1. Anatomy of the Skeletal System

2. Skeletal system facts
206 bones in an adult (~ 350 cartilaginous bones as a developing baby)
Skeleton reaches full maturity by age 25
Supports the body and protects vital organs
Manufactures blood cells at a rate of 1.2 million per second
Allows body movement by connecting with skeletal muscles

3. Skeletal system facts
Stores excess minerals – primarily calcium and phosphorous
Ligaments connect bone to bone
Tendons connect bone to muscle
2 broad divisions – axial and appendicular

4. Axial Skeleton
Includes the head (cranial and facial), spine, and thorax
80 bones total
Primary function is to support and protect the internal organs

5. Bones of the Head Cranial Bones
Made of 8 bones – parietal (2), temporal (2), frontal, occipital, sphenoid, ethmoid
Fit tightly together without moveable joints
One purpose is to
protect the brain and
other organs located in
the cranium

6. Bones of the Head Cranial Bones
When born, joints are not fused – instead connected by cartilage called fontanels (makes the “softspot”)
Skull growth is not complete until age four
Areas where bones join
are the sutures
Jagged edge of sutures
gives added strength

7. Bones of the Head Facial Bones
Made of 14 bones – maxilla (2), zygomatic (2), palatine (2), nasal (2), lacrimal (2), inferial nasal concha (2), mandible, vomer
Maxilla and palatine form
upper jaw and the roof of
the mouth
Mandible forms the
lower jaw – only moveable
bone in the skull

8. Bones of the Head Auditory Bones
Made of 6 bones – malleus (2), incus (2), stapes (2)
Also known as the hammer, anvil, and stirrup
Smallest bones in the
body
Necessary for hearing

9. Bones of the Head Hyoid (1)
Only bone that does not articulate with another bone
U-shaped
A point of articulation for many muscles (ex: tongue, pharynx)
Found just above the
larynx

10. Bones of the Spine Vertebral Column (general information)
Vertebrae – plural; vertebra – singular
Made of 26 vertebrae (originally 34, but 5 sacral bones fuse together and 4-5 coccygeal bones fuse together.
Intervertebral disks allow the spine to bend and act as shock absorbers – made of cartilage
Have a hollow area for the spinal cord to pass through

11. Bones of the Spine Cervical Vertebrae
First 7 vertebrae – make up the neck (C1-C7)
C1 – atlas
Point where the head is connected to the spine
Allows the head to pivot up and down
C2 – axis
Located right below the atlas
Allows the head to swivel left to right
Other cervical vertebrae allow the head to tilt and move in other directions

12. Bones of the Spine

13. Bones of the Spine Thoracic Vertebrae Made of 12 vertebrae (T1-T12)
Larger than the cervical vertebrae
Attachment point for the ribs

14. Bones of the Spine Lumbar Vertebrae Made of 5 vertebrae (L1-L5)
Largest vertebrae
Form the lower back
Support the weight of
the entire upper body

15. Bones of the Spine Sacral Vertebrae (or Pelvic Vertebrae)
Made of 5 vertebrae fused together (in adults)
Also called the sacrum
Joined to the hips to form the base of the spine

16. Bones of the Spine Coccyx
Made of 4-5 vertebrae fused together (in adults)
Also called the tailbone or coccygeal vertebrae
Used for muscle attachment and a shock absorber for the spine

17. Curvature of the Spine Four curves Cervical lordosis Thoracic kyphosis
Lumbar lordosis
Sacral/coccygeal curve

18. Curvature of the Spine Provide additional strength and flexibility
Can have excess curvature
Scoliosis – excessive lateral curvature
Kyphosis – excessive thoracic curvature (humpback)
Lordosis – excessive lumbar curvature (swayback)

19. Bones of the Chest Ribs Made of 24 bones (12 pairs)
Attaches to the thoracic vertebrae in the back and by cartilage to the sternum in front (the first 7 pairs)
Cartilage is flexible so the ribs
can expand and contract
during breathing

20. Bones of the Chest 3 types of ribs
True ribs- first 7 pairs, attach directly to the sternum
False ribs – next 3 pairs, attaches to the lowest true rib by cartilage
Floating ribs – last 2 pairs, do not attach to the sternum at all, also considered false ribs

21. Bones of the chest

22. Bones of the Chest Sternum Known as the breast bone
Contains the manubrium, body, and xiphoid process
Last bone to ossify

23. Appendicular Skeleton
General Information
Includes the shoulders, hips, arms, and legs
126 bones total
Primary function is support and to enable movement

24. Bones of the Shoulder Consists of 4 bones
Also known as the pectoral girdle

25. Bones of the Shoulder Scapulae (2) Clavicle (2) Singular is scapula
Also known as the shoulder blades
Contains sockets for the arms
Don’t rigidly attach to the axial skeleton
Only articulate with the humerus and clavicle
Clavicle (2)
Also known as the collar bone
Articulates with the scapula and the sternum

26. Bones of the Upper Extremities
Consists of 60 bones
Only 6 are in the arms with the rest in the wrists, hands, and fingers

27. Bones of the Upper Extremities
Humerus (2)
Makes the upper arm
Articulates with the scapula, ulna, and radius

28. Bones of the Upper Extremities
Forearm
Consists of 4 bones
Radius (2)
Located on the lateral side of the forearm (thumb side)
Rotates over the ulna
Ulna (2)
Locaed on the medial side of the forearm (little finger side)
Does not move when the arm is rotated
Has a “hook” to attach to the humerus

29. Bones of the Upper Extremities
Wrist
The bones as a group are known as the carpals
Consists of 16 bones (8 on each side) – pisiform, lunate, scaphoid, trapezium, trapezoid, capitate, hamate, triquetrium
The bones are arranged in two rows of 4
This allows the wrist to bend in various directions

30. Bones of the upper extremities

31. Bones of the Upper Extremities
Hands and Fingers
Consists of 38 bones
Metacarpals
These make up the palm of the hand
There are 10 of these bones (5 per side)
The metacarpal that makes up the thumb is held by ligaments that give it great mobility
Phalanges
28 phalanges make up the fingers (14 per side)
3 in each finger, 2 for each thumb

32. Bones of the upper extremities

33. Bones of the Pelvic Girdle
The pelvic girdle is made of a ring of bones: the sacrum makes up the back and the sides are made up of a pair of bones called the coxae
Each coxae is really three bones fused together: ilium, ischium, pubis
Coxae, coxal bone, and pelvic bone all refer to the same thing

34. Bones of the pelvic girdle

35. Bones of the Lower Extremities
Similar in basic layout to the upper extremities
Bones are thicker and stronger than in the upper extremities
Each lower limb has 30 bones – 4 in the leg and 26 in the foot and ankle

36. Bones of the Lower Extremities
Bones of the Leg
Femur
Makes up the thigh
Longest bone in the body
Strongest bone in the body
Attaches to the pelvic girdle at the hip joint

37. Bones of the Lower Extremities
Tibia
One of the bones in the lower leg
The main weight bearing bone of the leg
Extends from the knee to the ankle
Fibula
Much thinner than the tibia
Found on the lateral side
Does not attach to the femur

38. Bones of the Lower Extremities
Patella
Kneecap
Found on top of the joint between the femur and the tibia
Serves as a brace for the patellar tendon to increase leverage on the joint
Also helps to protect the joint from injury

39. Bones of the Lower Extremities
Bones of the Ankle and Foot
Tarsals
Make up the ankle
14 bones (7 per side): talus, calcaneus (heel bone), navicular, cuboid, and 3 cuneiform
Thick and strong to support the weight of the body
Talus connects with the tibia

40. Bones of the Lower Extremities
Metatarsals
Make up the base of the foot
Made of 10 bones (5 per side)
Forms the framework of the arches of the foot
Phalanges
Made of 28 bones (14 per side)
Makes up the toes
Arranged like the phalanges in the fingers: 2 in each big toe, 3 in every other toe

41. Bones of the lower extremities