Anatomy of the Back and Vertebral Column

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Questions and Answers

What is the primary function of the true back muscles?

Moving the upper limbs

Moving the axial skeleton (correct)

Maintaining posture

Protecting the spinal cord

What is the longest part of the axial skeleton?

Vertebral column (correct)

Sternum

Cranium

Ribs

What is the main purpose of the vertebral column?

To protect the spinal cord

To support the weight of the body

To provide a rigid axis for the body

All of the above (correct)

What percentage of the vertebral column is formed by intervertebral discs?

One quarter Signup and view all the answers

What is the role of the vertebral column in locomotion?

It plays an important role in posture and locomotion Signup and view all the answers

What is the length of the vertebral column in adults?

72-75 cm Signup and view all the answers

What is the function of the skin and subcutaneous tissue in the back?

To provide a layer of protection and support Signup and view all the answers

What is the function of the spinal cord and meninges in the back?

To transmit nerve impulses Signup and view all the answers

What is the term for the meningeal branches that run back through the foramina into the vertebral canal?

Recurrent Signup and view all the answers

Which structure is NOT supplied by nerve fibers from the nerves of the vertebral column?

Spinal cord Signup and view all the answers

What is the function of the nerve fibers that supply the anuli fibrosi and ligaments?

Proprioception Signup and view all the answers

What is the function of the sympathetic fibers that supply the blood vessels within the vertebral canal?

Vasoconstriction Signup and view all the answers

How many vertebrae are typically found in an adult vertebral column?

33 Signup and view all the answers

Where are the anuli fibrosi located?

IV discs Signup and view all the answers

What is the primary function of the vertebral body?

Giving strength to the vertebral column and supporting body weight Signup and view all the answers

What is the function of the nerve fibers that supply the periosteum?

Pain reception Signup and view all the answers

What is the name of the joint that facilitates flexibility in the vertebral column?

Synovial zygapophysial joint Signup and view all the answers

What is the term for the smaller, cylindrical bones that make up the vertebral column?

Vertebra Signup and view all the answers

What is the name of the region where the vertebral column and sacrum meet?

Lumbosacral angle Signup and view all the answers

What type of bone is found in the vertebral body?

Trabecular bone Signup and view all the answers

How many sacral vertebrae fuse in adults to form the sacrum?

5 Signup and view all the answers

At what age do the 4 coccygeal vertebrae fuse to form the coccyx?

After approximately 30 Signup and view all the answers

What is the primary function of the sacrum in the body?

To transmit the weight of the body to the pelvic girdle Signup and view all the answers

What is thebundle of spinal nerve roots arising inferior to the L1 vertebra known as?

Cauda equina Signup and view all the answers

What is the function of the posterior atlanto-occipital and atlanto-axial membranes?

To span the gaps between the atlas and occipital bone and the axis Signup and view all the answers

How many pairs of sacral foramina are typically found on the pelvic and posterior surfaces of the sacrum?

Four pairs Signup and view all the answers

What is the primary reason for the mobility of the vertebral column?

The compressibility and elasticity of the IV discs Signup and view all the answers

Which part of the S1 vertebra is an important obstetrical landmark?

Sacral promontory Signup and view all the answers

What is the term for bending of the vertebral column to the right or left from the neutral position?

Lateral flexion Signup and view all the answers

What is the term for returning to the erect posture from a position of lateral flexion?

Lateral extension Signup and view all the answers

What is the angle at which the sacrum articulates with the L5 vertebra?

130° to 160° Signup and view all the answers

What is the characteristic of the pelvic surface of the sacrum?

Smooth and concave Signup and view all the answers

What structure do the vertebral arteries penetrate before traversing the foramen magnum?

The atlanto-occipital membrane Signup and view all the answers

What is the characteristic of the dorsal surface of the sacrum?

Rough and convex Signup and view all the answers

What is the role of the anterolateral abdominal muscles in movements of the vertebral column?

They assist movement Signup and view all the answers

When does the fusion of the sacral vertebrae start?

After age 20 Signup and view all the answers

What is the axis of movement in the vertebral column?

The nuclei pulposi of the IV discs Signup and view all the answers

What is the effect of aging on the range of movement of the vertebral column?

It decreases by 50% or more Signup and view all the answers

Study Notes

Overview of Back

The back is the posterior aspect of the trunk, inferior to the neck and superior to the buttocks.
It comprises skin, subcutaneous tissue, muscles, vertebral column, ribs, spinal cord, and meninges.
The back is the region where the head, neck, and limbs are attached.

Overview of Vertebral Column

The vertebral column is the skeleton of the neck and back that forms the axial skeleton.
It extends from the cranium to the apex of the coccyx, approximately 72-75 cm long.
The vertebral column:
- Protects the spinal cord and spinal nerves.
- Supports the weight of the body superior to the level of the pelvis.
- Provides a partly rigid and flexible axis for the body.
- Plays an important role in posture and locomotion.

Vertebrae

There are 33 vertebrae in an adult, arranged in five regions: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 4 coccygeal.
Significant motion occurs only between the 25 superior vertebrae.
The vertebrae gradually become larger as the vertebral column descends to the sacrum and then become progressively smaller towards the apex of the coccyx.
The vertebral column is flexible due to the many small bones separated by resilient intervertebral discs.

Structure and Function of Vertebrae

A typical vertebra consists of a vertebral body, vertebral arch, and seven processes.
The vertebral body is the more massive, roughly cylindrical, anterior part of the bone that gives strength to the vertebral column and supports body weight.
The size of the vertebral bodies increases as the column descends, most markedly from T4 inferiorly, as each bears progressively greater body weight.
The vertebral body consists of vascular, trabecular (spongy, cancellous) bone enclosed by a thin external layer of compact bone.

Sacrum

The sacrum provides strength and stability to the pelvis and transmits the weight of the body to the pelvic girdle.
The sacral canal is the continuation of the vertebral canal in the sacrum, containing the bundle of spinal nerve roots arising inferior to the L1 vertebra.
There are four pairs of sacral foramina on the pelvic and posterior surfaces of the sacrum for the exit of the posterior and anterior rami of the spinal nerves.
The sacrum is tilted so that it articulates with the L5 vertebra at the lumbosacral angle, which varies from 130° to 160°.

Movements of the Vertebral Column

The range of movement of the vertebral column varies according to the region and the individual.
The vertebral column is capable of flexion, extension, lateral flexion, and rotation (torsion).
The range of movement is limited by the:
- Thickness, elasticity, and compressibility of the intervertebral discs.
- Shape and orientation of the zygapophysial joints.
- Tension of the joint capsules of the zygapophysial joints.
- Resistance of the back muscles and ligaments.
- Attachment to the thoracic (rib) cage.
- Bulk of surrounding tissue.

Nerves of Vertebral Column

As the spinal nerves exit the intervertebral foramina, most of the meningeal branches run back through the foramina into the vertebral canal.
Some branches remain outside the canal and are distributed to the anterolateral aspect of the vertebral bodies and intervertebral discs.
The nerves also supply the periosteum, annuli fibrosi, and anterior longitudinal ligament.
Inside the vertebral canal, transverse, ascending, and descending branches distribute nerve fibers to the:
- Periosteum.
- Ligamenta flava.
- Anuli fibrosi of the posterior and posterolateral aspect of the intervertebral discs.
- Posterior longitudinal ligament.
- Spinal dura mater.
- Blood vessels within the vertebral canal.

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Description

Learn about the structure and composition of the back, including skin, muscles, and vertebral column. Understand the functions and anatomy of the vertebral column.