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INTRODUCTION TOOSTEOLOGY

19. 11.2013

Kaan YücelM.D., Ph.D.

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Dr.Kaan Yücel yeditepeanatomy1.org Introduction to osteology

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Osteology (Gk, osteon, bone, logos, science) is the branch of medicine concerned with the development and diseases of bone tissue. The human skeleton is composed of 270 bones in the newborn, 222 bones in children and 206 bones in adults. • The axial skeleton consists of the bones of the head (cranium or skull), neck (hyoid bone and cervical vertebrae), and trunk (ribs, sternum, vertebrae, and sacrum).• The appendicular skeleton consists of the bones of the limbs, including those forming the pectoral (shoulder) and pelvic girdles.

Bone is a living tissue capable of changing its structure as the result of the stresses to which it is subjected. Like other connective tissues, bone consists of cells, fibers, and matrix. It is one of the hardest structures of the animal body, because of the calcification of its extracellular matrix. Living bones have some elasticity (results from the organic matter) and great rigidity (results from their lamellous structures and tubes of inorganic calcium phosphate).

The skeleton is composed of cartilages and bones. Cartilage is a resilient, semirigid form of connective tissue that forms parts of the skeleton where more flexibility is required—for example, where the costal cartilages attach the ribs to the sternum. Cartilage is an avascular form of connective tissue consisting of extracellular fibers embedded in a matrix that contains cells localized in small cavities.

Bone is a calcified, living, connective tissue that forms the majority of the skeleton. It consists of an intercellular calcified matrix, which also contains collagen fibers, and several types of cells within the matrix.

Bone has a protective function; the skull and vertebral column, for example, protect the brain and spinal cord from injury; the sternum and ribs protect the thoracic and upper abdominal viscera. It serves as a lever, as seen in the long bones of the limbs, and as an important storage area for calcium salts. It houses and protects within its cavities the delicate blood-forming bone marrow.

A fibrous connective tissue covering which is called periosteum surrounds each skeletal element like a sleeve, except where articular cartilage occurs; whereas that around cartilage is perichondrium. The periosteum and perichondrium nourish the external aspects of the skeletal tissue. They are capable of laying down more cartilage or bone (particularly during fracture healing) and provide the interface for attachment of tendons and ligaments.

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.

There are two types of bones according to histological features: • compact bone • spongy (trabecular) bone 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. 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 tendons and are found where

tendons cross the ends of long bones in the limbs; they protect the tendons from excessive wear and often change the angle of the tendons as they pass to their attachments.

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.

Bones are richly supplied with blood vessels. Most apparent are the nutrient arteries (one or more per bone) that arise as independent branches of adjacent arteries outside the periosteum and pass obliquely through the compact bone of the shaft of a long bone via nutrient foramina. Veins accompany arteries through the nutrient foramina. Nerves accompany blood vessels supplying bones. The periosteum is richly supplied with sensory nerves—periosteal nerves—that carry pain fibers. 2


Osteology (Gk, osteon, bone, logos, science) is the branch of medicine concerned with the

development and diseases of bone tissue. The human skeleton is composed of 270 bones in the newborn,

222 bones in children and 206 bones in adults.

The skeletal system may be divided into two functional/anatomical parts:

The axial skeleton consists of the bones of the head (cranium or skull), neck (hyoid bone and cervical

vertebrae), and trunk (ribs, sternum, vertebrae, and sacrum).

The appendicular skeleton consists of the bones of the limbs, including those forming the pectoral

(shoulder) and pelvic girdles.

Figure 1. The skeleton. The axial skeleton in green, and the appendicular skeleton in pink.http://www.encognitive.com/node/1125

Out of the 206 bones an adult has, 126 of them exist in the appendicular skeleton, whereas 80 of them

exist in the axial skeleton.

Bone is a living tissue capable of changing its structure as the result of the stresses to which it is

subjected. Like other connective tissues, bone consists of cells, fibers, and matrix. It is one of the hardest

structures of the animal body, because of the calcification of its extracellular matrix. Living bones have

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1.OSTEOLOGY

http://www.encognitive.com/node/1125


some elasticity (results from the organic matter) and great rigidity (results from their lamellous structures

and tubes of inorganic calcium phosphate). Its color, in a fresh state, is pinkish-white externally, and deep

red within.

The skeleton is composed of cartilages and bones.

Cartilage is a resilient, semirigid form of connective tissue that forms parts of the skeleton where

more flexibility is required—for example, where the costal cartilages attach the ribs to the sternum. Also,

the articulating surfaces (bearing surfaces) of bones participating in a synovial joint are capped with

articular cartilage that provides smooth, low-friction, gliding surfaces for free movement. Blood vessels do

not enter cartilage (i.e., it is avascular); consequently, 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 because they are mostly

composed of cartilage.

Cartilage is an avascular form of connective tissue consisting of extracellular fibers embedded in a

matrix that contains cells localized in small cavities. 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 and the cartilage is almost inextensible. In contrast, in

areas where weightbearing demands and stress are less, cartilage containing elastic fibers and fewer

collagen fibers is common. The functions of cartilage are to:

support soft tissues;

provide a smooth, gliding surface for bone articulations at joints; and

enable the development and growth of long bones.

There are three types of cartilage:

hyaline-most common; matrix contains a moderate amount of collagen fibers (e.g., articular surfaces

of bones);

elastic:-matrix contains collagen fibers along with a large number of elastic fibers (e.g., external ear);

fibrocartilage-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 that forms the majority of the skeleton. It consists of an

intercellular calcified matrix, which also contains collagen fibers, and several types of cells within the

matrix.

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2. CARTILAGES AND BONES


Bones of the adult skeleton provide:

support for the body and its vital cavities; it is the chief supporting tissue of the body.

protection for vital structures (e.g., the heart).

the mechanical basis for movement (leverage).

storage for salts (e.g., calcium).

continuous supply of new blood cells (produced by the marrow in the medullary cavity of many

bones).

Bone has a protective function; the skull and vertebral column, for example, protect the brain and

spinal cord from injury; the sternum and ribs protect the thoracic and upper abdominal viscera. It serves as

a lever, as seen in the long bones of the limbs, and as an important storage area for calcium salts. It houses

and protects within its cavities the delicate blood-forming bone marrow.

A fibrous connective tissue covering which is called periosteum surrounds each skeletal element like

a sleeve, except where articular cartilage occurs; whereas that around cartilage is perichondrium. The

periosteum and perichondrium nourish the external aspects of the skeletal tissue. They are capable of

laying down more cartilage or bone (particularly during fracture healing) and provide the interface for

attachment of tendons and ligaments. 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.

Figure 2. Diaphysis, metapyhysis, epiphyseshttp://en.wikipedia.org/wiki/File:Illu_long_bone.jpg


3. FUNCTIONS OF THE BONES

4. INSIDE A BONE

http://en.wikipedia.org/wiki/File:Illu_long_bone.jpg


There are two types of bones according to histological features:

compact bone

spongy (trabecular) bone

They are distinguished by the relative amount of solid matter and by 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, except where the latter 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. Spongy or cancellous bone consists of

a lattice of thin threads of bone called trabeculae and is less dense than compact bone. The orientation of

the trabeculae is modelled by the mechanical stress to which the bone is exposed (Wolff's law).

The architecture and proportion of compact and spongy bone vary according to function. Compact bone

provides strength for weight bearing. In addition, long bones have elevations (e.g., ridges, crests, and

tubercles) that serve as supports where large muscles attach.

Figure 3. Compact and spongy boneshttp://www.gla.ac.uk/ibls/US/fab/tutorial/generic/bone2.html

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 tendons and are found where tendons

cross the ends of long bones in the limbs; they protect the tendons from excessive wear and often change

the angle of the tendons as they pass to their attachments.


5. CLASSIFICATION OF BONES

http://www.gla.ac.uk/ibls/US/fab/tutorial/generic/bone2.html


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.

Here are some examples for the bone markings: (You do not need to know the examples for this class;

this means you are not responsible for them for the exam. Most of the examples for the bone markings I

have chosen out of the topics of the I. Committee, though.).

Linear elevations

Line (in Latin linea), crest (in Latine crista)

Examples for linear elevations

Figure 4. Crista galli (crest of the cock) in the anterior part of the skull; demonstrated in yellow. Some

anatomical terms, phrases are used in Latin, only and crista gali is one of them. http://www.med-college.de/de/life/wiki/artikel.php?id=1720&lan=2

Figure 5. Superior temporal line (in Latin linea temporalis superior)


6. BONE MARKINGS & FORMATIONS

http://www.med-college.de/de/life/wiki/artikel.php?id=1720&lan=2


Inferior temporal line (in Latin linea temporalis inferior) in the skullhttp://teleanatomy.com/General%20Anatomy/Introduction%20to%20Anatomy%203rd%20Edition/Skeletal%20system_files/image058.jpg

Round elevations

tubercule (small eminence), protuberance (swelling)

Examples for round elevations

Figure 6. Tubercle of a ribhttp://home.comcast.net/~wnor/typicalrib.jpg

Figure 7. External occipital protuberance, rear side of the head (skull) (protuberentia occipitalis externa) http://www.upstate.edu/cdb/education/grossanat/hnsklatob1.shtml

Sharp elevations

spine, process

Examples for sharp elevations

Figure 8. Spinous process of a vertebra (processus spinosus)http://www.indyspinemd.com/Normal/


http://www.indyspinemd.com/Normal/

http://www.upstate.edu/cdb/education/grossanat/hnsklatob1.shtml

http://home.comcast.net/~wnor/typicalrib.jpg

http://teleanatomy.com/General%20Anatomy/Introduction%20to%20Anatomy%203rd%20Edition/Skeletal%20system_files/image058.jpg


Figure 9. Styloid process (processus styloideus) in the skull http://www.gustrength.com/anatomy:mastoid-process-of-the-skull

Rounded articular areas

head, condyle

Examples for rounded articular areas

Figure 10. Head of the mandible (caput mandibularis), condylar process (processus condylaris), mental

tubercle (tuberculum mentale), submandibular fossa (fossa submandibularis), mental foramen (foramen

mentalis)http://www.becomehealthynow.com/images/organs/skeleton/mandible_ant_lat_superior.jpg

Depressions

fossae (small depression), groove (sulcus, long narrow depressions)


http://www.becomehealthynow.com/images/organs/skeleton/mandible_ant_lat_superior.jpg

http://www.gustrength.com/anatomy:mastoid-process-of-the-skull


Examples: For fossa; see submandibular fossa in Figure 10, and for groove; see costal groove in Figure 6.

Foramen

Hole

Example: See mental foramen in Figure 10.

Canal

a foramen having length

Example for canal

Figure 11. Optic canal in the skull (canalis opticus), in the orbita where the eye is located. http://img.medscape.com/pi/emed/ckb/clinical_procedures/834279-835021-60.jpg

Please note that fissure (fissura) - superior and inferior orbital fissures in the image below is another

depression just like the groove/sulcus is. The fissure,however, is deeper than the sulcus. In Turkish,

groove/sulcus means oluk, and fissure yarık). You also see an example for a foramen (infraorbital foramen,

foramen infraorbitalis) in the image below.

Meatus

a canal entering a structure

Example: See external auditory meatus (meatus acusticus externus) in Figure 8.

Facets are areas with a smooth surface where a bone articulates with another bone.

Figure 12. Facets of a thoracic vertebrahttp://spot.pcc.edu/~lkidoguc/Topics/vertebra.gif


http://spot.pcc.edu/~lkidoguc/Topics/vertebra.gif

http://img.medscape.com/pi/emed/ckb/clinical_procedures/834279-835021-60.jpg


Bones are richly supplied with blood vessels. Most apparent are the nutrient arteries (one or more

per bone) that arise as independent branches of adjacent arteries outside the periosteum and pass

obliquely through the compact bone of the shaft of a long bone via nutrient foramina. Veins accompany

arteries through the nutrient foramina. Many large veins also leave through foramina near the articular

ends of the bones. Bones containing red bone marrow have numerous large veins. Lymphatic vessels are

also abundant in the periosteum. Nerves accompany blood vessels supplying bones. The periosteum is

richly supplied with sensory nerves—periosteal nerves—that carry pain fibers. The periosteum is especially

sensitive to tearing or tension, which explains the acute pain from bone fractures. Bone itself is relatively

sparsely supplied with sensory endings. Within bones, vasomotor nerves cause constriction or dilation of

blood vessels, regulating blood flow through the bone marrow.

ACCESSORY BONESAccessory (supernumerary) bones develop when additional ossification centers appear and form

extra bones. Many bones develop from several centers of ossification, and the separate parts normally

fuse. Sometimes one of these centers fails to fuse with the main bone, giving the appearance of an extra

bone. Careful study shows that the apparent extra bone is a missing part of the main bone. It is important

to know that accessory bones are common in the foot, to avoid mistaking them for bone fragments in

radiographs and other medical images.

HETEROTOPIC BONES


7. VASCULATURE & INNERVATION OF BONES

CLINICAL ANATOMY


Bones sometimes form in soft tissues where they are not normally present (e.g., in scars). Horse

riders often develop heterotopic bones in their thighs (rider's bones), probably because of chronic muscle

strain resulting in small hemorrhagic (bloody) areas that undergo calcification and eventual ossification.

CHANGES IN BONES & BONE FRACTURES Bones are living organs that cause pain when injured, bleed when fractured, remodel in

relationship to stresses placed on them, and change with age. Like other organs, bones have blood vessels,

lymphatic vessels, and nerves, and they may become diseased. Atrophy (decrease in size) might develop in

unused bones, such as in a paralyzed limb. Bone may be absorbed, which occurs in the mandible when

teeth are extracted. Bones hypertrophy (enlarge) when they support increased weight for a long period.

Trauma to a bone may break it. For the fracture to heal properly, the broken ends must be brought

together, approximating their normal position. This is called reduction of a fracture. Fractures are more

common in children than in adults because of the combination of their slender, growing bones and

carefree activities. Fractures in growing bones heal faster than those in adult bones. Immediately after a

fracture, the patient suffers severe local pain and is not able to use the injured part. Deformity may be

visible if the bone fragments have been displaced relative to each other.

OSTEOPOROSISDuring the aging process, the organic and inorganic components of bone both decrease, often

resulting in osteoporosis, a reduction in the quantity of bone.The bones become brittle, lose their

elasticity, and fracture easily. Bone scanning is an imaging method used to assess normal and diminished

bone mass.

(BONE) SCINTIGRAPHYThe technique beyond the bone scintigraphy (radionuclide imaging, bone scan) depends on the metabolic

activity of bone and its affinity to uptake a detectable marker so that the image can be captured by a scan. The bone scintigraphy has a wide range of indications ranging from sports related injuries to detection of

metastasis (spreading of cancer) to the bones.

BONE DENSITOMETRY (DEXA, DXA)Bone density scanning, also called dual-energy x-ray absorptiometry (DXA) or bone densitometry, is

an enhanced form of x-ray technology that is used to measure bone loss. DXA is today's established

standard for measuring bone mineral density (BMD).

DXA is most often performed on the lower spine and hips. In children and some adults, the whole

body is sometimes scanned. DXA is most often used to diagnose osteoporosis, a condition that often

affects women after menopause but may also be found in men. DXA is also effective in tracking the effects

of treatment for osteoporosis and other conditions that cause bone loss.



An x-ray (radiograph) is a noninvasive medical test that helps physicians diagnose and treat medical

conditions. Imaging with x-rays involves exposing a part of the body to a small dose of ionizing radiation to

produce pictures of the inside of the body. X-rays are the oldest and most frequently used form of medical

imaging.

Ref @ http://www.radiologyinfo.org/en/pdf/dexa.pdf

Figure 13. Bone scintigraphyhttp://www.skeletalscintigraphy.com/


http://www.skeletalscintigraphy.com/

http://www.radiologyinfo.org/en/pdf/dexa.pdf

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