Human Axial Skeleton and Spinal Column

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What percentage of the entire height of the vertebral column do intervertebral disks constitute?

60-70%

40-50%

10-20%

20-33% (correct)

What role do intervertebral disks play in the vertebral column?

To absorb compression and bending loads

To bear and distribute loads and restrain excessive motion (correct)

To provide structural support

To provide lubrication to the joints

What percentage of the total disc area does the nucleus pulposus occupy in cross-section?

10-20%

30-50% (correct)

60-70%

80-90%

What is the characteristic of the nucleus pulposus that makes it expand outwardly under pressure?

Its high water content Signup and view all the answers

What type of loads is the annulus fibrosus particularly suited to resist?

Torsional loads Signup and view all the answers

Why are the posterior laminallae of the annulus fibrosus thinner than the anterior laminallae?

Due to the posterior location of the nucleus pulposus Signup and view all the answers

What type of cartilage makes up the cartilaginous end plates?

Hyaline cartilage Signup and view all the answers

What is the consequence of the posterior location of the nucleus pulposus in adult disks?

Predisposition to posterior disk herniation Signup and view all the answers

What is the primary function of the vertebral bodies in the vertebral column?

To bear mainly compressive loads Signup and view all the answers

What is the thickness of the intervertebral disk in the lumbar region?

9 mm Signup and view all the answers

What is the ratio of the thickness to the height of the vertebra in the cervical region?

2/5 Signup and view all the answers

What is the functional unit of the vertebral column?

Motion Segment Signup and view all the answers

What is the main reason for the vertebral bodies in the lumbar region being thicker and wider?

To sustain the larger loads to which the lumbar spine is subjected Signup and view all the answers

What is the mechanical and functional importance of the intervertebral disc?

It bears and distributes loads and restrains excessive motion Signup and view all the answers

What is the primary function of the vertebral column?

To transfer loads from the head and trunk to the pelvis and protect the spinal cord Signup and view all the answers

What is the arrangement of trabecular bone within the vertebral bodies?

Aligned with the trajectories of stress in three orientations Signup and view all the answers

What is the component of the motion segment that consists of the vertebral bodies and intervertebral disc?

Anterior portion Signup and view all the answers

What is the purpose of the facets on the vertebrae?

To form the intervertebral joints Signup and view all the answers

How many vertebrae make up the human spinal column?

24 Signup and view all the answers

What is the term for the functional unit of the spine?

Motion segment Signup and view all the answers

What is the component of the vertebral body that fails first under excessive loading?

Cancellous bone Signup and view all the answers

What is the orientation of the trabecular arrangement within the vertebral bodies?

One vertical and two oblique Signup and view all the answers

What percentage of loads on the spine can intra-abdominal pressure reduce?

40 % Signup and view all the answers

What is the importance of maintaining the natural curves in the back while lifting?

It provides strength and support for the back Signup and view all the answers

What is the advantage of tightening abdominal muscles before lifting an object?

It helps to reduce the load on the back Signup and view all the answers

Why is it important to test the weight of an object before lifting it?

To plan ahead and avoid overexertion Signup and view all the answers

What is the advantage of keeping objects close to the body while lifting?

It reduces the load on the back Signup and view all the answers

Why is it recommended to pivot with the feet instead of twisting the spine while lifting?

To reduce the load on the back Signup and view all the answers

What is the advantage of using a cart for heavy items?

It reduces the load on the back Signup and view all the answers

What happens to the compressive loads at the L3L4 motion segments during normal walking?

They increase with walking speed Signup and view all the answers

What is the primary function of the disc in the motion segment?

To store energy and distribute loads Signup and view all the answers

What is the approximate pressure in a disc loaded in compression?

1.5 times the externally applied load per unit area Signup and view all the answers

What type of stress is primarily produced in the disc during rotation?

Shear stress Signup and view all the answers

What is a mechanical factor that favours herniated disc?

Preexisting disc degeneration Signup and view all the answers

What percentage of the compressive load do the facets carry when the person is in the upright standing posture?

10-20% Signup and view all the answers

What happens to the load-sharing between the facets and the disc when the spine is in flexion?

The proportion of the total load shared by the disc increases Signup and view all the answers

What is the primary role of the postural muscles during standing?

To provide constant active support Signup and view all the answers

What is the approximate percentage of the anterior shear load on the spine in torsion carried by the facets?

More than 50% Signup and view all the answers