Skeletal System

Pps: 116-150, 155-157, Review starts on

pg 157S/A: #3, 4, 19, 20,

24, 27At the Clinic: #1, 3,

4, 5

Intro to the skeletal System

School House Rock Video

Components of Skeletal System

• Bones• Joints• Cartilages• Ligaments

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www.orthop.washington.edu

137.222.110.150

www.becomehealthynow.com

Functions of Skeletal System

•Support•Protection•Movement•Storage•Hemopoiesis

Basic Bone Types• Compact—

dense, looks smooth

• Spongy—composed of small, needle like pieces & lots of open space

www.gla.ac.uk

Four Categories of Bones•Long

longer than wide

mostly compact bone

137.222.110.150

adam.about.com

Four Categories of Bones

library.thinkquest.org

Shortcube shaped, contain mostly spongy bone

Four Categories of Bones

avalon.ira.uka.de

•Flatthin, flat, usually curved.

Four Categories of Bones

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•Irregularall the rest.

Bone Markings• Projections (Processes)—grow

out from bone surface; used to form joints or sites for muscle/ligament attachment.

• Depressions—indentations in bone; allow for blood vessels and nerves to pass.

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Long Bone Structure

• Diaphysis (shaft)—makes up most of bone’s length—compact

• Yellow bone marrow—storage of fat (cavity of shaft) in adults

• Periosteum—protective covering of diaphysis

• Epiphysis—end of long bone

Long Bone Structurecon’t:

• Red bone marrow—within long bone shafts in infants, forms RBCs, limited to few locations in adults

• Articular Cartilage—covers epiphyses of long bone

• Epiphyseal plate—flat plate of hyaline cartilage found in young bone; causes lengthwise growth of bone.

• Epiphyseal line—remnant of the epiphyseal plate

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Bone Formation and Growth

Most bones (except flat bones) undergo ossification—

http://embryology.med.unsw.edu.au/notes/images/skmus/endochondralbone600.jpg

Ossification Process

• Hyaline cartilage model of bone is completely covered with bony matrix (laid down by osteoblasts…bone builders)

Next, the enclosed hyaline cartilage will be digested away, opening up the medullary cavity within the newly formed bone.

http://www.cdb.ucl.ac.uk/research/arnett/arnett_lab/images/osteoclast_bfast_lunch_dinner.jpg

(Done by osteoclasts—bone destroyers)

Longitudinal Growth• New cartilage is formed on

external face of the epiphyseal plate farthest away from the medullary cavity

• At the same time, the old cartilage next to the medullary cavity is broken down and replaced by bone—effectively lengthening the bone

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Longitudinal Growth con’t:

• Ossification completed between 18-25 years old.

courses.washington.edu

How do bones widen?

• Osteoblasts in periosteum add bone tissue to outer surface at the same rate that osteoclasts break down bone from inner diaphysis wall.

http://www.web-books.com/eLibrary/Medicine/Physiology/Skeletal/bone_growth.jpg

Broken bones and how they mend…

• http://www.youtube.com/watch?v=U1qLUNXAhAY

• http://www.youtube.com/watch?v=YUK6EghcUdc

• http://www.youtube.com/watch?v=_fjGpMmmycw

Remodeling of bone

• Response to two factors:–Ca levels in blood

–Stress on bones (gravity and muscle action)

Ca levels• When Ca levels in your blood drop

below homeostatic levels, the parathyroid glands release PTH (parathyroid hormone) into blood

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Ca levels• PTH activates the osteoclasts to

break down bone to release Ca into blood

• If Ca levels in blood are high, your thyroid gland releases calcitonin which causes the extra Ca to be deposited into the bone

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Stress on bones• Gravity/Muscles pulling on

bones indicates where the bones must strengthen. This explains why bones grow large projections in areas that are heavily muscled…

Ca and Stress on bones work together…

• PTH determines IF Ca is needed and the effects of gravity/stress on bones determines WHERE the Ca is deposited in bone.

Factors that influence Bone

Growth, Remodeling and Health

MineralsMg deficiency slows osteoclasts and slows bone formation

Insufficient Ca and P are causes of weak bone

Insufficient B—boron aids in Ca absorption in digestive tract…

• Vit C deficiency results in decreased production of collagen = slower bone growth and slower fracture healing

• Vit B12 may play a role in osteoblast activity

Minerals

• Human Growth Hormone (hGH) produced by pituitary gland promotes general bone growth

• Estrogen and Testosterone—promote osteoblast activity

Hormones—(other than PTH and Calcitonin)

• Exercise creates electrical currents that stimulate formation of osteoblasts—especially exercise that puts stress on bones

• Stimulates production of Calcitonin (inhibiting osteoclasts)

• Lack of exercise induces removal of mineral salts and collagen

Exercise

• Smoking reduces estrogen levels thus lowering osteoblasts = greater risk of osteoporosis

• Smoking diminishes circulation which increases the risk of poor bone density

• Smokers tend to not exercise…see previous slide

Smoking

• Loss of Ca is correlated with aging

• Premature abandonment of exercise results in decreased ability to make bone matrix—older people who maintain exercise have stronger bones than same age peers who are sedentary…

Aging

Axial Skeleton

www.besthealth.com

Definition

• longitudinal axis of body.

•Skull, vertebral column, & bony thorax

www.besthealth.com

Bones of the skull

•Cranium—encloses & protects fragile brain tissue–Frontal --Occipital–Parietal --Sphenoid

–Temporal --Ethmoid

2 parts: the cranium and the facial bones

www.mc.maricopa.edu

Cranium

Facial bones•Holds eyes in the anterior portion of head and allows for muscle attachment/expressions–Mandible --Lacrimal–Maxilla --Nasal–Palatine --Vomer–Zygomatic

Facial Bones

training.seer.cancer.gov

Facial Bones con’t:

www.bartelby.net

Hyoid

•only bone in human body that doesn’t articulate with another bone.

bioweb.uwlax.edu

courses.washington.edu

Fetal SkullLarge compared to body size

(about ¼ of body, in adults 1/8)

fontenels—soft spots, allow for depression during birth and brain growth.

ossification between 22 – 24 months

Vertebral ColumnSupports skull and extends to

pelvis• flexible, curved structure of 26

irregular bones (33 at infancy)• spinal cord runs through the

center• Intervertebral discs—flexible

fibrocartilage to cushion and protect.

Vertebral Column

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Five types of vertebrae

Cervical (7)

Thoracic (12)

biology.kenyon.edu

www.biologydaily.com

Five types of vertebrae

Lumbar (5)

www.sandiego-spine.com

Five types of vertebrae

www.gla.ac.uk

Sacrum (5 fused)

Coccyx (3 – 5 fused)

VetebraeAnatomy

• Body—weight bearing part facing anteriorly

• vertebral foramen—canal for spinal cord

• transverse process—2 lateral projections

• spinous process—single projection from posterior aspects of vertebral arch

• superior/inferior articular processes—form joints with adjacent vertebrae

Vertebrae Anatomy con’t:

www.ispub.com

Bony Thorax

•Made up of the sternum and the ribs

academic.kellogg.cc.mi.us

Sternum

•Manubrium•Body•xiphoid process

www.yorku.ca

Ribs• 12 pairs, male and

female• true ribs (7) attach

directly to sternum• false ribs (5) attach

indirectly to sternum (or not at all)

• floating ribs (last 2)—lack sternal attachments

• intercostal spaces—spaces between ribs, aid in breathing www.mnsu.edu

Appendicular Skeleton

www.besthealth.com

Definition/Function

•Attach limbs to the axial skeleton

www.besthealth.com

Pectoral GirdleClavicle• slender, doubly curved bone• attaches to

manubrium medially and to the scapula laterally.

www.dccc.edu

Pectoral Girdle Scapula• Spine• Acromion

processenlarged end of the

spine

• Coracoid processpoints over the top

of shoulderanchors some arm

muscles

• Glenoid cavity—shallow socket that receives head of humerus.

www.artem-medicalis.com

Bones of Upper Appendage

biology.kenyon.edu

mywebpages.comcast.net

Bones of Upper Appendage•Humerus

• greater and lesser tubercles—muscle attachment, found opposite the head.

• deltoid tuberosity—midpoint of shaft, attachment point of deltoid muscle.

• trochlea—articulates with bones of forearm, “spool”.

• capitulum—“ball like”, articulates with bones of forearm.

biology.kenyon.edu

Bones of Upper Appendage

•Radiuslateral bone in anatomical positionradial tuberosity—just below the

head of radius, attachment point of biceps.

headneckstyloid process

Radius

http://king.victoriacollege.edu/dept/bio/Pig/HumanSkeleton/webpages/radius.html

Bones of Upper Appendage

Ulna•medial bone in anatomical

position•coronoid process•olecranon process—forms elbow•Trochlear notch—articulates

with humerus

Ulna

http://a-s.clayton.edu/biology/biol3650l/skeletal/human_skeleton.htm

Bones of Upper

AppendageCarpals• wrist bones• 2 rows of 4 bones each

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phalanges—14 in each hand, 3 in each finger (except thumb)

metacarpalsnumbered 1 – 5 starting with thumb, form palm

Hand bones

Pelvic GirdleCoxal—hip bones• bearing weight is most important function• protection of repro. organs, bladder and part

of large intestine.• ilium—forms large part of hip bones• ischium—forms most inferior part of coxal

bone• pubis—most anterior part of coxal bone• acetabulum—receives head of femurSacroiliac Joint—connects ilium to sacrum

Pelvic Girdle

en.wikipedia.org

Bones of Lower Appendages

biology.kenyon.edu

academic.wsc.edu

Bones of Lower Appendages

•Femur—heaviest and strongest bone in body.

biology.kenyon.edu

Femur—parts to know•Greater trochanter

•Head•Neck

Femur—parts to know

•Intertrochantic crest

•Lateral condyle•Medial condyle

Bones of Lower AppendagesTibia—shinbone• larger of 2 leg

bones—medial side of leg

• articulates with distal end of femur to form knee joint.

http://biology.kenyon.edu/heithausp/cat-tutorial/hindlimb/tibia.htm

Bones of Lower Appendages

Fibula• thin, sticklike• lateral

malleolus forms the outer part of ankle.

http://homepage.smc.edu/wissmann_paul/bones/2tibiaandFibula.html

Bones of Lower Appendages

Tarsals (7)Metatarsals (5)phalanges (14)

www.octc.kctcs.edu

Foot bones

bio.winona.edu

Articulations

Joint Types Synarthroses: • immovable,

fibrous joints• bones united by

fibrous tissue• e.g., sutures—

found in skull

swc2.hccs.edu

Joint Types Amphiarthroses: • slightly

movable• bone ends

connected by cartilage

commons.bcit.ca

2 main types of amphiarthroses

• syndesmosis—bones connected by a ligament (tibia connected to fibula)

• symphysis—bones separated by wedge of cartilage (interverterbral joints and pubic symphysis

commons.bcit.ca

Joint Types

Diarthroses:• freely movable, synovial joints

Characteristics• articular cartilage covering

ends of bones

Characteristics of diarthoses con’t:

• joint cavity filled with synovial fluid (thick solution, consistency of molasses) whose functions include lubrication, nutrient distribution and shock absorption

• ligaments for reinforcement.• meniscus—pad of fibrocartilage

between opposing bones within a synovial joint.

Skeletal System

Pathologies

Articulation Disorders

•Bursitisinflammation of bursae

https:/.../webmd/A-Z_Encyclopedia/Bursitis.jpg

Articulation disorder

Osteoarthritis• most common—

usually affects elderly

• affects articular cartilage

• usually slow and irreversible.

orthopedics.about.com

Arthritis—joint inflammation

Joint Diseases

Rheumatoid arthritis

• autoimmune disease

• chronic inflammatory disorder

• course varies and is marked by remissions and flare ups

• drug therapy

podiatry.curtin.edu.au

Most common bone fractures

•Simple (closed)

bone breaks but doesn’t penetrate skin layer

www.azaleaortho.com

Caution…next picture is graphic!

Most common bone fractures

•Compound (open)bone breaks through skin

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Most common bone fractures

•Impactedbroken bone ends are forced into each other

http://www.radiology.us/images/200/wristcollesapx3600.jpg

Most common bone fractures

•Greenstick—incomplete break

Disorders of the Skeletal System

Osteoporosis• bone thinning

disease• related to loss of

estrogen in body• vertebral collapse

causes hunched posture

• hugs and sneezes can cause fractures

www.nih.gov

Disorders of the Skeletal System

Osteomyelitis

bacterial infection of a bone.

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Disorders of the Skeletal System

•Tumors of bone--Osteosarcomas

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Disorders of the Skeletal System

•Dislocation

hipusa.com

Disorders of the Skeletal System

•Sprain—ligament is stretched/torn

www.nismat.org

Disorders of the Vertebrae

•Scoliosis

spine curves left or right

www.rad.washington.edu

Disorders of the Vertebrae

www.spinecolorado.com

•KyphosisAbnormal “hump” formed by thoracic vertebrae

Disorders of the Vertebrae

www.nlm.nih.gov

•Lordosisextreme curving at lumbar vertebrae

Disorders of the Vertebrae

www.chiro.org

•Herniated “slipped” discdrying discs which press on spinal nerves or spinal cord