the human skeleton (including diseases of the … · the skull the skull encloses and protects the...

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THE HUMAN SKELETON (INCLUDING DISEASES OF

THE SKELETON)

10.2.7


STRUCTURE OF THE HUMAN SKELETON

The word “skeleton” is derived from Greek meaning “dried out body” .

The human skeleton is excellently designed – strong and lightweight.

It is adapted to protect and to assist in movement.

All the bones of the skeleton can be divided into two main divisions, viz.; the axial skeleton and the appendicular skeleton.

The axial skeleton consists of the skull, the vertebral column, the ribs and the breast bone (sternum).

The appendicular skeleton consists of the shoulder girdle with the upper limbs and the pelvic girdle with the lower limbs.

cranium

mandible

sternum

ribs

ilium

sacrum

pubis

tarsals

metatarsals

phalanxes

carpals

metacarpals

phalanxes

scapula

humerus

radius

ulna

femur

patella

tibia

fibula

ischium

The human skeleton


THE CLASSIFICATION OF BONES

Long bones

A long bone consists of a cylindrical part, the shaft, (diaphysis), and two thickened ends (epiphysis). The shaft is made up of sturdy compact bone and surrounds a cavity, the marrow cavity.

The thickened ends (epiphyses) consists of spongy bone, covered by a thin layer of compact bone. A layer of hyaline cartilage covers each epiphysis.

Long bones are found in limbs, e.g. the thigh bone (femur), shin bone (tibia) etc.

Short bones

Short bones do not possess a shaft and marrow cavity. They consist completely out of spongy bone covered by a thin layer of compact bone.

hyaline cartilage

spongy bone (contains red bone

marrow)

endosteum

compact bone

marrow cavity

artery and vein

yellow marrow

periosteum

proximalepiphysis

diaphysis

distal epiphysis

Diagram of a long bone


THE CLASSIFICATION OF BONE

Flat bones

Flat bones consist of two layers of compact bone with spongy bone in between. They are mostly found in the body where much protection is needed, e.g. the bones of the cranium.

Irregular bones

As the name indicates, these kind of bones do not have a regular shape. They consist of spongy bone, covered by compact bone. Vertebrae and ossicles are examples of irregular bones.

Classification of bones

flat bones e.g. sternum

Long bones e.g. humerus

irregular bones e.g. vertebra

short bones e.g. talus in the

ankle


MAIN FUNCTIONS OF THE PARTS OF THE ENDOSKELETON: THE AXIAL SKELETON

The axial skeleton lies on the long axis of the body, hence the name.

The skull The skull encloses and protects the brain and sensory organs, viz. the eyes, ears, nose

and tongue.

It consists of 28 bones that form the cranium and facial bones. That includes the ossicles. The bones are joined by sutures. Sutures are immovable joints. The lower jaw is the only movable part of the skull.

The large opening at the base of the skull is called the foramen magnum. That is the opening whereby the spinal cord enters the skull.

The skull

occipital bone

mastoid process

frontal bone

nasal bone

suture

Cheek bone

maxilla

mandible


MAIN FUNCTIONS OF PARTS OF THE ENDOSKELETON: THE AXIAL SKELETON

The vertebral column This is the central axis to which all other parts of the endoskeleton are attached. It encloses

and protects the spinal cord and keeps the body upright.

It is a flexible bony column that consists of several irregular bones, called vertebrae.

The vertebral column consists of 33 vertebrae. Only 24 of these are separate bones. The other 9 vertebrae are fused to form the sacrum.

There are cartilaginous discs between the vertebrae. The S-shape of the vertebral column and the discs prevent shock waves from going to the brain when a person walks or runs.

The first two cervical (neck) vertebrae are the atlas (a carrier vertebra) and the axis (a pivoting vertebra).

The atlas and axis differ from other cervical vertebrae. The atlas carries the weight of the skull and enables one to nod the head. The axis forms a joint with the atlas and enables one to turn the head from side to side.

In all of the vertebra is an opening. The consecutive openings of all the vertebra together form the neural canal though which the spinal cord passes.

The vertebral column Cervical vertebrae

thoracic vertebrae

lumbar vertebrae

sacrum and coccyx

Structure of a thoracic vertebra


MAIN FUNCTIONS OF PARTS OF THE ENDOSKELETON: THE AXIAL SKELETON

Protect your spine It is important to protect your spine. Do not sit for long periods – get up every now and

then and move about. Use your leg muscles to lift heavy objects, not your spine.

Spinal injuries It is estimated that 400 to 500 South Africans get annually spinal injuries. Most people

who are injured in this way are between 15 and 29 years old. A spinal injury does not necessarily shorten a person’s life expectancy, but causes much pain and / or a body deformity.

Shifted intervertebral disc

Each intervertebral disc consists of a strong outside layer that covers a gelatinous substance on the inside. A spinal injury or even normal daily movement may cause the strong outside layer to ruptures and the jelly-like substance to bulge out.


MAIN FUNCTIONS OF THE ENDOSKELETON: THE AXIAL SKELETON

Spinal injuries Paralysis

The spinal cord consists of nervous tissue that connects the brain with the body. If the vertebrae are crushed by an accident, the spinal cord is usually also damaged. Nervous tissue cannot regenerate (heal like other tissues). The injured person may then lose control of muscles and other organs.

Abnormalities of the spinal curve Scoliosis – sideway curvature of the spine

Kyphosis – hump back

Lordosis – hollow back

Abnormal spinal curvatures

Kyphosis Lordosis Scoliosis


MAIN FUNCTIONS OF THE PARTS OF THE ENDOSKELETON: THE AXIAL SKELETON

The thorax (ribs and breast bone) The ribs, breast bone and thoracic vertebrae together form a sturdy basket-shape

structure that surrounds and protects the heart and lungs.

The thorax consists of the sternum (breast bone), ribs and thoracic vertebrae.

The thorax protects the heart, lungs and the large blood vessels in the thoracic cavity against injuries.

Twelve pairs of ribs form the sides of the rib cage. The first seven pairs, the true ribs, are directly joined to the sternum by means of cartilage. The following five pairs, the false ribs, are directly or not at all attached to the sternum. The remaining two pairs of false ribs are called the floating ribs, because they are not attached to the sternum.

The thorax

Clavicular keep

manubrium

sternal angle

corpus

intercostal space

rib cartilage

cervical vertebrae

true ribs(1 – 7)

false ribs

(8 – 10)

false ribs(11 – 12)

(floating ribs)

neural spine

articular facet for tubercle of

rib

non-articular part of rib process

articular part of rib process

neck of rib

lower articular facet for head of rib

articular facet for head of rib

head of rib

transverse process

articular facet for rib process

articular facet for head of rib

corpus (body)

Attachment of rib to thoracic vertebra


MAIN FUNCTIONS OF PARTS OF THE ENDOSKELETON: THE APPENDICULAR SKELETON

The pelvic and pectoral girdle join the legs and arms to the skeleton. The girdles are also important for the attachment of muscles and movement.

In the following slides we shall discuss joints and movement in more detail.


INJURIES OF THE SKELETON

Dislocation

A joint is dislocated when the bones of the joint move out of position. It is often caused by sudden impact on the joint and results in damage to the ligaments.

The shoulders, fingers, wrists and knees are often dislocated.

A joint can return to its original position, or a doctor will have to replace it.

If a dislocation is not treated immediately the blood circulation, ligament, bone and joint structures may be damaged.

As soon as a joint is replaced a splint can be applied to straight joints ,like fingers and toes. A bandage can be used to keep complex joints, like shoulders, in position.

Surgery is needed to repair serious dislocation.

normal finger

dislocated finger

crooked and swollen

Dislocation of a finger

Dislocation of bones in the foot



Spraining

When a joint is suddenly moved to the side, it may cause spraining. It happens when the ligaments and tendons are stretched too far.

A snapping sound may be heard, followed by pain and swelling.

The body protects the sprained joint by swelling and pain to prevent that it is used.

normal

ankle ligaments

Grade 1

Grade 2 Grade 3

Spraining of the ankle



Cramps

A cramp is a spasmodical, painful, involuntary contraction of skeletal muscles. The whole muscle or muscle group may go into a spasm.

Cramps are usually experienced in the lower limbs. A cramp may last several minutes and may last for 10 minutes or more.

Nerves that do not function correctly, cause muscle cramps. The cause may be an injury to the spinal cord in the back or neck. Other causes may be when muscles are injured or overstrained, dehydration, lack of certain minerals, mainly magnesium and calcium in the diet and poor blood circulation in the muscles.

Stretching or careful massage of the muscle may bring relief.

Cramp in the calve muscle



Fractures

Sudden hard contact with an object or surface may cause a fracture. A fracture arises when a bone breaks or cracks.

A hard fall, rapid moving hockey stick or soccer boot may cause a fracture in a bone.

Some soccer players have broken a knee cap by kicking into the ground instead of the ball. The muscle that contracts to kick, is attached to the knee cap. By kicking into the soil the leg stops moving, but the muscle keeps on stretching. That may result in a fracture of the knee cap or shin bone.

Types of bone fractures

Cross Linear Oblique Oblique Spiral fracture Green stick fracture fracture fracture fracture fracture crumbling

(non displaced) (displaced) fracture

Fractures



Straining

• Straining takes place when muscles are stretched to the extreme during physical effort, resulting in muscle cramps or torn muscles.

When muscles are strained the person will experience much pain and difficulty to move the muscles of that area. The pain is caused by the incessant contraction of the muscle fibres and possible tearing of the fibres.

A doctor or physiotherapist who examines the patient may feel a lump in the strained muscle.

Small strains, like when one wakes up with a stiff neck, does not cause permanent damage. More serious muscle straining, second grade muscle strains, cause torn muscle fibres and third grade strains cause serious damage to muscle fibres. These injuries require evaluation and treatment by medical practitioners.

Muscle straining without obvious or uncommon physical strain may be an injury due to work, e.g. when one’s neck is in an abnormal position for a long period while working at a desk without regular rest periods.

A wrong posture may also cause chronic muscle strain in the neck, back and shoulders, that may increase the damage to soft tissue and joints of the vertebral column.

straining

muscle

tendon

Straining of muscles


DISEASES OF THE SKELETON

Rickets

Vitamins are important components of the diet to keep the body healthy and let it function normally. In quarter 1 you learned that vitamin D is needed for the development of healthy bones and teeth. Our bodies produce vitamin D in the presence of sunlight.

Vitamin D is essential for the absorption of calcium for the proper formation of bone tissue.

Rickets is the result of weakened bones in children. It may cause fractures and malformation. It is one of the most common infant diseases in developing countries.

The main cause is a lack of vitamin D, but a lack of calcium may also result in rickets. Most cases occur in children who suffer from serious malnutrition, usually due to famine in early childhood. It may also occur in adults, but that is not very common.

Rickets can be prevented. Sufficient ultra-violet rays in sunlight daily and sufficient calcium and phosphorus in the diet can prevent rickets.

Children with dark skins should be exposed to UV-rays for longer periods.

Children with red hair produce the most vitamin D when exposed to sunlight.

Rickets can be healed. The treatment requires the intake of more calcium, phosphates and vitamin D in the diet. Exposure to sunlight and the intake of fish oils are good sources of vitamin D.

Effect of rickets

stunted growth

malformed back bone

malformed ribs

malformed pelvis

wide knee joints

wide ankle joints

malformed skull

“pigeon”breast

wide elbow joints

wide wrist joints

bent legs

Rickets



Arthritis

Arthritis is a condition that affects the joints. Bacteria enter the synovial fluid and cause infection of the joint. “Arthro” means joint and “itis” means infection.

Osteoarthritis is sometimes called wearing arthritis. The cartilage in joints crumble with age. The joints most affected are fingers, the cervical and lumbar joints, knee and hip joints.

Rheumatoid arthritis starts with infection of the synovial membranes. The infection destroys the cartilage of the joint. Later scar tissue forms and the ends of bone fuse. That often results in malformation of joints.

A serious type of arthritis affects young people under the age of 16 years. That causes inflammation that involves pain, stiffness and swelling in one or more joints. The inflammation lasts longer than six weeks and is not caused by an injury or another disease.



Arthritis (continues)

With juvenile arthritis the immune system of the body does not function properly any more. The immune system must fight disease and germs. In a person with juvenile arthritis the immune system attacks healthy tissue in the joints. That is called an auto-immune disease.

This type of arthritis is called rheumatoid arthritis. Its cause is unknown.

There is no cure for juvenile arthritis, but most children that suffer from it lead active lives. They should follow a regular exercise program to keep the joints flexible and the muscles strong and healthy. Strong, healthy muscles can better support and protect joints.

Remedies, called non- steroid, anti-inflammatory medicine, are often used to treat juvenile arthritis. These remedies lessen pain, stiffness and swelling, although they do not prevent further damage. Patients should be patient, because it takes time for the medication to have an effect.

Normal Rheumatoid arthritis

Arthritis



Muscular dystrophy

Muscular dystrophy is a disease that destroys the skeletal muscles. Connective tissue replaces the skeletal muscle tissue. That results in joints becoming immovable.

Muscular dystrophy refers to a group of genetically inherited muscle disorders, that cause progressive weakening and deterioration of skeletal muscles that control movement.

The muscles waste away as the muscle tissue dies. The most common type of this disease affects mainly boys and is genetically transferred by the mother.

Some types of muscular dystrophy appear in babies or infants, while other types only occur in middle ages. Some cases are moderate and slowly develop during a normal life time. Others may cause serious muscle weakness and general loss of movement.

Some children with muscular dystrophy die as babies, while others reach adulthood and are only slightly impaired.

At the moment there is no specific treatment to stop or prevent any form of muscular dystrophy.

normal biceps

atrophic biceps due to muscular dystrophy

Muscular dystrophy



Osteoporosis

Osteoporosis is a disease that involves the progressive loss of the mineral components of bone tissue. The bone weakens as it becomes thinner. That results in a loss of bone mass and bones in the vertebral column and neck become brittle. That is a general result of aging , mainly in women.

Factors that may contribute to osteoporosis are a lack of oestrogen (a hormone that is lacking in older women), a diet with too little calcium and proteins, a lack of vitamin D, smoking and inadequate mass carrying exercise to exert pressure on the bones.

healthy bone osteoporosisnormal osteoporosis

Osteoporosis

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