8. Classification of Bones
• Long Bones :-
• Ilustration mapping the different components of a long
bone
• The bones of the body come in a variety of sizes and
shapes.
• The four principal types of bones are long, short, flat and
irregular.
• Bones that are longer than they are wide are called long
bones.
• They consist of a long shaft with two bulky ends or
extremities.
9.
10.
11. Short Bones :-
Short bones are roughly cube shaped with
vertical and horizontal dimensions
approximately equal.
They consist primarily of spongy bone, which is
covered by a thin layer of compact bone.
Short bones include the bones of the wrist and
ankle.
12.
13. • Flat Bones :-
• Flat bones are thin, flattened, and usually
curved.
• Most of the bones of the cranium are flat
bones.
14.
15. • Irregular Bones:-
• Bones that are not in any of the above three
categories are classified as irregular bones.
• They are primarily spongy
• bone that is covered with a thin layer of compact
bone.
• The vertebrae and some of the bones in the skull
are irregular bones.
22. • Frontal bone. This is the flat bone that makes up your
forehead. It also forms the upper portion of your eye sockets.
• Parietal bones. This a pair of flat bones located on either
side of your head, behind the frontal bone.
• Temporal bones. This is a pair of irregular bones located
under each of the parietal bones.
• Occipital bone. This is a flat bone located in the very back
of your skull. It has an opening that allows your spinal cord to
connect to your brain.
• Sphenoid bone. This is an irregular bone that sits below the
frontal bone. It spans the width of your skull and forms a large part of
the base of your skull.
• Ethmoid bone. This is an irregular bone located in front of the
sphenoid bone. It makes up part of your nasal cavity.
24. The two palatine bones (L., palatum “palate”) form
portions of the hard palate, lateral walls of the nasal
cavity, and floors of the orbits.
Palatine bone
These small, L-shaped, facial bones are located
between the palatine processes of the maxilla bones
and the pterygoid processes of the
25. The two maxilla or maxillary bones (maxillae, plural)
form the upper jaw (L., mala, jaw).
Each maxilla has four processes (frontal, zygomatic,
alveolar, and palatine) and helps form the orbit, roof of
the mouth, and the lateral walls of the nasal cavity.
Maxilla Bone
Orbital surface (process) – posterior extension from body
that forms much of orbit floor. [Anterior view]
26. Some of the smallest are the two nasal bones, two
inferior turbinates (nasal conchae), and the single
vomer bone.
Nasal, Vomer
Nasal bones – are two small bones that form the bridge
of the nose.
Vomer bone – a thin bone that runs vertically along
the midline of the nasal cavity.
27. Hyoid bone
The hyoid bone (Gr. hyoeides, U-shaped) is a small, U-
shaped bone that is located between the mandible and
larynx and anterior to the third cervical vertebra.
It does not directly articulate with any other bones.
Instead, the hyoid bone is loosely held in place by
several ligaments and muscles that attach to the skull,
mandible, tongue, larynx, and scapula.
28. The Mandible (L., mandere – to chew) is the facial
bone that forms the lower jaw and contains the
lower teeth.
It consists of right and left halves that fuse together
early in life. The anterior portion of the mandible, called
the body, is horseshoe-shaped and runs horizontally.
29. The zygomatic bones (Gr., zygoma – yoke) are
two facial bones that form the cheeks and the
lateral walls of the orbits.
They are also commonly referred to as the
cheekbones or malar bones (L., mala – the cheek).
Each zygomatic bone articulates with the temporal
bone, frontal bone, maxilla, and sphenoid bones.
30. Lacrimal Bone
The lacrimal bone (L., lacrima – tear) is a small facial
bone that forms a portion of the anterior medial wall of
the orbit
Lacrimal fossa (or lacrimal sulcus; fossa for lacrimal sac) –
depression along the junction of the lacrimal bone and maxilla
bone that holds the lacrimal sac; tears formed by the sac drain
through a duct into the nasal cavity.
Orbital plate (or orbital surface) – thin plate of bone that forms a
portion of the medial wall of the orbit posterior to lacrimal fossa.
45. Review: Introduction to the Skeletal
System
• The human skeleton is well-adapted for the functions it
must perform.
• Functions of bones include support, protection, movement,
mineral storage, and formation of blood
• There are two types of bone tissue: compact and spongy.
• Compact bone consists of closely packed osteons, or
haversian system.
• Spongy bone consists of plates of bone, called trabeculae,
around irregular spaces that contain red bone marrow.
46. • Osteogenesis is the process of bone formation.
• Three types of cells, osteoblasts, osteocytes, and
osteoclasts, are involved in bone formation and
remodeling
• In intramembranous ossification, connective tissue
membranes are replaced by bone.
• This process occurs in the flat bones of the skull.
• In endochondral ossification, bone tissue replaces
hyaline cartilage models.
• Most bones are formed in this manner.
47. • Bones grow in length at the epiphyseal plate
between the diaphysis and the epiphysis.
• When the epiphyseal plate completely
ossifies, bones no longer increase in length.
• Bones may be classified as long, short, flat, or
irregular.
• The diaphysis of a long bone is the central
shaft.
• There is an epiphysis at each end of the
diaphysis.
48. • The adult human skeleton usually
consists of 206 named bones and these
bones can be grouped in two divisions:
axial skeleton and appendicular
skeleton.
• The bones of the skeleton are grouped
in two divisions: axial skeleton and
appendicular skeleton.
49. • There are three types of joints in terms of the amount of
movement they allow: synarthroses (immovable),
amphiarthroses (slightly movable), and diarthroses
(freely movable).
50.
51. Muscle Types
BUSINESS
• Skeletal Muscle :-
• Skeletal muscle, attached to bones, is responsible for
skeletal movements.
• The peripheral portion of the central nervous system
(CNS) controls the skeletal muscles.
• Thus, these muscles are under conscious, or voluntary,
control.
• The basic unit is the muscle fiber with many nuclei.
These muscle fibers are striated (having transverse
streaks) and each acts independently of neighboring
52.
53. • Smooth Muscle
• Smooth muscle, found in the walls of the hollow internal
organs such as blood vessels, the
gastrointestinal tract, bladder, and uterus, is
under control of the autonomic nervous system.
• Smooth muscle cannot be controlled
consciously and thus acts involuntarily.
• The non-striated (smooth) muscle cell is spindle-
shaped and has one central nucleus.
• Smooth muscle contracts slowly and
rhythmically.
54. • Cardiac Muscle
• Cardiac muscle, found in the walls of the heart, is also
under control of the autonomic nervous system.
• The cardiac muscle cell has one central nucleus, like
smooth muscle, but it also is striated, like skeletal muscle.
• The cardiac muscle cell is rectangular in shape.
• The contraction of cardiac muscle is involuntary, strong,
and rhythmical.
55. Function of the skeletal system :-
• supports the body
• facilitates movement
• protects internal
organs
• produces blood cells
• stores and releases
minerals
56.
57.
58. Joints are classified by their range of
movement:
• Immovable, or fibrous,
joints
• Partially movable, or cartilaginous
• Freely movable, or synovial
59. • Hinge joints :- allow movement in one
direction, as seen in the knees and elbows.
• Pivot joints:-allow a rotating or twisting motion,
like that of the head moving from side to side
• Ball-and-socket joints :-allow the greatest
freedom of movement.
• The hips and shoulders have this type of joint,
in which the round end of a long bone fits into
the hollow of another bone.
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Presented by...
Mr. JITENDRA BHARGAV
.
THE SKELETON SYSTEM