The document discusses bone growth and formation, describing the cells involved in bone remodeling including osteoclasts which resorb bone, osteoblasts which form bone, and osteocytes. It also covers bone structure, the layers of bone, the process of bone growth, and methods used in forensic anthropology to analyze skeletal remains such as macroscopic analysis, metric analysis, and radiography.

1. Osteology
BONE GROWTH AND FORMATION
SANIYA ZEDI, ASSISTANT PROFESSOR

2. Bone Anatomy
 Bone is a calcified connective tissue that supports and protects the soft
tissues of the body, provides attachment sites for muscles, produces blood
cells, and stores calcium, nutrients, and lipids.
 The inorganic constituent of bone is a carbonated hydroxyapatite
crystalline matrix (Ca10(PO4)6(OH)2).
 The organic component is primarily Type I collagen.
 The adult body has 206 bone.

4. Osteoclasts
 Osteoclasts are cells that dissolve (or
resorb) bone. Osteoclasts are formed by
the fusion of monocytes in the red
marrow, which is found in spongy bone.
 Osteoclasts have a specialized ruffled
acidic border that provides additional
surface area for bone resorption. First,
the acidic border demineralizes the
bone tissue, and then enzymes dissolve
the collagen.
 Osteoclasts live in resorptive bays, or
spaces, called Howship’s lacunae.

5. Osteoblast
 Osteoblasts are mononucleic bone
building cells that are formed from
differentiated mesenchymal
osteoprogenitor cells.
 Mesenchymal cells are embryonic
precursor cells, or stem cells, that are
capable of differentiating into a variety of
cell types, including bone cells, cartilage
cells, and fat cells.
 Osteoblasts produce osteoid, which is the
unmineralized organic portion of bone
matrix, and are responsible for laying
down new bone.
 Osteoid is comprised of collagen,
noncollagenous proteins, proteoglycans,
and water, making it a gel-like substance
when deposited. The water is replaced by
minerals (hydroxyapatite) as the osteoid
mineralizes.

6. Osteocytes
 Osteocytes are actually osteoblasts that
become surrounded by the bone matrix
secreted by the osteoblasts.
 Once the osteoblasts are encased in the
bone matrix, they become mature bone
cells (osteocytes), and their function is
converted from bone production to
bone maintenance and communication.
 Osteocytes reside in pores, or spaces,
called lacunae and communicate with
other osteocytes through tentacle-like
projections that are housed in canaliculi
(little canals)

7. Bone Layers
Periosteum
 The periosteum is an external
fibrocellular sheath that contains
collagen fibers and fibroblasts, which,
in turn, forms an
osteogenic/nourishing layer on the
compact bone surface. The
periosteum is connected to the
underlying bone by bundles of
collagen fibers (Sharpey’s fibers) that
protrude from the periosteum into the
outer layers of bone tissue.
Endosteum
 The endosteum lines the surface of
the inner marrow cavity as well as all
Haversian Canal.

8. Adult bone consists of two forms of bone:
trabecular and compact bone
Bone Structure Adult
 Trabecular bone, also known as cancellous or
spongy bone, is the internal porous bone
found in irregular bones, flat bones, and the
articular ends of long bones.
 Compact bone, also known as cortical bone,
is the dense bone that forms the outer
cortex covering the trabecular bone. Cortical
bone is most abundant in the shafts of long
bones, where its compact arrangement
provides much-needed strength

9. Bone Growth
Growth is a term used to describe the changes in size and shape, or morphology, which
occur as an organism develops and ages.
Endochondrial Ossification
 Bones develop in utero from cartilage
models
 endochondral ossification produces
cancellous bone
Intraembraneous Ossification
 Forms vascular membranous templates
 intramembranous ossification produces cortical and
diploic(spongy in between plates) bone.

10.  Secondary ossification centers or
epiphyses appear after birth and are
separated from the primary
ossification centers by a layer of
cartilage referred to as the epiphyseal
plate.
Primary ossification  The epiphyseal plate attributes to the
lengthening of the growing bone.
 Once bone growth is complete, the
primary and secondary ossification
centers fuse, the epiphyseal plate
disappears, and the bone assumes its
adult size and shape
 During this developmental process,
which is referred to as osteogenesis
or ossification, the embryonic
precursor tissues are replaced by
bone at sites called primary
ossification centers.
Secondary ossification

11. Anatomical Planes
 Because the human body can assume a number of positions and change position relative to its
environment, references to the body or parts of the body are made with respect to standard
anatomical position. The human body is in standard anatomical position when standing erect
with arms by the sides and palms facing forward
 Three primary reference planes, which are imaginary planes used to divide the body into
sections or halves.
 1. A coronal plane is any vertical plane that divides the body into anterior and posterior
portions. The mid-coronal plane divides the body into equal front and back halves.
 2. A sagittal plane is any vertical plane that divides the body into left and right sections; the
mid-sagittal plane divides the body into symmetrical left and right halves.
 3. A transverse plane is any horizontal plane that divides the body into superior and inferior
sections and is perpendicular to the coronal and sagittal planes.

12. -Ventral and dorsal are
used to refer to front and
back
-Superior and inferior
mean “above/toward the
head” and “below/away
from the head”
-Distal means “farthest
from the trunk” and
proximal means “nearest
the trunk.”
-Medial is toward the
midline of the body, and
lateral is away from the
midline of the body.

19. Skull Features

30. AGE Determination

32. Animal bones

34. Craniometric Landmarks

36. Mandible

39. Pelvis

43. Race Determination

44. Teeth

52. Bones of body
Hyoid bone

53. Tibia Femur

54. Humerus
Fibula Ulna

55. Radius

56. Clavicle and Scapula Sternum

58. Bone queries?
 Are the bones human? To whom do the skeletal remains belong? How
long have they been here? How did the individual die?
 The amount and condition of skeletal material present also affects which
methods are possible or most appropriate to apply.
 Common approaches used to make forensic anthropological assessments
and estimates from skeletal remains include macroscopic (visual) analysis,
metric analysis, and radiology. In some cases, other specialized techniques
or analyses such as histology or elemental analysis may also be employed.

59. Requirements in lab
 The analyses should be performed in a forensic anthropology laboratory which has access to some basic
examination equipment. This should include at least one table large enough to lay out an entire adult skeleton in
anatomical order. Large tables are useful for photographing the remains as well as providing a visual inventory.
 Ideally, the laboratory should be equipped with multiple large tables, especially if more than one case is likely to be
examined simultaneously. Since many cases are received with adhering soft tissue that may need to be removed the
laboratory should have a processing area with a water source and fume hood as well as any necessary processing
tools (such as hotplates, crock pots, scalpels, forceps, and scissors). The laboratory should be equipped with
necessary safety supplies (such as gloves and lab coats) and should also be capable of handling and managing
biohazardous waste.
 For many skeletal examinations, it will be necessary to have at least a low-power microscope, measurement tools,
and media for recording notes (such as paper or a computer). The laboratory examination area should also have
sufficient lighting. For certain analyses, specialized analytical equipment or instruments may be required. The
laboratory should also have sufficient storage for supplies, chemicals, reference materials, case files, and inactive
cases (such as those awaiting additional examination). Areas where evidence is examined or stored should be
securable, meaning that there is restricted access limited to analysts involved in the case. Specific requirements for
particular examination and documentation methods are discussed in the sections below.

60.  Macroscopic analysis is used in conducting an inventory of the remains, assessing the overall
condition of the material, describing taphonomic changes, estimating sex, age, and ancestry, and
interpreting pathology and trauma. For example, in the assessment of sex, the pelvis may be
examined for the presence or absence of a preauricular sulcus. In the assessment of ancestry, the
anterior nasal spine may be categorized as slight, intermediate, or marked. In the estimation of age,
the morphology of the pubic symphysis can be compared to written descriptions and exemplar
casts to determine which of the described phases it most closely resembles.
 Metric analysis in forensic anthropological cases involves recording and analyzing skeletal
measurements, also referred to as osteometrics, such as differences in size between males and
females, and differences in cranial shape between ancestral groups, stature estimation. Many of
these measurements, especially those of the skull, are taken from a set of specified osteometric
landmarks, which when applied to the skull are called craniometric landmarks.
 Radiography in forensic anthropology is useful for documentation as well as detection and
diagnostic applications. It can be used to produce a record of the condition of the remains at the
time of examination, detect the presence of foreign material such as a bullet, and visualize internal
skeletal structures that are not visible to the naked eye such as paranasal sinuses or developing
dentition. It can also be used to diagnose conditions such as antemortem fractures or pathological
conditions, or to see the placement of surgical implants.

61.  Histology is the study of the microscopic structure of tissues. A histological analysis of skeletal
material can be used in forensic anthropological examinations to determine whether unknown
material is bone, and whether or not the bone can be excluded as being human in origin. It can
be used in the assessment of skeletal age on the basis of bone remodeling. In addition, it can be
useful in the diagnosis of disease or recognizing the early stages of bone healing.
 Elemental analysis is the analysis of a material for its elemental or isotopic composition. First, it may
be used in the determination of whether a material is bone or some other material based on
or not it contains bone’s signature levels of calcium and phosphorus. Elemental analysis may also be
used in stable isotopic profiling of human tissues such as bones, teeth, hair, and fingernails as a
means of identifying an individual’s likely dietary or residence pattern based on food and water
consumed.

62. Burnt Bones
 Properties of bone, both physical and chemical, change drastically during
burning and these changes cause difficulties in forensic identification tests.
 Physical changes occurring in burnt bone, such as deformation and
fragmentation due to heat-induced shrinkage, alter the morphological
indicators that are critical for anthropometric analysis of species, sex, age,
and stature estimation.
 The degree of modification increases with rising temperatures, and
includes degradation of DNA, which compromises forensic identification
techniques.
 Natural taphonomic processes may also be responsible, including
weathering, sun bleaching, animal scavenging, soil and water chemistry
(diagenesis), and root etching

63. Bone/ Not a bone??
 Microscopic or histological analysis may reveal microstructures indicative of
osseous or dental tissue such as Haversian systems, trabecular bone, enamel
prisms, or cement layers.
 the utility of elemental analysis in the determination of skeletal or non-skeletal
origin (calcium and phosphorus). One method of elemental analysis involves
using scanning electron microscopy and energy dispersive X-ray spectroscopy
(SEM/EDS)
 Bone also fluoresces under shortwave light, and although the apatite component
can fluoresce under certain conditions, it is the collagen component of bone that
contributes most significantly to its fluorescent properties.
 Another method uses X-ray fluorescence spectrometry (XRF) to determine the
elemental composition of possible skeletal material

64. Animal or Human
 In many of the instances, partial or nearly complete skeletons, entire bones, or large fragments are
submitted to a medical examiner or forensic anthropologist for identification. Due to differences in
locomotion, growth and development, biomechanics, and diet, numerous differences exist between
the skeletons of different animal species.
 Presence of tails, claws, horns, bacula(bone in penis) , or metapodials.
 Assessment of human versus non-human can be undertaken at three fundamental levels:
macroscopic, microscopic, and biochemical.
 Macroscopic methods involve visual or radiographic assessment of skeletal and dental
morphology, with particular attention to the bone architecture (shape) but also with consideration
of size as well as stage of growth and development. The major differences between the human and
non-human mammal vertebrate skeleton are related to differences in locomotion – humans are
bipeds (walking on two legs) and most other land mammals are quadrupeds ( walking on four
legs). Knowledge of the stages of bone and tooth development and epiphyseal union sequences
gained through careful study of subadult skeletons is an important component of forensic
anthropological training.

65.  At the macrostructural level, non-human trabecular mammalian bone is more homogenously
distributed than human bone. Additionally, the boundary between cortical bone and trabecular bone
is more apparent in nonhuman mammals, and is less well-defined in humans. In cases of
fragmented, weathered, or burned bone fragments, it may be more difficult to determine whether
the remains are human or non-human. For these cases, microscopy may be useful for comparing the
microstructure of bones. human bone is arranged in Haversian systems (secondary osteons), which
are composed of concentric rings oriented along the long axis of the bone. Non-human bone, in
contrast, is primarily non-Haversian (fibrolamellar, laminar, and plexiform) bone, usually arranged in
a more linear pattern
 Protein-based methods, such as radioimmunoassay (pRIA), have been successfully applied to
human versus non-human assessments. Solid-phase doubleantibody radioimmunoassay can be used
to determine whether extracted protein is from a human or non-human bone.
 The extracted protein is combined with rabbit antisera which have been exposed to albumins or sera
of select animal species (e.g., human, bison, bear, rat, elephant, elk, goat, pig or dog). Species-
specific antibodies are then combined with the protein and antisera to observe antibody-antigen
reactions. Finally, radioactive antibodies are combined with each sample to determine the strongest
antibody-antigen reactions, which are species-specific.

66. Human, Horse, Pig

70. Taphonomy
 Laws of burial, to explain the process of “the transition (in all its details) of
animal remains from the biosphere into the lithosphere.
 In a medicolegal context, the term forensic taphonomy is often used,
referring to the study of postmortem processes which affect the
preservation and recovery of human remains, which helps in
reconstructing the circumstances surrounding the death event.
 It can aid in differentiating taphonomic events from antemortem and
perimortem events (such as trauma), and estimating the time since death
or postmortem interval (PMI).

71. Decomposition
 Algor Mortis- Starts at death, one degree drop till first 12 hours.
 Livor Mortis- Starts after 30mnts- 4hours, max after 12hours
 Rigor Mortis- Takes 12hours to set and stays for another day till
decomposition of muscle fibres.
 Decomposition: Autolysis and Putrefaction
 Saponification- Starts after 3 weeks, typical onset is after one to two
months.
 Mummification
 Differential Decomposition
 Skeletonization.

73. Postmortem Skeletal changes
 Once the soft tissues have decomposed, the skeleton is subject to modification and
degradation by a number of factors that are largely dependent on the depositional
environment.
 Diagenesis is the term used to refer to any chemical, physical, or biological change to a
bone after its initial deposition.
 Postmortem changes to bones and teeth typically include those due to interaction with
ground water and sediment, soil pH, as well as weathering, transport by natural or
physical forces, plant growth through bones, and microbes, which can also cause
structural damage to bones.
 Entomological activity, scavangers activity, wolves, coyotes, foxes, domesticated dogs,
cats, as well as omnivores such as bears and pigs. Scavengers will modify, consume,
disarticulate, and disperse soft and bony tissue during the scavenging process

74. In aquatic environments, remains are subject to a number of different factors that affect
movement and dispersion. Most bodies will sink when first deposited in water. This can be
influenced by a number of factors including: body weight and density, temperature, horizontal
velocity of the water, and pressure and volume of gases in the tissues. Once on the bottom, the
body can be moved due to drag forces from wave or current action. The movement of bodies or
skeletal remains in aquatic environments is referred to as fluvial transport. Unless heavily
weighted down or firmly caught on underwater debris, gases produced by putrefaction will
increase buoyancy, and the remains will rise to the surface of the water and float. Once floating
on the surface, body movement can be affected by factors such as surface currents, eddies, and
winds. The remains will float until they lose buoyancy through the release of decompositional
gases, and will then typically sink again. Disarticulation in water is influenced primarily by the
nature and relative anatomical position of the joint – more flexible joints (which are more affected
by wave and current action) disarticulate more quickly than less flexible joints. The first to
become disarticulated are usually the hands, followed by the mandible, cranium, and limbs, with
the pelvic girdle disarticulating last. Other factors affecting disarticulation include whether
remains are floating versus submerged, whether there is trauma present, scavengers, wave action,
and the presence of clothing.
Disarticulation in Submerged bodies.