Musculoskeletal System

Question 1

What is the function of the musculoskeletal system?

Answer 1

It provides form, support, stability and movement to the human body

Question 2

What does the musculoskeletal system consist of?

Answer 2

Bones of the skeleton (206 bones)
The bones of the skeleton serve to protect the body’s organs, support the weight of the body and move the body shape

Joints (360 joints)
A joint is an articulation between two bones and the body

Skeletal (voluntary) muscles (>600 muscles)
The muscles attach to the bones and pull on them to allow for movement of the body

Question 3

What are the functions of the human skeleton?

Answer 3

Protects the internal organs
Supports and gives shape to the body
Allows for movement
Site of blood cell production, which occurs in the marrow of some bones

Question 4

What two parts is the human skeleton divided into?

Answer 4

Axial skeleton

Appendicular skeleton

Question 5

What is the function of the axial skeleton?

Answer 5

It provides the surface for the attachment of muscles that moment the head, neck and trunk, performs respiratory movements and stabilises parts of the appendicular skeleton

Question 6

The axial skeleton consists of:

Answer 6

Skull:
This protects the brain and supports facial structure

Vertebral column (spine): 
This surrounds and protects the spinal cord and protects the head 

Thoracic cage (rib cage): 
Surrounds and protects the organs within the chest including the heart and lungs. Changes in the volume of the thorax enable breathing.

Question 7

What is the function of the appendicular skeleton?

Answer 7

It is compose of the bones of the upper limbs which function to grasp and manipulate objects and the lower limbs which permit locomotion.

Question 8

What does the appendicular skeleton consist of?

Answer 8

The pectoral girdle (shoulders)

Upper and lower limbs e.g. arms and legs

The pelvic girdle (hip bones)

Question 9

Describe one key difference in a bone between men and women

Answer 9

The female pelvis is slightly different from males. Over generations of evolution, females with a wider pubic angle and a large diameter pelvic canal reproduced more successfully. Therefore, their offspring also had pelvic anatomy that enabled successful childbirth

Question 10

Name the six different types of bones:

Answer 10

Long bones

Short bones

Flat bones

Irregular bones

Seasmoid bones

Structural bones

Question 11

What are long bones?

Answer 11

They are longer than they are wide and have a shaft and trio ends. Most of the limb bones are long bones.

Examples include the femur, tibia, ulna and radius

Question 12

What are short bones?

Answer 12

Short bones or cuboidal bones are both that are the same width and length, giving them a cure like shape.

For example, the bones of the wrist (carpals) and ankle (tarsals) are short bones

Question 13

What are flat bones?

Answer 13

Flat bones are thin and relatively broad bones that are found where extensive protection of organs is required or where broad surfaces of muscle attachment are required.

Examples of flat bones are the sternum (breast bone), ribs, scapulae (shoulder blades) and the roof of the skull

Question 14

What are irregular bones

Answer 14

Irregular bones are bones with complex shapes. These bones may have short, flat, notched or rigid surfaces.

Examples include vertebrae, hip bones and several skull bones

Question 15

What are sesamoid bones?

Answer 15

Small flat bones that are shaped similarly to a seasoned seed. The patellae are sesamoid bones. Sesamoid bones develop inside tendons and can be found near joints at the knees, hands and feet

Question 16

What are structural bones?

Answer 16

Small flat and irregularly shaped bones. They may be found between the flat bones of the skull

Question 17

What are the two types of bone tissue?

Answer 17

Compact and spongey

Question 18

What is compact (cortical) bone?

Answer 18

A hard outer layer that is dense, strong and durable. It makes up around 80% of adult bone mass.

Compact bone tissue consist is of units called osteons. Osteons in compact bone tissue are aligned in the same direction along lines and help the bone to resist fracturing or bending

Question 19

What is cancellous or spongey bone?

Answer 19

This consist is of a network of trabeculae or rod-like structures. It is lighter, less dense and more flexible than the compact bone.

Red bone marrow is found between the trabuculae. The red bone marrow of the femur and the interior of other large bones, such as the ileum, produces blood cells.

Question 20

Discuss the gross anatomy of a mature bone:

Answer 20

A long bone has two parts: the diaphysis and the epiphysis.
Each epiphysis meets the diaphysis at the metaphysis.
The hollow region in the diaphysis is called the medullary cavity,
which is filled with yellow marrow.
The medullary cavity has a delicate membranous lining called the endosteum (end- = “inside”; oste- = “bone”), where bone growth, repair, and remodeling occur.
The outer surface of the bone is covered with a fibrous membrane called the periosteum (peri– =“around” or “surrounding”). The periosteum contains blood vessels, nerves, and lymphatic vessels that nourish compact bone.
The walls of the diaphysis are composed of dense and hard compact bone.
The wider section at each end of the bone is called the epiphysis (plural = epiphyses), which is filled with spongy bone.
Red marrow fills the spaces in the spongy bone.
Tendons and ligaments also attach to bones at the periosteum. The periosteum covers the entire outer surface except where the epiphyses meet other bones to form joints. In this region, the epiphyses are covered with articular cartilage, a thin layer of cartilage that reduces friction and acts as a shock absorber.

Question 21

What four cell types are found in bone?

Answer 21

Osteoblasts, osteoclasts, osteocytes and osteo-progenitor (osteogenic) cells

Each cell type has a unique function and is found in different locations in bones

Question 22

What are osteoblasts?

Answer 22

They are found in the growing portions of the bone. They are responsible for bone formation,

They do not divide, synthesise or secrete the collagen matrix and calcium slats.
As the secreted matrix surrounding the osteoblast calcifies, the osteoblast becomes trapped within it. As a result of this, it changes in structure and becomes an osteocyte.

Question 23

What is an osteocyte?

Answer 23

The primary cell of mature bone and the most common type of bone cell.

They maintain the mineral concentration of the matrix via the secretion of enzymes,

They lack mitotic activity

Question 24

What are osteogenic cells?

Answer 24

They are stem cells with high mitotic activity, they are the only bone cells that divide

When they differentiate, they develop into osteoblasts. The dynamic nature of bones means that new tissue is constantly formed, while old, injured or unnecessary bone is dissolved for repair or for calcium release.

Osteogenic cells are important in the repair of fractures

Question 25

What is an osteoclast?

Answer 25

They originate from monocytes and macrophages rather than from osteogenic cells,

They are responsible for bone resorption or breakdown.

They continually break down old bone while osteoblasts continually form new bones. The ongoing balance between osteoblasts and osteoclasts is responsible for the constant, but subtle, reshaping of bones

Question 26

Draw the shape of the four types of bone cell

Answer 26

See lecture notes

Question 27

What is osteogenesis?

Answer 27

The process of bone formation by osteoblasts. It begins approximately sic weeks after fertilisation in an embryo.

Before this time, the embryonic skeleton consists entirely of fibrous membranes and hyaline cartilage .

Question 28

The development of bone from fibrous membrane is called the…?

Answer 28

Intramembranous ossification (involved in the formation of the flat bones of the skull, the mandible and the clavicles)

Question 29

What does endochondral ossification mean?

Answer 29

The process of bone development from hyaline cartilage (all of the bones of the body except the flat bones of the skull, the mandible and the clavicles)

Question 30

What is endochondral ossification?

Answer 30

Bone develops by replacing hyaline cartilage. Cartilage does not become bone, but instead it serves as a template to be completely replaced by a new bone

Bones at the base of the skull and long bones are formed by endochondral ossification

Question 31

Wha bones are formed by endochondral ossification?

Answer 31

The skull and long bones

Question 32

Describe the five steps of endochondral ossification:

Answer 32

A) mesenchymal cells differentiate into chondrocytes that produce a cartilage model of the future bony skeleton.

B) Blood vessels on the edge of the cartilage model bring osteoblasts that deposit a bony collar

C) capillaries penetrate cartilage and deposit bone inside cartilage model, forming primary ossification centre

D) cartilage and chondrocytes continue to grow at end of the bone while medullary cavity expands and remodels

E) secondary ossification centres develop after birth

F) hyaline cartilage remains at the epiphyseal (growth) plate and at joint surface as articular cartilage