THE SKELETAL SYSTEMCHAPTERS 6 & 7

The Skeletal System

• Parts of the skeletal system– Bones (skeleton)– Joints– Cartilages– Ligaments

• Divided into two divisions– Axial skeleton– Appendicular skeleton

Bones of the Human Body

• The adult skeleton has 206 bones

• Two basic types of bone tissue– Compact bone

• Homogeneous

– Spongy bone• Small needle-like

pieces of bone• Many open spaces

Figure 5.2b

Acro- -clast Lambd- -physis

Arthro- Chondr- Lumb- Semi-

Cap- Costa- Meta- Sterno-

-blast Crist- Os-, Osteo- Sym-

Cervic- Ethm- Peri- Synovi(o)-

Functions of Bones

• Support of the body

• Protection of soft organs

• Movement due to attached skeletal muscles

• Storage of minerals

• Blood cell formation

• Storage of fats

Classification of Bones on the Basis of Shape – pg 70 SG

Figure 5.1

Classification of Bones

• Long bones– Typically longer than wide– Have a shaft with heads at both ends– Contain mostly compact bone

• Examples: Femur, Humerus

Classification of Bones

• Short bones– Generally cube-shape– Contain mostly spongy bone

• Examples: Carpals, tarsals

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

Classification of Bones

• Irregular bones– Irregular shape– Do not fit into other

bone classification categories

• Example: Vertebrae and hip

Gross Anatomy of the typical long bone – pg 72 of SG

• Epiphysis• Diaphysis• Articular cartilage• Epiphyseal line• Spongy bone• Compact bone• Medullary cavity • Periosteum

Components

• Mature bone cells are Osteocytes

Microscopic Structure of Bone

• Haversian canal• Lacunae• Osteocytes• Lamellae• Canaliculi• Volkmann’s

canals• Matrix • Pg. text, 176• #A5 SG

Bone Markings

• Surface features of bones

• Sites of attachments for muscles, tendons, and ligaments

• Passages for nerves and blood vessels

• Categories of bone markings– Projections and processes – grow out from

the bone surface– Depressions or cavities – indentations

Bone MarkingsProjections/sites of muscle and ligament attachment

• Tuberosity • Crest• Trochanter• Line• Tubercle• Epicondyle• Spine• Process

Projections/sites that form joints

• Head• Facet• Condyle• Ramus

More Bone Markings

Cavities

• Sinus

Depressions/Openings

allow blood vessels and nerves to pass

• Meatus• Fossa• Groove• Fissure• Foramen

Table 7.2 pg 198

• Head – rounded articular process at the proximal end of a bone

• Condyle – rounded articular process at the distal end of a bone

• Epicondyle – a small raised area above a condyle for joint capsule attachment

• Foramen – a short passageway through bone for vessels and nerves

• Meatus – a long canal like passageway

• Fossa – a depression in bone

•  Sinus – a cavity in bone lined by a mucous membrane

• Trochanter – very large projection•  Tuberosity – a large rounded projection for

muscle attachment• Tubercle – a small rounded projection• Fissure – a slit like opening through bone• Facet – smooth flat articular surface

• Crest – prominent ridge or elongated projection

• Sulcus – furrow along a bone surface where a blood vessel, nerve or tendon is located

• Spine – sharp, slender often pointed projection

• Using an Anatomy Atlas, see if you can identify bone surface markings on the skeleton and unarticulated bones at the front of the room

Axial skeleton Appendicular skeleton

Pg 73 SG

• Color – Axial Skeleton– Appendicular

Skeleton

– With a key

• The Axial Skeleton

• Forms the longitudinal part of the body

• Divided into three parts– Skull– Vertebral column– Bony thorax

The Skull

• Text pg. 199 – 204

• Color each of the bones of the skull

• The Skull

• Two sets of bones– Cranium– Facial bones

• Bones are joined by sutures

• Only the mandible is attached by a freely movable joint

• Paranasal sinuses • Text pg. 211• Paranasal sinuses

The Vertebral Column

• Text pg. 213

• Each vertebrae is given a name according to its location

• Spinal abnormalities

– Lordosis– Kyphosis– Scoliosis

Text pg. 226

Function determines Stucture

Structure of a Typical Vertebrae

Figure 5.16

Regional Characteristics

Figure 5.17a–b

Regional Characteristics

Figure 5.17c–d

The Vertebrae

• Text pg. 217

• text pg.219

• Bony thorax– Rib cage

• Text pg. 223

• Forms a

cage to protect

organs

• Made up of 3 parts– Sternum– Ribs– Thoracic vertebrae

The Appendicular Skeleton

• Pectoral girdle • Text pg. 232

• Clavicle and Scapula

• The Pectoral (Shoulder) Girdle

• Composed of two bones– Clavicle – collarbone– Scapula – shoulder blade

• These bones allow the upper limb to have exceptionally free movement

Bones of the Shoulder Girdle

Figure 5.20c–d

• Upper limb– Text

• Pg235

• Wrist and hand– Text pg 239

Bones of the Pelvic Girdle

• Hip bones• Composed of three pair of fused bones

– Ilium– Ischium– Pubic bone

• The total weight of the upper body rests on thepelvis

• Protects several organs– Reproductive organs– Urinary bladder– Part of the large intestine

• Pelvic girdle– Text pg

240

Gender Differences

Figure 5.23c

• Lower limb– Text pg

245

• Bones of the feet– Text pg 250, 251

• Fractures text pg. 185

Bone Fractures

• 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

Common Types of Fractures

Compound fracture

Repair of Bone Fractures

• Hematoma (blood-filled swelling) is formed

• Break is splinted by fibrocartilage to form a callus

• Fibrocartilage callus is replaced by a bony callus

• Bony callus is remodeled to form a permanent patch

Stages in the Healing of a Bone Fracture

Figure 5.5

Diseases of the Skeletal System

Changes at around 60 years of age

• Bones become porous

• Haversian canals and canaliculi become plugged

• Osteons– Incompletely

mineralized– Hypermineralized– Hypomineralized

• Number of empty lacunae increases

• Blood vessels inside bones are sclerotic

• Microinfractions in areas of strain or over-use

• Osteoblasts and Osteoclasts no longer in balance

Diseases/Disorders

• Osteoporosis

• Osteogenic sarcoma

• Osteomalacia

• Osteomyelitis

• Osteopenia

• Osteoporosis– Decreased bone mass– Increased fractures– Loss of Estrogen

decreased Osteoblasts

• Osteomalacia– “soft” bones due to

inadequate calcification

• Osteogenic sarcoma– Malignant bone tumor

• Osteopenia– Decreased bone mass

• Osteomyelitis – Bone infection