Skeletal system

206 bones (in adults)206 bones (in adults)

CartilagesCartilages

Joints with ligaments and tendonsJoints with ligaments and tendons

Divisions of the skeleton

Axial - Axial - Ribs, sternum, vertebrae, skullRibs, sternum, vertebrae, skull

Appendicular – Appendicular – Arm and leg bones, clavicle, scapula, hip Arm and leg bones, clavicle, scapula, hip

bonesbones

Functions

1.    Supports body as a whole, supports individual 1.    Supports body as a whole, supports individual organs and organ systems.organs and organ systems.

2.    Directs the forces of skeletal muscle 2.    Directs the forces of skeletal muscle contraction, producing movement.contraction, producing movement.

3.    Individual bones store minerals.3.    Individual bones store minerals. 4.    Protect delicate tissues and organs by storing 4.    Protect delicate tissues and organs by storing

them within bones or surrounding them with a them within bones or surrounding them with a bony shield. Ex: brain.bony shield. Ex: brain.

5.    Blood cell formation in bone marrow of flat 5.    Blood cell formation in bone marrow of flat bones.bones.

Parts of a Long Bone

PeriosteumPeriosteum EpiphysisEpiphysis

Articular cartilageArticular cartilage DiaphysisDiaphysis

Medullary cavity - endosteumMedullary cavity - endosteumBone marrowBone marrow

• YellowYellow• Red - hematopoiesisRed - hematopoiesis

ProcessesProcesses, grooves, openings, depressions etc., grooves, openings, depressions etc.

Bone Development and Growth

Intramembranous bones Intramembranous bones Endochondral bones Endochondral bones Osteoblast – bone forming cellOsteoblast – bone forming cell Osteoclast – bone eroding cell Osteoclast – bone eroding cell

Development of Endochondral Bones 1. Develop from masses of hyaline cartilage.1. Develop from masses of hyaline cartilage.

2. Primary ossification center forms in center of 2. Primary ossification center forms in center of bone. Cartilage begins to break down. Periosteum bone. Cartilage begins to break down. Periosteum forms Blood vessels and osteoblasts invade forms Blood vessels and osteoblasts invade disintegrating cartilage, spongy bone is formed in disintegrating cartilage, spongy bone is formed in its place.its place.

3. Compact bone forms around p.o.c. Ends of bones 3. Compact bone forms around p.o.c. Ends of bones are still cartilage and continue to groware still cartilage and continue to grow

4. 4. Secondary ossification centers appear in Secondary ossification centers appear in each epiphysis, spongy bone forms in all each epiphysis, spongy bone forms in all directions from themdirections from them

5. Epiphyseal disk is a band of cartilage that 5. Epiphyseal disk is a band of cartilage that remains between p.o.c. and s.o.c. This still remains between p.o.c. and s.o.c. This still grows to increase bone lengthgrows to increase bone length

6. 6. Epiphyseal disk becomes ossified, bone can Epiphyseal disk becomes ossified, bone can not get any longer.not get any longer.

* Bone is continually broken down and * Bone is continually broken down and reformed throughout life.reformed throughout life.

Repair of Bone Fracture FractureFracture – break in bone – both blood vessels – break in bone – both blood vessels

within bone and Periosteum are ruptured. within bone and Periosteum are ruptured. Periosteum probably torn.Periosteum probably torn.

HematomaHematoma – blood escaping from broken blood – blood escaping from broken blood vessels forms a clot.vessels forms a clot.

Cartilaginous callus Cartilaginous callus – fibrocartilage that fills gap – fibrocartilage that fills gap between the ends of the broken bone.between the ends of the broken bone.

Bony callusBony callus – cartilaginous callus is broken down, – cartilaginous callus is broken down, area is invaded by blood vessels and osteoblasts. area is invaded by blood vessels and osteoblasts. More bone is produced than necessary. Over time, More bone is produced than necessary. Over time, osteoclasts remove excess and shape it.osteoclasts remove excess and shape it.

Types of breaks

Simple fracture Simple fracture – just the bone and – just the bone and Periosteum break.Periosteum break.

Compound fracture Compound fracture – ends of broken bone – ends of broken bone protrude through the skin. Much more protrude through the skin. Much more dangerous; susceptible to infection.dangerous; susceptible to infection.

HairlineHairline – bone breaks but does not – bone breaks but does not separate.separate.

TransverseTransverse – straight across the bone – straight across the bone

SpiralSpiral – diagonally across the bone, usually – diagonally across the bone, usually from a twisting pressure.from a twisting pressure.

GreenstickGreenstick – bone splinters – usually – bone splinters – usually happens in younger more supple bone. happens in younger more supple bone. Looks like a fresh branch broken off a tree.Looks like a fresh branch broken off a tree.

CollesColles – Processes of bones in the wrist – Processes of bones in the wrist break off.break off.

PottsPotts – Processes of bones in the ankle – Processes of bones in the ankle break off.break off.

CompressionCompression – Usually in vertebrae, from a – Usually in vertebrae, from a hard fall on the rear end or the head.hard fall on the rear end or the head.

Epiphyseal plateEpiphyseal plate – a break that occurs in the – a break that occurs in the cartilage band of a growing bone. May cartilage band of a growing bone. May stunt growth as epiphyseal plate ossifies stunt growth as epiphyseal plate ossifies during healing. Bone will stop growing at during healing. Bone will stop growing at that end.that end.

Joints – functional junctions between bones – articulations 1.    1.    Immovable joints Immovable joints – synarthroses– synarthroses Bones are fastened tightly together by a thin Bones are fastened tightly together by a thin

layer of fibrous connective tissue. Occur layer of fibrous connective tissue. Occur between bones that come in close contact between bones that come in close contact with one another.with one another.

Ex: Ex: suturessutures between flat bones of the between flat bones of the cranium.cranium.

2.    Slightly movable joints – amphiarthroses Bones are connected by fibrocartilage or Bones are connected by fibrocartilage or

ligaments.ligaments. Ex: Vertebrae, sacroiliac joints (in pelvis); Ex: Vertebrae, sacroiliac joints (in pelvis);

each joint only moves a little. The each joint only moves a little. The combination of many gives us motion in combination of many gives us motion in many directions.many directions.

3.    Freely movable joints – diarthroses/synovial joints surrounded by a capsule of synovial fluid surrounded by a capsule of synovial fluid

inside a membrane. Lubricates articular inside a membrane. Lubricates articular cartilage of joint. cartilage of joint. BursaeBursae – fluid filled sacs – fluid filled sacs inside the joint that act as ball bearings and inside the joint that act as ball bearings and aid in movement of tendons that pass over aid in movement of tendons that pass over bony parts or over other tendons. bony parts or over other tendons.

Types of freely movable joints

Ball and SocketBall and Socket Ball shaped head fits into cup shaped socket. Ball shaped head fits into cup shaped socket.

Widest range of motion of any joint. Movement Widest range of motion of any joint. Movement in all planes and rotationin all planes and rotation

Ex: hips and shouldersEx: hips and shoulders CondyloidCondyloid

Oval shaped condyle of one bone fits into an Oval shaped condyle of one bone fits into an elliptical cavity of another bone. Movement in elliptical cavity of another bone. Movement in different planes but no rotation.different planes but no rotation.

Ex. Joints between metacarpals and phalangesEx. Joints between metacarpals and phalanges

GlidingGliding Articulating surfaces nearly flat or Articulating surfaces nearly flat or

slightly curved. Sliding and twisting slightly curved. Sliding and twisting motion.motion.

Ex: carpals, tarsalsEx: carpals, tarsals HingeHinge

Convex surface of one bone fits into Convex surface of one bone fits into concave of another. Movement in one concave of another. Movement in one plane only.plane only.

Ex: Knee and elbow, phalangesEx: Knee and elbow, phalanges

PivotPivot Cylindrical surface of one bone rotates within a Cylindrical surface of one bone rotates within a

ring formed of bone and fibrous tissue. ring formed of bone and fibrous tissue. Movement is rotation about a central axis.Movement is rotation about a central axis.

Ex: joint between proximal ends of radius and Ex: joint between proximal ends of radius and ulna, top 2 vertebrae of spine (atlas and axis.)ulna, top 2 vertebrae of spine (atlas and axis.)

SaddleSaddle Articulating surfaces have both concave and Articulating surfaces have both concave and

convex regions. Surface of one bone fits the convex regions. Surface of one bone fits the complementary surfaces of the other. Movement complementary surfaces of the other. Movement in all planes but no rotation.in all planes but no rotation.

Ex: carpal and metacarpal of thumb (only place)Ex: carpal and metacarpal of thumb (only place)

Movements of Joints

FlexionFlexion – bending in toward the body or – bending in toward the body or forward.forward. Ex: make a fistEx: make a fist

ExtensionExtension – straighten or bend away from – straighten or bend away from the body.the body. Ex: kick a ball, extension of kneeEx: kick a ball, extension of knee

HyperextensionHyperextension – bend past straight – bend past straight Ex: bend head backEx: bend head back

AdductionAdduction – move medially – move medially Ex: legs together at attentionEx: legs together at attention

AbductionAbduction – move laterally – move laterally Ex: legs apart at easeEx: legs apart at ease

ElevationElevation – raise up – raise up Ex: shrug shoulders upEx: shrug shoulders up

DepressionDepression – lower – lower Ex : open mouth (depress jaw)Ex : open mouth (depress jaw)

RotationRotation – pivot on an axis – pivot on an axis Ex: shake head noEx: shake head no

CircumductionCircumduction – move in circles – move in circles Ex: giant arm circlesEx: giant arm circles

ProtractionProtraction – move anteriorly – move anteriorly Ex: grasp upper lip in teethEx: grasp upper lip in teeth

RetractionRetraction – move posteriorly – move posteriorly Ex: grasp lower lip in teethEx: grasp lower lip in teeth

Supination Supination – rotate hand palm up– rotate hand palm up PronationPronation – rotate hand palm down – rotate hand palm down Plantar flexionPlantar flexion – point toes down – point toes down DorsiflexionDorsiflexion – point toes up – point toes up InversionInversion – turn sole of foot medially – turn sole of foot medially EversionEversion – turn sole of foot laterally – turn sole of foot laterally