Anatomy of skeletal system

By: Dr Krishna Bhatt, Assistant Professor
ARIP, Charusat
Human Anatomy:
The Skeletal System:

Structure, Function, and
Diseases
of the bones and joints

Is this the correct anatomical position?

Introduction
• One of the most remarkable tissues of the
human body
• Far from inert and lifeless, bones are living,
dynamic structures
• Bones serve a wide variety of very diverse
functions within us
• Noted for their strength and resiliency
during life, bones will remain after we are
long gone

The Skeletal System
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 Parts of the skeletal system
 Bones (skeleton)
 Joints
 Cartilages
 Ligaments (bone to bone)(tendon=bone to
muscle)
 Divided into two divisions
 Axial skeleton
 Appendicular skeleton – limbs and girdle

Bones of the Human Body
 The skeleton has 206 bones
 Two basic types of bone tissue
Compact bone
 Homogeneous
Spongy bone
 Small needle-like
pieces of bone
 Many open spaces
Figure 5.2b

Microscopic Anatomy of Bone
Figure 5.3

Skeletal Cartilages
• Initially our skeleton is made up of
cartilages and fibrous membranes
• Gradually our skeletal cartilages are
replaced by bone
• Upon reaching adulthood the skeleton
becomes almost fully ossified
• Only a few cartilages remain in the adult
skeleton

Basic structure, type & location
• A skeletal cartilage is made of some variety
of cartilage tissue
• Each type contains a high proportion of
water which makes them resilient
• Cartilage has no nerves or blood supply
• It is surrounded by a dense tissue
membrane called a perichondrium

Basic structure, type & location
• There are three types of cartilage tissue:
hyaline, elastic, and fibrocartilage
• Each contains a matrix of jellylike ground
substance and fibers

Functions of Bones
 Support of the body
 Protection of soft organs
 Movement due to attached skeletal
muscles
 Storage of minerals and fats
 Blood cell formation

Function of Bones
• Support • Bones provide a hard
framework that
supports the body
• Bones provide support
for internal organs

Function of Bone
• Protection • Fused bones provide a
brain case that protects
this vital tissue
• Spinal cord is
surrounded by
vertebrae
• Rib cage protects vital
organs

Function of Bone
• Movement • Skeletal muscle
attached to bones use
the bones as levers to
move the body
• Arrangement of bones
and joints determine
the movements
possible

Function of Bones
• Mineral Storage • Bone serves as a
mineral reservoir
• Phosphate and calcium
ions can be released
into the blood steam for
distribution
• Deposition and removal
are ongoing

Function of Bones
• Blood cell formation • Hematopoiesis occurs
within the marrow
cavities of the long
bones
• The majority of
hematopoiesis occurs in
bones

Classification of Bone:
• Bones vary in shape and size
• The unique shape of each bone fulfills a
particular need
• Bones are classified by their shape as long,
short, flat, or irregular bone
• Bones differ in the distribution of compact
and spongy osseous tissues

Bones are classified by
their shape:
1.long
2.short
3.flat
4.irregular

Classification of Bones on the
Basis of Shape
Figure 5.1

Classification of Bones
 Long bones
Typically longer than wide
Have a shaft with heads at both ends
Contain mostly compact bone
• Examples: Femur, humerus

Types of Bone Cells
 Osteocytes
 Mature bone cells
 Osteoblasts
 Bone-forming cells
 Osteoclasts
 Bone-destroying cells
 Break down bone matrix for remodeling and
release of calcium
 Bone remodeling is a process by both
osteoblasts and osteoclasts

Bone Fractures
 A break in a bone
 Types of bone fractures
 Closed (simple) fracture – break that does not
penetrate the skin
 Open (compound) fracture – broken bone
penetrates through the skin
 Bone fractures are treated by reduction
and immobilization
 Realignment of the bone

Common Types of Fractures
Slide 5.17Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Table 5.2

Stages in the Healing of a Bone
Fracture
Figure 5.5

Axial skeleton supports and protects organs of head,
neck and trunk
Axial skeleton:
skull (cranium and facial bones)
hyoid bone (anchors tongue and muscles
associated with swallowing)
vertebral column (vertebrae and disks)
bony thorax (ribs and sternum)
Appendicular skeleton includes bones of limbs and
bones that anchor them to the axial skeleton
Appendicular skeleton:
pectoral girdle (clavicles and scapulae)
upper limbs (arms)
pelvic girdle (sacrum, coccyx)
lower limbs (legs)
Articulation- where joints meet, connect, and are formed.

22 bones in skull
6 in middle ears
1 hyoid bone
26 in vertebral column
25 in thoracic cage
4 in pectoral girdle
60 in upper limbs
60 in lower limbs
2 in pelvic girdle
206 bones in all

The Axial Skeleton
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
 Forms the longitudinal part of the body
 Divided into three parts
Skull
Vertebral column
Bony thorax

The Axial Skeleton
Figure 5.6

The skull
8 sutured bones in cranium
Facial bones: 13 sutured bones, 1 mandible
Cranium
encases brain
attachments for muscles
sinuses

Bones of the Skull
Figure 5.11

Human Skull, Superior View
Figure 5.8

Human Skull, Inferior View
Figure 5.9

Paranasal Sinuses
 Hollow portions of bones surrounding
the nasal cavity
Figure 5.10

The Vertebral Column
 Vertebrae
separated by
intervertebral discs
 The spine has a
normal curvature
 Each vertebrae is
given a name
according to its
location Figure 5.14

Vertebral column
7 cervial vertebrae
12 thoracic
5 lumbar
1 sacrum (5 fused
1 coccyx (4 fused)
Vertebrae vary in size and morphology

Structure of a Typical Vertebrae
Figure 5.16

Thoracic cage
ribs
thoracic vertebrae
sternum
costal cartilages
True ribs are directly attached to the sternum
(first seven pairs)
Three false ribs are joined to the 7th rib
Two pairs of floating ribs

Joints
• Fibrous-Fibrous joints connect bones without
allowing any movement. The bones of your
skull and pelvis are held together by fibrous
joints.
• Cartilaginous-Cartilaginous joints are joints
in which the bones are attached by cartilage.
These joints allow for only a little movement,
such as in the spine or ribs.
• Synovial-Synovial joints allow for much more
movement than cartilaginous joints. Cavities
between bones in synovial joints are filled
with synovial fluid. This fluid helps lubricate
and protect the bones. Bursa sacks contain
the synovial fluid. within fixed limits

• A joint, or articulation, is the place
where two bones come together.
• There are three types of joints
classified by the amount of
movement they allow:
 Immovable
 slightly movable
 freely movable

Types of Joints
Hinge- A hinge joint allows extension and
retraction of an appendage. (Elbow, Knee)

Ball and Socket- A ball and socket joint
allows for radial movement in almost
any direction. They are found in the hips
and shoulders. (Hip, Shoulder)

Gliding- In a gliding or plane joint bones
slide past each other. Mid-carpal and mid-
tarsal joints are gliding joints. (Hands,
Feet)

Saddle- This type of joint occurs when the
touching surfaces of two bones have both
concave and convex regions with the shapes
of the two bones complementing one other
and allowing a wide range of movement.
(Thumb)

Types of Synovial Joints Based on
Shape
Figure 5.29a–c

Types of Synovial Joints Based on
Shape
Figure 5.29d–f

Diseases and Conditions
of the Skeletal System

Anatomy of skeletal system

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