1 of 151

Essentials of Human Anatomy & Physiology

Seventh Edition

Elaine N. Marieb

Chapter 5�The Skeletal System

2 of 151

The Skeletal System

3 of 151

Essential Question

What is the purpose of the skeletal system?

4 of 151

The Skeletal System

Slide 5.1

Parts of the skeletal system

Bones (skeleton)
Joints
Cartilages
Ligaments (bone to bone)(tendon=bone to muscle)

5 of 151

The Skeletal System

Skeleton comes from a Greek word meaning dried up body.
Bone appears dead and dried up, but it is not!
Bone is living tissue
Newborn human has 350 bones
Adult human has 206 bones

6 of 151

Functions of Bones

Slide 5.2

Support of the body (framework)
Protection of soft organs
Serve as levers (with help from muscles)
Storage of minerals and fats (calcium)
Blood cell formation

7 of 151

Bones of the Human Body

Slide 5.3

Two basic types of bone tissue

Compact bone

Dense/hard

Spongy bone

(Cancellous)
Many open spaces

Decrease wt of bone/contain red bone marrow

Figure 5.2b

8 of 151

Classification of Bones on the Basis of Shape

Slide 5.4c

Figure 5.1

9 of 151

Classification of Bones

Slide 5.4a

Long bones

Typically longer than wide
Have a shaft with heads at both ends
Contain mostly compact bone
Found in legs and arms

Examples: Femur, humerus

10 of 151

Classification of Bones

Slide 5.4b

Short bones

Generally cube-shape and small
Contain mostly spongy bone
Found in wrist, ankles, and toes

Examples: Carpals, tarsals

11 of 151

Classification of Bones

Slide 5.5a

Flat bones

Thin and flattened
Usually curved
Cover organs/provide surface for lg. muscle
Thin layers of compact bone around a layer of spongy bone

Examples: Skull, ribs, sternum

12 of 151

Classification of Bones

Irregular bones

Irregular shape
Do not fit into other bone classification categories

Example: Vertebrae and hip

13 of 151

Gross Anatomy of a Bone

Diaphysis

Shaft
Composed of compact bone

Epiphysis

Ends of the bone
Composed mostly of spongy bone

14 of 151

Structure of a Long Bone

Periosteum

Outside covering of the diaphysis
Fibrous connective tissue membrane

Serves as an attachment for muscle

Arteries

Supply bone cells with nutrients

15 of 151

Structure of a Long Bone

Articular cartilage

Covers the external surface of the epiphyses
Made of hyaline cartilage
Decreases friction at joint surfaces

16 of 151

Structure 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

17 of 151

Changes in the Human Skeleton

Slide 5.12

In embryos, the skeleton is primarily hyaline cartilage
During development, much of this cartilage is replaced by bone
Cartilage remains in isolated areas

Bridge of the nose
Parts of ribs
Joints

18 of 151

Bone Growth

Slide 5.13a

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

19 of 151

Bone Growth

Slide 5.13b

Bones are remodeled and lengthened until growth stops

Grow longitudinally for height
Bones grow in width to support weight

20 of 151

Epiphyseal Disc

Refer to figure 8-3
Growth plate
The cartilage near the epiphyseal disc multiplies and eventually becomes ossified (turns to bone)
As long as new cartilage continues to form the bone continues to lengthen.

21 of 151

Epiphyseal Disc (cont.)

When the growth plate hardens and becomes ossified, growth stops
Hormones play a big part in this

Growth hormone stimulates growth
Sex hormones stop growth

22 of 151

Bone Width

Long after longitudinal bone growth has stopped, bones continue to grow in thickness and width.
Bones are continuously being reshaped

23 of 151

Types of Bone Cells

Slide 5.15

Osteocytes

Mature bone cells

Osteoblasts

Bone-forming cells

Osteoclasts

Bone-destroying cells
Break down bone matrix for remodeling and release of calcium

Bone remodeling is a process by both osteoblasts and osteoclasts

24 of 151

Bone Remodeling

A combined action of osteoblasts (bone forming cells) and osteoclasts (bone destroying cells)
Osteoblasts deposit bone on the external bone surface

Figure 8-5 (like a brick layer)

Osteoclasts break down bone from the inside

Figure 8-5 (like a sculptor)

25 of 151

Long Bone Formation and Growth

Slide 5.14a

Figure 5.4a

26 of 151

Bone Fractures

Slide 5.16

A break in a bone
Types of bone fractures

Closed (simple) fracture – break that does not penetrate the skin
Open (compound) fracture – broken bone penetrates through the skin

Bone fractures are treated by reduction and immobilization

Realignment of the bone

27 of 151

Common Types of Fractures

Slide 5.17

Table 5.2

28 of 151

Handout #1

Injuries to bones

29 of 151

Dislocation of joint

Displacement of bones at the joint

Often caused by impact trauma to that joint

Can be more damaging and painful than a fracture

Damage to the joint capsule and surrounding ligaments and tendons often takes much longer to heal than bone tissue.

30 of 151

Dislocated Finger

31 of 151

In Groups of 4

Locate the fracture/dislocation
Identify the type of fracture

32 of 151

Repair of Bone Fractures

Slide 5.18

Hematoma (blood-filled swelling) is formed
Break is splinted by fibrocartilage to form a soft callus

Blood vessels grow into the hematoma

Fibrocartilage callus is replaced by a bony callus
Bony callus is remodeled to form a permanent patch

33 of 151

Stages in the Healing of a Bone Fracture

Slide 5.19

Figure 5.5

34 of 151

Skeletal System

Divided into two divisions

Axial skeleton ~ bones of the cranium, face, vertebral column, and bony thorax.
Appendicular skeleton ~ includes the bones of the pelvic girdles, the upper extremities and lower extremities.

35 of 151

36 of 151

The Axial Skeleton

Slide 5.20a

Forms the longitudinal part of the body
Divided into three parts

Skull
Vertebral column
Bony thorax

37 of 151

The Axial Skeleton

Slide 5.20b

Figure 5.6

38 of 151

The Skull (28 bones) (18 names!)

Slide 5.21a

Sits on top of the vertebral column
Two sets of bones

Cranium (8 bones)
Facial bones (14 bones)

Bones are joined by sutures
Only the mandible is attached by a freely movable joint

39 of 151

The Cranium

Bony structure that encases and protects the brain.
8 bones

Frontal Bone ~ forehead/upper part of the bony structure surrounding the eyes.

40 of 151

The Skull

Slide 5.21b

Figure 5.7

41 of 151

Bones of the Skull

Slide 5.22

Figure 5.11

42 of 151

Human Skull, Superior View

Slide 5.23

Figure 5.8

43 of 151

Human Skull, Inferior View

Slide 5.24

Figure 5.9

44 of 151

The Cranium

Parietal Bone (2) ~ upper sides of the head and the roof of the cranial cavity (top of the head)

45 of 151

The Skull

Slide 5.21b

Figure 5.7

46 of 151

Bones of the Skull

Slide 5.22

Figure 5.11

47 of 151

Human Skull, Superior View

Slide 5.23

Figure 5.8

48 of 151

The Cranium

Temporal Bones (2) ~ sides of the head, close to ears.

Commonly called the temples
Includes the external auditory meatus

Opening for the ear

Includes the zygomatic process

Part of the cheekbone

49 of 151

The Skull (lateral view)

50 of 151

The Skull

51 of 151

The Skull (superior view)

52 of 151

The Cranium

Occipital Bone ~ back and base of the cranium

Includes the foramen magnum

Foramen means hole
Large hole for the brainstem/spinal cord

53 of 151

The Skull (lateral view)

54 of 151

The Skull

55 of 151

The Skull (superior view)

56 of 151

The Cranium

Sphenoid Bone ~ forms sides of cranium and parts of orbits of the eyes
Butterfly shaped

Includes Sella Turcica (Turk’s Saddle)

Where pituitary gland sits

57 of 151

The Skull (lateral view)

58 of 151

The Skull

59 of 151

The Skull (superior view)

60 of 151

The Cranium

Ethmoid Bone ~ irregularly shaped bone located between the eye orbits

Major supporting bone of the nasal cavity

61 of 151

The Skull (lateral view)

62 of 151

The Skull

63 of 151

The Skull (superior view)

64 of 151

The Cranium

That’s it! No more cranium bones!

206 bones - 8 bones = 198 bones to go…

65 of 151

Facial Bones

14 bones
Most of these bones come in pairs
Only the mandible and vomer are single bones

66 of 151

Facial Bones

Mandible ~ the lower jaw bone

Carries the lower teeth
The anterior portion forms the chin
Only freely movable joint in the skull

67 of 151

The Skull (lateral view)

68 of 151

The Skull

69 of 151

The Skull (superior view)

70 of 151

Facial Bones

Maxilla (2) ~ Upper jaw

Two bones fused together
Roof of the mouth
Also form parts of the nasal cavity and eye orbits

71 of 151

The Skull (lateral view)

72 of 151

The Skull

73 of 151

The Skull (superior view)

74 of 151

Facial Bones

Palantine Bones (2) ~ form the posterior part of the hard palate and the floor of the nasal cavity.

Failure of the palatine and/or maxillary bones to fuse causes a cleft palate.

75 of 151

76 of 151

The Skull (lateral view)

77 of 151

The Skull

78 of 151

The Skull (superior view)

79 of 151

The Facial Bones

Zygomatic Bones (2) ~ the cheekbones

Also forms a part of the orbits of the eyes

80 of 151

The Skull (lateral view)

81 of 151

The Skull

82 of 151

The Skull (superior view)

83 of 151

Facial Bones

Other Facial Bones

Lacrimal Bones (2) ~ inner wall of eye sockets
Nasal Bones (2) ~ bridge of nose
Vomer ~ nasal septum
Inferior Nasal Conchae (2)

84 of 151

The Skull (lateral view)

85 of 151

The Skull

86 of 151

The Skull (superior view)

87 of 151

Facial Bones

That’s it! No more facial bones!

198 bones - 14 bones = 184 bones to go…

88 of 151

Paranasal Sinuses

Slide 5.25b

Functions of paranasal sinuses
Air filled cavities

Lighten the skull
Give resonance and amplification to voice

Figure 5.10

89 of 151

The Fetal Skull

Slide 5.27a

The fetal skull is large compared to the infants total body length

Figure 5.13

90 of 151

The Fetal Skull

Slide 5.27b

Fontanelles – fibrous membranes connecting the cranial bones

Allow the brain �to grow
Convert to bone within 24 months after birth

Figure 5.13

91 of 151

The Hyoid Bone

Slide 5.26

U shaped
Found in the upper neck
The only bone that does not articulate with another bone
Serves as a moveable base for the tongue

Figure 5.12

92 of 151

Hyoid Bone

93 of 151

Middle Ear

3 Tiny bones ~ transmit vibrations
All derived from Latin words
Malleus (hammer)
Incus (anvil)
Stapes (stirrup)

Smallest bone in the body

94 of 151

Middle Ear and Hyoid Bones

That’s it!

184 bones - 4 bones = 180 bones to go…

95 of 151

The Vertebral Column

The backbone or spine
Consists of 26 bones called vertebrae

96 of 151

The Vertebral Column

Slide 5.28

Vertebrae separated by intervertebral discs (act as shock absorbers)
The spine has a normal curvature
Each vertebrae is given a name according to its location

Figure 5.14

97 of 151

Vertebral column

C1-C7 ~ in the neck region

7 cervical vertebrae

T1-T12 ~ located in the chest region

12 thoracic vertebrae

L1-L5 ~ located in the lower back

5 lumbar vertebrae

98 of 151

Vertebral column

Sacrum ~ curved bone of the lower back (posterior wall of the pelvis)
fused sacral vertebrae

5 vertebrae at birth

Coccyx ~ the tailbone

4 vertebrae at birth

99 of 151

Vertebral Column

The vertebrae become larger as the vertebral column descends…..WHY?
Vertebral foramen ~ opening for spinal cord.
What is the opening for the spinal cord in the skull called?

100 of 151

Vertebral Column

180 bones - 26 vertebral column bones = 154 bones to go!

101 of 151

The Bony Thorax (Thoracic Cage)

Slide 5.31a

The chest region
Forms a cage to protect major organs
Composed of sternum, ribs and thoracic vertebrae.

Figure 5.19a

102 of 151

Thoracic Cage

Sternum ~ breastbone.
Dagger-shaped bone located along the midline of the anterior chest.

103 of 151

Thoracic Cage

Ribs ~ 12 pairs of ribs attach posteriorly to the thoracic vertebrae
True ribs ~ first 7 pair
False ribs ~ last 5 pairs

104 of 151

That is it for the axial skeleton!

154 bones - 24 ribs -1 sternum = 129 bones to go!!!

105 of 151

The Appendicular Skeleton

Slide 5.32a

Limbs (appendages)
Pectoral (shoulder) girdle
Pelvic girdle

106 of 151

The Appendicular Skeleton

Slide 5.32b

Figure 5.6c

107 of 151

The Pectoral (Shoulder) Girdle

Slide 5.33

Composed of two bones

Clavicle – collarbone
Scapula – shoulder blade

These bones allow the upper limb to have exceptionally free movement

108 of 151

Bones of the Shoulder Girdle

Slide 5.34a

Figure 5.20a, b

109 of 151

Bones of the Upper Limb

Slide 5.35a

The arm is formed by a single bone

Humerus
Head of humerus allows for rotation

Figure 5.21a, b

110 of 151

Bones of the Upper Limb

Slide 5.35b

The forearm has two bones

Ulna
Radius

Figure 5.21c

111 of 151

Radius

Radius ~ locate on the lateral or thumb side when the palm of the hand is facing forward.

112 of 151

Ulna

Ulna~ the longer of the two forearm bones.
Located on the medial or little finger side of the forearm.

113 of 151

Bones of the Upper Limb

Slide 5.36

The hand

Carpals – wrist
Metacarpals – palm
Phalanges – fingers

Figure 5.22

114 of 151

Bones of the Pelvic Girdle

Slide 5.37

Composed of two coxal bones (hip bones)

Composed of three pair of fused bones

Ilium
Ischium
Pubis

The total weight of the upper body rests on the pelvis
Protects several organs

Reproductive organs
Urinary bladder
Part of the large intestine

115 of 151

The Pelvis

Slide 5.38a

Figure 5.23a

116 of 151

Gender Differences of the Pelvis

Slide 5.39

Figure 5.23c

117 of 151

Bones of the Lower Limbs

Slide 5.40a

The thigh has one bone

Femur – thigh bone

Figure 5.35a, b

118 of 151

Bones of the Lower Limb

Patella ~ knee cap
Triangular bone located within a tendon that passes over the knee.

119 of 151

Bones of the Lower Limbs

Slide 5.40b

The leg has two bones

Tibia ~ shin bone

larger

Fibula

Long and thin

Figure 5.35c

120 of 151

Bones of the Lower Limbs

Slide 5.41

The foot

Tarsal (7)– ankle
Metatarsals (5)– sole/instep
Phalanges (14) – toes

Figure 5.25

121 of 151

122 of 151

123 of 151

124 of 151

125 of 151

126 of 151

127 of 151

Joints

Slide 5.43

Articulations of bones
Functions of joints

Hold bones together
Provide flexibility

Ways joints are classified

By their function
By their structure

128 of 151

Functional Classification of Joints

Slide 5.44

Synarthroses – immovable joints
Amphiarthroses – slightly moveable joints
Diarthroses – freely moveable joints

129 of 151

Structural Classification of Joints

Slide 5.45

Fibrous joints

Generally immovable

Cartilaginous joints

Immovable or slightly moveable

Synovial joints

Freely moveable

130 of 151

Fibrous Joints

Slide 5.46

Bones united by fibrous tissue – synarthrosis or largely immovable.

Figure 5.27d, e

131 of 151

Cartilaginous Joints – mostly amphiarthrosis

Slide 5.47

Bones connected by cartilage
Examples

Pubic �symphysis
Intervertebral �joints

Figure 5.27b, c

132 of 151

Synovial Joints

Slide 5.48

Articulating bones are separated by a joint cavity
Synovial fluid is found in the joint cavity
Reinforced by ligaments

Figure 5.27f–h

133 of 151

The Synovial Joint

Slide 5.51

Figure 5.28

134 of 151

6 Types of Synovial Joints

Hinge joint

Movement is like two boards joined together by a hinge
Movement in one direction
Elbow, knees, fingers

135 of 151

136 of 151

137 of 151

Types of Synovial Joints

Ball and Socket Joint

When ball-shaped end of one bone fits into the cup-shaped socket of another
Bones can move in many directions
Shoulder, hip

138 of 151

139 of 151

140 of 151

Types of Synovial Joints

Pivot Joint

Allows for rotation around the length of a bone.
Allows only for rotation
Head (side to side “no” action)
Forearm joints (palms) supination/pronation

141 of 151

Types of Synovial Joints

Saddle Joint

When the surfaces of both articulation bones are saddle-shaped

Concave/convex

Thumb
Wide range of motion

142 of 151

Types of Synovial Joints

Gliding Joint

Interaction of flat surfaces of articulating bones
Limited but complex movement
Wrist, ankle

143 of 151

144 of 151

145 of 151

Types of Synovial Joints

Condyloid Joint

Oval-shaped articular surface of one bone fits into the oval-shaped depression of another
Mandible, knuckles

146 of 151

Inflammatory Conditions Associated with Joints

Slide 5.53

Bursitis – inflammation of a bursa usually caused by a blow or friction
Tendonitis – inflammation of tendon sheaths
Arthritis – inflammatory or degenerative diseases of joints

Over 100 different types
The most widespread crippling disease in the United States

147 of 151

Clinical Forms of Arthritis

Slide 5.54a

Osteoarthritis

Most common chronic arthritis
Probably related to normal aging processes

Rheumatoid arthritis

An autoimmune disease – the immune system attacks the joints
Symptoms begin with bilateral inflammation of certain joints
Often leads to deformities

148 of 151

149 of 151

150 of 151

Clinical Forms of Arthritis

Slide 5.54b

Gouty Arthritis

Inflammation of joints is caused by a deposition of urate crystals from the blood
Can usually be controlled with diet

Red meat and wine are high in uric acid