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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