2. FUNCTIONS
1. Support the body
2. Attachment of muscles
3. Protection of internal organs
4. Acts as levers for movement
5. Gives stability and framework and shape to the
body
6. Production of blood cell (in mammals)
4. As to Formation
Membrane or dermal bone
-formed by direct ossification in
connective tissue without an intervening
cartilage stage
Endochondral or cartilage bone
-formed by replacement of pre-existing
cartilage
5. As to Kinds of Bone Tissue
Spongy bone tissue
-located at the ends and interiors of long
bones
-also called bone marrow
-composed of an open lattice of bone
-within this lattice framework, RBC are
produced
Compact bone tissue
-surrounds the spongy bone tissue
-also found at the core of bones
-gives strength to withstand mechanical
stress
6. As to Location
Exoskeleton or dermal skeleton
-built up outside the body
-muscles are attached to the inner surface
-limits the size of the animal
-formed from a secretion called chitin which is made
hard by the deposition of calcium salts
-characteristics of arthropods
Endoskeleton
-built up inside the body surrounded by soft tissue
-muscles are attached to the outer surface
-characteristics of vertebrates
-divided into axial and appendicular skeletons
8. Notochord
the primitive axial skeleton, replaced by the
vertebral column
unsegmented and composed of dense fibrous
connective tissue
the first skeletal element to appear in the embryo of
chordates
9. Vertebral Column
the main axial support of vertebrates
commonly called back bone
composed of segmentally arranged vertebrate from
the base of the skull to the tip of the tail
protects the spinal cord
provides rigidity to the body
provides direct or indirect attachment of the
appendicular skeleton
in man, there are 26 vertebrae: 7 cervical (the first
vertebrae is the atlas and the second is the axis), 12
thoracic, 5 lumbar, 1sacral (five fused to form sacrum),
and 1 caudal vertebrae (three to five fused to form the
coccyx)
10. Regions of the vertebral column
in fishes - two regions, trunk tall
in frogs - four regions, no neck
in salamanders, reptiles, birds, and
mammals - five regions, neck or cervical,
chest or thoracic, lower back or lumbar,
pelvic or sacral, and tail or caudal
11. Ribs
series of cartilaginous or elongated bony structures attached
to the vertebrae
stout, arched structures surrounding the thoracic cavity and
uniting ventrally with the sternum
forms the thoracic cage
composed of the neck, shaft and the angle
in man, there are 12 pairs of ribs, the first seven pairs are
called vertebrosternal or true ribs, the next three pairs are
false ribs, and the last two pairs are floating ribs
Types of ribs
1. true ribs - directly connected to the sternum
2. false ribs - the distal cartilaginous ends unite with the costal
cartilages of the last true ribs
3. floating ribs - the distal cartilaginous ends terminate freely
12. Sternum
commonly called as the breast bone
elongated structure lying in the mid-ventral region of
the anterior trunk
articulates with the pectoral girdle
strengthen the anterior part of the trunk
not present in snakes, limbless lizards, and turtles
(with plastron)
in man, th sternum is flat and narrow, divided into three
parts: manubrium, the upper part; gladiolus, the middle
or body and largest part; xiphoid or ensiform process,
the lowest portion
the first two parts are notches for the reception of
sternal ends of the upper seven costal cartilages, while
xiphoid has no ribs attached to it but some abdominal
muscles
13. Skull
the framework of the head
the most complex of all parts of the
endoskeleton because of its origin
cartilaginous during embryonic stage
Origin of the skull
1. chondrocranium - composed of cartilage; base of the
skull, including sense capsule; replaced by bone
2. dermatocranium - composed of membrane bones; roof
over the chondrocranium
3. splanchnocranium - derived from the visceral skeleton;
cartilaginous covered by membrane bones
14. Parts of the skull
1. cranium - the brain case
2. three pairs of sense capsule for the organs of
smell, sight and hearing
3. visceral skeleton - in lower vertebrates: paired
arches providing the jaws, the support for the
tongue (hyoid apparatus), and support for the gill
region; in higher vertebrates; the hyoid
apparatus, the ear ossicles (incus, malleus, and
stapes) for sound conduction, the laryngeal or
thyroid cartilage and the tracheal or cricoid
cartilages
21. there are a total of 206 bones in an adult human
infants have more bones that adult due to
numerous joints
distributed as follows:
skull (cranium + face) - 22 (8 + 14)
ears - 6
hyoid - 1
vertebral column - 26
sternum - 1
ribs - 24
pectoral girdle and forelimbs - 64
pelvic girdle and forelimbs - 62
23. Types as to Amount of Movement and
Structural Composition
Synarthroses
immovable joints
connected by fibrous tissue or cartilage-like sutures,
which are the lines of junction of the skull
Amphiarthroses
slightly movable joints
Types of diarthroses
1. symphysis, a joint where two long bony surfaces are
connected by a broad, flat disc of fibrocartilage
2. synchondrosis, a temporary form of joint made of
cartilage; found between the epiphysis and bodies of
long bones
24. Diarthroses
freely movable joints, most common joint in the body
Types of diarthroses
1. gliding joint - gliding movement only; wrists, ankles,
vertebrae
2. hinge joint - angular movement in one direction; humerus
and ulna, knee, ankle, phalanges
3. condyloid joint- angular movement in two directions, as
when the condyle is received into an elliptical cavity as in
the wrist joint
4. saddle joint - concave in one direction and convex in
another; metacarpal bone of the thumb
5. pivot joint - rotary movement in one axis; atlas and axis,
radius and ulna, hand to the lower end of the radius
6. ball-and-socket joint - angular movement in all directions;
head of the femur in the acetabulum, and the head of the
humerus in the glenoid cavity, shoulder joint is the most
freely movable joint in the body
26. Types of Gait
1. plantigrade - entire sole of the foot touches the
ground; man, apes, bears, raccoons
2. digitigrade - digits with pads touch the ground
and the rest of the foot is elevated; cat family
3. ungultigrade - tips of the digits (specialized into
hoofs) touch the grounds; ungulates or hoofed
animals, cows, carabaos, pigs, horse, goats
28. bone is a special form of cartilage in which the
collagen fibers are coated by a calcium
phosphate salt
bone is formed in two stages:
1. collagen is laid down in a matrix of fibrils along lines
of stress
2. calcium-containing minerals (hydroxyapatite0
impregnate the fibril
hydroxyapatite provides rigidity, while the
collagen provides flexibility
bone is laid down in concentric layers called
lamellae
lamellae are laid down as a series of tubes
around narrow channels called Haversian canals
Haversian canals are interconnected containing
blood vessels and nerve
