living being.
b) System/Organ System - a group of organs working together to
perform a common action.
c) Organ - a discrete structure made up of several tissues working
together to perform a task.
d) Tissue - a group of related cells working together to perform a task.
1) There are four classes of tissue: epithelial, connective, muscle, &
nervous.
e) Cell - the basic unit of life.
1) Cells can exist either singly (unicellular life) or in highly
integrated groups (multicellular life).
2) A cell can perform all of the functions essential for life to exist.
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2. a] To accomplish this cells have a variety of functional units
termed “organelles” (ex; nucleus, mitochondrion).
f) Chemical Level - the atoms which make up an organism and their
arrangement into molecules and macromolecules.
1) There are four classes of macromolecules: carbohydrates,
proteins, lipids, and nucleic acids.
B. An Introduction to Gross Anatomy
1. Anatomical Position {p. 8, Fig. 1.3}
a) Describe the “anatomical position”.
b) Note: “right” and “left” refer to that portion of the anatomical
subject, not to the viewer’s right or left.
2. Directional and Regional Terminology
a) Directional Terminology {p. 9, table 1.1} -
Describe the position of a structure relative to another structure to
explain the terms: superior, inferior, anterior, posterior, medial,
lateral, intermediate, proximal, distal, deep, superficial,
cranial/cephalad, & caudal.
b) Regional Terminology {p. 10, f. 1.4} -
Regional terms are names for specific areas of the body.
1) The two most fundamental are:
a] Axial - the main axis of the body; the head, neck, and trunk.
b] Appendicular - the appendages; the arms and legs.
3. Sections and Planes of the Body {p. 11, fig.1.5}
a) Sections are cuts long a plane (i.e.; a flay surface).
1) The section takes the name of the plane along which the cut was
made.
a] Ex; a transverse section is a cut along the transverse plane.
b) There are three major planes of the body:
1) Transverse Plane (aka; horizontal plane, cross section) - a plane
running horizontally (left to right) dividing the body into inferior
and superior portions.
2) Sagittal Plane - a vertical plane dividing the body into left and
right portions.
a] Midsagittal (or Median Sagittal) Plane - runs along the midline
of the body.
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3. b] Parasagittal Plane - runs at other than the midline of the body.
3) Frontal Plane (aka; Coronal Plane) - a vertical plane which divides
the body into anterior and posterior portions.
4. The Human Body Plan is consistent with the basic vertebrate body plan.
a) The human body plan is consistent with the basic vertebrate body
plan. It consists of:
1) Bilateral Symmetry - most structures on the left half of the body
mirror those on the right side.
a] Most structures lateral to the midline are paired
(ex; arms,eyes).
b] Most structures along the midline are unpaired but divided into
similar halves (ex; the heart).
2) The Tube-Within-a-Tube Body Plan - The main body is said to be a
tube and the digestive tube running through it is said to form the
tube within a tube arrangement.
3) Segmentation - The outer tube of the body displays evidence of
segmentation.
a] Segments are repeating units of similar structure.
b] Ex; ribs, rectus abdominis
4) Dorsal, Hollow Nerve Cord - in the developing embryo, the CNS
first appears as a hollow tube on the dorsum which develops into
the brain and spinal cord.
5) Notochord - a solid rod of cartilage located just deep to the
developing CNS. It defines the main axis of the body.
a] In “higher” vertebrates it is replaced during development by
the vertebrae.
1] Although vestiges of it remain as the intervertebral discs.
6) Pharyngeal Pouches - These structures form clefts between the
gills in more primitive vertebrates. In tetrapods they have
become developed into other structures.
5. Abdominal Regions and Quadrants
a) There are two basic strategies for the division of the abdominal
region into subregions:
1) The Four Abdominal Quadrants {p. 17, f. 1.12}
a] Designated by two planes, one midsagittal and one transverse,
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4. dividing the abdomen into four quadrants: upper right, upper
left, lower right, lower left.
2) The Nine Abdominal Regions {p. 17, fs. 1.11}
a] Designated by two equidistant parasagittal and two equidistant
transverse planes which divide the abdomen into nine
subregions: right hypochonriac, epigastric, left hypochondriac,
right lumbar, umbilical, left lumbar, right inguinal/iliac,
hypogastric/pubic, left iliac/inguinal.
6. Body cavities and Their Membranes {p. 14, f. 1.8}
a) The body’s cavities are broadly divided into two:
1) Dorsal Body Cavity - houses the CNS and is located within the
skull and vertebral column.
a] It is divided into:
1] Cranial Cavity housing the brain.
2] Vertebral Cavity housing the spinal cord.
b] Its membranes are the meninges.
2) Ventral Body Cavity - houses the viscera.
a] It is divided into;
1] Thoracic Cavity housing the heart, lungs, and mediastinum.
a} Further divided into the cardiac, pleural, and
mediastinal chambers.
2) Abdominoplevic Cavity housing a variety of organs.
a} Separated from the thoracic cavity by the diaphragm.
b} It is subdivided further into the pelvic and abdominal
cavities.
b] Its membranes are called serous membranes.
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5. CHAPTER 2: THE CELL
A. Introduction
1. The cell is the basic unit of life.
a) Cells were first discovered by Robert Hooke in the late 17th century.
b) Cells perform all of the functions essential for life and these
activities are facilitated by organelles.
2. The Cell Membrane (aka; plasmallema, plasma membrane) {p. 29, f. 2.2}
a) The cell membrane separates the cell from the external environment
allowing it to maintain its own internal environment.
1) This is essential for it to conduct metabolism.
b) Features of Cell Membrane Structure: The Fluid Mosaic Model
1) The Fluid Mosaic Model, proposed by Singer and Nicholson in 1971, describes the
cell membrane structurally as a phospholipid bilayer interdigitated by proteins and other
lipids.
2) The Phospholipid Bilayer - is the result of the amphipathic nature of the phospholipid
molecule.
a] The phospholipid molecule has a hydrophobic “tail” and a
hydrophilic “head”. That is what is meant by the term “amphipathic”.
1] This feature causes the phospholipid molecules to
spontaneously form a bilayer so that the “heads” are facing
an aqueous environment externally or internally and the
“tails” are in a water free zone.
2] As a result of the amphipathic nature of the phospholipid
molecule, the cell membrane will spontaneously form,
maintain, and heal itself.
3) Other lipids (ex; triglycerides, cholesterol) are integrated into the phospholipid bilayer
and serve a variety of functions.
a] Cholesterol serves to stabilize the “fluidity” of the cell membrane so it is
not dependent on the kinetic energy of the molecules alone.
4) Membrane Proteins
a] Membrane Proteins make up almost 50% of the plasmalemma.
b] They serve a variety of functions such as: recognition,
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6. receptors, and the transport of molecules.
c] There are two classes of membrane proteins:
1] Peripheral Proteins - are membrane proteins which do not
extend into the hydrophobic portion of the phospholipid
bilayer; they are not embedded in the membrane.
a} They are found on both the external and internal
environment facing surfaces (E face and P face,
respectively) of the cell membrane.
2] Integral Proteins - are membrane proteins which do extend
into the hydrophobic portion of the phospholipid bilayer.
a} Transmembrane Proteins - are integral proteins which
pass through the entire phospholipid bilayer.
c) Functions of the Cell Membrane
1) The cell membrane serves to separate the cellular components from the external
environment of the cell. This allows it to maintain its own internal environment.
a] The cell membrane can not be a complete barrier however or the
constituents and results of metabolism could not cross it.
1] As a result, the cell membrane is described as being
semipermeable (aka; selectively permeable) allowing some substances to
cross but serving as a barrier to the transport of other substances.
2) Membrane Transport of Small Molecules
a] Passive Transport - is the movement of substances across the
cell membrane without the use of cellular energy (i.e.; ATP).
1] Diffusion - is the net movement of molecules from an area of
higher concentration to an area of lower concentration.
a} This process requires no energy on the part of the cell.
1} The energy comes from the kinetic energy of the
molecules themselves.
b} Osmosis - is the net movement of solvent molecules
from an area of higher concentration to an area of lower
concentration.
c} Dialysis - is the net movement of solute molecules from
an area of higher concentration to an area of lower
concentration.
2] Facilitated Diffusion - is the net movement of molecules
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7. from an area of higher concentration to an area of lower
concentration but its occurrence is regulated by transport proteins.
a} Again, the energy comes from the kinetic energy of the
molecules themselves but membrane proteins regulate the
event to maintain the cell’s metabolism.
b] Active Transport - is the movement of molecules across the cell membrane requiring
cellular energy.
1] ATP is required for this since:
a} the molecules are being moved against the diffusion
gradient
b} or the molecules are too large to diffuse across the cell
membrane.
3) Membrane Transport of Large Molecules
a] Exocytosis(aka; secretion) - is the movement of large
molecules out of the cell.
1] The substance is enclosed in a membrane bound structure
called a vesicle. This vesicle is then transported through the
cytoplasm to the membrane where it fuses to the plasmalemma and
extrudes the product into the external environment.
b] Endocytosis - is the movement of large molecules into the cell.
1] Outward extensions of the plasmalemma surround and engulf
the substance. The membrane then pinches off, into the
cytosol, forming a vesicle.
2] There are three types of endocytosis:
a} Phagocytosis (“cell eating”)
b} Pinocytosis (“cell drinking”)
C} Receptor Mediated Endocytosis is similar to phagocytosis
but uses membrane proteins to recognize the substance.
B. Organelles
1.The Nucleus
a) The nucleus is a large double membraned organelle which contains
the genetic blue-print of the cell.
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8. 1) It averages 5um in diameter.
2) Since our cells possess nuclei, we are said to be eucaryotic.
a] Most of our cells have only one nucleus each and are termed
uninucleated.
b] Some of our cells possess more than one nuclei and are termed
multinucleated (ex; skeletal muscle cells).
c] Some of our cells lack a nucleus and are termed uninucleated
(ex; RBCs).
b) The Nuclear Membrane (aka; nuclear envelope) - is the double
membraned structure which separates the internal environment of
the nucleus, the nucleoplasm, from the cytoplasm.
1) It is made up of two parallel oriented membranes.
2) The nuclear membrane is even more selectively permeable than is
the cell membrane so as to protect the DNA.
a] The nuclear membrane possesses openings called nuclear pores
which allow for the movement of material across the nuclear
membrane.
c) The Genetic Code is held in the nucleus.
1) The genetic code is found on DNA molecules.
2) DNA is tightly packed within the nucleus. {p. 37, f. 2.15, 2.16}
a] The DNA is tightly wound about special proteins called histones
forming a condensed unit termed the nucleosome.
b] The nucleosome is further condensed into chromatin.
c] During cell division the chromatin is even further condensed
down into the chromosome.
1] Chromosomes are composed of two chromatids held together
by a centromere.
2] Humans have 23 homologous pairs of chromosomes in each
nucleus.
d) The Nucleolus
1) Nucleoli are dark staining structures located within the nucleus.
2) The nucleolus is the site where the DNA is being read and copied
to form mRNA (transcription).
a] The mRNA will leave the nucleus and enter into the cytoplasm
where protein synthesis will occur.
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9. 2. Ribosomes
a) Ribosomes are very small organelles which are composed of two
subunits, both being made up of proteins and RNA (rRNA).
1) The two subunits come together when in contact with an mRNA
molecule.
a] They serve in translation where the genetic code is translated
into an amino acid code in the process of protein synthesis.
2) Ribosomes can conduct translation either freely in the cytosol or
in association with another organelle, the endoplasmic reticulum,
based on the nature of the protein being produced.
3. The Endoplasmic Reticulum {p. 35}
a) The ER is an extensive, maze-like network of double walled cell
membranes running throughout the cytoplasm.
1) It serves a variety of purposes but primarily connects the
organelles and plasmalemma of the cell.
2) Sometimes the ER will fold back on itself forming blind pockets
termed cisternae.
b) There are two classes of Endoplasmic Reticulum:
1) Rough Endoplasmic Reticulum - this is ER to which ribosomes are
attached giving it a studded or roughened appearance.
a] This class of ER is involved in protein synthesis.
2) Smooth Endoplasmic Reticulum - lacks ribosomes and so has a
smoother appearance.
a] This class of ER is involved in lipid metabolism, the storage of
certain ions (ex; Ca), and poison detoxification.
4. The Golgi {p. 31, 32}
a) The Golgi is another membranous organelle. It serves primarily in
packaging the products of the cell.
1) It has the appearance of stacks of double membraned structures.
b) Transport vesicles carry the product to the cis surface of the Golgi
where it enters the Golgi and is packaged and modified if necessary
(ex; glycoproteins) . The product will then exit the Golgi from the trans surface.
5. Lysosomes
a) Lysosomes are one such cellular product. They are membrane-bound
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10. organelles containing digestive enzymes.
1) There are a wide variety of enzymes which have been identified in
lysosomes.
b) Functions in:
1) digestion of foreign invaders and large substances
2) self digestion during periods of cell starvation
3) self digestion to remove dead cells.
6. Perioxysomes
a) Perioxysomes are another class of organelles which are vesicles
containing active chemical substances.
1) The most important of these being peroxide forming enzymes
which remove dangerous free radicals. They convert these free
radicals into peroxide which can then be converted into water and
oxygen.
2) Some of these chemical substances are also used to detoxify
certain poisons.
7. Mitochondria {p. 33}
a) The mitochondria serve as the power plants of the cell and are the
actual site of aerobic cellular respiration.
b) Structure:
1) They are peanut-shaped organelles heaving two membranes: an
outer mitochondrial and inner mitochondrial membrane.
a] The inner membrane is larger and arranged into folds termed
crista.
b] The space between the two mitochondrial membranes is termed
the intermembrane space.
c] The space enclosed by the inner mitochondrial membrane is
termed the matrix.
c) ATP, adenosine triphosphate, is produced in the mitochondria during
the stages Kreb’s cycle and oxidative phosphorylation of aerobic
respiration.
d) Mitochondria also contain their own DNA termed mitochondrial DNA.
1) Mitochondrial DNA is inherited with the mitochondria from the
mother.
8. The Cytoskeleton
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11. a) The cytoskeleton is, in effect, the cell’s skeleton.
1) It serves to support the cell and assists in the movement both of
the cell
(ex; flagella) and of structures within the cell.
b) In animal cells there are three recognized classes of cytoskeletal
elements:
1) Microfilaments - are the smallest of the three classes being
~7nm in diameter.
a] They are solid rods composed of the protein actin.
1] Actin serves in muscle contraction.
2) Intermediate Filaments - are intermediate in size being ~8nm in
diameter.
a] These are also solid rods of protein.
3) Microtubules - are the largest of the three classes being ~25nm in
diameter.
a] They are hollow tubes made up of dimer units of the protein
tubulin.
b] They make up a number of skeletal structure such as: flagella,
cilia, spindle fibers, centrioles, and centrosomes.
1] Centrioles are hollow structures made up of nine
microtubules.
2] Centrosomes (aka; microtubule organizing centers) are
structures which produce and breakdown the cytoskeleton.
a} They are made up of two centrioles arranged
perpendicularly.
C. Mitosis and the Cell Cycle
1.The Cell Cycle is the life cycle of the cell. It runs from the birth of a
cell until the completion of cytokinesis.
a) It can be divided up into: Interphase, Mitosis, and Cytokinesis.
2. Interphase
a) This is the longest stage of the cell cycle.
b) It was once thought to be a period of rest but it is now known to be a
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12. period of great chemical activity in the cell.
1) This cellular activity has allowed Interphase to be divided into
three stages of distinctly different activity:
a] G1 (the first Gap, or Gap 1, phase)
1] This is the last stage for nondividing cells (ex; muscle cells,
neurons).
2] It is a period of protein synthesis producing the proteins
required for DNA replication.
b] S (Synthesis phase)
1] A period of DNA replication
c] G2 (the second Gap, or Gap 2, phase)
1] This is another period of protein synthesis where the
proteins required for mitosis are constructed.
3. Mitosis {p. 46 - 47}
a) During this stage of the cell cycle the replicated DNA is sorted
segregated and divided to ensure that the two new cells produced
by cytokinesis have the right number and types of
chromosomes.
b) Mitosis is divided into”
1) Prophase
2) Metaphase
3) Anaphase
4) Telophase
4. Cytokinesis
a) This stage of the cell cycle is the division of the cytoplasmic
component of the cell allowing for the production of two new
daughter cells.
1) It occurs at the end of telophase when two new nuclei have
been formed.
CHAPTER 3: TISSUES
A. Introduction
1. A tissue is defined as a group of closely associated cells which are
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13. similar in structure and perform related functions.
a) Tissues also include nonliving materials, however.
1) This acellular matter is termed extracellular material (ex;
mineral component of bone tissue).
2. There are four classes of tissue: epithelial, connective, muscle, and
nervous.
B. Epithelial Tissue
1. Introduction to the Epithelia
a) Epithelial tissues cover the body and lines the body cavities;
covering all inner and outer body surfaces.
b) Epithelial Tissues serve a number of functions:
1) Protection - serve as the first line of defense of the body from
foreign invaders
2) Secretion - the release of products from cells (ex; glands)
3) Absorption - the intake of molecules by the cells
4) Sensory reception - involved in some of the special senses
(i.e.; neuroepithelial cells)
5) Filtration - the filtration of bodily fluids
6) Ion Transport - the movement of ions throughout the body
c) Special Features of Epithelium {p. 76, f. 4.1}
1) Epithelium is composed mostly of epithelial cells in very close
contact with one another.
a] This close contact helps the epithelia to protect the body.
b] The close contact is facilitated by intercellular junctions
including:
1] Desmosomes - cellular junctions which bind cells to one
another.
a} Made up of protein plaques of the P faces of the
opposing cell membranes from which radiate
microfilaments anchoring the two cells together.
b} Leaves a small space (~5nm) between the two cells.
2] Tight Junction - is another class of cellular junction binding
cells together.
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14. a} In this case the two cells are so close to one another
that their opposing cell membranes fuse in spots.
1} leaving no space between the cells
3] Gap Junction - is a third class of intercellular junction.
Unlike the other two., it serves to allow for communication
between cells.
a} A specialized transmembrane protein runs through
both cell membranes serving as an ion channel.
2) Epithelium is serparated from underlying tissues by a Basement
Membrane.
a] The basement membrane is an acellular structure made up by
both the epithelium and the underlying c.t.
b] Functions:
1] It serves to bind and support the epithelium.
2] It also allows for the regeneration of epithelia.
3] It separates the epithelium from the c.t.
4] It serves as a line of defense
3) All epithelia has an underlying support of loose c.t.
4) Epithelia, due to the tight packaging of its cells, lacks blood
vessels and nerves.
a] This is why epithelia must be supported by a loose c.t. having a
good blood supply.
b] This feature is unique to epithelia.
5) Epithelia has a high regenerative capability.
a] This allows it repair itself so as to better protect the body.
b] C.T. has little regeneration (it decreases as you age) and
muscle and nerve cells can not be regenerated after
birth.
6) Some epithelial cells have special surface modifications such a
microvilli and cilia.
2. Epithelial Tissue Classification
a) Epithelium can be classified based on two features: cell shape and
number of cell layers.
1) Classification Based on Cell Shape {p. 77, f. 4.2}
a] Squamous Cells - are low, flattened cells. They are scale-like
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15. in appearance.
b] Cuboidal Cells - are cube shaped cells (in 2D), of an equal
height and width.
c] Columnar Cells - are column shaped cells (in 2D). They are
taller than they are wide.
2) Classification based on Number of Cell Layers
a] Simple - composed of one cell layer.
b] Stratified - composed of more than one cell layer
c] Pseudostratified - composed of one layer of cells of uneven
height. Due to the height differences, they appear to be more
than one cell layer but each cell is in contact with the basement
membrane.
b) Types of Epithelia {p. 79 - 82, fig. 4.3}
1) Simple Squamous - composed of one layer of flattened cells.
(ex; blood vessels, lymphatis vesels, serosa, glomeruli, alveoli)
a] Mesothelium - epithelium lining the ventral body cavities and
their associated organs.
b] Endothelium - epithelium lining all the hollow organs of the
circulatory system.
2) Simple Cuboidal - a single layer of cube-shaped cells.
(ex; small glands, ovary surface, kidney tubules)
3) Simple Columnar - a single layer of columnar-shaped cells.
(ex; lining of alimentary canal from stomach to anal canal)
a] In some cases the cells possess cilia on their apical surfaces.
These are termed simple ciliated columnar epithelium (ex;
uterine tube).
4) Pseudostratified Columnar - a single layer of columnar-shaped
cells of varying height giving the false impression of being more
than one cell layer in thickness.
(ex; ducts of large glands, portions of the male urethra)
a] Includes pseudostratified ciliated columnar epithelium of the
upper respiratory tract.
5) Stratified Squamous - more than one layer of flattened cells.
(ex; skin, linings of vagina, mouth, & esophagus)
a] Found in areas subject to much abrasion.
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16. b] There are two types:
1] Stratified Squamous Keratinized (ex; skin)
2] Stratified Squamous Nonkeratinized (ex; esophagus)
6) Stratified Cuboidal - more than one layer (usually 2 - 3) of cube-
shaped cells.
a] Rare (ex; portions of large glands such as the mammaries)
7) Stratified Columnar - more than one layer (usually 2 - 3) of
column- shaped cells.
a] Rare (ex; portions of large glands such as the mammaries)
8) Transitional - a stratified epithelium made up of variably shaped
cells (ex; lining the urinary bladder).
a] A unique tissue which allows for some distension/stretching.
3. Glands
a) Glands are structures composed of epithelial cells which secrete an
aqueous fluid product.
b) They can be classified in two ways:
1) Number of cells making up the gland -
a] Unicellular Glands are made up of one cell.
b] Multicellular Glands are made up of more than one cell.
2) Mode of secretion -
a] Exocrine Glands secrete their products into ducts.
1] They can be either multicellular (ex; salivary glands) or
unicellular (ex; goblet cells of the stomach).
b] Endocrine Glands do not secrete their products into ducts.
1] Aka; “the ductless glands”
2] Their products are actually released into the blood stream
for delivery to the target organ.
a} These products are called hormones.
3] They can be multicellular (ex; pituitary) or unicellular.
C. Connective Tissue
1) Introduction
a) Connective Tissues are an extremely diverse class of tissues ranging
from bone to adipose to blood.
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17. 1) C.T. is broadly subdivided into four main classes:
connective tissues proper, blood, cartilage, and bone.
b) C.T. serves a variety of functions including: connecting organs and
cells, forming the skeleton, allow for the transport of gases and
nutrients, and to protect the body via the immune system.
c) Some diagnostic features of c.t. are:
1) an extensive extracellular matrix.
a] Unlike epithelium, c.t. cells are separated by the matrix.
b] The nature of this matrix varies from type to type of c.t.
2) a common origin. All c.t. are derived from an embryonic tissue
called mesenchyme.
2. Connective Tissues Proper - this is a diverse group (divided further into the two
subclasses of loose and dense c.t.s) and may be best understood by using one type,
areolar c.t. as a model and comparing the others to it.
a) Loose Connective Tissues
1) Areolar Connective Tissue {p.90, FIG. 4.14}
a] It underlies most of the body’s epithelia and surrounds small
nerves and blood vessels.
b] The Extracellular Matrix of Areolar C.T.
1] The Fibers -all three types of c.t. fibers are found in areolar
c.t. and allow it to play a supportive role in organs.
a} Collagen Fibers - are the strongest and most
abundant class. they are able to withstand a great deal
of tension.
b} Reticular Fibers - are branching fibers which can also
withstand tension, but to a lesser extent than can
collagen, but are also more flexible/resilient than is
collagen.
c} Elastic Fibers - are the weakest but most flexible of
the three fiber types. They are composed of the protein elastin.
2] The Ground Substance - a material of varying consistency
which is made up of constituents which are able to soak up
interstitial fluid.
a} Interstitial Fluid is a deriviative of blood.
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18. c] The Cellular Component of Areolar C.T. - there are a variety of
cell types found in areolar c.t.
1] Fibroblasts - are immature c.t. cells which produce the
fibers of areolar c.t.
a} N.B. - the suffix -blast means an immature c.t. cell.
typically this cell will be producing part of the c.t.’s
extracellular matrix.
b} The fibroblast may continue to secrete fibers or
mature into an inactive cell type called the fibrocyte.
2] Macrophages - nonspecific phagocytic cells derived from
WBCs that range throughout the c.t.s.
3] Mast Cells - inflammation fighting cells.
4] Plasma Cells - antibody secreting B lymphocytes.
5] Other WBC types such as neutrophils, eosinophils, &
lymphocytes.
2) Reticular Connective Tissue - {p.93}
a} Reticular c.t. is much like areolar c.t. except that it has only
one fiber type, the reticular fiber.
b] Found in areas where some degree of stretch and strength is
required (ex; spleen, bone marrow, lymph nodes).
3) Adipose Tissue - {p.93}
a] Adipose tissue serves to store nutrients, insulate the body, and
protect the body from trauma.
b} The cells of adipose tissue are called “adipocytes”.
b) Dense Connective Tissues - have a much higher fiber content and a
resulting lower cellular content than does loose c.t. It is a stronger,
more resilient tissue than is loose c.t. {p.94}
1) Dense Irregular Connective Tissue - has its fibers (primarily
collagen) running in a random or irregular pattern.
a] Found in the dermis and the fibrous capsules of some organs
such as the kidneys.
2) Dense Regular Connective Tissue - has its fibers (again, primarily
collagen) arranged into a regular repeating pattern.
a] The collagen fibers are running parallel to one another.
1] This gives it a great deal of tensile strength along one axis.
18

19. b] ex; ligaments, tendons
3) Elastic Connective Tissue - is a dense regular c.t. where the fiber
type is the elastic fiber.
a] It is found in areas requiring strength and flexibility (ex; vocal
cords).
3. Blood {p. 97}
a) The extracellular matrix of blood is very fluid and termed “plasma”.
b) It has three classes of cells: wbcs, rbcs, and platelets.
c) Blood serves in the transport of materials throughout the body and in
the defense of the body.
4. Cartilage {p. 95. 96}
a) Cartilage is a firm but resilient c.t.
1) Cartilage is found in the embryonic skeleton. most of it is
replaced during development but some will remain (ex; tracheal
rings, costal cartilages).
2) It also forms the framework for areas of the body needing support
but also flexibility (ex; nose, ears).
b) The main cell of cartilage is termed the chondrocyte.
1) Chondrocytes mature from chondroblasts which secrete the
extracellular matrix of the tissue.
2) The matrix however is too dense for the chondrocytes to exist in
it directly. Instead they reside in fluid-filled cavities in the
matrix termed “lacunae”.
c) There are three classes of cartilage: hyaline, elastic, and
fibrocartilage.
5. Bone {p. 98}
a) Bone is the densest of the c.t. due to minerals in its extracellular
matrix.
b) Bone serves to support and protect the body. It allows for movement
and stores mineral ions.
c) The main cell type of bone is the osteocyte.
1) Osteocytes mature from osteoblasts which secrete the matrix of
bone.
2) As is the case with cartilage, the matrix of bone is too dense to
allow osteocytes to reside in it directly and so they are located
19

20. in lacunae.
D. Muscle Tissue
1. Muscle tissue allows for the movement of the body and of structures within the body.
a) To do this muscle cells, called myofibers, must be able to contract.
1) This is facilitated by the cytoskeletal structures actin and
myosin.
2. There are three classes of muscle tissue:
a) Skeletal Muscle - {p. 101}
1) Characteristics: striated, multinuceated, voluntary, associated
with the skeleton
b) Cardiac Muscle - {p. 101}
1) Characteristics: striated, 1 -2 nuclei, involuntary, branching
cells, found only in the heart
c) Smooth Muscle - {p. 102}
1) Characteristics: nonstriated, uninuceated, involuntary, associated
with the hollow organs (ex; stomach) and glands
E. Nervous Tissue
1. Nervous tissue serves to regulate and control bodily functions. {p. 103}
2. It contains two classes of cells:
a) Neurons - the nerve cells which are modified to conduct information.
b) Supporting Cells - a variety of cells which support and assist the
neurons.
3. Nerve tissue makes up the nerves, spinal cord, and brain.
20

21. CHAPTER FIVE: THE INTEGUMENTARY SYSTEM
A. Introduction
1. The integumentary system is composed of the epidermis, dermis,
hypodermis, and associated organs such as hair, nails, sweat glands,
and oil glands.
2. It comprises approximately 7% of our total weight and covers the body.
3. The skin is the epidermis and dermis.
a) That is why the hypodermis is referred to as the “subcutaneous
layer”.
b) The skin varies in thickness throughout the varying regions of the
body.
1) It ranges from 1.5 to 4.0 mm.
2) It is thickest on the soles and palms, forming what is called
“thick skin”.
a] All other skin is called “thin skin”. It is thicker on the dorsum
than on the ventral surface.
B.The Skin and Hypodermis
1.The Epidermis {p. 112, f. 5.1; p. 113, f. 5.2}
a) The epidermis is a stratified squamous epithelium.
1) To increase its protective functioning, this tissue is keratinized.
b) The epidermis is composed of four cell types:
1) Keratinocytes - are the principle cells of the epidermis.
a] These epithelial cells arise from the deepest layers of the
epidermis and mature as they move superficially.
1] As they mature, their living portion is replaced by the
protein keratin.
2) Melanocytes - are the pigment producing cells of the epidermis.
a] They produce the pigment melanin to protect from u.v. rays.
3) Merkel Cells - are sensory cells believed to be involved in touch
reception.
21

22. 4) Langerhans Cells - are macrophages which phagocytize foreign
invaders of the skin.
a] One of the few macrophages found outside of our c.t.s.
c) The epidermis is arranged into layers based on the life stage of the
keratinocytes present. There are 4 layers in thin skin and 5 layers in
thick skin:
1) Stratum Basale (aka; stratum germinativum)
a] This is the deepest layer of the epidermis and rests on the
basement membrane.
b] It is composed of one layer of keratinocytes undergoing a great
deal of mitosis to produce more cells.
1] All of these keratinocytes are in contact with melanocytes
which are transferring melanin to them.
c] All four types of epidermal cells are found here.
2) Stratum Spinosum
a] This layer is named for an artifact. In early slides the cells of
this layer had spine-like extensions due to over dehydration
of the tissue.
b] This is several cell layers thick.
1] Its keratinocytes are undergoing some mitosis but not to the
extent of the stratum basale.
2] Three of the four types of epidermal cells are present; only
the Merkel cells are absent.
3) Stratum Granulosum
a] This layer consists of 3 to 5 layers of flattened keratinocytes
beginning to undergo keratinization.
1] The more superficial the layer, the greater the extent of
keratinization.
2] The more superficial layers are also too far removed from
the underlying dermis to receive nourishment from the
blood and so the keratinocytes are dead.
b] The keratinocytes become invested with keratohyaline and
lammellated granules of keratin.
1] These granules give this layer its name.
22

23. 2] These granules will produce more keratin so that the cells
become increasingly filled with it.
4) Stratum Lucidum
a] This layer is found only in thick skin.
b] It is a translucent layer of flattened, dead, keratin rich cells.
1] It has only keratinocytes.
5) Stratum Corneum
a] This is the most superficial layer of the epidermis.
b] This is layer is called the “horny layer” because it is made up
by many layers of flattened, dead, keratin rich cells.
1] These cells are said to be “cornified”.
2] Thee cells are being continuously shed (exfoliation) and
replaced.
2.The Dermis {p. 112, f. 5.1}
a) The dermis is the second, deepest, layer of the skin.
1) It is deep to the epidermis.
2) The dermis is a connective tissue layer.
a] So it contains fibroblasts, fibrocytes, macrophages, mast cells
and other c.t. type cells.
b] Since it is a c.t., the dermis is well vascularized and
innervated.
1] The blood vessels of this layer exert control over body
temperature through vasodilation and vasoconstriction.
3) The dermis is said to bind the entire body together.
b) The dermis is composed of two layers.
1) The Papillary Layer
a] This layer comprises the superficial 20% of the dermis.
b] It is an areolar connective tissue.
c] The papillary layer gets its name from its dermal papillae.
1] Dermal papillae are finger-like extensions of the dermis
which interdigitate with the epidermis and help to hold the
two layers together.
2) The Reticular Layer
a] This layer comprises the deeper 80% of the dermis.
b] It is a dense irregular c.t.
23

24. 1] The maze, or retinaculumn, of its collagen fibers give it its
name.
c] The dermis varies in thickness from area to area causing the
formation of tension lines (aka; lines of cleavage, Langerhans
lines) in the skin.
1.The Hypodermis {p. 112, f. 5.1}
a) The hypodermis is not, technically, considered to be part of the skin.
1) It is found just deep to the skin.
a] So it is also called the “subcutaneous layer” or “superficial
fascia”.
b) In humans the hypodermis is composed primarily of adipose tissue.
1) It functions to:
a] store fat
b] anchor the skin to underlying structures
c] allows for some degree of skin mobility
d] insulation of the body.
B.The Structures of The Skin
1.Glands of the Skin - These are epidermal invaginations into the deeper
layers of the integument.
a) Sudoriferous Glands (aka; sweat glands)
1) Sudoriferous glands are located on all body surfaces excepting the
nipples and external genitalia.
2) Functions:
a] removal of nitrogenous wastes [slight]
b] regulation of body temperature by cooling the body
3) There are two types of sudoriferous glands:
a] Eccrine Glands {p. 120, f. 5.7b}
1] These are the most numerous and widely distributed sweat
glands.
2] They are coiled, tubular glands which secrete their products
onto the surface of the skin by a duct.
3] They are active throughout your life time.
b] Apocrine Glands
24

25. 1] These glands are much less numerous and distributed.
a} They are located in the anal, genital, and axillary regions
primarily.
2] Their glandular openings are found at the base of hair
follicles.
3] They become active with the onset of puberty.
4) Modified Sudoriferous Glands
a] Mammary Glands
b] Ceruminous Glands - apocrine glands modified to produce
ceruminen, ear wax.
b) Sebaceous Glands (aka; oil glands) {p. 120, f. 5.7a}
1) Sebaceous glands are found throughout the skin in all areas except
for the soles and palms.
2) These glands produce sebum, oil and become active at puberty.
3) Their glandular openings are found connected to hair follicles.
2. Hair {p. 118, f. 5.4}
a) Hair is a flexible strand made up of keratinized cells.
1) Unlike epidermal cells, the cells of hair have hard keratin.
b) Functions:
1) insulation from the cold
2) protection from the effects of direct sunlight on the head
3) protection from particulate matter entering the eyes/nose
4) detection of insect pests.
c) Structure:
1)The hair can be divided into the shaft (the exposed portion) and the
root (the portion embedded in the skin.
2) Cross sectionally, hair can be divided into three concentric rings
of slightly dissimilar cells: medulla, cortex, and cuticle.
3) Hair Follicles are tubular invaginations of the epidermis from
which the hair proper grows.
a] Hair follicles extend from the epidermis into the dermis or
even the hypodermis (in the scalp).
b] Hair follicles have associated structures which aid the hair in
performing its functions:
25

26. 1] Root Hair Plexus - a cluster of sensory nerve endings at the
base of the follicle which allows for touch reception.
2] Arrector Pili Muscle - a smooth muscle found at the base of
the follicle which serves to erect the hair in response to a
decrease in ambient air temperatures.
3. Nails {p. 122, f.5.8}
a) Both fingernails and toenails are modified extensions of the
epidermis, rich in hard keratin, found at the distal edge of the digits.
b) Parts:
1) Free Edge - extends beyond the digit tip.
2) Body - is the attached part.
3) Root - the portion embedded within the skin of the digit.
4) Nail Matrix - the site of nail growth.
5) Nail Bed - a layer of epidermis upon which the nail sits.
a] It gives rise to the nail matrix.
b} It lacks the outer, keratinized layers of the epidermis.
26

27. CHAPTER 6: OSTEOLOGY 1 - SKELETAL TISSUE
A. Cartilage
1. Introduction
a) The early embryonic skeleton is composed mostly of cartilage.
1) In more advanced vertebrates the cartilage is largely replaced by
bone.
a] In humans cartilage is found in the adult in: {p.131}
1] the costal cartilages which connect the ribs to the sternum
2] the articular cartilages which cover the ends of most bones
and movable joints
3] the intervertebral cartilages located between the vertebrae
4] cartilages supporting the respiratory tubes (ex; tracheal
rings)
5) cartilages of, and associated with, the larynx
6) cartilages of the pinna
7) cartilages of the nose.
2. The Nature Of Cartilage As A Tissue
a) Cartilage is a firm but resilient tissue which is able to respond to
pressure and to give support.
1) This is due to its extracellular matrix which is firm due to its
fiber and mineral content.
a] Due to the firmness of the matrix, cartilage tissue is devoid of
nerves and blood vessels.
1] Nutrients reach the chondrocytes (the mature cartilage
cells) by diffusion.
b] Also due to the firmness of the matrix, the chondrocytes reside
in lacunae, fluid filled chambers within the matrix.
c] Chondroblasts, the immature cartilage cells, secrete the
matrix.
b) The cartilage organ will be surrounded by a layer of dense, fibrous
c.t. called the perichondrium.
27

28. 1) The inner layer of the perichondrium contains chondroblasts
which assist in the growth and repair of the organ.
2) The fibrous outer layer of the perichondrium helps the cartilage
organ to maintain its shape under pressure.
3. The Growth of Cartilage
a) Cartilage displays two patterns of growth:
1) Appositional Growth (“growth from without”) - chondroblasts in
the surrounding perichondrium produce new cartilage tissue.
2) Interstitial Growth (“growth from within”) - chondrocytes within
the cartilage undergo mitosis and the resulting chondroblasts
begin secreting new cartilage tissue.
b) Cartilage growth, as is the case of all skeletal growth, ceases
with maturity (middle to late teens).
1) At this time the chondrocytes lose their ability to divide.
a] Due to this, cartilage possesses little regenerative capability
and so heals poorly.
1] Some healing is possible due to the chondrocytes ability to
secrete new matrix.
4. There Are Three Classes of Cartilage:
a) Hyaline Cartilage
1) This is the most abundant and widely distributed type of cartilage
2) It provides support with some flexibility and resiliency.
3) Its matrix has only collagen fibers and these are arranged into
thin strands giving a clear look to it.
4) ex; costal cartilage, articular cartilage
b) Elastic cartilage:
1) Less widely distributed it is found in areas requiring support but
also a good deal of flexibility.
a] ex; epiglottis, pinna
b] This flexibility is possible due to the presence of elastic fibers
(in addition to collagen fibers) in the matrix.
c) Fibrocartilage:
1) Fibrocartilage often serves as a structural intermediate between
hyaline cartilage and dense regular c.t.
a] ex; where hyaline cartilage meets a tendon (eg; knee joint)
28

29. b] Its microscopic appearance is also intermediate between
hyaline cartilage and dense regular c.t. being composed of
rows of chondrocytes arranged between prominent bundles of
collagen.
2) Fibrocartilage is found where both the ability to withstand
pressure and tensile strength are required.
B. Bone
1. Introduction
a) Bone Tissue vs. Bone Organs
1) Bone tissue is the dominant tissue of bones organs but bone
organs contain more than simply bone tissue.
a] It also contains blood vessels, lymph vessels, nerves, marrows,
and other c.t.s.
b) The endoskeleton serves a number of purposes:
1) support (ex; pelvis supports the abdominal organs)
2) protection (ex; skull protects the brain)
3) movement (the bones act as the levers acted upon by skeletal
muscles to produce movement)
4) blood cell formation ( which occurs in red marrow housed within
bone)
5) mineral storage (for minerals such as calcium and phosphorus)
c) Bones are classified based on their shape: {p. 133, f. 6.2}
1) Long Bones - length>width
a] ex; femur, humerus
b] long bones have a “shaft”
2) Short Bones - length<width
a] Short bones are generally cuboidal in shape (ex; carpals).
b] A subdivision of the short bones are sesamoid bones.
1] Sesamoid bones are short bones which are encased in
tendons and ligaments. They do not articulate with the
skeleton directly.
2] ex; patella
3) Flat Bones -flattened, thin bones
29

30. a] ex; ribs, many skull bones, ilium
4) Irregular Bones - bones with an irregular shape
a] ex; vertebrae, ethmoid, sphenoid
2. Types of Bone Cells
a) Osteoblasts - are the immature bone cells they will produce the
organic portion of bone matrix and mature into osteocytes.
10 They are bone matrix depositing cells.
b) Osteocytes - are the mature bone cells.
c) Osteoclasts - are bone degrading cells.
1) They will break down the matrix to release stored minerals (i.e.;
calcium) back into the blood stream.
3. The Gross Anatomy of Bone
a) All bone organs have two types of bone tissue; a thick, dense outer
layer termed compact bone and an inner layer of sponge-like bone
full of small openings termed spongy bone/cancellous bone.
1) Compact Bone {p.138}
a] Although it may appear to be completely solid, compact bone is
actually perforated with blood vessels, lymph vessels, and
nerves.
1] These vessels are a portion of a subunit called the Osteon or
Haversian System.
a} An osteon appears as a group of concentric tubes
arranged in a cylinder along the long axis of the bone.
1} They act as weight bearing pillars within the bone.
b} Each of these concentric tubes has its collagen fibers
arranged parallel to one another within the tube.
1} Such an arrangement is called a lamella.
2} The collagen fibers of adjacent lamellae
however are arranged in alternating patterns
(relative to each other) so as to give more
strength to the organ.
c} In the center of each osteon is the Haversian Canal.
1}The Haversian canal is also known as the
Central Canal.
2} This canal allows a nutrient artery and vein to
30

31. enter into the bone tissue.
(a) The osteocytes are arranged into concentric
rings, the lamellae, around the Haversian canal
so as to receive nutrients and oxygen from the
blood.
3} At right angles to the Haversian canals are
Volksmann’s Canals (aka; Perforating Canals)
which connect Haversian canals in neighboring
osteons.
b] The osteocytes reside in lacunae within the matrix due to its
density.
1] Unlike cartilage tissue, the matrix of bone is too dense to
allow for the diffusion of materials to and from the cells.
a} That is why we see the perforation of blood vessels
into bone tissue.
b} It is also why we see radiating processes extending
from the lacunae called canaliculi.
1} These structures act as little irrigation canals
carrying materials between the Haversian canal and
the osteocytes.
2) Spongy Bone (aka; diploe bone, cancellous bone) {p. 135, f. 6.3d}
a] Due to its numerous perforations, spongy bone does not require
the osteon organization of compact bone.
1] These perforations are crossed by tiny bridges of bone
tissue called trabeculae.
2] The spaces between the trabeculae are called
intertrabecular spaces. They are not open spaces but filled
with blood vessels and red marrow.
b) The Structure of Bone Organs
1) Long Bones {p. 135, f. 6.3}
a] Long bones have a distinct shaft with heads on either side.
1] Epiphysis - the heads of long bones; these are expanded
regions which allow for better articulation.
a} At the border between the epiphysis and the shaft is the epiphyseal line.
1} It is the remains of a cartilagenous structure called the epiphyseal growth plate from
31

32. which long bones grow in youth.
(a) The epiphyseal plate is composed of hyaline cartilage.
2] Diaphysis - is the term for the shaft of a long bone.
3] Medullary Cavity (aka; marrow cavity) - is an area within
the diaphysis devoid of bone tissue and filled with marrow.
a} There are two classes of marrow:
1} Red Marrow - found in the intertrabecular spaces it is
hemopoeitic tissue.
2} Yellow Marrow - found in the medullary cavity of
children and adults it is actually stored fat.
b] Blood Vessels
1] The two main blood vessels of the long bone are the nutrient
artery and nutrient vein.
a} They enter the bone through the nutrient foramen on the
shaft of the bone.
c] Membranes of the Bone Organ
1] Periosteum - is a layer of dense, fibrous c.t. covering the
outer surfaces of bone organs except at the articular cartilage.
a} It has an inner layer of osteoblasts and osteoclasts to
allow for the remodeling and repair of the bone.
b} It is richly vascularized and innervated.
c} The periosteum is attached to the bone surface by thick
bundles of collagen called Sharpey’s Fibers or
Perforating Fibers.
2] Endosteum - is the c.t covering the inner surfaces of the
bone organ.
a} It lines the trabeculae, Haversian canals, and
Volksmann’s canals.
2) The Structure of Short, Flat, and Irregular Bones {p. 136, f. 6.4}
a] These three bone classes closely resemble long bone structure
in that there is an outer layer of compact bone and an inner
layer of spongy bone.
b} However, structurally they differ from long bones in that they
lack the epiphyses, diaphysis, and medullary cavity.
4. The Chemical Composition of Bone
32

33. a) The organic component of bone matrix is called the Osteoid.
1) The osteoid makes up ~ 35% of the mass of bone tissue.
2) It serves to add tensile strength and some flexibility to the bone.
3) The osteoid has a high collagen fiber content.
b) The inorganic component of bone is termed the hydroxyapitate.
1) It is made up of mineral salts, primarily calcium salts.
2) It makes up the remaining ~ 65& of bone mass.
3) It gives bone its hardness.
5. Bone Development (aka; Osteogenesis, Ossification)
A) Osteogenesis begins at about the eight week of development in the
embryo. It is when the cartilagenous skeleton precursor is replace
with bone. There are two processes:
1) Intramembranous Ossification - where the bones develop directly
from mesenchyme.
a] So these bones do not develop from a hyaline cartilage
precursor.
b] Bones that develop in this way are termed “membrane bones”.
1] ex; many of the skull bones and clavicle
2) Endochondral Ossification - where the bones replace a
cartilagenous precursor.
a] These bones are termed “endochondral bones”.
1] ex; femur, humerus
b) The Process of Intramembranous Ossification {p. 140, f. 6.8}
1) Unlike endochondral bones, membrane bones do not develop from a
cartilage model but directly from the mesenchyme.
a]This process applies to most of the skull bones and the clavicle.
2) Procedure
a] During the eighth week of development a group of mesenchymal
cells differentiate into osteoblasts.
b] The osteoblasts begin to secrete the osteoid.
c] the newly forming tissue becomes mineralized (adding the
inorganic component).
d] The osteoblasts will then become osteocytes existing within
their self-created matrix.
c) The Process of Endochondral Ossification {p. 141, f. 6.9}
33

34. 1) This process applies to all of the other bones, the endochondral
bones.
a] These bones are first modeled by hyaline cartilage which will
gradually be replaced by bone tissue.
2) Procedure
a] A bone collar forms about the diaphysis of the cartilage model.
1] The perichondrium which surrounds the cartilage becomes a
periosteum.
2] This periosteum then lays down a collar of bone tissue.
b] The calcification of cartilage begins at the diaphysis of the
cartilage model.
1] Chondrocytes at the center of the diaphysis enlarge and
signal for the calcification of the cartilage matrix.
2] However, as the matrix calcifies the diffusion of nutrients
to the chondrocytes becomes impossible and the cells begin
to die.
3] As a result, the cartilage in this central area begins to
deteriorate.
c] A Periosteal Bud invades the diaphysis.
1] As the cartilage deteriorates a cavity forms in the diaphysis
which is invaded by the periosteal bud.
a} The periosteal bus consists of a nutrient artery, a
nutrient vein, osteoclasts and immature osteoblasts.
2] The osteoblasts begin to secrete the osteoid around the
remaining fragments of calcified cartilage forming the
first of the bone trabeculae (the beginning of spongy bone
formation).
3] By the third month the bone tissue has begun to appear both
within and around the diaphysis forming the Primary
Ossification Center.
d] Formation of the medullary cavity
1] So far during this process the epiphysis has kept its
cartilage healthy so as to allow for rapid growth which
(allows the bone to lengthen).
a} As the cartilage grows outwards, the cartilage which is
34

35. left behind begins to calcify and deteriorate forming the
trabeculae.
2] Meanwhile the center of the diaphysis continues to
disintegrate forming the medullary cavity.
e] Ossification at the epiphysis
1] Shortly prior to or after birth the epiphyses begin to ossify.
a} Cartilage in the center begins to calcify and die.
b} An Osteogenic Bud enters the epiphysis.
1} An osteogenic bud is much like a periosteal bud being
an artery, vein, osteoblasts, and osteoclasts.
c} Spongy bone begins to form in the epiphysis.
d} These areas are called the Secondary Ossification
Centers.
2] This leaves cartilage only at the epiphyseal plates and on
the articular surfaces.
a] Further growth will occur at the epiphyseal plate.
35

36. CHAPTER 7 & 8; OSTEOLOGY 2; THE SKELETON
A. The Axial Skeleton
1. The axial skeleton includes the skull, vertebral column, and rib cage.
a) It is composed of 80 named bones, most of these being in the skull.
b) It serves to protect the CNS and thoracic organs and to support the
head, neck, and trunk.
2. The Skull {p.155 -167, p.168-9 Table 7-2}
a) The skull is a complex structure composed of two sets of bones: the
facial and cranial bones.
1) For the most part these bones are flat bones.
2) They are joined by interlocking joints called sutures.
b) The Cranium/Cranial Bones
1) Frontal Bone - a single, broad, flat bone which forms the forehead.
a] The frontal bone also contributes to the anterior cranial fossa
which holds the frontal lobes of the cerebrum.
2) Parietal Bones - a pair of bones that form the bulk of the cranial
vault.
a] Where the parietal bones articulate with other cranial bones
the coronal, squamosal, sagittal and lambdoidal sutures are
found.
3) Sutural Bones (aka; Wormian ossicles) - are small, unnamed bones
found within sutures.
4) Occipital Bone - a single bone which makes up the cranial base
and the posterior cranium.
5) Temporal Bones - a pair of bones found on the sides of the
cranium.
6) Sphenoid Bones - a singular, irregular shaped bone which makes up
a significant portion of the cranial floor.
7) Ethmoid Bone - an irregular bone located between the sphenoid
and nasal bones.
c) The Facial Bones
36

37. 1) Mandible - the singular bone of the lower jaw.
2) Maxillary Bones - these paired bones form the upper jaw and the
central portion of the face.
3) Zygomatic Bones - the cheek bones, they join the temporal bones
to form the zygomatic arch.
4) Nasal Bones - form the bridge of the nose.
5) Lacrimal Bones - form a portion of the medial orbital wall.
6) Palatine Bones - form part of the roof of the mouth.
7) Vomer - a singular, medial bone of the face.
8) Inferior Nasal Conchae - paired bones locate in the nasal cavity.
3. Hyoid Bone {p. 167, f. 7.12}
a) The hyoid bone is located anterior to the cervical region and below
the mandible.
1) It is held in place by ligaments connecting it to the larynx and the
attachment of certain tongue and neck muscles.
4. The Vertebral Column {p. 170, f. 7.13}
a) The vertebral column is composed of 33 irregularly shaped bones
called the vertebrae.
1) The vertebrae actually appear as 26 bones, 2 being composites of
5 fused bones in the case of the sacrum and 4 fused bones in the
case of the coccyx.
. 2) The vertebral column is able to maintain its position through the
support of muscles and ligaments.
a] The muscles include the erector spinae group and the
iliocostalis.
b] The ligaments are divided into two groups: the anterior and
posterior longitudinal ligaments.
3) Between the vertebrae are cartilagenous discs which serve to
cushion and protect the spine called the intervertebral discs.
a] The intervertebral discs are composed of: {p. 171, f. 7.14}
1] a central nucleus pulposus
2] surrounded by the annulus fibrosis, twelve concentric rings
of fibrocartilage.
b) The vertebral column has five major divisions:
1) Cervical Vertebrae - the 7 vertebrae of the neck.
37

38. 2) Thoracic Vertebrae - the 12 vertebrae of the upper torso/thorax.
3) Lumbar Vertebrae - the 5 vertebrae of the lower
torso/back/abdominal area.
4) Sacral Vertebrae or Sacrum - the 5 fused vertebrae which
articulate with the pelvis.
5) Coccageal Vertebrae or Coccyx - the 4 fused vertebrae of the
vestigal tail.
c) The Gross Anatomy of a Vertebra {p. 172, f. 7.15}
1) Centrum (or body) - the weight bearing portion of the vertebra.
2) Vertebral Arch - the bony structure, posterior to the centrum,
which encases and protects the spinal cord.
a] The spinal cord passes through the Vertebral Foramen.
b] The vertebral arch is actually a composite of 2 vertebral
pedicles and 2 vertebral laminae.
c] The vertebral arch has 7 processes radiating off from it:
1] (Dorsal) Spinous Process - the single posterior projection
formed at the junction of the two laminae.
2] Transverse Process - Two lateral projections of the
vertebral arch.
a} Both the spinous and transverse processes serve for
muscle and ligament attachment.
3] Superior Articular Process - a pair of processes which
extend superior to the vertebra so as to articulate
with the vertebra above it.
4] Inferior Articular Process - a pair of processes which
extend inferior to the vertebra so as to articulate
with the vertebra below it.
a} The points of articulation between the articulating
processes of two vertebrae are smooth
surfaces called articulating surfaces or facets.
d] The space between the pedicles of two successive vertebrae
are the intervertebral foramen which allow for the passage of
the spinal nerves to and from the spinal cords.
d) Regional Specializations in the Vertebrae {p. 174}
1) Cervical Vertebrae
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39. a] These 7 vertebrae are designed to support and to move the head
(as well as to protect the spinal cord).
b] Due to their functional role the cervical vertebrae differ from
the typical pattern:
1] C3 -> C7 -
a} bifid spinous process
b} transverse foramen for the passage of blood vessels
servicing the brain (i.e.; the vertebral
arteries).
2] C1 ; the Atlas -
a} Lacks a centrum and spinous process
b} It is basically a vertebral arch with two lateral masses
designed to support the skull.
3] C2 ; the Axis -
a} It looks like a typical vertebra except that it has a
superiorly projecting process called the
Dens or Odontoid process.
1} The dens is designed to act as a pivot for the
rotation of the head.
2} Actually, the dens is the centrum of the atlas. It
separated from the atlas and
migrated to, and fused to, the axis during
development.
2) Thoracic Vertebrae
a] These 12 vertebrae articulate with the ribs and so will be
modified for this purpose.
1] Each will have articulating surfaces, either Facets or
Demifacets, for the attachment of the head of the
ribs.
2] Their transverse processes will also have facets to
articulate with the rib tubercle.
a} Often the transverse process is elongated to allow for
better articulation.
b] Thoracic vertebrae will generally also have long, inferiorly
pointing spinous processes which overlap to help
39

40. stabilize
our bipedal stance.
3) Lumbar Vertebrae
a] These 5 vertebrae are found in the region of the back exposed to
the greatest amount of stress due to weight bearing. As a
result they are thicker and have shorter, broader processes.
4) Sacral Vertebrae {p. 177, f. 7.18}
a] These 5 vertebrae are fused together to form the Sacrum.
1] The sacrum articulates with the pelvis and helps to support
the weight of the trunk.
5) Coccygeal Vertebrae {p. 177, f. 7.18}
a] Tese 4 vertebrae are fused together to form the Coccyx, the
vestigial remnants of the vertebrate tail.
5. The Rib Cage and Sternum {p. 178}
a) The Sternum
1) The sternum is a composite of six bones and serves as the
anterior point of attachment for the ribs via their costal
cartilages.
2) The sternum is made up of:
a] Manubrium - a singular bone,it is the most superior portion of
the sternum.
1] It articulates with the first and second ribs as well as the
clavicles.
b] Body/ Blade/ Gladius - four fused bones making up the bulk of
the sternum.
1] It articulates with the second through the seventh ribs.
c] Xiphoid Process - the inferiormost portion of the sternum.
1] It is actually composed of cartilage until it ossifies at
about the age of 40.
2] It articulates with the body at the xiphisternal joint.
b) The Ribs {p. 167}
1) The twelve pairs of ribs serve to protect the thoracic organs.
a] The ribs are flattened, curved bones.
2) The categories of ribs:
a] True Ribs: R1-R7
40

41. 1] They are also called the Vertebrosternal Ribs since they
attach directly to the sternum by their own
costalcartilage.
b] False Ribs: R8-R12
1] These ribs attach to the sternum either indirectly or not at
all. They can be further subdivided:
a} Vertebrochondral Ribs: R8-R10
1} They attach to the sternum indirectly by having
their costal cartilages attaching to the
costal cartilage of R7.
b} Vertebral Ribs: R11-R12
1} These ribs do not attach to the sternum at all.
They are attached only at the vertebral
column.
B. The Appendicular Skeleton
1. The appendicular skeleton is composed of the bones of the limbs and their
associated girdles.
a) It serves primarily for movement.
2. The Upper Limb and Its Girdle
a) The Pectoral Girdle (the clavicle and scapula) {p. 187, f. 8.1 a}
1) The Clavicle - is a slender, slightly curving flat bone which
articulates anteriorly with the manubrium (the sternal
extremity) and posteriorly with the scapula (the acromial
extremity).
2) The Scapula - is a flat, thin, triangular shaped bone found posterior
to the rib cage (R2-R7) and the two scapula are separated by the
vertebral column. {p. 188, f. 8.2}
a] Each scapula has three borders: superior, medial/vertebral, and
lateral/axillary.
b] The scapula articulates with the humerus at the Glenoid Cavity.
c] The scapula has two hook-like processes, the Acromion and
Coracoid Process, which are attached to the clavicle by
41

42. ligaments.
b) The Arm (the humerus) {p. 189, f. 8.3}
1) The arm, commonly called the “upper arm”, has only one bone, a
long bone called the humerus.
a] The proximal epiphysis of the humerus has a spherical head
which articulates with the scapula at the glenoid.
1] Due to its morphology this allows for rotational movement.
b] The distal epiphysis has two points if articulation termed
condyles.
1] On the lateral condyle is the trochlea which articulates with
the ulna.
2] On the medial condyle is the capitulum which articulates
with the radius.
c) The Forearm (the ulna and radius) {p. 191, f. 8.4}
1) This portion of the limb is composed of two parallel bones, the
radius and ulna.
a] they are in contact -
1] at both epiphyses by the Radioulnar Joints.
2] and along their lengths by the Interosseous membrane, a
ligament.
2) The Ulna
a] The ulna is the larger of the two forearm bones and does the
bulk of articulation with the humerus.
1] To facilitate this it has two prominent projections on the
proximal epiphysis which form a hinge joint:
a} The Coronoid Process
b} The Olecranon Process.
3) The Radius
a] The distal epiphysis is much wider than is the proximal (the
opposite of the ulna) to better articulate with the carpal
bones.
b] The proximal epiphysis is shaped to allow for some rotation of
the forearm.
d) The Bones of the Hand {p. 193, f. 8.6}
1) The Carpus - the anatomical wrist
42

43. a] The carpus is composed of eight bones loosely arranged into
two rows of four bones each:
1] proximal row - scaphoid, lunate, triquetral, pisiform
2] distal row - trapezium, trapezoid, capitate, hamate.
2) The Metacarpus - the “palm”
a) The metacarpus is composed of five metacarpal bones, one to
articulate with each finger.
3) The Phalanges - the digits or fingers
a] Each finger is termed a phalange.
1] It is composed of three phalanx bones: distal, intermediate,
and proximal phalanx.
a} The exception to this is the Pollex, the thumb which
has only two phalanx bones in it.
3. The Lower Limb and Its Girdle {p. 195}
a) The Pelvic Girdle (ilium, Ischium, and Pubis) {p. 197, f. 8.7}
1) Unlike the pectoral girdle which served to articulate and support
the limb, the pelvic girdle must also support the weight of the
superior body, especially the viscera.
a] Due to this role, the pair of hip bones form a bowl-shaped
structure called the Pelvis.
2) The “hip bone” is anatomically known as the Innominate, os coxa,
or Coxal Bone. It is made up of three bones which are fused
together: ilium, ischium, and pubis.
a] Ilium - is the superiormost bone of the innominate.
1] The ilium consists of a “body” and the broad, flat “ala”.
a} Many muscles attach at the ala at its thickened
superior edge, the iliac crest.
2] The ilium articulates with the sacrum via the sacroiliac
joint at the auricular surface.
b] Ischium - is inferior to the ilium and posterior to the pubis.
1] The ischium is an “L”-shaped bone which can be divided into
a thickened “body”, containing the ischial
tuberosity, and the thin ramus, which articulates with
the pubis.
c] Pubis - the anterior portion of the innominate.
43

44. 1] It is a “V”-shaped bone having two rami; the superior ramus
which articulates with the ilium and the inferior
ramus which articulates with the ischium.
b) The Thigh {p. 201, f. 8.9}
1) The thigh is composed of only one bone, the Femur.
a] In some ways the femur is comparable to the humerus:
1] ball-like head at the proximal epiphysis to articulate with
the girdle at the acetabulum
2] a long bone
3] distal epiphysis has two articular surfaces, the lateral and
medial condyles, for articulation with the bones of the
lower limb
b] The femur also has a patellar surface for articulation with the
patella.
c) The Patella (the knee cap)
1) The patella is a triangular bone with one broad articular region
divided into two articular surfaces for the lateral and medial
condyles of the femur.
d) The Leg {p. 203, f. 8.10}
1) The leg is composed of two parallel bones, the Tibia and Fibula.
a] they are in contact -
1] at both epiphyses by the Tibiofibular Joints.
2] and along their lengths by the Interosseous membrane, a
ligament.
2) Tibia
a] The tibia is much more massive than is the fibula.
b] It articulates with both condyles of the femur proximally and
with the talus of the ankle inferiorly.
3) Fibula
a] The fibula is a slender long bone which articulates with the
tibia at both epiphyses and with the talus.
1] The portion of the fibula articulating with the talus is the
lateral malleolus.
b] The fibula does not bear any significant weight.
e) The Foot {p. 204}
44

45. 1) The Tarsus (the posterior foot)
a] The tarsus contains seven bones called the Tarsals which are
designed to support the weight of the body and to allow for
motion.
b] The tarsal bones are:
1] Talus - articulates with the lower leg and calcaneus.
2] Calcaneus - the heel, the sight of attachment for the calf
muscles.
3] Cuboid
4) Navicular
5) Cuneiforms - there are three; medial, intermediate, and
lateral or first, second, and third cuneiform
respectively.
2) The Metatarsus
a] The metatarsus is made up of five small, long bones called the
metatarsal bones.
3) The Phalanges - the digits or toes
a] Each toe is termed a phalange.
1] It is composed of three phalanx bones: distal, intermediate,
and proximal phalanx.
a} The exception to this is the Hallux, the big toe which
has only two phalanx bones in it.
45