The Vertebral Column Spine The Vertebral Column Spine

The Vertebral Column (Spine)

The Vertebral Column (Spine) • Your spine is made up of vertebrae, which protects your valuable spinal column and allows for twisting and bending of the torso (trunk). • All of the somatic sensory signals from your body to your brain travel from the sensory receptor, through the peripheral nervous system to the spinal cord, then up to the brain.

The Vertebral Column (Spine) • All of the signals from your brain for conscious muscle control, travel from the brain through the spinal column, then to the peripheral nervous system to your muscles. • If the spinal column gets destroyed (by being cut or crushed or destroyed by disease), the person will be paralyzed from the level of the injury down! • In addition, they will have no feeling below the injury point. • Of course there are many cases in which the destruction is not complete and the person may have some sensory or muscular function.

The Vertebral Column (Spine) • After a spinal injury, the spinal cord swells. • The spinal cavity (part of the dorsal cavity) is filled with cerebral-spinal fluid (or cerebrospinal fluid) and there is no room for swelling. • This causes compression of the nerves of the spinal cord. It is possible that some function may return after the swelling dissipates. • Also, in some cases, the nerves can be retrained (using physical therapy) to find new pathways that circumvent the damaged area.

The Anatomy of the Vertebral Column The vertebral column consists of 33 vertebrae; • 7 cervical vertebrae • 12 thoracic vertebrae • 5 lumbar vertebrae • 5 fused sacral vertebrae that make up the sacrum • 4 fused coccygeal vertebrae that form the coccyx (tail bone).

The Anatomy of the Vertebral Column A "typical cervical vertebra" consists of the following structures: • THE BODY • ARTICULATING PROCESS (articulation means joint). This is where the vertebrae are forming joints. • TRANSVERSE PROCESS • SPINOUS PROCESS • LAMINA • *THE VERTEBRAL FORAMEN (where the spinal cord travels through) • ONLY THE CERVICAL VERTEBRA HAVE THE TRANSVERSE FORAMEN

the transverse foramina • In order to identify the cervical vertebra, you will need looks for the holes; the transverse foramen. • Cervical vertebrae are the only vertebrae that have these structures.

The Cervical Vertebrae THE CERVICAL VERTEBRAE • You have 7 cervical vertebrae. • They are numbered starting with number 1 at the top (superior) end of the vertebral column (spine).

The Structures of a Typical Cervical Vertebrae • The Transverse Foramen - The cervical vertebrae are the only vertebrae that contain the transverse foramen. The transverse foramen is a hole within the area of the transverse process that functions as a passageway for the vertebral artery and vein. • The vertebral foramen is a large opening at the center of the vertebra that the spinal cord passes through. • The spinous process is a narrow posterior projection from the junction of the two laminae. It is an attachment point for ligaments and muscles that move the head and neck. This is the portion of the spine you can see through the skin in some people. (Ridges you can feel running down your back). This process proceeds dorsally. • Articulate process - Each bone has 2 superior articulate processes and 2 inferior. These articulation points that connect the vertebra to the vertebrae lying superiorly and inferiorly. • Lamina - flat wing-like surface between spinous and transverse process. • The body of the vertebra acts as a surface for the intervertebral (or vertebral) discs. • The transverse process is a small extension that projects laterally from the body and acts as an attachment site for muscles. are out to the side of the vertebra (laterally).

The Cervical Vertebrae The 1 st and 2 nd cervical vertebrae have unique features and they are given special names. • C 1 is called "The Atlas" • C 2 is called "The Axis".

WARNING! • For practical exams, you will be expected to identify not only the specific structures of individual vertebrae, but you will need to identify what level of the spine (the vertebral column) an unarticulated vertebra is from.

The Atlas (C 1) • In anatomy, the atlas (C 1) is the most superior cervical vertebra of the spine. • The ATLAS is the ONLY VERTEBRA that does NOT have a BODY! This is the feature you should look for to identify this bone!

The Atlas (C 1) • The Atlas articulates with the occipital condyles that are structures on the posterior region of the occipital bone (part of the skull). • It gets its name from the character named "Atlas" from Greek mythology that held the "weight of the world" on his shoulders. In a somewhat similar manner, the atlas of your spine supports the head. (globe).

Superior View of the Axis The Axis (C 2) • The AXIS (C 2) is the 2 nd cervical vertebra. • It has a noticeable phallic protrusion called the Dens or the Odontoid Process, which no other vertebra has. This is the area you should look for to help you identify this bone.

The Axis (C 2) • The AXIS (C 2) is the 2 nd cervical vertebra. • It has a noticeable phallic protrusion called the Dens or the Odontoid Process, which no other vertebra has. This is the area you should look for to help you identify this bone. Inferior View of the Axis

The Axis (C 2) • The atlas (C 1) and the axis (C 2) together form the joint that connects the skull to the spine.

THE THORACIC VERTEBRAE • The vertebral column has 12 thoracic vertebrae. • Each of these vertebra articulate with the ribs. • The point of articulation on the thoracic vertebrae, occurs at specialized structures that look like a thin patch of super glue, called the demifacets. • Demifacets are only found in thoracic vertebrae.

THE THORACIC VERTEBRAE • Each of the vertebra articulate with the ribs. • The thoracic vertebrae are the ONLY vertebrae that articulate with the ribs.

The point of articulation on the thoracic vertebrae, occurs at specialized structures that look like a thin patch of super glue, called the demifacets. Demifacets are only found in thoracic vertebrae.

• Unlike the cervical vertebrae, the thoracic vertebrae DO NOT have Transverse Foramina. • You may recall that the transverse foramina were the two openings; one on each of the transverse processes in the typical cervical vertebrae. The Structures of the Thoracic Vertebrae

The Structures of the Thoracic Vertebrae The other structures of the thoracic vertebrae are common to vertebrae at the other levels, but will be defined here again, just for completeness. • The vertebral foramen is a large opening at the center of the vertebra that the spinal cord passes through. • The spinous process is the portion of the spine you can see in some people (or the "ridges" you can feel running down your back) • Articulate Processes - Each bone has 2 superior articulate processes and 2 inferior • Lamina - flat wing-like surface between spinous and transverse process. • The Body of the vertebra acts as a surface for the intervertebral (or vertebral) discs. • The Transverse Process is a small extension that projects laterally from the body and acts as an attachment site for muscles. They project out to the sides of the vertebrae (laterally).

The Structures of the Thoracic Vertebrae • Also, each thoracic vertebra has two small specialized structures (or bone markings) called the demifacets that act as articulation points for the ribs. • The demifacets are only found in the thoracic vertebra and is one of the ways you can distinguish a thoracic vetebra from the cervical or the lumber vertebrae.

The Structures of the Thoracic Vertebrae • The thoracic vertebrae all have structure (or bone marking) located laterally on each side, called the demifacets. • The demifacets of the thoracic vertebrae articulation points for the ribs. • All 12 of the thoracic vertebrae connect to the ribs, so all 12 thoracic vertebrae will have a set of demifacets. • It almost looks like an area of superglue.

The Lumbar Vertebrae • The human vertebral column has 5 lumbar vertebrae that lie in the lumbar region (lower back area).

The Lumbar Vertebrae • The lumbar vertebra DO NOT have transverse foramina that we saw in the cervical vertebrae, and they DO NOT have the demifacets that were seen in the thoracic vertebrae, because they do not connect to the ribs.

• Articulate Processes - Each bone has 2 superior articulate processes and 2 inferior. • The Structures of the Lumbar Vertebrae The articulate processes of the lumbar vertebrae are very pronounced and help to distinguish it from vertebrae from other areas. • Lamina - flat wing-like surface between spinous and transverse process. • The vertebral foramen is a large opening at the center of the vertebra that the spinal cord passes through. • The spinous process is the portion of the spine you can see in some people (or the "ridges" you can feel running down your back). In the lumbar region these are "squared off" instead of "pointy". • Articulate Processes - Each bone has 2 superior articulate processes and 2 inferior • Lamina - flat wing-like surface between spinous and transverse process. • The vertebral foramen is a large opening at the center of the vertebra that the spinal cord passes through. • The Body of the vertebra acts as a surface for the intervertebral (or vertebral) discs. • The Transverse Process is a small extension that projects laterally from the body and acts as an attachment site for muscles. are out to the side of the vertebra (laterally).

THE SACRAL REGION • THE SACRUM • The sacrum is easy to spot. It is made up of either four or five fused vertebrae with holes for the spinal nerve to pass. • One of its jobs is to transmit the weight of your body from the spine down into the two halves of the pelvis, which then take it through the legs into the feet and eventually into the ground.

• THE COCCYX • The very last part of the spine is the coccyx (tailbone). • The word coccyx comes from the Greek word for "cuckoo bird". • The coccyx got this name, because it sort of looks like a bird’s beak. • The coccyx is made up of approximately four remnant vertebrae fused together. THE SACRAL REGION • When placed in alignment with the sacrum, it simply hooks onto the end of the sacrum and continues the curve pattern set by the sacrum.

IDENTIFYING THE REGION • For the practical exam, the vertebrae will be sitting by themselves (not articulated). • You will need to be able to identify the LEVEL (the Region of the Vertebral Column) that the vertebra is from, as well as the structures (bone markings) of that vertebra.

You need to be able to tell the differences between the vertebrae that come from… - the Cervical Level (or Region) of the Vertebral Column - the Thoracic Level (or Region) of the Vertebral Column or - the Lumbar Level (or Region) of the Vertebral Column

• The intervertebral foramen is the passageway for the spinal nerve roots to leave the spinal cord. • This structure is not a hole in the bone, like the vertebral foramen or the transverse foramen. • Instead, this hole is created when the vertebrae articulated with one another. The intervertebral foramen • The spinal cord travels inferiorly through the vertebral foramina of the vertebrae.

• The spinal cord gives rise to a bundle of spinal nerves at each level of the vertebrae. • These nerves travel from the spinal cord to various targets through the intervertebral foramina (plural foramen). The intervertebral foramen • In addition, nerves carrying sensory information from the periphery will enter the vertebral column through the intervertebral foramina and join with the spinal cord on their way to the brain.