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  Anatomy Basics »  Viewing Osteology 3     [Image 8 of 24]  :: Jump To  
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De Humani Corporis Fabrica * Title page from De Humani Corporis Fabrica For a long period of time, the knowledge of anatomy was a hidden treasure waiting to be explored. The invention of printing in the 15th century made it possible to publish multiple copies of illustrated studies of anatomy, to teach anatomy and to eradicate previous errors. One of the most popular studies of the time was Andreas Vesalius’s De Humani Corporis Fabrica (1543), which marked a revolutionary step forward in anatomy. Vesalius was able to correct most errors in ancient writings and anatomic illustrations by his studies of dissection. De Humani Corporis Fabrica became the founding text of modern anatomy, and inspired many scientists, who compared their results with existing texts, corrected errors, and produced new texts with illustrations. The production of images based on dissection became a central component of scientific anatomy.

Development of Bones * Development of long bones Image based on a template from the LifeART Collection, Lippincott Williams & Wilkins, ©1989- 2001 The arrows show the direction of endochondral ossification within a hyaline cartilage model, which provides a template of the shape of the bone to be formed. In the next step, the cartilage is replaced by bone. This type of ossification is found in long and short bones, but not in flat bones (which are formed by the intramembranous ossification in membranes of fibrous connective tissue).

Diaphysis * Diaphysis of a Long BoneDiaphysis is the shaft of long bones. It is located between both Metaphyses and consists of compact bone walls and an inner cavity (Cavitas medullaris), filled with the yellow (fatty) bone marrow. The external surface of the Diaphysis is covered by the Periosteum.

Osteology 1 * Frontal section through the head of Femur (thigh- bone) Photography by Pekny P., ©2003 Two different bone components can be found (macroscopically) in human bones: one is dense in texture (Substantia compacta or compact bone tissue) found in the outer parts of bones (thick wall at the shaft of long bones, thin layer at the ends), the other consists of thin fibers and sheets of bone, (trabeculae) which form a reticular, sponge- like network at the ends of long bones and in vertebrae (Substantia spongiosa, trabecular or cancellous bone tissue). Substantia compacta (cortical bone) is found primarily in the shafts of long bones and forms the outer shell around Substantia spongiosa (cancellous bone) at the end of the joints. The inner parts of the head are filled with spongy bone tissue.

Osteology 2 * Gross Structure of Long BonesThe gross structure of a long bone can be divided into the following regions: - Epiphysis with articular (joint) cartilages - Metaphysis - Diaphysis - Epiphyseal (growth) plate (Physis) in actively growing bones Epiphysis is located at the ends of long bones, between the articular cartilages and the growth plate. It is present at each end of long limb bones. Exceptions are the metacarpal and metatarsal bones, the bones of fingers and toes (Phalanges), the ribs (Costae) and the collarbones (Claviculae), where the Epiphysis is present at only one end. The interior of this region is filled with spongy trabecular bone tissue with only a thin external cover of compact bone. It houses the red (bone) marrow. The external surface is covered by the articular cartilage. The non- articulating parts are covered by a dense connective tissue called the Periosteum. Diaphysis is the shaft of long bones. It is located between both Metaphyses and consists of compact bone walls and an inner cavity (Cavitas medullaris), filled with the yellow (fatty) bone marrow. The external surface of the Diaphysis is covered by the Periosteum. The external surface of bones (except the articular cartilages) is surrounded by a thin layer of dense connective tissue and Osteoprogenitor cells (see next chapter), called Periosteum. It is anchored to the bony surface by Sharpey fibers (fibrae) that penetrate into the bone. The articular cartilage (Cartilago articularis) is located at the joints, where the epiphyseal part of the bone articulates with another bone. The function of the articular cartilage is to provide smooth contact surface in a joint (Facies articularis). Similar to other connective tissues, it consists of cells (Chondrozytes) and an extracellular matrix. In contrast to other tissues, it has no vascularization (vessels) and nutrients have to diffuse from synovial fluid (nutrient rich fluid in the joint capsule).

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Osteology 3.jpg - nov 23, 2004
Parts of the Body 2 * Parts of the Body The human body consists of the following parts (Partes corporis): Caput- the head Collum- the neck Thorax- the chest Abdomen- the stomach Pelvis- the pelvis Membrum superius- the arm(s) Membrum inferius- the leg(s)

Parts of the Body * Parts of the Human Body The human body consists of the following parts (Partes corporis): Caput- the head, Collum- the neck, Thorax- the chest, Abdomen- the stomach, Pelvis- the pelvis, Membrum superius- the arm(s), Membrum inferius- the leg(s). The regions (Regiones corporis) are described similarly to the body parts, but in more detail. Their anatomic borders consist of skeletal, muscular and surface components. Their knowledge is important in medical practice, for instance when describing localizations of pain in patients.

Planes of the Body * Planes of the human body Because of different presentations of body structures in images (for example illustration, x-ray, or Ct), it is important to know the various planes of reference: - The sagittal (median) plane is a vertical anteroposterior plane, which divides the body into right and left halves. The slices paralleling this plane are called paramediansagittal or parasagittal planes. - The frontal (or coronal) plane is situated at a right angle to the sagittal plane and divides the body into anterior and posterior halves. - The transverse (or horizontal) plane, perpendicular to the sagittal and coronal plane, divides the body into superior and inferior halves. In case of an organ or other body structure, the horizontal plane is at a right angle to the long axis of that structure (cross section). It is also possible to make oblique planes (for example MR- tomography special cuts), which lie at any other angles. Image based on a template from the LifeART Collection, Lippincott Williams & Wilkins, ©1989- 2001

Position Location Direction * Positions, Relative Locations and DirectionsTo describe topographic relationships of structures or parts to other structures in the body, we use the following terms: - Superior or cranial (cephalic) indicate that a structure is located at a higher level or closer to the head. The opposite of these are inferior or caudal, which indicate that a structure is located at a lower level or downwards. In case of the limbs, the terms proximal and distal indicate the level or the relative distance from the attached end of the limb (for example: the arm in standard anatomic position; proximal would mean near to the shoulder; distal would mean further away or located below). - The terms anterior or ventral indicate a relation to the front of the body or of a bone (e.g. anterior surface). The terms posterior or dorsal indicate that a structure is located near to the back of the body. - The terms medial and lateral refer to a position in relation to the medial plane (or the long axis) of the body or of a structure (medial: toward midline; lateral: away from midline or located at the side). - The terms superficial or profundal are used to describe a position or location relative to the surface of areas, structures or tissues. The term superficial indicates that a structure is located close to the surface of a tissue, the term profundal indicates that it is located more deeply. - The terms internal and external describe a structure's position or a view in relation to inner and outer surfaces (for example in organs or cavities). - The term ipsilateral indicates that two structures are located on same side of the body. - The term contralateral indicates the opposite (opposite side of the body).

Regiones Abdominales * Regiones abdominales 1 - Regio epigastrica, 2 - Regio hypochondriaca, 3 - Regio umbilicalis, 4 - Regio lateralis, 5 - Regio pubica, 6 - Regio inguinalis. The regions of the stomach (Regiones abdominales) can be described with virtual lines: a vertical line through the middle of the Clavicula (medioclavicular line), a horizontal line halfway between the upper Sternum and the upper genital region (the horizontal layer is called Planum transpyloricum), and a horizontal line between the humps of the pelvic bone (Tuberculum iliacum) on both sides (the horizontal layer is called Planum intertuberculare). Regio epigastrica is located right under the Processus xiphoideus (at the bottom of Sternum) of the skeletal Thorax, marked by Planum transpyloricum at the bottom, and the medioclavicular lines on both sides. Regio hypochondriaca is located on both sides of Regio epigastrica, marked also by the Thorax, the medioclavicular line and Planum transpyloricum. Regio umbilicalis (the area around the belly) is marked by medioclavicular lines on both sides, by Planum transpyloricum at the top and Planum intertuberculare at the bottom. Regio lateralis is located on both sides of Regio umbilicalis, marked by Planum transpyloricum, Planum intertuberculare and medioclavicular lines on both sides. Regio pubica is located under the Regio umbilicalis, with a flowing transition into the lower located non-abdominal genital region (Regio urogenitalis). Regio inguinalis is located on both sides of Regio pubica. It is marked at the top by the Planum intertuberculare and the groin ligament (Ligamentum inguinale between the frontal upper spine of the pelvic bone= Spina iliaca anterior superior to the hump of the pubic bone= Tuberculum pubicum) at the bottom.

Image: Microscopic view of compact bone tissue with Haversian systems
Image based on a template from the LifeART Collection, Lippincott Williams & Wilkins, ©1989- 2001

Compact bones are organized into strong units called Osteons or Haversian systems. These are lamellar cylinders along the long axis of the bones with an average diameter of 0,05mm. Each Haversian system consists of a central canal (Haversian canal or Canalis centralis Havers), surrounded by concentric thin concentric rings of bony tissue (Lamellae). The lamellae are held together by oblique (Sharpey) and reticular fibers between them. The Lacunae are also situated between the Lamellae. They are occupied by Osteocytes. The small communication canals (through Lamellae) between two Lacunae are called Canaliculi. They connect with the central (Haversian) canals. The Haversian canal contains one or two blood vessels and thin nerve filaments. It communicates with the bone marrow cavity (Cavitas medullaris) and the Periosteum (outside of bone) through oblique canals (Volkmann canals, which penetrate the lamellar structures.
Page last updated on nov 23, 2004
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