SEHS Topic 1.1 Part 1

The skeletal system

Musculoskeletal system

System formed by the muscular and skeletal system.

Function: plays an important role in daily movements

Anatomical position

• Upright standing.

• Facing straight ahead.

• Parallel feet and close together.

• Palms facing forward.

  • Commonly used.

Fundamental position

• Identical to anatomical position.

• DIFFERENCE:

  The hands face the body.

What is the skeletal system made up of?

Bones, cartilage, ligaments, and joints.

Outline the functions of the skeletal system.

1. Protection of the vital organs.

2. Support and maintenance of posture.

3. Providing attachment points for muscles.

4. Storage and release of minerals such as calcium and phosphorus.

5. Storage of energy.

6. Blood cell production or hemopoiesis.

The skeleton is divided in…

• The axial skeleton.

• The appendicular skeleton.

The axial skeleton is formed by…

1. Skull.

2. Ribs.

3. Sternum.

4. Vertical column.

What is the main function of the axial skeleton?

The protection of the vital organs.

Apart from the protection of the vital organs, what are the other functions of the axial skeleton?

1. Support and maintenance of posture/structure. (vertebral column)

2. Providing attachment points for the muscles. (sternum)

3. Storage and release of minerals such as calcium and phosphorus. (ribs)

4. Blood cell production. (ribs & sternum)

Characteristics of the skull

• Made up of 22 bones.

• Divided into the face and the cranium.

  FUNCTIONS:

  • Protect the brain, eyes, and ears.

  • Contain teeth.

  • Provides attachment for muscles involved in chewing.

Characteristics of the sternum

• The flat bone that starts at the bottom of the throat and runs down to about halfway to the center of the chest.

  FUNCTIONS:

  • Protect the vital organs within the thorax.

  • Attachment for the ribs.

Characteristics of the ribs

• Curved bones that articulate with the sternum at the front and the thoracic vertebrae at the back.

• There are 12 pairs of ribs in total.

Which bones form the thoracic cage?

Sternum, ribs, and thoracic vertebrae.

Outline the functions of the thoracic cage

1. Protects vital organs.

2. Involved in breathing.

   • The intercostal muscles (essential for breathing) are situated in between the ribs, which is why any damage to the ribs affects breathing.

What is the vertebral column?

It is a strong and flexible column made up of 33 units called vertebrae stacked one on each other.

What is the vertebral foramen?

It is a hole where the spinal cord is located.

What are intervertebral discs?

Structures made of fibrocartilage and a gel-like elastic structure in the middle.

• They work as shock absorbers.

• Make the column more flexible.

Outline the different sections of the vertebral column

1. Cervical vertebrae.

2. Thoracic vertebrae.

3. Lumbar vertebrae.

4. Sacral vertebrae.

5. Coccyx.

   

Characteristics of the cervical vertebrae

1. Smallest ones.

2. More movement than thoracic and lumbar.

Characteristics of the thoracic vertebrae

1. The movements are more restricted.

2. Ribs attach to each side of the vertebrae.

Characteristics of lumbar vertebrae

1. Biggest and strongest.

2. Major role in weight-bearing.

3. Absorbs high compression loads.

Characteristics of the sacral vertebrae

1. Transmit body weight.

Characteristics of the coccyx

1. Last part of the vertebral column.

2. Stabilizes the body while sitting.

Movement of the axial skeleton?

Rigid and limited

How many curves does vertebrae arrangement provides?

4 curves

Difference between primary and secondary curves of the vertebral column

Primary curves:

• Thoracic and sacral.

Secondary curves:

• Cervical and sacral.

Outline the main functions of the vertebral column and add more to them

Functions:

1. Increases strength.

2. Helps to maintain an upright balance.

3. Absorbs shocks during weight-bearing exercise.

More…

• Supports the head.

• Encloses and supports the spinal cord.

• Transmits weight from body to legs.

• Provide attachment for the ribs and muscles of the back.

Appart from the axial skeleton, what is the name of the other part of the skeletal system?

Appendicular skeleton, and it is divided into upper body and lower body.

What is an important characteristic of the appendicular skeleton?

Bones in the appendicular skeleton enclose important structure.

What is the main function of the appendicular skeleton?

Body movement

Which bones make up the upper body part of the appendicular skeleton?

1. The pectoral girdle.

2. The upper limb.

3. Hands.

Which bones make up the lower body part of the appendicular skeleton?

1. Pelvic girdle.

2. Legs.

3. Feet.

What is the pectoral girdle formed by?

Scapulae and clavicle

What is the clavicle?

S-shaped bones.

• Position the arm in the body and articulate laterally with the scapulae shoulder joint and to the axial skeleton on the sternum.

What is the scapulae?

Scapulae is a flat triangle-shaped bone located at the back of the pectoral girdle.

• Articulate with the clavicle and the humerus.

• Supports the muscle crossing the shoulder joint.

What is the main function of the pectoral girdle?

Arms movement.

What is the upper limb formed by?

Humerus, radius, and ulna.

What is the humerus?

The humerus is a long bone that goes from the shoulder to the elbow.

• The upper end articulates with scapulae to form the shoulder joint.

• The lower end articulates with ulna to form the elbow joint.

What are radius and ulna?

They are two long bones that run parallel to each other.

• The radius is located on the thumb side.

• The ulna is located on the medial side.

These two bones are held together by the interosseous membrane, which provides stability.

What do the radius and ulna form?

They form the radioulnar joint, where bones rotate around each other.

Outline the parts of the hands

1. Carpals.

2. Metacarpals.

3. Phalanges.

   

Characteristics of the carpals

• Hand bones in the wrist where the radius and ulna articulate.

• Made of two rows of 8 short bones.

• The proximal row of the carpals articulates with the radius and ulna.

• The distant row articulates with the metacarpals.

Characteristics of metacarpals

• They are the hands’ framework and articulate with the distal row of the carpals.

• Metacarpals on the distal side articulate with the phalanges.

What are the phalanges?

• Most distal hand bones of the hand.

• Each finger has three phalanges.

• The thumb has two.

Which bones make up the pelvis girdle?

3 bones fused together:

1. Ilium.

2. Ischium.

3. Pubis.

Outline the functions of the pelvic girdle

• It articulates with the sacrum.

• Provides the link between the lower extremities and the axial skeleton.

• Supports body weight.

• Protects internal organs.

• Provides attachment for thigh muscles.

  

Which bones make up the legs?

• Femur.

• Patella.

• Tibia.

• Fibula.

  

What does hold the bones together?

Interosseous

What is the femur? Which bones does it articulate with? Joints it forms?

The femur is the longest and heaviest bone of the body.

It articulates with the pelvis girdle to make up the hip joint. Distally, it articulates with the tibia to form the knee joint.

What is the tibia?

The tibia is the long prominent bone that runs anteriorly in the lower leg.

What is the fibula?

The fibula is the other bone of the lower leg that runs parallel to the tibia.

What is the patella? Outline its functions.

The patella is the small triangle bone located at the knee joint.

FUNCTIONS:

1. Protects the knee joint.

2. Maintains the tendons when the knee bends.

3. Increases the leverage of the tendon of the quadriceps muscle.

Outline the bones of the foot?

1. Tarsals.

2. Metatarsals.

3. Phalanges.

   

How many tarsals do feet have? Which bones do they articulate with? Special characteristics (2)?

• 7 tarsal bones.

• They articulate with the tibia in the proximal end and with the metatarsals in the distal end.

  • The bone attached to the tibia is called TALUS.

  • The most prominent tarsal is the CALCANEUS.

What are the metatarsals?

The metatarsals are 5 long bones situated between the tarsals and phalanges.

Foot phalanges?

• Each toe has 3 phalanges except the big toe which only has two.

Distinguish between the axial and appendicular skeleton in terms of function.

AXIAL SKELETON:

1. Provides protection for internal organs (brain, spinal cord, heart, and lungs).

2. Acts as support and maintenance of posture.

3. Provides attachment points for muscles (sternum).

APPENDICULAR SKELETON:

1. Protects reproductive organs.

2. Provides attachment for muscles responsible for movement.

3. Provides levers to allow movement.

BOTH:

• Store calcium and other minerals.

• Blood cell production (long bones, and ribs).

• Energy storage (yellow marrow).

What does inferior mean?

• Below or further away from the head, lower part of the structure.

What does superior mean?

• Above or nearer to the head, the upper part of the structure.

What does proximal mean?

• Closer to where a limb attaches to the body or the origin of a body part.

What does distal mean?

• Further away from where a limb attaches to the body or the origin of a body part.

What does posterior mean? DORSAL

Behind or nearer to the back.

What does anterior mean? VENTRAL

In front of or nearer to the front.

What does lateral mean?

Further away from the midline of the body.

What does medial mean?

Closer to the midline of the body.

State the four types of bones

1. Long bones.

2. Short bones.

3. Flat bones.

4. Irregular bones.

Explain LONG BONES

• Long cylindrical shaft.

• Always longer than wider.

• Most important bones for movement.

Examples of long bones

Femur, ulna, tibia, humerus, metatarsals, clavicle.

Explain SHORT BONES

• They are small and cube-shaped.

• Always as long as they are wide.

• Usually articulate with more than one bone.

• Provide support and stability.

Examples of SHORT BONES

Carpals and tarsals

Explain FLAT BONES

• Curved surfaces that can be thick or thin.

• They provide protection and a BIG SURFACE for muscle attachment.

Examples of flat bones

Scapula, pelvis, ribs, and sternum.

Explain IRREGULAR BONES

• Special shapes and functions.

Examples of irregular bones

Vertebrae, sacrum, coccyx.

Draw and annotate the structure of a long bone

What is connective tissue and its functions?

Connective tissue is a group of cells that connects different cells and structures of the body.

1. Protecting.

2. Insulating.

3. Transporting substances withing the body.

4. Binding structures.

5. Providing support.

6. Storing.

Types of connective tissue?

Ligaments, tendons, cartilage.

Ligaments? Functions

• Connect bone to bone.

• Strong and flexible.

• Stabilize.

• Important for bone growth.

• Prevents friction between articulating bones.

Tendons? Functions

• Connect muscle to bone and are mainly made of collagen.

• Transmitting force between bones and muscle.

• Facilitating joint movement.

Cartilage? Functions

• Strong and smooth substance made of specialized cells.

• Absorbs shocks.

• Protects the end of bones.

• Reduces friction.

What is a joint?

A joint occurs where two or more bones meet and articulate.

State the three types of joints

1. Fibrous joint.

2. Cartilaginous joint.

3. Synovial joint.

Characteristics of fibrous joints

• No movement is allowed at this joint.

• Made of a thin layer of connective tissue that connects two bones.

• Classifies as sutures.

  • Roots of the teeth.

  • Skull.

  • Syndesmosis tibiofibular.

• More stable.

• Bones held by fibres.

  

Cartilagous joint

• Bones hold together by a flexible cartilage.

• Less stable and slightly moveable.

• Bones held by cartilage.

2 types

• Hyaline cartilage (little or no movement)

  • Intervertebral discs.

    

• Symphysis joints (little movement).

  • Joints connecting the ribs to the sternum.

What is the common type of joint in the appendicular skeleton?

Synovial joints

Synovial joints? Functions?

• Really mobile and structurally complex.

• The difference from the other joints is the presence of a cavity filled with synovial fluid.

  • Synovial fluid increases the ability to move the articulating surfaces one to each other.

Draw and outline the features of a synovial joint

Carpal and metacarpal joint of the thumb

Saddle joint

Joint between carpals and tarsals

Gliding joint

Neck

Pivot joint

Radius and carpal bones

Ellipsoidal joint

Knees, elbows, and phalanges

Hinge joint

Hip and shoulders

Ball and socket joint