MUSCULOSKETAL SYSTEM

Windsor University School of Medicine

Premed BiologySeptember 2014

Pre Med – Biology Chapter 13

Musculoskeletal System

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SKELETON

• Animals have a framework similar to the framework of a home. The framework in animals is called the skeleton. In animals or man, the framework has muscles attached to it instead of walls or roof.

• “Endoskeleton” • Protection, support, and movement of the

body

EXOSKELETONEXOSKELETON

ENDOSKELETONENDOSKELETON

• Bones serve the following functions: -

• Protect the vital organs inside the body• Provide anchor or support to the muscles• Produce blood cells

The Skeletal System• Gives form to the body

• Protects vital organs

• Consists of 206 bones

• Acts as a framework for attachment of muscles

• Designed to permit motion of the body

• Bone cells are living, they can reproduce resulting in the hardening of the bones called “ossification” and bone growth

• Not only does bone size change, their number also changes. As you grow the number of your bones increases although some bones fuse

• Skeletal system includes the bones, cartilage, ligaments, and tendons. These are tissues that make up the skeleton.

• A bone is a hard, living tissue and contains blood vessels, nerves and dividing cells

• Bones are hollow or spongy inside• Hollow portion of the bone is made of “Marrow”• The marrow produces red and white blood cells

and stores some of the body’s excess fat

• Cartilage – Tough, flexible tissue that functions as cusioning

• Found in lower nose, earlobes, trachea, voicebox

• Ligaments – Tough, connective tissue that connect one bone to another

• E.g. Hurt when sprain an ankle

• Tendons – Connect a bone to a muscle

Skeletal System

• Bone types• Bone structure• Bone function

• Bone growth and metabolism affected by calcium and phosphorous, calcitonin, vitamin D, parathyroid, growth hormone, glucocorticoids, estrogens and androgens, thyroxine, and insulin.

• There are 3 main parts of the AXIAL skeleton – • Skull• Rib cage• Back bone or spinal cord

• Appendages which includes the hands, arms, shoulders and collar bone and the back appendages composed of the feet, legs, knees and hip bone.

VERTEBRAE• BACKBONE is made up of thirty-three small bones

called vertebrae• Neck to tailbone

• 33 bones Total:• 1. Cervical = 7• 2. Thoracic = 12• 3. Lumbar = 5• 4. Sacral = 5• 5. Coccyx = 4

MusculoskeletalAnatomy and Physiology

• Anatomy– Flat, Short, Long, Irregular bones– Muscles – visceral, cardiac, skeletal– Joints – freely & slight moveable, synovial fluid– Cartilage,Ligaments, Tendons, Fascia, Bursae

• Physiology– Structure, shape, movement, protection, support,

hematopoiesis

JointsTypes include synarthrodial, amphiarthrodial,

diarthrodial• Structure and function of the diarthrodial or synovial

joint• Subtyped by anatomic structure

– Ball-and-socket– Hinge– Condylar– Biaxial– Pivot

Functions of the Musculoskeletal System

– Gives the body shape– Protects internal organs– Provides for movement– Consists of more than 600 muscles

Anatomy

• Muscles - provide movement & generate heat.

• Ligaments - connect bone to boneinjury = sprain

• Tendons - connect bone to muscleinjury = strain

• Bones - protection & shape

The Skull

The Neck

The Spinal Column

The Thorax

The Pelvis

The Lower Extremity• Hip

• Thigh

• Knee

• Leg

• Ankle

• Foot

The Upper Extremity

• Shoulder girdle

• Arm

• Elbow

• Forearm

• Wrist

• Hand

Joints

Types of Muscle (1 of 2)• Skeletal (voluntary) muscle

– Attached to the bones of the body

• Smooth (involuntary) muscle

– Carry out the automatic muscular functions of the body

Types of Muscle (2 of 2)• Cardiac muscle

– Involuntary muscle

– Has own blood supply and electrical system

– Can tolerate interruptions of blood supply for only very short periods

THE MUSCULOSKELETAL SYSTEMTHE MUSCULOSKELETAL SYSTEM

The musculoskeletal system includesall of the bones in a body and the musclesthat make them move. It supports the bodyand protects delicate organs.

THE MUSCULOSKELETAL SYSTEMTHE MUSCULOSKELETAL SYSTEM

• The skeleton consists of bones, ligaments, and cartilage, which are three types of connective tissue.

THE MUSCULOSKELETAL SYSTEMTHE MUSCULOSKELETAL SYSTEM

• The other component of the musculoskeletal system is muscles. Muscle tissue consists of bundles of long cells called muscle fibres, which contain specialized proteins. These proteins cause muscles to contract when signalled by nerve cells.

THE MUSCULOSKELETAL SYSTEM

THE MUSCULOSKELETAL SYSTEM

• Skeletal muscles are attached to the bone by tendons. The other muscle types include smooth muscles (generally located in the intestines) and cardiac muscles in the heart.

THE MUSCULOSKELETAL SYSTEMTHE MUSCULOSKELETAL SYSTEM

• Similar to other organ systems, the musculoskeletal system is susceptible to disease. Osteoporosis is a common disease that involves the loss of bone tissue, which makes bones weak and brittle. It is common among older women. As well, extreme movements can fracture bones and damage muscles, ligaments, and cartilage.

• Some invertebrates have no rigid frame to give them structure, while others have their skeletal system on the outside (exoskeleton).

The skeletal systemThe skeletal system

Structure and function of boneStructure and function of bone Organization of the skeletonOrganization of the skeleton JointsJoints

Functions of bone (skeleton)Functions of bone (skeleton) Support and protectionSupport and protection

Blood cell formationBlood cell formation

Mineral storage (calcium especially)Mineral storage (calcium especially)

Site for muscle attachment Site for muscle attachment body movement body movement

Bones classified by shape: long, short, flat, Bones classified by shape: long, short, flat, irregular, roundirregular, round

Bone enclosed in periosteum, which is continuousBone enclosed in periosteum, which is continuouswith tendons and ligamentswith tendons and ligamentsblood vessels in periosteumblood vessels in periosteum

Epiphysis- endsEpiphysis- endsspongy bone contains red marrowspongy bone contains red marrowcompact bone, articular cartilagecompact bone, articular cartilage

Diaphysis- middleDiaphysis- middlecompact bonecompact bonemedullary cavity- contains yellow marrow medullary cavity- contains yellow marrow

(fat)(fat)lined with endosteum (squamous epithelium)lined with endosteum (squamous epithelium)

Compact boneCompact boneosteocytes within lacunaeosteocytes within lacunaearranged in concentric circles called lamellaearranged in concentric circles called lamellae

This surround a central canal; complex is calledThis surround a central canal; complex is calledHaversian systemHaversian system

Canaliculi connect osteocytes to central canal andCanaliculi connect osteocytes to central canal andto each otherto each other

Prenatal developmentPrenatal developmentskeleton is mostly cartilaginousskeleton is mostly cartilaginous

Cartilage cells and then osteoblasts start toCartilage cells and then osteoblasts start todeposit mineralsdeposit minerals

Cartilaginous disk (epiphyseal disk) remainsCartilaginous disk (epiphyseal disk) remainsin epiphysisin epiphysis

Cells eventually stop dividingCells eventually stop dividing

Adults continually break down and build up boneAdults continually break down and build up bone

Osteoclasts remove damaged cells and releaseOsteoclasts remove damaged cells and releasecalcium into bloodcalcium into blood

Osteoblasts remove calcium from blood and buildOsteoblasts remove calcium from blood and buildnew matrix. They become trappednew matrix. They become trappedosteoclastsosteoclasts

Types of bone breaksTypes of bone breaks

Simple- skin is not piercedSimple- skin is not piercedCompound- skin is piercedCompound- skin is piercedComplete- bone is broken in halfComplete- bone is broken in halfPartial- broken lengthwise but not into twoPartial- broken lengthwise but not into two

partspartsGreenstick- incomplete break on outer arcGreenstick- incomplete break on outer arcComminuted- broken into several piecesComminuted- broken into several piecesSpiral- twistedSpiral- twisted

Fracture repairFracture repair

Hematoma- blood clot in space between edgesHematoma- blood clot in space between edgesof breakof break

Fibrocartilage callus- begins tissue repairFibrocartilage callus- begins tissue repair

Bony callus- osteoblasts produce trabeculaeBony callus- osteoblasts produce trabeculae(structural support) of spongy bone and(structural support) of spongy bone andreplace fibrocartilagereplace fibrocartilage

Remodeling- osteoblasts build new compact bone,Remodeling- osteoblasts build new compact bone,osteoclasts build new medullary cavity osteoclasts build new medullary cavity

Axial skeletonAxial skeletonskull (cranium and facial bones)skull (cranium and facial bones) hyoid bone (anchors tongue and muscleshyoid bone (anchors tongue and muscles

associated with swallowing)associated with swallowing) vertebral column (vertebrae and disks)vertebral column (vertebrae and disks) thoracic cage (ribs and sternum)thoracic cage (ribs and sternum)

Appendicular skeletonAppendicular skeletonpectoral girdle (clavicles and scapulae)pectoral girdle (clavicles and scapulae)upper limbs (arms)upper limbs (arms)pelvic girdle (coxal bones, sacrum, coccyx)pelvic girdle (coxal bones, sacrum, coccyx)lower limbs (legs)lower limbs (legs)

posterior viewposterior viewp. 135p. 135

Axial skeleton supports and Axial skeleton supports and protects organsprotects organs

of head, neck and trunkof head, neck and trunk

Appendicular skeleton- bones of Appendicular skeleton- bones of limbs and limbs and

bones that anchor them to the bones that anchor them to the axialaxial

skeletonskeleton

Articulation- where joints are Articulation- where joints are formedformed

22 bones in skull22 bones in skull6 in middle ears6 in middle ears1 hyoid bone1 hyoid bone26 in vertebral column26 in vertebral column25 in thoracic cage25 in thoracic cage

4 in pectoral girdle4 in pectoral girdle60 in upper limbs60 in upper limbs60 in lower limbs60 in lower limbs2 in pelvic girdle2 in pelvic girdle

206 bones in all206 bones in all

The skullThe skull

8 sutured bones in cranium8 sutured bones in craniumFacial bones: 13 sutured bones, 1 mandibleFacial bones: 13 sutured bones, 1 mandible

CraniumCraniumencases brainencases brainattachments for musclesattachments for musclessinusessinuses

Allows forAllows forgrowth growth

Vertebral column Vertebral column

7 cervial vertebrae7 cervial vertebrae12 thoracic12 thoracic5 lumbar5 lumbar1 sacrum (5 fused 1 sacrum (5 fused 1 coccyx (4 fused)1 coccyx (4 fused)

Vertebrae vary in size and morphologyVertebrae vary in size and morphology

Thoracic cageThoracic cageribsribsthoracic vertebraethoracic vertebraesternumsternumcostal cartilagescostal cartilages

True ribs are directly attached to the sternumTrue ribs are directly attached to the sternum(first seven pairs)(first seven pairs)Three false ribs are joined to the 7Three false ribs are joined to the 7thth rib ribTwo pairs of floating ribsTwo pairs of floating ribs

Clavicles and scapulaeClavicles and scapulae

Help brace shouldersHelp brace shouldersAttachment sites for musclesAttachment sites for muscles

Bones of upper limbBones of upper limb

Humerus (upper arm)Humerus (upper arm)Radius; ulnaRadius; ulnaCarpals, metacarpals, phalangesCarpals, metacarpals, phalanges

Bones of lower limbBones of lower limb

FemurFemurPatellaPatellaTibia, fibulaTibia, fibulaTarsals, metatarslas, phalangesTarsals, metatarslas, phalanges

JointsJoints

Immovable (synarthoses) bones sutured togetherImmovable (synarthoses) bones sutured togetherby connective tissue: skullby connective tissue: skull

Slightly movable (amphiarthoses) connected bySlightly movable (amphiarthoses) connected byfibrocartilage or hyaline cartilage:fibrocartilage or hyaline cartilage:vertebrae, rib/sternum joint, pubicvertebrae, rib/sternum joint, pubicsymphysissymphysis

Freely movable (diarthroses)- separatedFreely movable (diarthroses)- separatedligaments- hold bones togetherligaments- hold bones togethertendons- muscle to bonetendons- muscle to bonelined by synovial membranelined by synovial membrane

Types of freely movable jointsTypes of freely movable joints

Saddle: carpal and metacarpal bones of thumbSaddle: carpal and metacarpal bones of thumb

Ball and socket: shoulder and hip jointsBall and socket: shoulder and hip joints

Pivot- rotation only: proximal end of radius and ulnaPivot- rotation only: proximal end of radius and ulna

Hinge- up and own movement in one plane:Hinge- up and own movement in one plane:knee and elbowknee and elbow

Gliding- sliding and twisting: wrist and ankleGliding- sliding and twisting: wrist and ankle

Condyloid- movement in different planes but notCondyloid- movement in different planes but notrotations: btw metacarpals and phalangesrotations: btw metacarpals and phalanges

Types of movement and examples (with muscles)Types of movement and examples (with muscles)flexion- move lower leg toward upperflexion- move lower leg toward upperextension- straightening the legextension- straightening the leg

abduction- moving leg away from bodyabduction- moving leg away from bodyadduction- movong leg toward the bodyadduction- movong leg toward the body

rotation- around its axisrotation- around its axissupination- rotation of arm to palm-up positionsupination- rotation of arm to palm-up positionpronation- palm downpronation- palm down

circumduction- swinging arms in circlescircumduction- swinging arms in circles

inversion- turning foot so sole is inwardinversion- turning foot so sole is inwardeversion- sole is outeversion- sole is out

Elevation and depression- raising body part upElevation and depression- raising body part upor downor down

Aging and bonesAging and bonesboth bone and cartilage tend to deteriorateboth bone and cartilage tend to deterioratecartilage: chondrocytes die, cartilage cartilage: chondrocytes die, cartilage becomes calcifiedbecomes calcified

osteoporosis; bone is broken down faster osteoporosis; bone is broken down faster than it can be builtthan it can be builtbones get weak and brittle; tend to fracturebones get weak and brittle; tend to fracture

easilyeasily

Risk factors for osteoporosisRisk factors for osteoporosis

Inadequate calciumInadequate calciumLittle weight-bearing exerciseLittle weight-bearing exerciseDrinking alcohol, smokingDrinking alcohol, smokingBeing female: decreased estrogen secretionBeing female: decreased estrogen secretion

after menopauseafter menopauseSmall frameSmall frameCaucasian or Asian ethnicityCaucasian or Asian ethnicity

Skeleton and other systemsSkeleton and other systems

Skin makes vitamin D which enhances calciumSkin makes vitamin D which enhances calciumabsorptionabsorption

Skeleton stores calcium for muscle contraction,Skeleton stores calcium for muscle contraction,nervous stimulation, blood clot formationnervous stimulation, blood clot formation

Red marrow- site of blood cell formationRed marrow- site of blood cell formation

Calcium levels regulated byCalcium levels regulated byparathyroid hormone and calcitoninparathyroid hormone and calcitoninkidneys (can help provide vitamin D)kidneys (can help provide vitamin D)digestive system (can release calciumdigestive system (can release calciuminto bloodinto blood

Growth hormone regulates skeletal growthGrowth hormone regulates skeletal growthstimulates cell division in epiphyseal disksstimulates cell division in epiphyseal disksin long bonesin long bones

Growth stops when epiphyseal disks are Growth stops when epiphyseal disks are converted to boneconverted to bone

When excess growth hormone is produced inWhen excess growth hormone is produced inchildhoodchildhoodgigantismgigantism

In adulthood- acromegaly. Bones can’t growIn adulthood- acromegaly. Bones can’t growbut soft tissue canbut soft tissue can

When muscle contracts, it shortens and causesWhen muscle contracts, it shortens and causesmovementmovement

Skeletal muscles attached to bones by tendonsSkeletal muscles attached to bones by tendons

Insertion- attachment to more movable boneInsertion- attachment to more movable boneOrigin- less movableOrigin- less movable

Flexors and extensors act on the same joint Flexors and extensors act on the same joint to produce opposite actionsto produce opposite actions