The skeletal system has several key functions: providing points of attachment for muscles to facilitate movement, supporting the body, protecting internal organs, producing blood cells, and storing minerals. It consists of the axial skeleton including the skull, spine, ribs and sternum, and the appendicular skeleton including the shoulders, arms, hips and legs. Bones come in four basic shapes and have a layered structure consisting of periosteum, compact bone, spongy bone and bone marrow. Joints allow bones to move and come in both immovable and movable forms including ball-and-socket, hinge, pivot and gliding joints.

1. Skeletal System

2. Functions of
the Skeletal
System

3. 1. Movement: Skeletal
system provides points of
attachment for muscles.
Your legs and arms move
when the muscles pull on
the bones.

4. 2. Support: The backbone
is the main support center
for the upper body. It
holds your head up and
protects your spinal cord.

5. 3. Protection: The bones
of your skull protect your
brain. Your ribs protect
your lungs and heart from
injury.

6. 4. Makes Blood: Red and
white blood cells are
formed by tissue called
marrow, which is in the
center of the bone.

7. 5. Storage: Bones store
minerals, such as calcium
and phosphorus, for use
by the body

8. Two Major Skeletal
System Parts

9. ►Axial Skeleton: The
axial skeleton includes the
skull, spine, ribs and
sternum.

10. ►Appendicular Skeleton:
The appendicular skeleton
includes the appendages
of the body, which are the
shoulders, arms, hips, and
legs.

12. What are the
Basic Bone
Shapes?

13. ►Four basic bone shapes:
1. Long- arms, legs and
fingers
2. Short- wrist and ankles
3. Flat- skull and sternum
4. Irregular- spine

15. What is the
Structure of
Bone?

16. ►Typical Four Layers:
–Periosteum: Covers
Bones
–Compact Bone: Lies
beneath the periosteum

17. –Spongy Bone: Lies
beneath the compact
bone
–Bone Marrow: Fills the
gaps between the
spongy bone

18. What is the Structure of
Bone?
► Typical Four Layers:
– Periosteum: Covers
Bones
– Compact Bone: Lies
beneath the
periosteum
– Spongy Bone: Lies
beneath the compact
bone
– Bone Marrow: Fills the
gaps between the
spongy bone

20. What is the
Structure of Bone?

21. Bones are complex living
structures that undergo
growth and development.
–Beneath the outer
membrane is a layer of
compact bone (hard

22. Bones are complex living
structures that undergo
growth and development.
Beneath the outer
membrane is a layer of
compact bone (hard and

23. compact bone (hard and
dense, but not solid – it is
filled with holes and has
small canals for blood
vessels and nerves).

24. Inside the compact bone
is a layer of spongy
bone.
It has many small
spaces, is light weight,
but strong.

25. What is the
Structure of Bone?
– In the spaces of many
bones there is a soft
connective tissue called
marrow.
– Two types of Marrow:
►Red
►Yellow
– Red Marrow
produces most of
the body’s blood
cells.
– Yellow Marrow
stores fat that can
serve as an energy
reserve.

26. How Strong are
Bones?
– The structure of
bones make it both
strong and light
weight.
– 20 % of an adults
body weight is bone.
– Bone is made up of
2 minerals:
►Calcium
►Phosphorus

27. How Do Bones
Develop?
– As an infant, most of your
skeleton is cartilage.
– Cartilage is a strong flexible
tissue.
– Over time the cartilage is
replaced by solid bone,
usually complete by the time
you stop growing.
– Not all cartilage is replaced in
adults. Many joints contain
cartilage, protecting the ends
of bones (ears and the end of
the nose is also cartilage).

28. Clavicle or Collarbone
► The clavicle, or collar bone, holds the
shoulder joint away from the rest of the
upper body and is only as thick as your
little finger.

29. Scapula
► The scapula is located on the back side
of the ribcage and helps provide part of
the shoulder joint and movement for the
arms.

30. Vertebral Column or Spinal Cord
1) The cervical region (neck bones)
2) The thorasic region (what the ribs attach to)
3) The lumbar region (the lower part of the back)

31. Coccyx and Sacrum

32. Humerus (Upper Arm Bone)

33. Radius and Ulna
►Radius on Top
►Ulna on Bottom

34. Carpals or (Wrist Bones)

35. Metacarpals (Top of Hands)

36. Phalanges (Little Fingers)

37. Rib Cage

38. Sternum (Breastbone)

39. Pelvis

40. Femur
(Largest Bone in the Body)

41. The Tibia and Fibula

42. Tarsals

43. Metatarsals

44. Phalanges

45. What are Joints?
• A joint is a place where
two bones come
together.
• Joints allow the bones
to move in different
ways.
• Two types of joints:
• Immovable
• Movable

46. What are Immovable
Joints?
• A joint that allows
little or no
movement

47. What are Movable
Joints?
• Most of the joint are
movable joints.
• Allow the body to move in
a wide range of
movements.
• Bones in movable joints
are held together by
strong connective tissue
called ligaments.
• Four types of movable
joints:
• Hinge
• Ball-and-socket
• Pivot

48. What is a Ball-and-
Socket Joint?
• Round end of bone fitting
snuggly within another bone.
 Ex. Shoulder and Hip
• Allows the greatest range of
motion.
 The ball-and-socket
joint allows you to
swing your arm freely
in a circle.

49. What is a Hinge
Joint?
► Movement in one direction like
a door.
– Ex. Knee and Elbow
► Allows forward or backward
motion.

50. What is a Pivot
Joint?
►Bone resting atop another
bone permitting free
movement.
– Ex. Neck, Wrist and
Ankles
►Allows one bone to rotate
around another.
– Allows you to turn your head

51. What is a Gliding Joint?
• Allows one bone to
slide over another.
 Ex. Knuckles, wrist,
ankle
• Allows your to bend
and flex as well as
make limited side to
side motions.

52. What is a
Ligament?
• Connects bone to
bone.

53. What is a
Tendon?
• Attaches
muscles to
bones.