1. Chapter 5 The Skeletal System

2. The Skeletal System Parts of the skeletal system
Bones (skeleton)
Joints
Cartilages
Ligaments
Divided into two divisions
Axial skeleton
Appendicular skeleton
Individual bones are the organs of the skeletal system.
Bone contains very active, living tissues.
The skeleton can be divided into axial and appendicular portions.
The axial skeleton consists of the skull, hyoid bone, vertebral column, and thoracic cage.
The appendicular skeleton consists of the pectoral girdle, upper limbs, pelvic girdle, and lower limbs.

3. Functions of Bones Support of the body Protection of soft organs
Movement due to attached skeletal muscles
Storage of minerals and fats
Blood cell formation
Functions of Bones
1. Support and protection
Skeletal parts provide shape and form for body structures.
They support and protect softer, underlying tissues.
2. Body movement
Bones and muscles function together as levers to move the body and its parts
3. Blood cell formation
Red marrow functions in the production of red blood cells, white blood cells, and blood platelets
Yellow marrow stores fat.
4. Storage of inorganic salts
The intercellular material of bone tissue contains large quantities of calcium phosphate.

4. Bones of the Human Body The skeleton has 206 bones
Two basic types of bone tissue
Compact bone
Spongy bone
Many open spaces
Compact bone provides strength and resistance to bending.
Spongy bone provides strength and reduces the weight of bone.

5. Classification of Bones
Long bones
Typically longer than wide
Have a shaft with heads at both ends
Contain mostly compact bone
Examples: Femur, humerus

6. Classification of Bones
Short bones
Generally cube-shape
Contain mostly spongy bone
Examples: Carpals, tarsals

7. Classification of Bones on the Basis of Shape

8. Classification of Bones
Flat bones
Thin and flattened
Usually curved
Thin layers of compact bone around a layer of spongy bone
Examples: Skull, ribs, sternum

9. Classification of Bones
Irregular bones
Irregular shape
Do not fit into other bone classification categories
Example: Vertebrae and hip

10. Classification of Bones on the Basis of Shape

11. Gross Anatomy of a Long Bone
Diaphysis
Shaft
Composed of compact bone
Epiphysis
Ends of the bone
Composed mostly of spongy bone
1. Parts of a long bone
Epiphyses are the ends of the bones, and are covered with articular cartilage and articulate with other bones.
The shaft of a bone is called the diaphysis.

12. Structures of a Long Bone
Periosteum
Outside covering of the diaphysis
Fibrous connective tissue membrane
Arteries
Supply bone cells with nutrients
Except for the articular cartilage, a bone is covered by a periosteum.
The diaphysis contains a medullary cavity filled with marrow.

13. Structures of a Long Bone
Articular cartilage
Covers the external surface of the epiphyses
Made of hyaline cartilage
Decreases friction at joint surfaces

14. Structures of a Long Bone
Medullary cavity
Cavity of the shaft
Contains yellow marrow (mostly fat) in adults
Contains red marrow (for blood cell formation) in infants

15. Bone Growth
Epiphyseal plates allow for growth of long bone during childhood
New cartilage is continuously formed
Older cartilage becomes ossified
Cartilage is broken down
Bone replaces cartilage

16. Bone Growth Bones are remodeled and lengthened until growth stops
Bones change shape somewhat
Bones grow in width

17. Long Bone Formation and Growth

18. Long Bone Formation and Growth

19. The Skeletal System Axial Skeleton

20. The Axial Skeleton Forms the longitudinal part of the body
Divided into three parts
Skull
Vertebral column
Bony thorax
The axial skeleton consists of the skull, hyoid bone, vertebral column, and thoracic cage.

21. The Axial Skeleton

22. The Skull Two sets of bones Bones are joined by sutures
Cranium
Facial bones
Bones are joined by sutures
Only the mandible is attached by a freely movable joint
Skull
The skull consists of 22 bones, which include 8 cranial bones,
13 facial bones, and 1 mandible.
1. Cranium
The cranium encloses and protects the brain.
Some cranial bones contain air-filled sinuses.
Cranial bones include the frontal bone, parietal bones, occipital bone, temporal bones, sphenoid bone, and ethmoid bone.
2. Facial skeleton
Facial bones provide the basic shape of the face and attachments for muscles.
Facial bones include the maxillary bones, palatine bones, zygomatic bones, lacrimal bones, nasal bones, vomer, inferior nasal conchae, and mandible.

23. The Vertebral Column Vertebrae separated by intervertebral discs
The spine has a normal curvature
Each vertebrae is given a name according to its location
Vertebral Column
The vertebral column extends from the skull to the pelvis and protects the spinal cord.
It is composed of vertebrae, separated by intervertebral disks.
It has four curvatures, which give it resiliency.

24. Structure of a Typical Vertebrae
A typical vertebra consists of a body and a bony arch, which surrounds the spinal cord.
Notches on the lower surfaces provide intervertebral foramina, through which spinal nerves pass.

25. The Bony Thorax Forms a cage to protect major organs Thoracic Cage
The thoracic cage includes the ribs, thoracic vertebrae, sternum, and costal cartilages.
It supports the shoulder girdle and arms, protects visceral organs, and functions in breathing.
Ribs
The ribs are attached to the thoracic vertebrae.
The cartilages of the true ribs join the sternum directly; those of the false ribs join it indirectly.
Sternum
It articulates with the clavicles.

26. The Bony Thorax
Made-up of three parts
Sternum
Ribs
Thoracic vertebrae

27. The Skeletal System Appendicular Skeleton

28. The Appendicular Skeleton
Limbs (appendages)
Pectoral girdle
Pelvic girdle
The appendicular skeleton consists of the pectoral girdle, upper limbs, pelvic girdle, and lower limbs.

29. The Appendicular Skeleton

30. The Pectoral (Shoulder) Girdle
Composed of two bones
Clavicle – collarbone
Scapula – shoulder blade
These bones allow the upper limb to have exceptionally free movement
Pectoral Girdle
The pectoral girdle is composed of two clavicles and two scapulae.
It forms an incomplete ring that supports the arms and provides attachments for muscles.

31. Bones of the Shoulder Girdle
Clavicles
They function to hold the shoulders in place and provide attachments for muscles.

32. Bones of the Shoulder Girdle
Scapulae
The scapulae are broad, triangular bones.
They articulate with the humerus and provide attachments for muscles.

33. Bones of the Upper Limb The arm is formed by a single bone Humerus
provide frameworks for arms, wrists, palms, and fingers.
provide attachments for muscles and function in levers that move the limb and its parts.
Humerus – bone of the upper arm

34. Bones of the Upper Limb The forearm has two bones Ulna Radius
Radius – one of the bones of the lower arm
Ulna – the other bone of the lower arm

35. Bones of the Upper Limb The hand Carpals – wrist Metacarpals – palm
Phalanges – fingers
Hand
The hand is composed of a wrist, palm, and 5 fingers.
It includes carpals, metacarpals, and phalanges.

36. Bones of the Pelvic Girdle
Hip bones – Coxal Bones
Composed of three pair of fused bones
The total weight of the upper body rests on the pelvis
Protects several organs
Reproductive organs
Urinary bladder
Part of the large intestine
Pelvic Girdle
The pelvic girdle consists of two coxal bones that articulate with each other anteriorly and with the sacrum posteriorly.

37. The Pelvis The sacrum, coccyx, and pelvic girdle form the pelvis.
Figure 5.23a

38. The Pelvis
Coxal bones
Each coxal bone consists of three bones, which are fused
The ilium
The ischium
The pubis
Figure 5.23b

39. Gender Differences of the Pelvis
The ilium – female pelvis is larger
The ischium – inlet on female larger
The pubis – pubic arch is greater than 90◦ on female
Figure 5.23c

40. Bones of the Lower Limbs
The thigh has one bone
Femur – thigh bone
Lower Limb
Bones of the lower limb provide frameworks for the leg, ankle, instep, and toes.
Femur
The femur extends from the knee to the hip.
The patella articulates with its anterior surface

41. Bones of the Lower Limbs
The leg has two bones
Tibia
Fibula
Tibia
The tibia is located on the medial side of the lower leg.
It articulates with the talus of the ankle.
Fibula
The fibula is located on the lateral side of the tibia.
It articulates with the ankle, but does not bear body weight.

42. Bones of the Lower Limbs
The foot
Tarsus – ankle
Metatarsals – sole
Phalanges – toes
Foot
The foot consists of an ankle, instep, and 5 toes.
It includes tarsals that form the tarsus, metatarsals, and phalanges.