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Human Movement Systems:
Skeletal System
Objectives
• After this presentation, the participant will be able to explain the basic structure and function of:
– Skeletal System Organization
– Types of bones
– Bone remodeling
– Joints (including stability vs. mobility)
– Connective Tissue
– Role of Exercise
The Skeletal System
Provides:
– Structure
– Protection of vital organs
– Levers for movement
– Storage for mineral
Bones form junctions that
are connected by
muscles and connective
tissue known as joints. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Vertebral Column
Series of irregularly shaped
bones called vertebrae.
Houses the spinal cord.
– Cervical spine has 7 (concave curve) vertebrae.
– Thoracic spine has 12 (convex curve).
– Lumbar spine has 5 (concave curve).
– Sacrum is fused triangle attached to pelvis.
– Coccyx is tail bone.
Divisions of the Skeletal System
Axial skeleton:
• Skull
• Rib cage
• Vertebral column
Appendicular skeleton:
• Upper and lower extremities
• Shoulder and pelvic girdles
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Types of Bones
Long bones: Long
cylindrical shaft and irregular
or widened ends
Epiphysis: End of long bone
Diaphysis: Shaft of long bone;
Epiphyseal plate: growth plate
Periosteum: Hard membrane
Medullary cavity: marrow
Articular cartilage: Covers
articular surfaces of bones
Types of bone tissue
Types of bone tissue:
Compact Bone (a.k.a.
cortical bone)
– Dense bone found primarily in
shaft of long bones.
Cancellous Bone (a.k.a.
spongy or trabecular bone)
– Found at end of long bones and
in irregularly shaped bones.
– Less dense, more flexible
– Prone to effects of osteoporosis
– Site of red blood cell production
•
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Irregular bones:
• Unique shape
and function
Copyright © 2012 Wolters Kluwer
Health | Lippincott Williams & Wilkins
Types of bones
Copyright © 2012 Wolters Kluwer
Health | Lippincott Williams & Wilkins
Flat bones:
• Thin, protective
Short bones:
• Similar in length and
width and appear
somewhat cubical in
shape
Copyright © 2012 Wolters Kluwer Health | Lippincott
Williams & Wilkins
Bone Markings
Depressions:
• Flattened or
indented portions
of the bone
• Common
depressions:
• Fossa
• Sulcus
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Processes:
• Projections protruding from the bone to which muscles, tendons, and ligaments attach
• Common processes:
• Condyle
• Epicondyle
• Tubercle
• Trochanter
Bone Growth & Remodeling
Bones under go remodeling throughout life cycle:
Osteoblasts build up new bone tissue.
Osteoclasts chew up old bone tissue.
Remodeling is the constant process building up and
breaking down of these cells.
In children, osteoblasts are more active; as we age,
osteoclasts become more active.
Bone Growth & Remodeling
Wolff’s Law: Bone will adapt to the loads under which it is
placed.
– Sensitive to direction and amount of force.
Importance of weight bearing exercise:
– Exercise that forces the body to work against gravity appear to
stimulate bone growth the best:
– Running, lifting weights, calisthenics are weight bearing
– Swimming and cycling are not, so less bone stimulation than land
training.
Kyphosis of the upper back
due to osteoporotic
fractures of the thoracic
vertebrae.
Dowager’s Hump
Osteoporosis Fracture
Aging and Bone Density
Race:
Caucasian
Asian
Diet:
Low Calcium Low Vitamin D
Medication:
Corticosteroids
Size:
Small Frame
Low weight
Hormones
Menopause
Premature menopause
Amenorrhea
Hyperthyroidism Low testosterone in men
Advanced Age
Smoking
Inactivity
Alcohol & Caffeine
Osteoporosis
Low Bone Density Risk Factors
Joints
One bone that articulates with another bone.
Joint motion is referred to as arthrokinematics.
Typical joint motions seen in the human articular system include:
• Roll: Rolling on joint surface on another such as femoral condyles rolling over the tibial condyles during a squat
• Slide: Sliding of a joint surface across another such as tibial condyles moving (sliding) across the femoral condyles during a knee extension
• Spin: Rotation of one joint surface on another such as head of the radius rotating on the end of the humerus during pronation and supination of the forearm
Classifications of Joints
Synovial joints:
– Produce synovial fluid
– Have a joint cavity and fibrous connective tissue
– Example: Knee
Non-synovial joints:
– No joint cavity and fibrous connective tissue
– Little or no movement
– Example: Sutures of the skull
16
Connective Tissue anatomy
Connective tissue —serves to connect, support, and anchor various body parts. Characterized by poor vascularity and do not repair or adapt as easily as other tissues in the body
– Fascia —a sheet or band of fibrous tissue that lies deep to the skin or forms an attachment for muscles and organs
– Tendon —when a muscle contracts to produce movement, it pulls on a tendon, which attaches the muscle to the bone
– Ligaments —supportive structures found at joints that connect bones to other bones
– Cartilage —serves as padding between the bones at a joint and functions to provide cushioning and the smooth gliding of joint movement
Connective Tissue
Davis’s Law - Soft tissue models
along the lines of stress.
– If muscle is in a constant shortened state
(such as when you sit all day), your
connective tissue remodels to adapt to the
shorter length, resulting in:
• Relative flexibility (seeking the path of least
resistance)
• Poor neuromuscular efficiency (altered
length-tension relationship, and force-
couple relationships.
• Synergistic Dominance (muscles other than
prime movers help too much)
Myofascial Release
Myofascial release applies pressure to tight, restricted areas of fascia and
underlying muscle in an attempt to relieve tension and improve flexibility
– It is thought that sustained pressure to a tight area can inhibit tension in a
muscle by stimulating the GTO to bring about autogenic inhibition.
– Trigger points can be diminished through the application of pressure followed by
static stretching of the tight area.
In the fitness setting, a foam roller is used, allowing the exerciser to control
his or her own intensity and duration of pressure.
Summary
Structure & function of the skeletal system
Bone growth and remodeling
Joints
Connective Tissue
Role of Exercise