Human Skeleton Anatomy

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Questions and Answers

What is the primary function of the skeleton in the human body?

To regulate body temperature

To produce hormones

To provide support for the body and its vital cavities (correct)

To aid in digestion

What are the two main parts of the human skeleton?

Upper and Lower

Left and Right

Axial and Muscular

Axial and Appendicular (correct)

What is the function of the marrow in the medullary cavity of many bones?

To store salts

To produce vitamins

To produce new blood cells (correct)

To regulate blood pressure

How many vertebrae make up the vertebral column?

33 Signup and view all the answers

What is the function of the intervertebral discs?

To absorb shock between vertebrae Signup and view all the answers

What are the two parts that make up the shoulder girdle?

Clavicle and Scapula Signup and view all the answers

What is the function of compact bone?

To provide strength to the bone Signup and view all the answers

How many segments do each of the upper and lower limbs consist of?

3 Signup and view all the answers

What is the main function of a sesamoid bone?

To reduce friction on the tendon Signup and view all the answers

Which type of bones develops through endochondral ossification?

Long and irregularly shaped bones Signup and view all the answers

What is the characteristic of cancellous bone?

A less dense branching network of bone trabecula Signup and view all the answers

Which type of joint is characterized by bones joined by fibrous connective tissue?

Fibrous joint Signup and view all the answers

What is the term for the process of bone formation in connective tissue?

Intramembranous ossification Signup and view all the answers

What is the characteristic of short bones?

They are cuboidal in shape Signup and view all the answers

Which type of bones are characterized by air-filled cavities?

Pneumatic bones Signup and view all the answers

What fills the spaces between the spicules of cancellous bone?

Bone marrow Signup and view all the answers

What type of joint is characterized by the presence of a thin layer of hyaline cartilage and a joint cavity filled with synovial fluid?

Synovial joint Signup and view all the answers

What is the primary function of the dens of the axis (C2 vertebra) in the median atlanto-axial joint?

Pivotal movement of the atlas Signup and view all the answers

Which type of joint is characterized by the presence of a fibrocartilaginous disc?

Secondary cartilaginous joint Signup and view all the answers

What type of joint is the elbow joint?

Hinge joint Signup and view all the answers

Which type of joint is the radiocarpal joint?

Ellipsoid joint Signup and view all the answers

What is the main characteristic of suture joints?

The bones are connected directly Signup and view all the answers

Which type of joint is the metacarpo-phalangeal joint?

Condyloid joint Signup and view all the answers

What type of joint is the sternoclavicular joint?

Plane joint Signup and view all the answers

Study Notes

The Skeleton of the Human Body

The skeleton forms a rigid supporting system in the human body, providing support for the body and its vital cavities, protection for vital structures, and serving as the mechanical basis for movement.

Axial Skeleton

The axial skeleton consists of the central supporting axis of the body, including the skull, vertebral column, ribs, and sternum.
The vertebral column consists of 33 vertebrae, divided into five groups: cervical (7), thoracic (12), lumbar (5), sacral (5), and coccygeal (4).
The vertebral column includes intervertebral discs of fibrocartilage between most of the vertebrae.

Appendicular Skeleton

The appendicular skeleton includes the bones of the upper limb and pectoral girdle, and bones of the lower limb and pelvic girdle.
The shoulder girdle consists of the clavicle and scapula, while the pelvic girdle consists of the hip bones.
The shoulder girdle and the pelvic girdle provide connection points between the appendicular and the axial skeletons, facilitating mechanical load transfer.
Each of the upper and lower limbs consists of three segments: proximal, intermediate, and distal.

Bone Structure

Bones are found in two forms: compact bone and cancellous bone.
Compact bone is a dense mass of bone, forming the superficial layer of bone and the tubular shafts of long bones, providing strength.
Cancellous bone (spongy or trabecular) is a less dense branching network of bone trabecula, occurring in the ends of long bones and filling the flat and irregular bones.

Bone Classification

Bones are classified according to their shape into:
- Long bones (e.g., the humerus in the arm)
- Short bones (cuboidal, found in the tarsus and carpus)
- Flat bones (e.g., the sternum, scapula, and vault of the skull)
- Irregular bones (e.g., the vertebrae, hip bones, and bones of the face)
- Sesamoid bones (e.g., the patella or knee cap, developing in certain tendons)
- Pneumatic bones

Bone Development

Bones develop in one of two ways:
- Intramembranous ossification (membranous bone formation): flat bones develop in this way by direct calcium deposition into a mesenchymal model.
- Endochondral ossification (cartilaginous bone formation): long and irregularly shaped bones develop by calcium deposition into a cartilaginous model of the bone.

Joints

Joints (articulations) are unions or junctions between two or more bones or rigid parts of the skeleton.
Joints exhibit a variety of forms and functions.

Types of Joints

Fibrous joints (synarthrosis): bones joined by fibrous connective tissue, including:
- Suture
- Syndesmosis
- Gomphosis
Cartilaginous joints: bones joined by cartilage, or by cartilage and fibrous tissue, including:
- Primary cartilaginous joints (e.g., the epiphysial plate of the growing long bones)
- Secondary cartilaginous (symphysis) joints (e.g., the intervertebral joints between the vertebral bodies)
Synovial joints (diarthroses): the most common type of joint, characterized by:
- Articular surfaces covered by a thin layer of hyaline cartilage
- A joint cavity filled with a small amount of synovial fluid
- Subtypes include:
  - Plane (gliding) joints
  - Hinge joints
  - Pivot joints
  - Saddle joints
  - Condyloid joints
  - Ball and socket joints
  - Ellipsoid joints