the skeletal system
DESCRIPTION
The Skeletal System......Bones......Joints.....Joints Types......Bone Structure.TRANSCRIPT
Function Support
Internal framework of body Ex: Legs support body trunk, rib cage supports chest wall
Protection Protects soft body organs (skull protects brain, ribs protect heart
and lungs, etc) Movement*
Muscles use bones as levers to move body NOT a function skeletal system can do on it’s own
Storage Fat storage
In yellow marrow Mineral storage
Calcium, phosphorus, and others. Blood cell formation
Hematopoeisis Occurs in bone marrow of long bones
Bones206 bones in the adult skeletonTwo types of bone
Compact boneHomogeneous appearanceDense, looks smooth
Spongy boneSmall needle-like piecesLots of open spaces(Looks like a sponge, hence the name)
Bone ClassificationLong Bones
Longer than wideContain shaft with
head at each endMostly compact boneLimbs (not ankle or
wrist bones)Short Bones
Cube-shapedMostly spongy boneWrist and ankle
bonesPatella (kneecap)
Flat BonesThin, flat, usually
curvedTwo layers of
compact bone with spongy bone in between
Skull, ribs, breastbone
Irregular BonesDon’t fit into the
other categoriesVertebrae, hip bones
Bone Classification
Long Bone AnatomyDiaphysis
ShaftMade of compact
boneEpiphyses
Ends of long boneMade of compact
bone surrounding spongy bone
Covered with articular cartilageSmooth, glassy,
decreases friction at joints
Long Bone AnatomyEpiphyseal Line
Line of bone tissue that looks different from rest of bone
Remnant of epiphyseal plateHyaline cartilageCauses long bones to
grow lengthwise
Long Bone AnatomyPeriosteum
Outer covering of shaft
Like “skin” on chicken bone
Sharpey’s fibersAttach periosteum
to boneArteries
Supply nutrients to bone cells
Long Bone AnatomyMedullary Cavity
In shaftContains yellow
marrow (adipose) in adults
Contains red marrow in infants (for blood cell formation)
Microscopic Anatomy of BoneOsteon (Haversian system)
A “unit” of boneCentral (Haversian) canal
Opening in center of osteonContains blood vessels
Perforating (Volkman’s) canalPerpendicular to central canalContains blood vessels and nerves
Microscopic Anatomy of Bone
Microscopic Anatomy of BoneLacunae
Cavities that contain osteocytes (bone cells)
Arranged in concentric rings (like tree rings)
LamellaeRings around the
central canalWhere the lacunae
can be found
Microscopic Anatomy of BoneCanaliculi
Tiny canalsRadiate from
central canal to lacunae
Transport nutrients to bone cells
Other FactsBone is one of the hardest parts of the
bodyVery lightweightCan resist tension
Calcium salts make it hardCollagen fibers make it strong and flexible
Bone FormationIn embryos…
Skeleton made of hyaline cartilageGets replaced by bone with age
Cartilage remains in a few places…Bridge of noseParts of ribsJoints
Bone GrowthEpiphyseal plates allow for growth of long bone
during childhoodNew cartilage is continuously formedOlder cartilage becomes ossifiedCartilage is broken downBone replaces cartilageBones remodeled, lengthened until growth
stopsBones change shape somewhatBones grow in width
Long Bone Growth
Long Bone Growth
Types of Bone CellsOsteocyte
Mature bone cellOsteoblast
“Bone builders”Osteoclast
“Bone destroyers”Break down bone matrix to remodel and/or
release calcium
Bone RemodelingBone remodeling is done by osteoblasts and
osteoclastsEssential for bones to keep normal proportions
and strengthBones get larger/thicker when…
Large muscles are attached to them Need more bone to attach the large muscle to
Bones get smaller/weaker when…Physical inactivity
Non-use of musclesatrophySmall muscles don’t need large bones to attach to
Bones remodeled to become smaller
FracturesA break in a boneTypes of Fractures
Simple (closed) fractureBone breaks cleanly, does not penetrate skin
Compound (open) FractureWhen bone ends penetrate through skin
Treated by reduction and immobilizationRealignment of bone ends
Common Fractures
Bone RepairHematoma forms
Blood vessels rupture when bone breaks
Blood filled swellingCells without
nutrients dieFibrocartilage callus
formsMade of connective
tissueSplints the breakPhagocytes dispose
of dead tissue
Bony callus formsOsteoblasts/clasts
move in, create callus of spongy bone
RemodelingOsteoblasts/clasts
remodel in response to stress on the boneHelps strengthen boneCreates a permanent
“patch” at the siteOften, a healed fracture
can be stronger than the rest of the bone
Bone Repair
Axial SkeletonMakes up longitudinal part of the bodyThree parts
SkullVertebral columnBony thorax
**Note: notes on specific bones are not included. Make sure you are using your textbook to help identify shapes/functions of bones!!
Axial Skeleton **Shown in green
SkullFormed by two sets of bones
CraniumEncloses/protects brain
Facial bonesHolds eyes forward (anterior position)Allow facial muscles to show feelings
SuturesInterlocking, immovable joints holding most
skullbones togetherMandible-only freely movable bone in skull
Skull
Skull
Paranasal SinusesHollow portions of bone around nasal cavity
Named for bones they are found inLighten skullAmplify sounds when speaking/ give resonance
Fetal SkullLarge in comparison
to body length of infant
Contains fontanellesSoft fibrous
membranes connecting cranial bones “Soft Spots”Usually convert to
bone around 24 months after birth
The Vertebral ColumnVertebrae named for
their location7 cervical vertebrae
C1 = Atlas C2 = Axis
12 thoracic vertebrae5 lumbar vertebraeSacrum
5 fused vertebraeCoccyx
4 fused vertebrae
Vertebrae separated by fibrocartilage discsCushions/absorbs shock
Vertebrae Structure
Regional Characteristics
Regional Characteristics
Bony Thorax Forms a cage to protect organs
Three partsSternum
Flat bone3 fused bones
Manubrium Body Xyphoid process
Attached to first 7 pr of ribs
Rib Cage12 pairs
True Ribs= 7 pr False Ribs = 5 pr Floating Ribs = 2 pr
Thoracic vertebrae
Appendicular SkeletonLimbs
(appendages)Pectoral girdlePelvic girdle
**shown in yellow
Pectoral Girdle (shoulder)Two bones
Clavicle-collarboneScapula-shoulder
blade
Upper Limb (arm)Arm bone-
humerusForearm bones-
Radius (thumb side)
UlnaHand bones
Carpals-wristMetacarpals-palmPhalanges-fingers
Pelvic Girdle (hip bones)Three pairs of
fused bonesIliumIschiumPubic bone
Carries total weight of upper body
ProtectsReproductive
organsBladderPart of large
intestine
Gender Differences in PelvisFemale inlet
larger/more circularFemale pelvis is
shallower, bones lighter/thinner
Female hip bones flare wider
Female sacrum is shorter/less curved
Female pubic arch is more rounded/angle is greater
Lower Limb (leg)Thigh bone-femurTwo leg bones
Tibia (larger, medial bone)
Fibula (smaller, lateral bone)
FootTarsals-ankleMetatarsals-solePhalanges-toes
JointsArticulations of
bonesFunctions
Hold bones togetherMobility
Classified by structure/function
**we’ll use structural classification
Fibrous jointsImmovable
EX: sutures of skull
Cartilaginous jointsImmovable OR
slightly movableEX:Pubic symphysis
and Vertebrae
Synovial jointsFreely movable**Be familiar with types of
synovial joints (illustrations to follow)
Synovial JointsArticulating bones
separated by joint cavityArticular cartilage
covers bone endsJoint surfaces enclosed
by fibrous capsuleCavity contains
synovial fluidLigaments help
reinforce the joint
Associated Joint StructuresBursae
Flat fibrous sacs Lined with synovial
membrane Contains synovial fluid Common where
ligaments, muscles, skin, tendons rub together
Tendon sheath Elongated bursa
wrapping around a tendon that deals with lots of friction Like a bun around hot dog
Synovial Joints
Types of Synovial Joints by Shape
Types of Synovial Joints by Shape