Joints of the vertebral bodies Joints of the vertebral arches

(Zygapophysial joints, Facet joints) Craniovertebral (atlanto-axial and atlanto-occipital) joints Costovertebral joints Sacroiliac joints

Joints of the Vertebral Column 

A typical vertebra has 6 joints with adjacent vertebrae.

4 synovial joints (2 above & 2 below) 2 symphyses (1 above & 1 below)

Each symphysis includes an intervertebral disc.

Symphyses (Secondary cartilaginous joints) Designed for weight-bearing and strength.

The articulating surfaces of adjacent vertebrae are connected by intervertebral discs and ligaments.

The intervertebral disc consists of an outer anulus fibrosus, which surrounds a central nucleus pulposus.

JOINTS OF VERTEBRAL BODIES

Anulus fibrosus consists of an outer ring of collagen surrounding a wider zone of fibrocartilage arranged in a lamellar configuration.

This arrangement of fibers limits rotation between vertebrae.

Nucleus pulposus (L. pulpa, fleshy) core of the intervertebral disc. Fills the center of the intervertebral disc, is gelatinous, and absorbs compression forces between vertebrae.Their semifluid nature is responsible for much of the flexibility and resilience of the intervertebral disc/column.

Intervertebral discs Provide strong attachments between the vertebral bodies Unite them into a continuous semirigid column Form the inferior half of the anterior border of the IV foramen.

In aggregate, the discs account for 20-25% of the length (height) of the vertebral column.

No intervertebral disc between C1 & C2 Most inferior functional disc is between L5 & S1

Thickness of the discs increases - Vertebral column descends. Relative thickness (Disc thickness/Body size)- Range of movementMost clear--- Cervical & Lumbar regions

Disc thickness most uniform in thoracic region.

The discs are thicker anteriorly in the cervical and lumbar regions, their varying shapes producing the secondary curvatures of the vertebral column.

The semifluid nature of the nucleus pulposus allows it to change shape and permits one vertebra to rock forward or backward on another, as in flexion and extension of the vertebral column.

Function of the Intervertebral Discs

A sudden increase in the compression load on the vertebral column causes the semifluid nucleus pulposus to become flattened.

The outward pushing of the nucleus is accommodated by the resilience of the surrounding anulus fibrosus.

Sometimes, outward push is too great for anulus fibrosus It ruptures Allows nucleus pulposus to herniate Protrude into the vertebral canal, where it may press on the spinal nerve roots, spinal nerve, or even the spinal cord.

With advancing age, the water content of the nucleus pulposus diminishes and is replaced by fibrocartilage.

The collagen fibers of the anulus degenerate and, as a result, the anulus cannot always contain the nucleus pulposus under stress.

In old age the discs are thin and less elastic, and it is no longer possible to distinguish the nucleus from the anulus.

20 y old male 66 year old male

Plane synovial joints between superior and inferior articular processes of adjacent vertebrae.

Those in the cervical region are especially thin and loose, reflecting the wide range of movement.

Accessory ligaments unite the laminae, transverse processes, and spinous processes and help stabilize the joints.

JOINTS OF VERTEBRAL ARCHES(ZYGAPOPHYSIAL JOINTS-FACET JOINTS

Zygapophysial joints permit gliding movements between the articular processes.

Shape and disposition of the articular surfaces determine the types of movement possible.

UNCINATE PROCESS Lateral margins of the upper surfaces of typical cervical vertebrae; elevated into crests or lips.

«UNCOVERTEBRAL» JOINTSClefts (of Luschka

May articulate with the body of the vertebra above to form small "uncovertebral" synovial joints.Commonly develop between the unci of the bodies of C3 or 4-C6 or 7. @ lateral and posterolateral margins of the intervertebral discs.

Considered as synovial joints by some; others; by others as degenerative spaces (clefts) in the discs occupied by extracellular fluid.

1= First rib 2 = Vertebral body of C7 3 = Spinous processes 4 = Uncinate process 5 = Uncovertebral (apophyseal or Luschka's) joint

Joints between vertebrae are reinforced and supported by numerous ligaments, which pass between vertebral bodies and interconnect components of the vertebral arches.

Anterior and posterior longitudinal ligaments On the anterior and posterior surfaces of the vertebral bodies.

Extend along most of the vertebral column.

LIGAMENTS

Anterior longitudinal ligament

Attached superiorly to the base of the skull Extends inferiorly to the anterior surface of the sacrum

Along its length it’s attached to vertebral bodies & intervertebral discs.

Posterior longitudinal ligament

On the posterior surfaces of vertebral bodiesLines the anterior surface of the vertebral canalAttached along its length to vertebral bodies &intervertebral discs. Tectorial membraneUpper part of posterior the longitudinal ligament Connects C2 to intracranial aspect of the base of the skull

Ligamenta flava Between the laminae of adjacent vertebrae on each side.Thin, broad ligaments , and of elastic tissue Form part of the posterior surface of the vertebral canal.

Runs between posterior surface of the lamina on the vertebra below to the anterior surface of the lamina of the vertebra above.

Resist separation of the laminae in flexion Assist in extension back to anatomical position.

Supraspinous ligamentAlong the tips of the spinous processes from C7 to the sacrum

Ligamentum nuchae From C7 to the skull A triangular, sheet-like structure in the median sagittal plane.

Base of the triangle attached to the skullApex attached to the tip of the spinous process of C7Deep side of the triangle attached to the posterior tubercle of C1 &

spinous processes of the other cervical vertebraeSupports the headResists flexion & facilitates returning head to anatomical position

Interspinous ligaments (Interspinal ligaments)

Between adjacent vertebral spinous processes. Attach from the base to the apex of each spinous process

Blend with the supraspinous ligament posteriorly Blend with the ligamenta flava anteriorly

on each side.

2 sets of jointsAtlanto-occipital jointsBetween atlas (C1) & occipital bone of the craniumAtlanto-axial jointsBetween atlas and axis (C2)

A wider range of movement than in rest of the vertebral column. Articulations: Occipital condyles, Atlas & Axis.

CRANIOVERTEBRAL JOINTS

Synovial joints without intervertebral discs

Articulations between Superior articular surfaces of the lateral masses of the atlas

& Occipital condyles

Synovial joints of the condyloid type

Atlanto-occipital Joints

Nodding of the head, flexion and extension of the head occurring when indicating approval (the “yes” movement).

Sideways tilting of the head. Main movement

Flexion, with a little lateral flexion & rotation

Atlanto-occipital Joints

The cranium and C1 are also connected by Anterior & posterior atlanto-occipital membranes Extend from the anterior and posterior arches of C1 to the

anterior and posterior margins of the foramen magnum.

Help prevent excessive movement of atlanto-occipital joints.

3 atlanto-axial articulations 2 (right & left) lateral atlantoaxial joints – plane type jointbetween inferior facets of lateral masses of C1 & superior facets of C2

1 median atlantoaxial joint – pivo type jointbetween dens of C2 & anterior arch of atlas

Atlanto-axial Joints

Head turns from side to side, disapproval (“no” movement).

Cranium and C1 rotate on C2 as a unit.

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Atlanto-axial Joints

During rotation of the head, dens of C2axis or pivot held in a socket or collar formed Anteriorly by anterior arch of the atlas Posteriorly by transverse ligament of the atlasA strong band extending between tubercles on the medial aspects of lateral masses of C1

Atlanto-axial Joints

LigamentsSuperior and inferior longitudinal bands Apical ligament Alar ligamentsCruciate ligament of the atlasTectorial membrane (Membrana tectoria)

Range of movementRegion & individual

The mobility primarily from the intervertebral discs.

The normal range of movement possible in healthy young adults is typically reduced by 50% or more as they age.

Although the movement between any two vertebrae is limited, the summation of movement among all vertebrae results in a large range of

movement by the vertebral column.

Movements of the Vertebral Column

Movements by the vertebral columnFlexion Extension Lateral flexionRotationCircumduction

The range of movement of the vertebral column is limited by the: Thickness, elasticity, and compressibility of the IV discs Shape and orientation of the zygapophysial joints Tension of the joint capsules of the zygapophysial joints Resistance of the back muscles and ligaments (e.g., the ligamenta flava

and the posterior longitudinal ligament) Attachment to the thoracic (rib) cage Bulk of surrounding tissue.

CLINICAL NOTES

A tear within the anulus fibrosus

Material of the nucleus pulposus can track

This material tracks into the vertebral canal or into the intervertebral foramen

Pressure on neural structures.

This is a common cause of back pain.

Disc Hernia & Back Pain

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A prolapsed intervertebral disc may impinge upon the meningeal (thecal) sac, cord, and most commonly the nerve root, producing symptoms attributable to that level.

Neurological signs- Surgery

It is of the utmost importance that the level of the disc protrusion is identified before surgery. This may require MRI scanning and on-table fluoroscopy.

Discectomy/laminectomy

Part of the trunk inferoposterior to the abdomen Area of transition between the trunk and the lower limbs

Pelvic cavityInferiormost part of the abdominopelvic cavity.

Anatomically, the pelvis is the part of the body surrounded by the pelvic girdle (bony pelvis), part of the appendicular skeleton of the lower limb.

PELVISL. Basin

Pelvis is subdivided into greater and lesser pelves. Greater pelvis Surrounded by the superior pelvic girdle. Occupied by inferior abdominal viscera, affording them protection.

Lesser pelvisSurrounded by the inferior pelvic girdle, which provides the skeletal framework for both the pelvic cavity and the perineum—compartments of the trunk separated by the musculofascial pelvic diaphragm.

A basin-shaped ring of bones that connects the vertebral column to the two femurs.

Primary functions of the pelvic girdle: Bear the weight of the upper body when sitting and standing. Transfer that weight from the axial to the lower appendicular

skeleton for standing and walking. Provide attachment for the powerful muscles of locomotion and

posture and those of the abdominal wall.

PELVIC GIRDLE

The pelvic bone is irregular in shape and has two major parts separated by an oblique line on the medial surface of the bone: pelvic bone above this line represents lateral wall of the false

pelvis, part of the abdominal cavity. pelvic bone below this line represents the lateral wall of the

true pelvis, contains the pelvic cavity. Linea terminalis lower two-thirds of this line & contributes to the margin of the pelvic inlet.

Pelvic girdle is formed by 3 bones:Right and left hip bones (coxal bones; pelvic bones): large, irregularly shaped bones, each of which develops from the fusion of three bones 1. Ilium2. Ischium3. Pubis Sacrum: formed by the fusion of five, originally separate, sacral vertebrae.

In infants and children, hip bones are 3 separate bones united by a triradiate cartilage at the acetabulum, the cup-like depression in the lateral surface of the hip bone, which articulates with the head of the femur.

After puberty, the ilium, ischium, and pubis fuse to form the hip bone. The two hip bones are joined anteriorly at the pubic symphysis (L. symphysis pubis) and articulate posteriorly with the sacrum at the sacroiliac joints to form the pelvic girdle.

Superior, fan-shaped part of the hip boneAla, or wing, of the ilium spread of the fanBody of the ilium, the handle of the fan.On its external aspect, the body participates in formation of the acetabulum.

Ilium

IliumThe entire superior margin of the ilium is thickened to form a prominent crest (iliac crest) terminates anteriorly as the anterior superior iliac spine and posteriorly as the posterior superior iliac spine.

Inferior to the anterior superior iliac spine, rounded protuberance called anterior inferior iliac spine.

A prominent tubercle, tuberculum of iliac crest, projects laterally near the anterior end of the crest; the posterior end of the crest thickens to form the iliac tuberosity.

Posteriorly, the sacropelvic surface of the ilium has an auricular surface and an iliac tuberosity articulation with sacrum.

Ilium

Has a body and ramus (L. branch).Body of the ischium forms the acetabulum Ramus of the ischium forms part of the obturator foramen.

Ischium

Ischial tuberosity: large posteroinferior protuberance of ischiumIschial spine: Small pointed posteromedial projection near the junction of the ramus and body Lesser sciatic notch: Concavity between the ischial spine and the ischial tuberosity Greater sciatic notch: Larger concavity superior to the ischial spine and formed in part by the ilium.

Ischium

An angulated bone Superior ramus helps form the acetabulumInferior ramus helps form the obturator foramen.Pubic crest thickening on the anterior part of the body Pubic tubercle Pubic crest ends laterally as a prominent swellingPecten pubis Oblique ridge@ lateral part of superior pubic ramus

Pubis

The pelvis divided into greater (false) and lesser (true) pelves by the oblique plane of the pelvic inlet (superior pelvic aperture).

Pelvic Inlet & Pelvic Outlet

The bony edge (rim) surrounding and defining the pelvicFormed by the: Promontory and ala of the sacrum A right and left linea terminalis (terminal line)

Pelvic Brim

Pubic archformed by the ischiopubic rami (conjoined inferior rami of the pubis and ischium) of the 2 sides.

These rami meet at the pubic symphysis, their inferior borders defining the subpubic angle. The width of the subpubic angle is determined by the distance between the right and the left ischial tuberosities, which can be measured with the gloved fingers in the vagina during a pelvic examination.

Pelvic outlet (inferior pelvic aperture) is bounded by: pubic arch,anteriorly ischial tuberosities, laterally sacrotuberous and sacrospinous ligaments, posterolaterally tip of the coccyx, posteriorly

Medial to the anterior inferior iliac spine is a broad, shallow groove which is bounded medially by the iliopubic eminence (or iliopectineal eminence), which marks the point of union of the ilium and pubis. It constitutes a lateral border of the pelvic inlet.The iliopectineal line is the border of the eminence.

Circular opening between abdominal cavity and pelvic cavity. Promontory of the sacrum protrudes into the inlet, forming its posterior margin in the midline. Formed anteriorly by the pubic symphysis, posteriorly by the sacrum, and laterally by the iliopectineal line.

Pelvic Inlet (Superior Pelvic Aperture)

Part of the pelvis superior to the pelvic inlet.

Bounded by the iliac alae posterolaterally and the anterosuperior aspect of the S1 vertebra posteriorly.

Occupied by abdominal viscera (e.g., the ileum and sigmoid colon).

Greater pelvis (False pelvis)

Part of the pelvis between the pelvic inlet and the pelvic outlet.Bounded by the pelvic surfaces of the hip bones, sacrum, and coccyx.Includes the true pelvic cavity and the deep parts of the perineum (perineal compartment). That is of major obstetrical and gynecological significance.

Lesser pelvis (True pelvis)

The blue line in this 3-D volume rendered CT image (above) represents the linea terminales that separates the false pelvis, which is above it from the true pelvis below it. The false pelvis consists of the iliac wings and has no anterior wall. The pubis bones, sacrum and coccyx, and both ischium bones delimit the false pelvis.

Linea terminalis consists of the arcuate line, pecten pubis, pubic crest.

The pecten pubis forms part of the pelvic brim and the continuation on the superior ramus pubis of the linea terminalis, forming a sharp ridge.

Arcuate line of the ilium is a smooth rounded border on the internal surface of the ilium.

It is immediately inferior to the iliac fossa. It forms part of the border of the pelvic inlet.

The primary joints Sacroiliac joints & pubic symphysis

Sacroiliac joints link the axial skeleton and the inferior appendicular skeleton.

Lumbosacral & sacrococcygeal joints, although joints of the axial skeleton, are directly related to the pelvic girdle. Strong ligaments support and strengthen these joints.

Joints and Ligaments of Pelvic Girdle

Strong, weight-bearing compound joints An anterior synovial joint between the earshaped auricular surfaces of the sacrum & iliumA posterior syndesmosisbetween the tuberosities of the same bones

Differ from most synovial joints in that limited mobility is allowed, a consequence of their role in transmitting the weight of most of the body to the hip bones.

SACROILIAC JOINTS

Weight from the axial skeleton:Sacroiliac ligaments ilia

Femurs –during standing- Ischial tuberosities –during sitting-

Sacrum is actually suspended between the iliac bonesFirmly attached to iliac bones by posterior and interosseous sacroiliac ligaments.

Anterior sacroiliac ligaments Anterior part of the fibrous capsule of the synovial part of the joint. Interosseous sacroiliac ligaments Lie deep between the tuberosities of the sacrum and ilium.Primary structures involved in transferring the weight.Posterior sacroiliac ligaments Posterior external continuation of the same mass of fibrous tissue.

Formed by the posterior sacroiliac ligaments joined by fibers extending from posterior margin of the ilium & base of the coccyx

Passes from posterior ilium, lateral sacrum & coccyx to ischial tuberosity, transforming the sciatic notch of the hip bone into a large sciatic foramen.

Sacrotuberous l igament

Sacrospinous ligament, from lateral sacrum & coccyx to ischial spine, further subdivides this foramen into greater and lesser sciatic foramina.

Most of the time, movement at the sacroiliac joint is limited by interlocking of the articulating bones and the sacroiliac ligaments.

By allowing only slight upward movement of the inferior end of the sacrum relative to the hip bones, resilience is provided to the sacroiliac region when the vertebral column sustains sudden increases in force or weight.

Secondary cartilaginous joint Consists of a fibrocartilaginous interpubic disc & surrounding ligaments uniting the bodies of the pubic bones in the median plane. Interpubic disc is generally wider in women.

PUBIC SYMPHYSIS

Superior & inferior pubic ligamentsSuperior & inferior margins of the symphysis

Superior pubic ligament connects the superior aspects of the pubic bodies and interpubic disc.

Inferior (arcuate) pubic ligament a thick arch of fibers connects the inferior aspects of the joint components, rounding off the subpubic angle as it forms the apex of the pubic arch.

L5 & S1 articulate Anterior intervertebral (IV) joint formed by L5/S1 IV disc

between their bodies &

2 posterior zygapophysial joints (facet joints) between the articular processes of these vertebrae

Fan-like iliolumbar ligaments radiating from the transverse processes of the L5 vertebra to the ilia.

LUMBOSACRAL JOINTS

Secondary cartilaginous joint with an intervertebral disc.

Fibrocartilage & ligaments join apex of the sacrum base of coccyx.

Anterior & posterior sacrococcygeal ligaments long strands that reinforce the joint.

SACROCOCCYGEAL JOINT

CLINICAL NOTES

Sexual differences are related mainly 1. Heavier build and larger muscles of most men 2. Adaptation of the pelvis (particularly the lesser pelvis) in women for parturition (childbearing).

MALE PELVİS V.S. FEMALE PELVİS

Although anatomical differences between male and female pelves are usually clear cut, the pelvis of any person may have some features of the opposite sex. Gynecoid pelvis normal female type; its pelvic inlet typically has a rounded oval shape and a wide transverse diameter. Android pelvis (masculine or funnel-shaped) in a woman may present hazards to successful vaginal delivery of a fetus.

In forensic medicine (the application of medical and anatomical knowledge for the purposes of law), identification of human skeletal remains usually involves the diagnosis of sex.

A prime focus of attention is the pelvic girdle because sexual differences usually are clearly visible.

Even fragments of the pelvic girdle are useful in determining sex.

Feature Male pelvis Female pelvis

GeneralStructure

Thick & Heavy Thin & Light

Greater pelvis

Deep Shallow

Lesserpelvis

Narrow and deep, tapering

Wide and shallow,cylindirical

Pelvic inlet Heart-shaped, narrow Oval and rounded, wide

Pelvic outlet Comparatively small Comparatively large

Ischial spines

Project further medially into the pelvic cavity

Do not project as far medially into the pelvic cavity & smooth

Feature Male pelvis Female pelvis

Obturatorforamen

Round Oval

Acetabulum Large Small

Greater schiatic notch

Narrow, inverted V(approximately 70

degrees)

Almost 90 degrees

Subpubic angle

Smaller (50-60 degrees)

Larger (80-85 degrees)

Sacral promontory

Prominent Not prominent

Size of the lesser pelvis important in obstetrics

Because it is the bony canal through which the fetus passes during a vaginal birth.

To determine the capacity of the female pelvis for childbearing, diameters of the lesser pelvis are noted radiographically or manually during a pelvic examination.

PELVIC DIAMETERS (CONJUGATES)

Diameters of pelvic outletAntero - posterior diameters:Anatomical antero-posterior diameter =11cmfrom the tip of the coccyx to the lower border of symphysis pubis.Obstetric antero-posterior diameter = 13 cmfrom the tip of the sacrum to the lower border of symphysis pubis as the coccyx moves backwards during the second stage of labour.Transverse diameters:Bituberous diameter = 11 cmbetween the inner aspects of the ischial tuberosities.Bispinous diameter = 10.5 cmbetween the tips of ischial spines.

Diameters of pelvic inletAntero -posterior diameters:Anatomical antero-posterior diameter (true conjugate) = 11cmfrom the tip of the sacral promontory to the upper border of the symphysis pubis.Obstetric conjugate = 10.5 cmfrom the tip of the sacral promontory to the most bulging point on the back of symphysis pubis which is about 1 cm below its upper border. It is the shortest antero-posterior diameter.Diagonal conjugate = 12.5 cmi.e. 1.5 cm longer than the true conjugate. From the tip of sacral promontory to the lower border of symphysis pubis (or inferior pubic ligament)

Minimum anteroposterior (AP) diameter of the lesser pelvisTrue (obstetrical) conjugate

From Middle of the sacral promontory To Posterosuperior margin (closest point) of the pubic symphysis

Narrowest distance through which the baby's head must pass in a vaginal delivery.

This distance, however, cannot be measured directly during a pelvic examination because of the presence of the bladder.

Diagonal conjugate (from inferior pubic lig. to promontory) Measured by palpating sacral promontory with the tip of the middle finger, using the other hand to mark the level of the inferior margin of the pubic symphysis on the examining hand.

After the examining hand is withdrawn, the distance between the tip of the index finger (1.5 cm shorter than the middle finger) and the marked level of the pubic symphysis is measured to estimate the true conjugate, which should be 11.0 cm or greater.

Transverse diameter is the greatest distance between the linea terminalis on either side of the pelvis.

Anteroposterior compression of the pelvis occurs during crush accidents (as when a heavy object falls on the pelvis).

This type of trauma commonly produces fractures of the pubic rami.

When the pelvis is compressed laterally, the acetabula and ilia are squeezed toward each other and may be broken.

Pelvic Fractures

Fractures of the bony pelvic ring are almost always multiple fractures or a fracture combined with a joint dislocation.

Pelvic fractures can result from direct trauma to the pelvic bones, such as occurs during an automobile accident, or be caused by forces transmitted to these bones from the lower limbs during falls on the feet.

Weak areas of the pelvis, where fractures often occur:Pubic ramiAcetabula Region of the sacroiliac jointsAlae of the ilium

25 Year Old Male with displaced fracture of the sacrum andsymphysis pubis. The most severe pelvic fractures separate the two sides of the pelvis from each other.

Pelvic fractures may cause injury to pelvic soft tissues, blood vessels, nerves, and organs.

Fractures in the pubo-obturator area are relatively common and are often complicated because of their relationship to the urinary bladder and urethra, which may be ruptured or torn.