Musculoskeletal SystemMusculoskeletal System

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ContentsContentsIntroductionFunctions of the skeletonDivisions of skeletonAxial skeletonAppendicular skeletonBone structureJointsSynovial jointsMovement

Growth and development in bonesRole of calcium in boneDisorders of the musculoskeletal system• Arthritis• OsteoporosisOther Musculoskeletal disorders

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IntroductionIntroduction• This is a method of movement using

muscles and bones in response to a stimulus.

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Functions of the skeletonFunctions of the skeletonSupport - keeps the body upright and gives

it shape.Protection - of delicate organs e.g. brain,

lungs, heart and spinal cord.Movement - without the skeleton movement

would be very slow e.g. earthworm.Long bones - manufacture red blood

corpuscles, white blood cells and platelets.

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Divisions of skeletonDivisions of skeleton

Axial skeleton,

and

Appendicular skeleton

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Axial skeletonAxial skeleton (1/3) (1/3)

AXIAL SKELETON = skull + vertebral column + sternum + ribs.

THE SKULL - composed of

- the CRANIUM - protects brain and eyes, and gives shape to the head.- the JAWS - contain the teeth used in feeding.- attached to the top of the vertebral column.

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Axial skeletonAxial skeleton (2/3) (2/3)

THE VERTEBRAL COLUMN - composed of (33) vertebrae

- cervical (7) - neck - thoracic (12) - ribs attached - lumbar (5) - small of back - sacral (5) - hips - caudal (4) – tail

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Intervertebral discsIntervertebral discsMuscles and ligaments hold vertebrae

together.Discs found between two vertebrae.Flexible and allow a little movement

between each pair of vertebrae.Prevent bones rubbing off each other and

act as shock absorbers.

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Vertebrae diagramVertebrae diagram

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Axial skeletonAxial skeleton (3/3) (3/3)

THE STERNUM AND RIBS - ribs 1 to 7 attached to sternum - true

ribs - ribs 8 to 10 attached to rib no. 7 - false

ribs - ribs 11 & 12 - shorter with no

attachments - floating ribs.Ribs protect the lungs and heart and used

in breathing.

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APPENDICULAR APPENDICULAR SKELETONSKELETONAPPENDICULAR SKELETON = all other

bones - names should be known.pectoral girdle: the bones that attach the

arms to the axial skeleton – shoulder blades & colar bones.

pelvic girdle: the fused bones of the hips, attached to the sacrum surrounding a cavity, that support the legs.

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Bone structure Bone structure (1/2)(1/2)

Bones need to be of maximum strength and minimum weight in order to provide support and be moved by muscles.

Compact bone – strength and rigidity – living cells – needs blood and nerve supply.

Spongy bone – strength and rigidity – contains bony bars and plates separated by irregular spaces – spaces filled with

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Red bone marrow – produces blood cellsYellow bone marrow – in centre of long

bones (medullary cavity) – stores fat.Cartilage - at ends of bones at a joint –

rubbery matrix – may contain elastic protein fibres – reduces friction between hard bones.

Bone structure Bone structure (2/2)(2/2)

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JointsJoints (1/2) (1/2)

are where two bones meet.Three types of joints: -1. Immovable – bones held together

without cartilage e.g. skull

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JointsJoints (2/2) (2/2)

2. Slightly movable joints – where flexibility is required e.g. vertebra in vertebral column.

3. Freely movable joints – cartilage and a space at the joint – called synovial joints – four types

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Synovial jointsSynovial joints1. BALL AND SOCKET JOINT e.g.

shoulder, hip - allows circular movement.

2. HINGE JOINT e.g. elbow, knee - allows movement in one plane only.

3. GLIDING JOINT e.g. wrist, ankle - allows limited circular movement.

4. PIVOT JOINT e.g. in neck - skull rests on axis to allow head move from side to side and nod.

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Synovial joints structureSynovial joints structureSynovial membrane surrounds joint and secretes synovial fluid – lubricantBones covered with cartilageBones held together by ligaments

LIGAMENTS - join bone to bone - elastic.TENDONS - join muscle to bone - non-

elastic.

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MovementMovementMuscles can only contract and relax

(cannot expand or elongate). To contract they need energy - ATP, from

respiration of glucose or glycogen with oxygen.

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Antagonistic musclesAntagonistic muscles (1/2) (1/2)

These are muscles working in pairs, opposing each other, controlling the movement of a joint.

 e.g. movement about the elbow controlled by biceps (= flexor muscle = bring bones closer to each other) and triceps (= extensor muscle = pull bones away from each other ).

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Antagonistic musclesAntagonistic muscles (2/2) (2/2)

To raise hand - biceps contract and triceps relax and is stretched by the upward movement of the radius and ulna.

 To lower hand - triceps contract and biceps relax and is stretched by the downward movement of the radius and ulna.

27Bend

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Bending at the elbowBending at the elbow

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Growth and development Growth and development in bonesin bones (1/2) (1/2)

Bone forming cells are called osteoblasts.These replace cartilage with bone during

the growth stage in a human.The bone eventually stops increasing in

size and limits the height of the individual.In adults bone is continually being broken

down and replaced.As osteoclasts break bone down,

osteoblasts build it up.

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Growth and development Growth and development in bonesin bones (2/2) (2/2)

osteoclast: a large cell, having more than one nucleus, that can break down and absorb calcified bone.

The broken down bone is absorbed by osteoclasts.

They remove worn cells and deposit calcium into the blood.

The continued renewal of bone is dependent upon physical activity, hormone levels and diet.

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Role of calcium in boneRole of calcium in bone• Bone contains a hard, rigid matrix

comprised of a protein impregnated with a calcium salt and phosphorous

• The calcium gives strength to bones• The protein gives flexibility and prevents

the bone from being brittle

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Disorders of the Disorders of the musculoskeletal systemmusculoskeletal systemStudy one of the following: -

ArthritisOR

Osteoporosis

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ArthritisArthritis (1/2) (1/2)

arthritis: inflammation of a joint. There are many pathological (disease-

related) causes, including bacterial or viral infection, inflammatory or degenerating disease, commonly rheumatoid arthritis and osteoarthritis.

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ArthritisArthritis (2/2) (2/2)

Arthritis can affect different joints, and sufferers may have symptoms of pain, swelling over the joint and restricted movement.

The treatment of arthritis depends on its cause – if inflammatory, specific drugs help to relieve pain and swelling. Infection, anti-bacterial drugs and severe arthritis may require joint replacement.

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OsteoporosisOsteoporosis (1/2) (1/2)

osteoporosis: a reduction in the density of bones as result of the ageing process or from enforced inactivity = brittle bone disease.

It is caused by excess reabsorption of bone and leads to an increased risk of fractures.

Osteoporosis often follows the menopause, because oestrogen is responsible for maintaining bone calcium and levels of oestrogen fall after the menopause.

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OsteoporosisOsteoporosis (2/2) (2/2)

Osteoporosis may also be induced by long-term treatment with steroids, and may occur in males as well as females.

Diagnosis is normally made using a DEXA scan (dual-energy X-ray absorptiometry).

Damage can be limited by taking vitamin D and calcium tablets and by taking exercise e.g. walking. HRT can benefit some women.

Other Musculoskeletal Other Musculoskeletal disordersdisordersnot examinablefor information only

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Disc prolapseDisc prolapse

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Whiplash injuryWhiplash injury

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Ligament injuryLigament injury

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Torn cartilageTorn cartilage

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END