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
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.
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
movement
Most 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.
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.
 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.
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.
1= First rib
2 = Vertebral body of C7
3 = Spinous processes
4 = Uncinate process
5 = Uncovertebral
(apophyseal or Luschka's) joint
Considered as synovial joints by some; others; by others as degenerative
spaces (clefts) in the discs occupied by extracellular fluid.
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.
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 bodies
Lines the anterior surface of the vertebral canal
Attached along its length to vertebral bodies &intervertebral discs.
Tectorial membrane
Upper 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 ligament
Along 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 skull
Apex attached to the tip of the spinous process of C7
Deep side of the triangle attached to the posterior tubercle of C1 &
spinous processes of the other cervical vertebrae
Supports the head
Resists 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 joints
Atlanto-occipital joints
Between atlas (C1) & occipital bone of the cranium
Atlanto-axial joints
Between atlas and axis (C2)
Synovial joints without
intervertebral discs
A wider range of movement than in rest of the vertebral column.
Articulations: Occipital condyles, Atlas & Axis.
Articulations between
Superior articular surfaces of the lateral masses of the atlas
&
Occipital condyles
Synovial joints of the condyloid type
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
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 joint
between inferior facets of lateral masses of C1 & superior facets of C2
1 median atlantoaxial joint – pivot type joint
between dens of C2 & anterior arch of atlas
Head turns from side to side, disapproval (“no” movement).
Cranium and C1 rotate on C2 as a unit.
.
During rotation of the head, dens of C2
axis or pivot held in a socket or collar formed
Anteriorly by anterior arch of the atlas
Posteriorly by transverse ligament of the atlas
A strong band extending between tubercles on the medial aspects of lateral masses of C1
Ligaments
Superior and inferior longitudinal bands
Apical ligament
Alar ligaments
Cruciate ligament of the atlas
Tectorial membrane (Membrana tectoria)
Range of movement
Region & 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 by the vertebral column
Flexion
Extension
Lateral flexion
Rotation
Circumduction
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.
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.
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.
L. Basin
Part of the trunk inferoposterior to the abdomen
Area of transition between the trunk and the lower limbs
Pelvic cavity
Inferiormost 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.
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 pelvis
Surrounded 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.
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. Ilium
2. Ischium
3. 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 bone
Ala, or wing, of the ilium spread of the fan
Body of the ilium, the handle of the fan.
On its external aspect, the body participates in formation of the
acetabulum.
The 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.
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.
Inferior to the anterior superior iliac spine, rounded protuberance
called anterior inferior iliac spine.
Posteriorly, the sacropelvic surface of the ilium has
an auricular surface and an iliac tuberosity articulation with
sacrum.
Has a body and ramus (L. branch).
Body of the ischium forms the acetabulum
Ramus of the ischium forms part of the obturator foramen.
Ischial tuberosity: large posteroinferior protuberance of ischium
Ischial 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.
An angulated bone
Superior ramus helps form the acetabulum
Inferior 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 swelling
Pecten pubis Oblique ridge@ lateral part of superior pubic ramus
The pelvis divided into greater (false) and lesser (true) pelves by
the oblique plane of the pelvic inlet (superior pelvic aperture).
The bony edge (rim) surrounding and defining the pelvic
Formed by the:
 Promontory and ala of the sacrum
 A right and left linea terminalis (terminal line)
Pubic arch
formed 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.
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).
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.
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.
Joints and Ligaments of Pelvic Girdle
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.
Strong, weight-bearing compound joints
An anterior synovial joint
between the earshaped auricular surfaces of the sacrum & ilium
A posterior syndesmosis
between 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.
Weight from the axial skeleton:
Sacroiliac ligaments
ilia
Femurs –during standingIschial tuberosities –during sittingSacrum is actually suspended between the iliac bones
Firmly 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.
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.
Superior & inferior pubic ligaments
Superior & 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.
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.
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).
The difference
between the male
and female pelvis
Difference
Between Male
& Female
Pelvis
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
General
Structure
Male pelvis
Female pelvis
Thick & Heavy
Thin & Light
Greater
pelvis
Deep
Shallow
Lesser
pelvis
Narrow and deep,
tapering
Wide and shallow,
cylindirical
Heart-shaped, narrow
Oval and rounded, wide
Comparatively small
Comparatively large
Project further medially
into the pelvic cavity
Do not project as far medially
into the pelvic cavity & smooth
Pelvic inlet
Pelvic outlet
Ischial
spines
Feature
Male pelvis
Obturator
foramen
Round
Oval
Acetabulum
Large
Small
Narrow, inverted V
(approximately 70
degrees)
Almost 90 degrees
Smaller
(50-60 degrees)
Larger
(80-85 degrees)
Prominent
Not prominent
Greater
schiatic
notch
Subpubic
angle
Sacral
promontory
Female pelvis
PELVIC DIAMETERS (CONJUGATES)
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.
Diameters of pelvic outlet
Antero - posterior diameters:
Anatomical antero-posterior diameter =11cm
from the tip of the coccyx to the lower border of symphysis pubis.
Obstetric antero-posterior diameter = 13 cm
from 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 cm
between the inner aspects of the ischial tuberosities.
Bispinous diameter = 10.5 cm
between the tips of ischial spines.
Diameters of pelvic inlet
Antero -posterior diameters:
Anatomical antero-posterior diameter (true conjugate) =
11cm
from the tip of the sacral promontory to the upper border of the
symphysis pubis.
Obstetric conjugate = 10.5 cm
from 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 cm
i.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 pelvis
True (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.
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 rami
Acetabula
Region of the sacroiliac joints
Alae of the ilium
25 Year Old Male
with displaced
fracture of the
sacrum and
symphysis 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.