n Chapter 5

Slide 5.1

The Skeletal System

n Parts of the skeletal system

§ Bones (skeleton)

§ Joints

§ Cartilages

§ Ligaments

n Divided into two divisions

§ Axial skeleton

§ Appendicular skeleton

Slide 5.2

Functions of Bones

n Support of the body

n Protection of soft organs

n Movement due to attached skeletal muscles

n Storage of minerals and fats

n Blood cell formation

Slide 5.3

Bones of the Human Body

n The skeleton has 206 bones

n Two basic types of bone tissue

§ Compact bone

§ Homogeneous

n Spongy bone

§ Small needle-like pieces of bone

§ Many open spaces

(insert Fig. 5.2 (b) – remove “Articular cartilage” and leader)

Slide 5.4

Classification of Bones

n Long bones

§ Typically longer than wide

§ Have a shaft with heads at both ends

§ Contain mostly compact bone

§ Femur, humerus

n Short bones

§ Generally cube-shaped

§ Contain mostly spongy bone

§ Carpals, tarsals

(insert Fig. 5.1 – remove part (c) and (d) and their leader arrows)

Slide 5.5

Classification of Bones

n Flat bones

§ Thin and flattened

§ Usually curved

§ Thin layers of compact bone around a layer of spongy bone

§ Skull, ribs, sternum

n Irregular bones

§ Irregular shaped

§ Do not fit into other bone classification categories

§ Vertebrae and hip

(insert Fig. 5.1 – remove part (a) and (b) and their leader arrows)

Slide 5.6

Gross Anatomy of a Long Bone

n Diaphysis

§ Shaft

§ Composed of compact bone

n Epiphysis

§ Ends of the bone

§ Composed mostly of spongy bone

(insert Fig. 5.2(a) – remove box for expansion to(b) and (c) and their leader arrows)

Slide 5.7

Structures of a Long Bone

n Periosteum

§ Outside covering of the diaphysis

§ Fibrous connective tissue membrane

n Sharpey’s fibers

§ Secure periosteum to underlying bone

n Arteries

§ Supply bone cells with nutrients

(insert Fig. 5.2(c))

Slide 5.8

Structures of a Long Bone

n Articular cartilage

§ Covers the external surface of the epiphyses

§ Made of hyaline cartilage

§ Decreases friction at joint surfaces

n Medullary cavity

§ Cavity of the shaft

§ Contains yellow marrow (mostly fat) in adults

§ Contains red marrow (for blood cell formation) in infants

(insert Fig. 5.2(a) – remove box for expansion to (c))

Slide 5.9

Bone Markings

n Surface features of bones

n Sites of attachments for muscles, tendons, and ligaments

n Passages for nerves and blood vessels

n Categories of bone markings

§ Projections and processes – grow out from the bone surface

§ Depressions or cavities – indentations

Slide 5.10

Microscopic Anatomy of Bone

n Osteon (Haversian System)

§ A unit of bone

n Central (Haversian) canal

§ Opening in the center of an osteon

§ Carries blood vessels and nerves

n Perforating (Volkman’s) canal

§ Canal perpendicular to the central canal

§ Carries blood vessels and nerves

(insert Fig. 5.3)

Slide 5.11

Microscopic Anatomy of Bone

n Lacunae

§ Cavities containing bone cells (osteocytes)

§ Arranged in concentric rings

n Lamellae

§ Rings around the central canal

§ Sites of lacunae

n Canaliculi

§ Tiny canals

§ Radiate from the central canal to lacunae

§ Form a transport system

(insert Fig. 5.3 – upper right part of figure only)

Slide 5.12

Changes in the Human Skeleton

n Embryos – the skeleton is primarily hyaline cartilage

n During development, much of this cartilage is replaced by bone

n Cartilage remains in isolated areas

§ Bridge of the nose

§ Parts of ribs

§ Joints

Slide 5.13

Bone Growth

n 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

n Bones are remodeled and lengthened until growth stops

§ Bones change shape somewhat

§ Bones grow in width

Slide 5.14

Long Bone Formation and Growth

(insert Fig. 5.4 (a) and (b))

Slide 5.15

Types of Bone Cells

n Osteocytes

§ Mature bone cells

n Osteoblasts

§ Bone forming cells

n Osteoclasts

§ Bone destroying cells

§ Break down bone matrix for remodeling and release of calcium

n Bone remodeling is a process by both osteoblasts and osteoclasts

Slide 5.16

Bone Fractures

n A break in a bone

n Types of bone fractures

§ Closed (simple) fracture – break that does not penetrate the skin

§ Open (compound) fracture – broken bone penetrates through the skin

n Bone fractures are treated by reduction

§ Realignment of the bone

Slide 5.17

Common Types of Fractures

(insert Table 5.2)

Slide 5.18

Repair of Bone Fractures

n Hematoma (blood filled swelling) is formed

n Break is splinted by fibrocartilage to form a callus

n Fibrocartilage callus is replaced by a bony callus

n Bony callus is remodeled to form a permanent patch

Slide 5.19

Stages in the Healing of a Bone Fracture

(insert Fig. 5.5)

Slide 5.20

The Axial Skeleton

n Forms the longitudinal part of the body

n Divided into three parts

§ Skull

§ Vertebral column

§ Bony thorax

(insert Fig. 5.6)

Slide 5.21

The Skull

n Two sets of bones

§ Cranium

§ Facial bones

n Bones are joined by sutures

n Only the mandible is attached by a freely movable joint

(insert Fig. 5.7)

Slide 5.22

Bones of the Skull

n (Insert Fig. 5.11)

Slide 5.23

Human Skull, Superior View

(insert Fig. 5.8)

Slide 5.24

Human Skull, Inferior view

(insert Fig. 5.9)

Slide 5.25

Paranasal Sinuses

n Hollow portions of bones surrounding the nasal cavity

n Functions of paranasal sinuses

§ Lighten the skull

§ Give resonance and amplification to voice

(insert Fig. 5.10)

Slide 5.26

The Hyoid Bone

n The only bone that does not articulate with another bone

n Serves as a moveable base for the tongue

(insert Fig. 5.12)

Slide 5.27

The Fetal Skull

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

n Fontanelles – fibrous membranes connecting the cranial bones

§ Allow the brain to grow

§ Convert to bone within 24 months after birth

(insert Fig. 5.13)

Slide 5.28

The Vertebral Column

n Vertebrae separated by intervertebral discs

n The spine has a normal curvature

n Each vertebrae is given a name according to its location

(insert Fig. 5.14)

Slide 5.29

Structure of a Typical Vertebrae

(insert Fig. 5.16)

Slide 5.30

Regional Characteristics of Vertebrae

(insert Fig. 5.17)

Slide 5.31

The Bony Thorax

n Forms a protective cage to protect major organs

n Made-up of three parts

§ Sternum

§ Ribs

§ Thoracic vertebrae

(insert Fig. 5.19 (a))

Slide 5.32

The Appendicular Skeleton

n Limbs (appendages)

n Pectoral girdle

n Pelvic girdle

(insert Fig. 5.6)

Slide 5.33

The pectoral (shoulder) girdle

n Composed of two bones

§ Clavicle or collarbone

§ Scapula or shoulder blade

n These bones allow the upper limb to have exceptionally free movment

Slide 5.34

(insert Fig. 5.20)

Slide 5.35

Bones of the Upper Limb

n The arm is formed by a single bone

§ Humerus

n The forearm has two bones

§ Ulna

§ Radius

(insert Fig. 5.21)

Slide 5.36

Bones of the Upper Limb

n The hand

§ Carpals – wrist

§ Metacarpals – palm

§ Phalanges – fingers

(insert Fig. 5.22)

Slide 5.37

Bones of the Pelvic Girdle

n Hip bones

n Composed of three pair of fused bones

§ Ilium

§ Ischium

§ Pubic bone

n The total weight of the upper body rests on the pelvis

n Protects several organs

§ Reproductive organs

§ Urinary bladder

§ Part of the large intestine

Slide 5.38

The Pelvis

(insert Fig. 5.23(a) and (b))

Slide 5.39

Gender Differences of the Pelvis

(insert Fig. 5.23 (c))

Slide 5.40

Bones of the Lower Limbs

n The thigh has one bone

§ Femur – thigh bone

n The leg has two bones

§ Tibia

§ Fibula

(insert Fig. 5.24)

Slide 5.41

Bones of the Lower Limbs

n The foot

§ Tarsus – ankle

§ Metatarsals – sole

§ Phalanges – toes

(insert Fig. 5.25)

Slide 5.42

Arches of the Foot

n Bones of the foot are arranged to form three strong arches

§ Two longitudinal

§ One transverse

(insert Fig. 5.26)

Slide 5.43

Joints

n Articulations of bones

n Functions of joints

§ Hold bones together

§ Allow for mobility

n Ways joints are classified

§ Functionally

§ Structurally

Slide 5.44

Functional Classification of Joints

n Synarthroses – immovable joints

n Amphiarthroses – slightly moveable joints

n Diarthroses – freely moveable joints

Slide 5.45

Structural Classification of Joints

n Fibrous joints

§ Generally immovable

n Cartilaginous joints

§ Immovable or slightly moveable

n Synovial joints

§ Freely moveable

Slide 5.46

Fibrous Joints

n Bones united by fibrous tissue

n Examples

§ Sutures

§ Syndesmoses

§ Allows more movement than sutures

§ Example: distal end of tibia and fibula

(insert Fig. 5.27(d) and (e) with skeleton)

Slide 5.47

Cartilaginous Joints

n Bones connected by cartilage

n Examples

§ Pubic symphysis

§ Intervertebral joints

(insert Fig. 5.27(b) and (c) with skeleton)

Slide 5.48

Synovial Joints

n Articulating bones are separated by a joint cavity

n Synovial fluid is found in the joint cavity

(insert Fig. 5.27(f), (g) and (h) with skeleton)

Slide 5.49

Features of Synovial Joints

n Articular cartilage (hyaline cartilage) covers the ends of bones

n Joint surfaces are enclosed by a fibrous articular capsule

n Have a joint cavity filled with synovial fluid

n Ligaments reinforce the joint

Slide 5.50

Structures Associated with the Synovial Joint

n Bursae – flattened fibrous sacs

§ Lined with synovial membranes

§ Filled with synovial fluid

§ Not actually part of the joint

n Tendon sheath

§ Elongated bursa that wraps around a tendon

Slide 5.49

The Synovial Joint

(insert Fig. 5.28)

Slide 5.50

Types of Synovial Joints Based on Shape

(insert Fig. 5.29)

Slide 5.51

Inflammatory Conditions Associated with Joints

n Bursitis – inflammation of a bursa usually caused by a blow or friction

n Tendonitis – inflammation of tendon sheaths

n Arthritis – inflammatory or degenerative diseases of joints

§ Over 100 different types

§ The most widespread crippling disease in the United States

Slide 5.52

Clinical Forms of Arthritis

n Osteoarthritis

§ Most common chronic arthritis

§ Probably related to normal aging processes

n Rheumatoid arthritis

§ An autoimmune disease – the immune system attacks the joints

§ Symptoms begin with bilateral inflammation of certain joints

§ Often leads to deformities

n Gouty Arthritis

§ Inflammation of joints is caused by a deposition of urate crystals from the blood

§ Can usually be controlled with diet

Slide 5.53

Developmental Aspects of the Skeletal System

n At birth, the skull bones are incomplete

n Bones are joined by fibrous membranes = fontanelles

n Fontanelles are completely replaced with bone within 2 years after birth