THE THE VERTEBRAL VERTEBRAL

COLUMNCOLUMN

The SkeletonThe Skeleton

• Consists of bones, cartilage, joints, and ligaments

• Composed of 206 named bones grouped into two divisions

• Axial skeleton (80 bones)

• Appendicular skeleton (126 bones)

The Axial and Appendicular SkeletonThe Axial and Appendicular Skeleton

The axial skeleton includes the skull, the hyoid bone, the vertebral column (spine, sacrum, and coccyx), the sternum, and the ribs. Its components are aligned along the long axis of the body.

The appendicular skeleton includes the bones of the upper extremities (arms, forearms, and hands), the pectoral (shoulder) girdle, the pelvic (hip) girdle, and the bones of the lower extremities (thigh, knee, leg, and foot). Its components are outside the body main axis.

The vertebral column is composed of a The vertebral column is composed of a series of 33 separate bones known as series of 33 separate bones known as vertebrae. vertebrae. There are seven cervical or neck vertebrae, There are seven cervical or neck vertebrae, Twelve thoracic vertebrae, Twelve thoracic vertebrae, and five lumbar vertebrae. and five lumbar vertebrae. The sacrum is composed of five fused The sacrum is composed of five fused vertebrae, vertebrae, and there are four fused coccygeal vertebraeand there are four fused coccygeal vertebrae

The Vertebral Column The Vertebral Column

Normal CurvaturesNormal Curvatures

NORMAL CURVATURES OF THE VERTEBRAL COLUMNIn the early embryo, the vertebral column is C-shaped; pre-natal and post-natal growth accounts for 4 distinct curvilinear regions in the adult

Normal Curvatures Normal Curvatures

NORMAL CURVATURES OF THE VERTEBRAL COLUMN

1. Primary curvatures:Posterior convexities present at birthImmobile: attach. to skeletal components (rib cage and pelvis)Thoracic and Sacral 2. Secondary curvatures:Anterior convexities that develop after birthFlexible: lack of skeletal connectionsCervical (child hold head erect) and Lumbar (child stand erect/walk)

Abnormal Curvatures Abnormal Curvatures

Presence of an abnormal Presence of an abnormal lateral curvature is called lateral curvature is called scoliosis.scoliosis.

Exaggeration of curvatures Exaggeration of curvatures for example in for example in thoracic region is called thoracic region is called kyphosiskyphosis and and in lumbar region is called in lumbar region is called lordosislordosis. .

SCOLIOSIS, KYPHOSIS AND LORDOSIS

General Structure of VertebraeGeneral Structure of Vertebrae

Spinous Processes (1 per vertebra) project posteriorly or posteroinferiorly in the median plane arise from the point of union of left and right laminaeTransverse Processes (2 per vertebra: left and right) extend posterolaterally from the point of union of pedicles and laminae Articular Processes (Zygapophyses) (4 per vertebra) Left and right, superior and inferioralso arise from the junction of pedicles and laminae Superior processes project superiorly and inferior processes project inferiorly

VERTEBRAL PROCESSES: 7 IN NUMBER ON TYPICAL VERTEBRAE

General Structure of VertebraeGeneral Structure of Vertebrae

Encircled by the body Encircled by the body anteriorly, vertebral arch anteriorly, vertebral arch posteriorly and the pedicles posteriorly and the pedicles laterally is the laterally is the vertebral vertebral foramenforamen, which lodges the , which lodges the spinal cord with its spinal cord with its membranes and blood membranes and blood vessels. vessels.

The vertebral foramina of The vertebral foramina of the successive vertebrae the successive vertebrae form the form the vertebral canalvertebral canal..

There are 4 typical and 3 atypical (atlas, axis and C7) cervical vertebrae.

Typical cervical vertebra has a bifid spine.

Only cervical vertebrae have foramina in their transverse processes .

TYPICAL CERVICAL VERTEBRAE.

The vertebral artery, a venous plexus and autonomic nerve fibres pass through the transverse foramina of the majority of cervical vertebra.

However, the vertebral artery does not pass through the transverse foramen of C7.

TYPICAL CERVICAL VERTEBRAE.

The first cervical vertebra (C1) is called the Atlas.

The Atlas is ring-shaped and supports the skull.

Axis is C2. The axis is non-typical because it has an extra protruding process known as the dens (dental - looks like a tooth).

ATLAS

C7 is non-typical

1. It does not have a bifid spine and the

2. The vertebral artery does not pass through its transverse foramen.

1. Spinous process2. Lamina3. Transverse process4. Pedicle5. Body6. Vertebral formen

C7

There are 8 typical and 4 non-typical (T1, 10, 11 & 12) thoracic vertebrae.

The body of a thoracic vertebra is heart-shaped and typical thoracic vertebra have a round vertebral foramen.

THORACIC VERTEBRAETHORACIC VERTEBRAE

1. Spinous process 2. Lamina 3. Transverse process4. Pedicle 5. Body 6. Vertebral foramen

THORACIC VERTEBRAETHORACIC VERTEBRAE

There are 5 lumbar vertebrae.

It has a distinct large body.

vertebral foramen is triangular and

Costal facets are absent.

5 LUMBAR VERTEBRAE

1. Spinous process

2. Lamina

3. Transverse process

4. Pedicle

5. Body

6. Vertebral foramen

LUMBAR VERTEBRA

There are 5 sacral vertebrae that are fused together.

Distinguishable from other vertebra by its large size, sacral foramen and triangular vertebral foramen.

This bone is the base of the vertebral column and part of the pelvis.

5 FUSED SACRAL VERTEBRAE AND COCCYX

1. Ala

2. Anterior sacral foramen

3. Coccyx

5 FUSED SACRAL VERTEBRAE AND COCCYX

1. Articular surface

2. Median sacral crest

The iliac bones articulate with the articular surfaces of the sacrum forming the sacroiliac joints.

5 FUSED SACRAL VERTEBRAE AND COCCYX

The bodies of adjacent vertebrae are connected by specialized cartilaginous joints known as intervertebral discs.

Intervertebral Discs Intervertebral Discs

Cushion-like pads between vertebraeAct as shock absorbersCompose of about 25% of height of vertebral column

Intervertebral Discs Intervertebral Discs

Intervertebral Discs Intervertebral Discs

• Composed of nucleus pulposus and annulus fibrosis

The annulus is a sturdy tire-like structure that encases a gel-like center, the nucleus pulposus. The annulus enhances the spine’s rotational stability and helps to resist compressive stress.The intervertebral discs are the largest structures in the body without a vascular supply.

Intervertebral Discs Intervertebral Discs

Normally body weight is transmitted through the disc by loading the nucleus pulposus, which is then compressed and transfers its loading to the annulus fibrous.

In most individuals, the fibers of the annulus fibrosus effectively resist this load, but in some people they do not and the nucleus pulposus is forced out of the disc, or is herniated.

A herniated nucleus pulposus can have a profound effect on the adjacent spinal nerves

LigamentsLigaments

Ligament Name Description

Anterior Longitudinal Ligament (ALL) A primary spine stabilizer

About one-inch wide, the ALL runs the entire length of the spine from the base of the skull to the sacrum. It connects the front (anterior) of the vertebral body to the front of the annulus fibrosis.

Posterior Longitudinal Ligament (PLL) A primary spine stabilizer

About one-inch wide, the PLL runs the entire length of the spine from the base of the skull to sacrum. It connects the back (posterior) of the vertebral body to the back of the annulus fibrosis.

Supraspinous Ligament This ligament attaches the tip of each spinous process to the other.

Interspinous Ligament This thin ligament attaches to another ligament called the ligamentum flavum that runs deep into the spinal column.

Ligamentum Flavum The strongest ligament

This yellow ligament is the strongest. It runs from the base of the skull to the pelvis, in front of and between the lamina, and protects the spinal cord and nerves. The ligamentum flavum also runs in front of the facet joint capsules.

(4 per vertebra) joints between articular processes of adjacent vertebral arhces permit gliding movements between vertebrae

Zygapophyseal (facet) joints (4 per vertebra)

superior articular facets of the atlas articulates with the occipital condyles of the skull facilitate nodding (flexion) of the head

Atlanto-occipital joints

The dens of the axis (C2) articulates with he body of the atlas (C1)

facilitates pivoting of the head

Atlanto-axial joint

REMEMBER THESE TERMS

Osteology - Lt. Ossis a bone, i.e the study of bones.

Arthrology - The branch of anatomy dealing with the joints and ligaments of the body.

Myology - Gr. Myo(s) a mouse, muscle + logos (word, speech, reason) a combining form designating a specified science or study, i.e the study of muscles.

The spinal cord lies within the vertebral canal and is covered by three membranes, known as meninges.

The outermost layer is the dura mater, a tough fibrous sheath closely applied to the inner layer of bone surrounding the spinal canal.

Between the dura and the bone is a potential space, the epidural space, which normally contains a small amount of fat and vertebral veins.

Beneath the dura mater is a thin and delicate membrane called the arachnoid mater

MENINGES

MENINGESNormally the arachnoid mater is closely applied to the underside of the dura mater, but a potential space exists, the subdural space, which can fill with blood or pus under pathologic conditions

Beneath the arachnoid mater and intimately applied to the spinal cord is the pia mater.

The space between the arachnoid mater and pia mater is the subarachnoid space (normally filled with cerebrospinal fluid, which surrounds the entire brain and spinal cord).

A rope like extension of the pia mater, the filum terminale attaches the end of the spinal cord to the caudal end of the dura mater.

In the adult the spinal cord usually ends (4) at the L1/2 disc, but at L2/3 in the infant.

Under aseptic conditions CSF sample is collected from the subarachnoid space by inserting a specific needle in the midline between the spinous processes of L3 and L4 (or L4 and L5).

At these levels there is little danger of damaging the spinal cord in adults.

Lumbar spinal puncture

The spinal cord receives its arterial supply from three small, longitudinally running arteries-the two posterior spinal arteries and one anterior spinal artery.

The posterior spinal arteries, which arise either directly or indirectly from the vertebral arteries, run down the side of the spinal cord, close to the attachments of the posterior spinal nerve roots.

The anterior spinal arteries, which arise from the vertebral arteries, unite to form a single artery, which runs down within the anterior median fissure.

The veins of the spinal cord drain into the internal vertebral venous plexus.

BLOOD SUPPLY OF THE SPINAL CORD

BLOOD SUPPLY OF THE SPINAL CORD

oChronic degenerative disease of intervertebral discs and/or vertebral bodies

oMay compress spinal cord, nerves, or roots

SPONDYLYSIS; SPONDYLOSIS

Results in loss of all sensation and voluntary movement inferior to the lesion

ParaplegiaParalysis of lower body including both lower extremitiesResults from spinal cord transection between cervical and lumbosacral enlargements

QuadriplegiaParalysis of all four limbsResults from spinal cord transection superior to C3

SPINAL CORD TRANSECTION

Pain resulting from irritation of the sciatic nerve

Usually caused by compression or trauma to the sciatic nerve or its roots

SCIATICA

Shooting pain that radiates down one or both legs in a dermatomal distribution, often with associated sensory and motor impairment

oUsually caused by compression or stretching of spinal nerves or roots

RADICULOPATHIES

OSTEOPOROSIS

Most common in postmenopausal women

Loss of endogenous estrogen leads to severe decrease in vertebral bone density, due to demineralization

Can be prevented or slowed by hormone replacement therapy.

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