Skeletal SystemSkeletal System

Functions:1) Supports body

2) 2) Protects internal organs

3) 3) Provides for movement

4) 4) Stores mineral reserves 5) Provides a site for blood cell

formation

Skeletal SystemSkeletal System

►Has 206 bonesHas 206 bones

►Divided into two sections:Divided into two sections:

1) 1) AxialAxial: skull, vertebral column, ribs, : skull, vertebral column, ribs, and and

sternumsternum

2) 2) AppendicularAppendicular: all other bones: all other bones

Structure of BonesStructure of Bones

►Bones are living tissue!!Bones are living tissue!!►PeriosteumPeriosteum – tough layer of connective – tough layer of connective

tissue surrounding bonetissue surrounding bone►Compact boneCompact bone – beneath the – beneath the

periosteum (dense but not solid)periosteum (dense but not solid)►Haversian canalsHaversian canals– tubes that run – tubes that run

through compact bone and contain through compact bone and contain blood vessels and nervesblood vessels and nerves

Structure of BonesStructure of Bones

► Spongy boneSpongy bone – inside outer layer of – inside outer layer of compact bonecompact bone

►OsteocytesOsteocytes – digest away old bone – digest away old bone►OsteoclastsOsteoclasts – maintain healthy bone – maintain healthy bone►OsteoblastsOsteoblasts – make new bone – make new bone

3-D Section of Bone Tissue3-D Section of Bone Tissue

Bone HomeostasisBone Homeostasis

►1.Most of our skeleton is constantly being broken down, and built back up

►2.Amount of bone built up = amount of bone broken down

►3.This balance of breakdown and buildup is called bone homeostasis

►Bone marrowBone marrow – soft tissue center of – soft tissue center of bonebone Maintains the balance of mineralsMaintains the balance of minerals Serves as a storage for minerals (Ca, P)Serves as a storage for minerals (Ca, P) Two Types:Two Types:

1) 1) YellowYellow – made mostly of fats, aids in – made mostly of fats, aids in Red Blood Cell (RBC) productionRed Blood Cell (RBC) production

2) 2) Red Red – produces RBCs, white BC, and – produces RBCs, white BC, and cells to help clottingcells to help clotting

Skeletal DevelopmentSkeletal Development

►The skeleton of the embryo is made of The skeleton of the embryo is made of cartilagecartilage

►Bone begins to replace cartilage by 9Bone begins to replace cartilage by 9thth week of development (known as week of development (known as ossificationossification))

JointsJoints

► Joints – where two or more bones Joints – where two or more bones meetmeet

► Most allow movementMost allow movement► Some are fixed (no movement): skullSome are fixed (no movement): skull

Pelvis, Sexual DimorphismPelvis, Sexual Dimorphism

Types of Joints Types of Joints

► Five types:Five types:1)1) Ball and socketBall and socket: allows rotational : allows rotational

movements (shoulder, hip)movements (shoulder, hip)

Ball and Socket MovementBall and Socket Movement

Types of Joints, Cont’dTypes of Joints, Cont’d

2) 2) PivotPivot: bones twist against each other : bones twist against each other (atlas and axis of your vertebrae)(atlas and axis of your vertebrae)

Pivot Joint in ArmPivot Joint in Arm

Types of Joints Cont’dTypes of Joints Cont’d

3) 3) HingeHinge: back and forth movements much like a : back and forth movements much like a door (elbow, knee)door (elbow, knee)

Types of JointsTypes of Joints

4) 4) GlidingGliding: bones slide : bones slide against each other against each other (wrist)(wrist)

5) 5) SaddleSaddle: Freely : Freely moveable joint found moveable joint found only in the thumbonly in the thumb

Joint supportJoint support

► LigamentsLigaments: : bands of tissue that connect bone bands of tissue that connect bone to boneto bone Surrounds joints with wide range of motion and Surrounds joints with wide range of motion and

little skeletal supportlittle skeletal support

► CartilageCartilage: : covers bone ends and allows for covers bone ends and allows for smooth movement. Can also be found in joint to smooth movement. Can also be found in joint to provide cushion (meniscus)provide cushion (meniscus)

► BursaBursa: : sacs of fluid that act as shock absorberssacs of fluid that act as shock absorbers

► TendonsTendons: : bands of tissue that connect muscle bands of tissue that connect muscle to bone (patella tendon, Achilles)to bone (patella tendon, Achilles)

Problems with Skeletal System - Problems with Skeletal System - BreaksBreaks

►Complete/Incomplete (Greenstick)Complete/Incomplete (Greenstick)►DisplacedDisplaced►Simple/Compound (breaks skin)Simple/Compound (breaks skin)► Impacted or ComminutedImpacted or Comminuted►SpiralSpiral►HairlineHairline

Breaks - Complete & Breaks - Complete & DisplacedDisplaced

Breaks - Breaks - Incomplete/GreenstickIncomplete/Greenstick

Breaks - SpiralBreaks - Spiral

Breaks - CompoundBreaks - Compound

Breaks - ComminutedBreaks - Comminuted

Breaks - Hairline Breaks - Hairline

OsteoporosisOsteoporosis

Problems with Skeletal System -Problems with Skeletal System -Rheumatoid arthritisRheumatoid arthritis

► Inflammation in joints Inflammation in joints ►Redness, warmth, swelling, pain, Redness, warmth, swelling, pain,

fatiguefatigue►Occurs on both sides of bodyOccurs on both sides of body►Genetic, environmental, hormonal Genetic, environmental, hormonal

factors; immune system attacks the factors; immune system attacks the joints and other organsjoints and other organs

Rheumatoid arthritisRheumatoid arthritis

Problems with Skeletal System - Problems with Skeletal System - DislocationDislocation

Normal DislocatedNormal Dislocated

DislocationDislocation

Normal DislocatedNormal Dislocated