INTRODUCTION TO ANATOMY
&
TERMINOLOGY IN ANATOMY
&
INTRODUCTION TO OSTEOLOGY
19. 09.2014
Kaan Yücel
M.D., Ph.D.
http://mdp120.org
SOURCES USED
 Richard L. Drake, A. Wayne Vogl, Adam W. M. Mitchell. Gray's Anatomy for Students. 3rd Edition:
Churchill Livingtsone, Philadelphia, PA, USA, 2014. ISBN: 978-0-7020-5131-9
 Keith L. Moore, Arthur F. Dalley, Anne M. R. Agur. Clinically Oriented Anatomy. 7th Edition, Lippincott
Williams & Wilkins, Philadelphia, PA, USA, 2013. ISBN: 9781-45111-9459
 Richard S. Snell Clinical Anatomy by Regions. 8th Edition, Lippincott Williams & Wilkins, Philadelphia,
USA, 2008. ISBN: 0781764041
 Kaplan Arıncı, Alaittin Elhan. Anatomi. I. Cilt. 5. Baskı., Güneş Kitabevi, Ankara, 2014. ISBN: 978-975277-513-8
 Ulucam E, Gokce N, Mesut R. Turkish Anatomy Education From the Foundation of The First Modern
School to Today. Journal of the International Society for the History of Islamic Medicine (ISHIM), 2003,2
READABILITY SCORE
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Dr.Kaan Yücel
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Introduction to anatomy & Terminology in anatomy & Introduction to osteology
Introduction to anatomy
Definition of anatomy
Etymology: “Cutting through” in Ancient Greek and Latin. Anatomy deals with parts of the human body and
investigates the body by the naked eye.
Types of anatomy
1. Regional (topographical) anatomy 2. Systemic anatomy 3. Clinical (applied) anatomy
In systemic anatomy, various structures may be separately considered. On the other hand, in topographical or
regional anatomy, the organs and tissues may be studied in relation to one another. Surface anatomy is an essential
part of the study of regional anatomy. Clinical (applied) anatomy emphasizes aspects of bodily structure and
function important in the practice of medicine, dentistry, and the allied health sciences. It incorporates the regional
and systemic approaches to studying anatomy and stresses clinical application.
The ways of learning anatomy; Cadaver; Dissection; Prosection
Other materials of learning human anatomy: anatomy models, anatomy atlases, videos, textbooks, charts, medical
dictionaries, etc.
The field of Human Anatomy has a prestigious history, and is considered to be the most prominent of the biological
sciences of the 19th and early 20th centuries. The final major anatomist of ancient times was Galen (of Bergama),
active in the 2nd century. His collection of drawings, based mostly on dog anatomy, became the anatomy textbook
for 1500 years. Andreas Vesalius is the first modern anatomist who wrote the first anatomy textbook of the modern
times; De humani corporis fabrica (On the Fabric of the Human Body.
Anatomical position
All anatomical descriptions are expressed in relation to one consistent position, ensuring that descriptions are not
ambiguous.
Head, gaze (eyes), and toes directed anteriorly (forward), arms adjacent to the sides with the palms facing anteriorly,
and lower limbs close together with the feet parallel
Variations: Occasionally a particular structure demonstrates so much variation within the normal range that the
most common pattern is found less than half the time!
Terminology in anatomy
Anatomical planes
median, sagittal, frontal-coronal, and transverse-axial) that intersect the body in the anatomical position.
The sagittal plane, like an arrow, divides the body into right and left, coronal anterior to posterior, and axial superior
to inferior parts.
With reference to the anatomical planes
Superior, inferior, anterior, posterior, medial, lateral
Relating primarily to the body's surface
Superficial, intermediate, and deep (Lat. profundus, profunda) external internal proximal distal
Terms of laterality
Unilateral and bilateral, ipsilateral and contralateral
Terms of movemement
Flexion, extension, abduction, adduction, circumduction (medial and lateral), rotation
Pronation, supination, eversion, inversion, opposition, reposition, elevation, depression
Positions of the body
The supine position of the body is lying on the back. The prone position is lying face downward.
Introduction to Osteology
Osteology is the science of bones. There are 206 bones in adults. The skeletal system is divided into two functional
parts. The axial skeleton: bones of the head (cranium or skull), neck (hyoid bone and cervical vertebrae), and trunk
(ribs, sternum, vertebrae, and sacrum).The appendicular skeleton: bones of the limbs, including of the shoulder and
pelvic girdles. Bone is the hardest structure after teeth. The calcification of its extracellular matrix is the reason for
that. Living bones have some elasticity. This elasticity results from the organic matter. They also have great rigidity.
The rigidity results from their lamellous structures and tubes of inorganic calcium phosphate.
There are four principal types of bone cells: osteogenic cells, osteoblasts, osteocytes, and osteoclasts. Histologically,
bone is composed of units termed Haversian systems or osteons. In osteons concentric rings of osteocytes are
arranged around a central blood vessel. All bones are covered externally, by a fibrous connective tissue membrane.
It is called periosteum. The skeleton is composed of cartilages and bones. Hyaline is the most common type of
cartilage. Bones are classified according to their
shape: long, short, flat, irregular and sesamoid bones.
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Introduction to anatomy & Terminology in anatomy & Introduction to osteology
1. INTRODUCTION TO ANATOMY
45.3%,10.9
Anatomy is the study of the structure of the human body.
1. 1. DEFINITION OF ANATOMY
The word “anatomy” has a Latin and Ancient Greek origin. The prefix “ana-“means “up", “temnein, tome”
means "to cut." Anatomy means “cutting up, cutting through”. The name of the technique became the name of
the discipline throughout the history.
The term human anatomy is about the consideration of the structures of the human body. It deals with the
parts which form the fully developed individual. This observation is evident to the naked eye.
1.2. TYPES OF ANATOMY
The three main approaches to studying anatomy: regional, systemic, and clinical (or applied) anatomy. In
systemic anatomy, anatomy is studied under the title: “systems”. In topographical or regional anatomy, the
organs and tissues may be studied in relation to one another, i.e. in regions.
Surface anatomy is an essential part of the regional anatomy. It provides knowledge of what lies under
the skin. The surface anatomy requires a thorough understanding of the anatomy of the structures beneath the
surface.
Clinical (applied) anatomy is about structures and functions important in the practice of health sciences.
It incorporates the regional and systemic approaches to studying anatomy. Clinical anatomy stresses clinical
application. Physical examination is the clinical application of surface anatomy.
1.3. THE IMPORTANCE OF LEARNING ANATOMY AS A FUTURE PHARMACIST
 To understand bodily function and how both structure and function are modified by disease.
 To understand the pathway for targeting therapy to a specific site
 To communicate with the colleagues properly
1.4. WAYS OF LEARNING ANATOMY
Cadaver: (Merriam Webster dictionary) from Latin, from cadere 'to fall'.A dead body; especially : one intended
for dissection.
Dissection: (Oxford dictionary) from Latin dissectus, past participle of dissecare to cut apart, from dis- + secare to
cut. The action of dissecting a body or plant to study its internal parts.
Prosection: A prosection is the dissection of a cadaver (human or animal) or part of a cadaver by an experienced
anatomist in order to demonstrate anatomical structures for students. In a dissection, students learn by doing; in
a prosection, students learn by either observing a dissection being performed by an experienced anatomist or
examining a specimen that has already been dissected by an experienced anatomist (etymology: Latin pro"before" + sectio "a cutting).
Other materials of learning human anatomy:
 Anatomy models
 Anatomy atlases (Pictures, drawings)
 Videos
 Textbooks
 Charts
 Medical dictionaries, etc.
1.5. HISTORY OF ANATOMY
The development of anatomy extends from the earliest examinations of sacrificial victims to the
sophisticated analyses of the body performed by modern scientists. It has been characterized, over time, by a
continually developing understanding of the functions of organs and structures in the body. The field of Human
Anatomy has a prestigious history. It is considered to be the most prominent of the biological sciences of the
19th and early 20th centuries. Methods have also improved dramatically. These methods advanced from
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Introduction to anatomy & Terminology in anatomy & Introduction to osteology
examination of animals through dissection of cadavers to technologically complex techniques developed in the
20th century.
The study of anatomy begins at least as early as 1600 BCE, the date of the Edwin Smith Surgical Papyrus.
The final major anatomist of ancient times was Galen (of Bergama), active in the 2nd century. He compiled
much of the knowledge obtained by previous writers. He furthered the inquiry into the function of organs. Due
to a lack of readily available human specimens, discoveries through animal dissection were broadly applied to
human anatomy as well. His collection of drawings, based mostly on dog anatomy, became the anatomy
textbook for 1500 years.
The works of Galen and Avicenna (Ibn-I Sina), especially The Canon of Medicine which incorporated the
teachings of both, were translated into Latin, and the Canon remained the most authoritative text on anatomy in
European medical education until the 16th century. Andreas Vesalius is the first modern anatomist who wrote
the first anatomy textbook of the modern times; De humani corporis fabrica (On the Fabric of the Human Body).
In our land, anatomy education commenced as a distinct course at “Tıbhane-i Cerrahhane-i Amire”. It is
the first medical school founded by Sultan Mahmut II in March 14th, 1827. Sultan Abdülmecid signed imperial
edict allowing dissections with the purpose of education; practical applications on cadavers began initially in
1841.
1.6. ANATOMICAL POSITION
All anatomical descriptions are expressed in relation to one consistent position. As a result; the
descriptions are clear. The anatomical position is the standard reference position of the body used to describe
the location of structures.
When you are describing a patient or the cadaver you have to keep the anatomical position in mind. By
using this position and appropriate terminology, you can relate any part of the body precisely to any other part.
The patient is lying on one side; we still use the anatomical position. He is in supine position or prone;
again the anatomical position is the guide. [In supine position, one lies on the back, face up. In prone position the
person lies on the abdomen; face down].
You should know that gravity causes a downward shift of internal organs (viscera) when then upright
position is assumed. People are typically examined in the supine position. So, it is often necessary to describe the
position of the affected organs when supine. We make specific note of this exception to the anatomical position.
So what is this “famous” anatomical position?
The anatomical position is about the body position while the person is standing upright. His (or her) head,
eyes and toes are directed anteriorly (forward). The arms are near the sides. The mouth is closed and the facial
expression is neutral. The palms of the hands face forward (anteriorly) with the fingers straight and together and
with the pad of the thumb turned 90 ° to the pads of the fingers. The lower limbs are close to each other. The
feet are parallel.
1.7. ANATOMICAL VARIATIONS
Anatomy books describe the structure of the body as it is usually observed in people: most common
pattern. However, occasionally a particular structure demonstrates so much variation within the normal range
that the most common pattern is found less than half the time!
2. TERMINOLOGY IN ANATOMY
1
It is important for medical personnel to have a sound knowledge and understanding of the basic anatomic
terms. With the aid of a medical dictionary, understanding anatomic terminology greatly assists you in the
learning process.
The accurate use of anatomic terms by medical personnel enables them to communicate with their
colleagues both nationally and internationally. Without anatomic terms, one cannot accurately discuss or record
the abnormal functions of joints, the actions of muscles, the alteration of position of organs, or the exact location
of swellings or tumors.
Anatomical terms are descriptive terms standardized in an international reference guide; Terminologia
Anatomica (TA). These terms, in English or Latin, are used worldwide. Colloquial terminology is used by—and to
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communicate with—lay people. Many anatomical terms have both Latin and Greek equivalents. But some of
these are used in English only as roots. Thus the tongue is lingua (L.) and glossa (Gk), and these are the basis of
such terms as lingual artery and glossopharyngeal nerve.
Various adjectives, arranged as pairs of opposites, describe the relationship of parts of the body or
compare the position of two structures relative to each other. Anatomical directional terms are based on the
body in the anatomical position. Four anatomical planes divide the body, and sections divide the planes into
visually useful and descriptive parts.
2.1. TERMS RELATED TO POSITION
All descriptions of the human body are based on the assumption that the person is standing erect. The
upper limbs are by the sides and the face and palms of the hands directed forward. This is the anatomical
position. The various parts of the body are then described in relation to certain imaginary planes.
2.1.1. ANATOMICAL PLANES
1 2
Three imaginary planes pass through the body in the anatomical position.
Sagittal, coronal, and axial planes
Sagittal planes are vertical planes. They pass through the body parallel to the median plane. Parasagittal is
commonly used. It, however, is unnecessary as any plane parallel to and on either side of the median plane is
sagittal by definition. A plane parallel and near to the median plane may be referred to as a paramedian plane.
The plane that passes through the center of the body is the median sagittal plane. It divides the body into equal
right and left halves.
Frontal (coronal) planes are vertical planes. They pass through the body at right angles to the median plane.
They divide the body into anterior (front) and posterior (back) parts.
Transverse (axial) planes are horizontal planes. They pass through the body at right angles to the median and
frontal planes. They divide the body into upper and lower parts. Radiologists refer to transverse planes as
transaxial. This is commonly shortened as “axial planes”.
Anatomists create sections of the body and its parts anatomically. Clinicians create them by planar
imaging technologies, such as computerized tomography (CT), to describe and display internal structures.
2.1.2. Anatomical terms specific for comparisons made in the anatomical position, or with reference to the
anatomical planes:
 Superior refers to a structure nearer the vertex. Vertex is the topmost point of the skull. The head is superior
to shoulders.
 Cranial relates to the cranium. It means toward the head or cranium (skull).
 Inferior means a structure situated nearer the sole of the foot.
 Caudal (1) (L. tail) means toward the feet or tail region. It is represented in humans by the coccyx (tail bone).
The coccyx is the small bone at the inferior (caudal) end of the vertebral column (spine).
 Posterior (dorsal) means the back surface of the body (or the structure) or nearer to the back.
Anterior (ventral) means the front surface of the body or the structure. We’re talking about the concept of
“relative to each other” again. The nose’s an anterior (ventral) structure; the spine is a posterior structure.
 Medial indicates that a structure is nearer to the median plane of the body. For example, the little finger is
medial to the others. On the contrary, lateral means a structure is away from the median plane. The thumb is
lateral to the other fingers.
 Dorsum means the superior aspect of any part that protrudes anteriorly from the body. Examples are:
dorsum of the tongue, nose, penis, or foot.
Combined terms describe intermediate positional arrangements. “Inferomedial” means nearer to the feet
and median plane. The anterior parts of the ribs run inferomedially. “Superolateral” means nearer to the head
and far from the median plane.
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Introduction to anatomy & Terminology in anatomy & Introduction to osteology
2.1.3. Terms, independent of the anatomical position or the anatomical planes, relating primarily to the
body's surface or its central core:
 Superficial, intermediate, and deep (Lat. profundus) describe the position of structures relative to the surface
of the body. They also might tell you the relation of one structure to another underlying or overlying structure.
 External means outside of or farther from the center of an organ or cavity. Internal means inside or closer to
the center.
 Proximal and distal are used when contrasting positions nearer to or farther from the attachment of a limb or
the central aspect of a linear structure. Proximal means close to the body relatively. Distal means away from the
body. For example, the arm is proximal to the forearm. The hand is distal to the forearm.
2.2. TERMS OF LATERALITY
Paired structures having right and left members (e.g., the kidneys) are bilateral. Those on one side only
(e.g., the spleen) are unilateral. Something occurring on the same side of the body as another structure is
ipsilateral. The right thumb and right big toe are ipsilateral. Contralateral means occurring on the opposite side
of the body relative to another structure.
2.3. TERMS OF MOVEMENT
Various terms describe movements of the limbs and other parts of the body. Most movements are
defined in relationship to the anatomical position, with movements occurring within, and around axes aligned
with, specific anatomical planes. Most movements occur at joints where two or more bones or cartilages
articulate with one another. But several non-skeletal structures also exhibit movement (e.g., tongue, lips,
eyelids). Terms of movement may also be considered in pairs of oppositing movements: Flexion and extension
movements generally occur in sagittal planes around a transverse axis.
Flexion indicates bending or decreasing the angle between the bones or parts of the body. For most joints
(e.g., elbow), flexion involves movement in an anterior direction, but it is occasionally posterior, as in the case of
the knee joint. Lateral flexion is a movement of the trunk in the coronal plane. Just like this!
Extension indicates straightening or increasing the angle between the bones or parts of the body. Extension
usually occurs in a posterior direction. The knee joint, rotated 180° to other joints, is exceptional in that flexion of
the knee involves posterior movement and extension involves anterior movement.
Dorsiflexion describes flexion at the ankle joint, as occurs when walking uphill or lifting the front of the foot
and toes off the ground.
Plantarflexion bends the foot and toes toward the ground, as when standing on your toes. Extension of a limb
or part beyond the normal limit—hyperextension (overextension)—can cause injury, such as “whiplash” (i.e.,
hyperextension of the neck during a rear-end automobile collision).
Abduction and adduction movements generally occur in a frontal plane around an anteroposterior axis.
Except for the digits, abduction means moving away from the median plane (e.g., when moving an upper limb
laterally away from the side of the body) and adduction means moving toward it.
In abduction of the digits (fingers or toes), the term means spreading them apart—moving the other fingers
away from the neutrally positioned 3rd (middle) finger or moving the other toes away from the neutrally
positioned 2nd toe. The 3rd finger and 2nd toe medially or laterally abduct away from the neutral position.
Adduction of the digits is the opposite—bringing the spread fingers or toes together, toward the neutrally
positioned 3rd finger or 2nd toe.
Circumduction is a circular movement. It involves sequential flexion, abduction, extension, and adduction (or
in the opposite order). This way the distal end of the part moves in a circle. It can occur at any joint at which all
the above-mentioned movements are possible (e.g., the shoulder and hip joints).
Rotation is turning or revolving a part of the body around its longitudinal axis. An example is turning one's
head to face sideways.
Medial rotation (internal rotation) brings the anterior surface of a limb closer to the median plane In lateral
rotation (external rotation) the anterior surface is taken away from the median plane.
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Pronation rotates the forearm medially so that the palm of the hand faces posteriorly and its dorsum faces
anteriorly. When the elbow joint is flexed, pronation moves the hand so that the palm faces inferiorly (e.g.,
placing the palms flat on a table).
Supination is the opposite rotational movement, rotating the forearm laterally, returning the pronated
forearm to the anatomical position. When the elbow joint is flexed, supination moves the hand so that the palm
faces superiorly.
Eversion moves the sole of the foot away from the median plane, turning the sole laterally.
Inversion moves the sole of the foot toward the median plane (facing the sole medially).
Opposition is the movement by which the pad of the 1st digit (thumb) is brought to another digit pad. This
movement is used to pinch, button a shirt, and lift a teacup by the handle.
Reposition describes the movement of the 1st digit from the position of opposition back to its anatomical
position.
Elevation raises or moves a part superiorly, as in elevating the shoulders when shrugging, the upper eyelid
when opening the eye, or the tongue when pushing it up against the palate (roof of mouth).
Depression lowers or moves a part inferiorly, as in depressing the shoulders when standing at ease, the
upper eyelid when closing the eye, or pulling the tongue away from the palate.
2.4. POSITIONS OF THE BODY
The supine position of the body is lying on the back. The prone position is lying face downward.
3. INTRODUCTION TO OSTEOLOGY
Osteology (Gk, osteon, bone, logos, science) is the science of bones. There are 206 bones in adults.
A newborn has 270 bones. That is how we come to this world! With 270 bones! Then some bones fuse together.
The 15% of the weight of a 25-30 years old human is made by the skeleton. It makes 5-6 kg.
The skeletal system is divided into two functional parts.
The axial skeleton: bones of the head (cranium or skull), neck (hyoid bone and cervical vertebrae), and trunk
(ribs, sternum, vertebrae, and sacrum).
The appendicular skeleton: bones of the limbs, including of the shoulder and pelvic girdles.
Bone is the hardest structure after teeth. The calcification of its extracellular matrix is the reason for that.
Living bones have some elasticity. This elasticity results from the organic matter. They also have great rigidity.
The rigidity results from their lamellous structures and tubes of inorganic calcium phosphate. Its color, in a fresh
state, is pinkish-white externally. Its color is red inside.
3.1. HISTOLOGY OF THE BONE
Bone is created from osseous connective tissue. Like other types of connective tissue, osseous tissue is
composed of relatively sparse cells surrounded by an extracellular network, or matrix.
Osteoblasts are bone cells that secrete proteins into the matrix. This protein provides strength. It provides
resistance to stretching and twisting.
Mature bone is composed of proteins and minerals. Approximately 60% the weight of the bone is
mineral. The rest is water and matrix. About 90% of the matrix proteins are collagen (1/3 of the bone weight).
Collagen is the most abundant protein in the body. It is very strong. It forms bone, cartilage, skin, and tendons.
The minerals of the matrix are mainly calcium phosphate and calcium carbonate. The minerals are embedded in
the protein network. They provide hardness and compressive strength.
There are four principal types of bone cells: osteogenic cells, osteoblasts, osteocytes, and osteoclasts (1)
, (2). The matrix is maintained by osteocytes. They are the characteristic cells of the bone. Histologically, bone is
composed of units termed Haversian systems or osteons (1). In osteons concentric rings of osteocytes are
arranged around a central blood vessel.
All bones are covered externally, by a fibrous connective tissue membrane. It is called periosteum (1).
There is no periosteum in the area of a j oint where articular cartilage is present. The periosteum has the unique
capability of forming new bone. This membrane receives blood vessels. The branches of these vessels supply the
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outer layers of compact bone. A bone without periosteum will not survive. Nerves accompany the vessels that
supply the bone and the periosteum.
The periosteum not only particiapates in bone growth but also in repairing of the bone. The endosteum
lines the marrow cavity. It is active during bone growth, repair, and remodeling. It covers the trabeculae of
spongy bone and lines the inner surfaces of the central canals.
3.2. CARTILAGES AND BONES
The skeleton is composed of cartilages and bones.
Cartilage is a resilient, semirigid form of connective tissue .It forms parts of the skeleton. It is found in
places where more flexibility is required. The costal cartilages attach the ribs to the sternum. As you need
flexibility for your thoracic cage while you are breathing. Also, the articulating surfaces of bones in a synovial
joint are capped with articular cartilage. This provides smooth, low-friction, gliding surfaces for free movement.
Blood vessels do not enter cartilage (i.e., it is avascular). Its cells obtain oxygen and nutrients by diffusion.
The proportion of bone and cartilage in the skeleton changes as the body grows. The younger a person is,
the more cartilage he or she has. The bones of a newborn are soft and flexible as they are mostly composed of
cartilage.
The amount and kind of extracellular fibers in the matrix varies depending on the type of cartilage. In
heavy weightbearing areas or areas prone to pulling forces, the amount of collagen is greatly increased. In areas
where weightbearing demands and stress are less, cartilage contains elastic fibers with fewer collagen fibers.
Functions of cartilages
 They support soft tissues.
 They provide a smooth, gliding surface for bone articulations at joints.
 They enable the development and growth of long bones.
There are three types of cartilages.
 Hyaline: most common type. The matrix contains a moderate amount of collagen fibers (e.g., articular
surfaces of bones).
 Elastic: The matrix contains collagen fibers along with a large number of elastic fibers (e.g., external ear).
 Fibrocartilage: The matrix contains a limited number of cells and ground substance amidst a substantial
amount of collagen fibers (e.g., intervertebral discs).
Bone is a calcified, living, connective tissue. It forms the majority of the skeleton. It consists of an
intercellular calcified matrix. This matrix contains collagen fibers, and several types of cells.
Functions of bones
 They are supportive structures for the body.
 They are the protectors of vital organs. Sternum and ribs protect the thoracic and upper abdominal viscera.
The skull and vertebral column protect the brain and spinal cord from injury.
 They are reservoirs of calcium and phosphorus.
 The bones lever on which muscles act to produce movement; as seen in the long bones of the limbs
 They are the containers for blood-producing cells.
3.3. TYPES OF BONES
Bones are classified according to their shape (gross anatomy).
1) Long bones are tubular (e.g., the humerus in the arm).
2) Short bones are cuboidal and are found only in the tarsus (ankle) and carpus (wrist).
3) Flat bones usually serve protective functions (e.g., the flat bones of the cranium protect the brain).
4) Irregular bones have various shapes other than long, short, or flat (e.g., bones of the face).
5) Sesamoid bones (e.g., the patella or knee cap) develop in certain muscles. These bones are found where
tendons cross the ends of long bones in the limbs. They protect the tendons from excessive wear. They often
change the angle of the tendons as they pass to their attachments.
Long bones develop by replacement of hyaline cartilage plate (endochondral ossification). They have a shaft
(diaphysis) and two ends (epiphyses). The metaphysis is a part of the diaphysis adjacent to the epiphyses. The
diaphysis encloses the marrow cavity. The metaphysis is the active zone for bone growth in puberty, especially
for long bones.
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There are two types of bones according to histological features. They are compact bone and spongy
(trabecular) bones. They have relative amount of solid matter. They are also special with the number and size of
the spaces they contain. All bones have a superficial thin layer of compact bone around a central mass of spongy
bone. An exception is the place where the spongy bone is replaced by a medullary (marrow) cavity. Spongy bone
is found at the expanded heads of long bones and fills most irregular bones. Compact bone forms the outer shell
of all bones and also the shafts in long bones.
3.4. OSSIFICATION
Ossification means “bone formation”. Developmentally, all bones come from mesenchyme. There are
two tyes of ossification. 1. Intramembranous ossification. 2. Endochondral ossification [1]. In intramembranous
ossification without turning into cartilaginous models, bones are formed directly from mesenchymal models. In
the latter one, cartilaginous models of bones form from mesenchyme and undergo ossification. The
intramembranous calcification is seen particularly in clavicle and flat skull bones.
3.5. BONE MARKINGS AND FORMATIONS
Bone markings appear wherever tendons, ligaments, and fascias are attached or where arteries lie
adjacent to or enter bones. Other formations occur in relation to the passage of a tendon (often to direct the
tendon or improve its leverage) or to control the type of movement occurring at a joint. Surfaces of the bones
are not smooth. Bones display elevations, depressions and holes. The surface features on the bones are given
names to distinguish and define them.
3.6. VASCULATURE AND INNERVATION OF BONES
Bones are richly supplied with blood vessels. Veins accompany arteries. Nerves accompany blood vessels
supplying bones. Bone itself has few sensory nerve fibers. On the other hand, the periosteum is supplied with
numerous sensory nerve fibers. The periosteum is very sensitive to any type of injury.
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