The human skeletal system consists of bones and cartilage that provide structure, protect organs, allow for movement, store minerals, and produce blood cells. The skeletal system is divided into the axial skeleton which includes the skull, vertebral column, and rib cage, and the appendicular skeleton which includes the pectoral and pelvic girdles and upper and lower limbs. Bones develop through either intramembranous ossification which forms bone directly from mesenchymal cells, or endochondral ossification which first forms cartilage that is then replaced with bone.

1. The Human Skeletal System

2. DO YOU KNOW?

3. Major Functions:
1. Gives structural support for
the entire body
2. Protects delicate organs and
tissues.
3. Moves the body as muscles
pull on them.
4. Stores minerals and adipose
(fat) tissues in long bones
(yellow marrow)

4. Major Functions:
5. Stores calcium and
phosphorus and releases
them when needed.
6. Regulates energy
metabolism in the body as
part of the endocrine
system
7. Produces blood in red
bone marrow

5. • The HUMAN SKELETAL SYSTEM consists of
the axial skeleton and the appendicular
skeleton.

6. • The axial skeleton lies in the
central axis of the body, and it
serves to maintain your upright
posture.

7. • The axial
skeleton is
made up of 80
bones.
• The major
parts of axial
skeleton include
the skull, the
vertebral
column, and the
rib cage.

8. SKULL
• The skull protects
the brain and
other sensory
organs.

9. 1. SKULL
• It is composed of :
eight (8) cranial bones
(named after the lobes
of the brain)
14 facial bones
 six auditory or ear
bones
one hyoid bone that
supports the tongue.

10. • It is composed of
seven cervical
vertebrae
-the first cervical
bone is called the
atlas and the second
cervical bone is
called the axis
2. Vertebral
Column(backbone)

11. • It is composed of
12 thoracic
vertebrae
- where the
ribs are
attached,
2. Vertebral
Column(backbone)

12. • It is composed of
five lumbar
vertebrae
2. Vertebral
Column(backbone)

13. • It is composed of
Sacrum
- made up of
4-5 fused sacral
bones
2. Vertebral
Column(backbone)

14. • It is composed of
coccyx or
tailbone
- made up of
4-5 fused
coccygeal bones
2. Vertebral
Column(backbone)

15. Vertebral
Column(backbone)
• The vertebral
column protects
the spinal cord and
is also responsible
for your upright
posture.

16. 3. Rib Cage
• It consists of 12
pairs o ribs and
sternum,
• protects the heart,
lungs, and other
delicate organs.

17. 3. Rib Cage
• The first seven (7) pairs
(ribs 1-7) are called true
ribs.
• Ribs 8-10 are called
false ribs because they
have been fused to
attach to the sternum
• the last two pairs of ribs
(11-12) are called
floating ribs because
they are not attached to
the sternum

18. • The appendicular skeleton is
located at the sides and serves
to support your limbs.

19. • The appendicular skeleton is
composed of 126 bones and
includes the bones of the pectoral
and pelvic girdles, as well as the
upper and lower limbs.

20. PECTORAL GIRDLE
• is attached to the
upper portion of the
sternum
• consists of two
clavicles or
collarbones, and two
scapula or shoulder
blades, which are flat
triangular bones at
the back of the rib
cage.

21. PELVIC GIRDLE
• Consists of two hip
bones
• Each hip bone consists
of the fused ilium,
ischium and pubis
bones, and is attached
to the sacrum and
coccyx.
• The pelvic girdle
stabilizes the individual
as he/she performs
different tasks.

22. • Each upper and lower limb
contains 30 bones.
• The bones of the upper limb
include the:
humerus (upper arm),
the radius and
ulna (forearm),
eight carpal bones (wrist),
five metacarpal bones (palm),
14 phalanges (fingers).

23. • Each finger has 3 phalanges,
except for the thumb which
has only two.

24. • The bones of the lower
limb consist of the:
 femur (thighbone)
 patella (knee bone)
tibia and fibula (bones of
the legs)
seven tarsus bones
(ankles)
 five metatarsus bones
(bones of the sole)
 14 phalanges (toes).

25. • The phalanges of the
bones are arranged similar
to the fingers.

26. • Ossification is the process of bone
formation.
• Bones start to form during the 4th
week of prenatal development.

27. Classifications of Bones Based on
their Modes of Development
1. Intramembranous development
Forms the bone directly
Flat bones such as the facial bone,
cranial bone, and clavicle undergo
intramembranous development

28. Classifications of Bones Based on
their Modes of Development
2. Endochondral development
Involves the formation of cartilage
first before the bone
Long bones undergo ossification
Cartilage – is a kind of tissue that is
not as hard and rigid bones