Study of the Skeletal System

Question 1

How many bones are there is the human body?

Answer 1

• An adult has 206 bones
• New born babies have 270 bones

The axial skeleton consists of 80 bones and is formed by the:
•Vertebral column consisting of 26 vertebrae
• Rib cage consisting of 12 pairs of ribs and the sternum
•skull consisting of 22 bones and 7 associated bones.

The 366 skeletal muscles acting on the axial skeleton position the spine, allowing for large movements in the thoracic cage for the function of breathing and to manage the movement of the head.

The appendicular skeleton consist of 126 bones is formed by the:
•shoulder girdles (4),
• upper limbs (60),
• pelvic girdle (2),
• lower limbs (60). Their functions are to make the power of movement (locomotion) possible and to protect the major organs of digestion, excretion, and reproduction.

Question 2

List the six (6) types of bones

Answer 2

1. Long bones – have greater length than width and consist of a shaft and a variable number of endings (extremities). They are usually somewhat curved for strength. Examples include femur, tibia, fibula, humerus, ulna and radius and are designed to provide leverage
2. Short bones – are roughly cube-shaped and have approximately equal length and width. e.g. carpals and tarsals (wrist and ankles bones) which are designed for weight bearing
3. Flat bones – have a thin shape/structure and provide considerable mechanical protection and extensive surfaces for muscle attachments. Examples include cranial bones (protecting the brain), the sternum and ribs (protecting the organs in the thorax), and the scapulae (shoulder blades).
4. Irregular bones – have complicated shapes and so cannot be classified into any of the above (shape-based) categories. Their shapes are due to the functions they fulfill within the body e.g. providing major mechanical support for the body yet also protecting the spinal cord e.g. vertebrae in the spine which also protects the spinal cord
5. Sesamoid bones – develop in some tendons in locations where there is considerable friction, tension, and physical stress e.g. the patella. They may also form in the palms of the hands and the soles of the feet, however their presence and quantity varies considerably from person to person.
6. Sutural bones - are classified by their location rather than by their shape. They are very small bones located within the sutural joints between the cranial bones. The number of sutural bones varies considerably from person to person; therefore, these are un-named bones.

Question 3

What is the relationship between Bandha and joint stability?

Answer 3

Traditionally, Bandha was applied as energetic locks to various or all areas of the torso and not physical muscular contractions. However there has since developed a western focus of Bandha to apply muscular contraction to protect/support the physical body and joints to reduce the risk of injury and to improve the individual āsana and vinyasa during a Yoga class.

Bandha can also be used to support the joints and muscle groups throughout the body by applying the Bandha Principle which is that every muscle must be ‘switched on’ to support the joints during static and moving postures.

Therefore, limbering and Bandha during the pracitce is so crucial, as the stretching action on the ligaments prepares and supports the joints to be more pliable and supple.

The term “double-jointed” refers to people who have more elastic ligaments, allowing their joints to stretch and contort further and can present as hyper extended knees as well as elbows. Applying the Bandha Principle will alleviate this and ensure that the correct muscles support appropriately and safely.

Question 4

What are the three (3) classifications of joints?

Answer 4

Structural classification determines how the bones are connected to each other.

Fibrous joint – joined by dense irregular connective tissue that is rich in collagen fibres. Fibrous joints are also called “fixed” or “immoveable” joints, e.g. the skull bones are connected by fibrous joints.

Cartilaginous joint – joined by cartilage. Cartilage is a flexible connective tissue found in many areas of the body including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs. It is not as rigid as bone but is stiffer and less flexible than muscle.

Synovial joint – not directly joined - the bones have a synovial cavity and are united by the dense irregular connective tissue that forms the articular capsule that is normally associated with accessory ligaments. The main structural differences between synovial and fibrous joints is the existence of capsules surrounding the articulating surfaces of a synovial joint and the presence of lubricating synovial fluid within that capsule known as the synovial cavity.

Question 5

List the six (6) types of synovial joints

Answer 5

Āsana helps circulate the synovial fluid inside the joints, however contrary to common perception; it does not warm up or stimulate the manufacture of synovial fluid. Once the synovial fluid has been reduced (which may be caused by aging or injury) the body does produce more synovial fluid but is responsible for maintaining the level synovial fluid in each synovial joint. Any joint movement helps circulate the synovial fluid, which feeds the cartilage; practicing yoga poses therefore helps keep the cartilage well nourished.

Ball & Socket Joints - Shoulder and Hip joints
Condyloid Joints (or ellipsoidal joints) - The carpals of the wrist
Gliding joints (or planar joints)The carpals of the wrist
Hinge Joints - The elbow (between the humerus and the ulna)
Pivot Joints - The elbow (between the radius and the ulna)
Saddle Joints - The thumb (between the metacarpal and carpal)

Question 6

What are the three (3) components that form a joint

Answer 6

• Synovial Membrane
• Synovial fluid
• Cartilage

Question 7

What is a ligament?

Answer 7

• A ligament is a strand of fibres that keeps bones together in and in their sockets.
• A sheet or band of tough fibrous tissue connecting bones or cartilages or supporting muscles or organs

Question 8

What is a tendon?

Answer 8

• A Tendon is found at the end of your muscle and which connects the muscle to the bone.
• A white fibrous cord of dense regularly arranged connective tissue that attaches muscle to bone.