This document provides an overview of the anatomy of the thorax, pelvis, and back. It describes the bones and structures that make up the thoracic cage, including the sternum, ribs, and thoracic vertebrae. It then discusses the regional characteristics of the different types of vertebrae, including the cervical, thoracic, lumbar, sacral and coccygeal vertebrae. Key features of each region are identified, such as the transverse processes of the cervical vertebrae which contain the transverse foramina through which structures like the vertebral arteries pass.

1. Anatomy of the Thorax, Pelvis and
Back
1
By Addis T.

2. Thorax
The thorax (chest) is the
superior part of the
trunk between the neck
and abdomen
The superior thoracic
aperture bordered by
vertebra TI, rib I, and the
manubrium of sternum
The inferior thoracic
aperture bordered by
vertebra T12, rib 12, the
end of rib 11, the costal
margin, and the xiphoid
process of sternum By Addis T. 2

3. The Bony Thorax (thoracic cage)
 Sternum
Composed of Manubrium, Body, Xiphoid Process
form anterior boundary with costal cartilages
 Ribs (12 pair)
7 pair True Ribs
3 pair False Ribs
2 pair are floating
 Form lateral boundaries
 Vertebrae
Thoracic(12)
Forms Posterior boundary of the cage
By Addis T. 3

4. The Sternum
Manubrium
Has Jugular (sternal)
notch
Articulats with rib #1 & 2
Articulate with clavicle at
Clavicular facets
Sternal Angle –articulate
2nd rib which is a major
surface landmark used by
clinicians
Body
Articulates with ribs
2-7
Xiphosternal joint
Xiphoid process
Cartilage-calcifies
through time
Partial attachment of
many muscles
By Addis T. 4

5. By Addis T. 5

6. The Ribs
Twelve pairs
Ribs 1-7 attach directly to sternum by separate
costal cartilages - true ribs
Ribs 8-10 attach indirectly to sternum by attaching
to costal cartilages –false immediately above
Ribs 11-12 have no anterior attachments - floating
ribs
By Addis T. 6

7. By Addis T. 7

8. Rib Anatomy
Typical Ribs
(3rd-9th)
Head (2 facets)
Neck
Tubercle
Angle
Shaft
Subcostal Groove
By Addis T. 8

9. 9
By Addis T.

10.  Atypical Ribs (1st , 2nd ,
10th , 11th & 12th )
 1st rib-short, wider,
posses subclavian groove ,
no angle
 1st , 10th, 11th -12th
articulate with only = one
vertebra (single articular
facet)
 #11, 12
– don’t articulate with
transverse processes (not
have tubercle), or anteriorly
at all,
– very short neck,
– poor/no angle and costal
groove
By Addis T. 10

11. By Addis T. 11

12. Vertebral Column
 The vertebral column the main
part of the axial skeleton, which
extends from the cranium
(skull) to the apex of the coccyx.
 Composed of:-
 The vertebrae, IV discs &
associated ligaments.
 The adult vertebral column is
72-75 cm long
 one quarter is formed by the
IV discs
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By Addis T.

13. Vertebrae…
 The vertebral column consists of 33
vertebrae arranged in five regions.
 7 cervical, 12 thoracic, 5 lumbar, 5
sacral, and 4 coccygeal.
 Of the 9 inferior vertebrae,
 the 5 sacral vertebrae are fused in
adults to form the sacrum
 after approximately age 30, the 4
coccygeal vertebrae fuse to form the
coccyx.
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By Addis T.
Significant motion occurs only between 25 superior vertebrae
The vertebrae gradually become larger as the vertebral
column descends to the sacrum and then become
progressively smaller toward the apex of the coccyx

14. Vertebral Column
By Addis T. 14

15. Structure and Function of the Vertebrae
• Vertebras are vary in size but
their basic structure is the
same.
• Classified as typical and
atypical
• Typical vertebra consists of
 Vertebral body
 Vertebral arch
 Seven processes
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By Addis T.

16. Structure and Function of the Vertebrae
Vertebral body:
– Massive and roughly
cylindrical anterior part of the
bone
– The size of the vertebral bodies
increases as the column
descends, most markedly from
T4 inferiorly, as each bears
progressively greater body
weight.
– Separated from above and
below by intervertebral discs
(IVD)
– Used for hematopoiesis.
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By Addis T.

17. Structure and Function of the Vertebrae…
Vertebral arch
– Is U shaped and posterior to
the vertebral body
– Formed by two pedicles and
laminae
Pedicles: short cylindrical
processes, that project
posteriorly from the vertebral
body to laminae
Laminae: two flat parts that
connects the spinous process
and the transverse process of
the vertebrae
By Addis T. 17

18. Structure and Function of the Vertebrae…
 Seven processes: arise from the
vertebral arch
– Spinous process (1)
– Transverse processes (2)
– Articular processes ( 4)
Function of processes
 Attachment for deep back muscle
 Keeping adjacent vertebrae
aligned, i.e. preventing one
vertebra from slipping anteriorly
on the vertebra below.
 Determine type of movement &
weight bearing (temporarily)
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By Addis T.

19. Vertebral foramen
 Bounderis:
 anteriorly by the posterior
surface of the vertebral body
 laterally and posteriorly: the
vertebral arch.
 Contains the spinal cord and
the roots of the spinal nerves
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By Addis T.
Structure and Function of the Vertebrae…

20. Structure and Function of the Vertebrae…
Vertebral notches
• are indentations(concavities) on
the superior surface and inferior
surface of the pedicle on each side of
a vertebra
• The superior and inferior vertebral
notches of adjacent vertebrae and
the IV discs connecting them form
the intervertebral foramina, in
which the spinal nerves emerge from
the vertebral column with their
accompanying vessels.
By Addis T. 20

21. Structure and Function of the Vertebrae…
In general vertebral column
 Support the body's weight
 Protection
 Plays an important role in posture and
locomotion
By Addis T. 21

22. Regional Characteristics of the Vertebrae
• Each of the 33 vertebrae is unique.
• However, most of the vertebrae have
characteristic features identifying
them as belonging to one of the five
regions of the vertebral column
• e.g. Cervical vertebrae have
foramina in their transverse
processes
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By Addis T.

23. Cervical Vertebrae
• Cervical vertebrae form the skeleton of the
neck.
• Smallest of the 24 moveable vertebrae
• are located between the cranium and the
thoracic vertebrae.
• they bear less weight than do the larger
inferior vertebrae.
• Although the cervical IV discs are thinner than
those of inferior regions
• Thickness of the disc & horizontal orientation
of the articular facet , small amount of
surrounding body mass, give high mobility. 23
By Addis T.

24. Cervical Vertebrae
• The most distinctive feature of each cervical
vertebra is a foramen on transverse process
called foramen transversarium (transverse
foramen).
• The vertebral arteries and their
accompanying veins pass through the
transverse foramina, except those in C7,
which transmit only small accessory veins.
• The transverse processes has two projections:
– anterior tubercle and
– posterior tubercle By Addis T. 24

25. Cervical Vertebrae
• The tubercles provide attachment
for a laterally placed group of
cervical muscles (levator scapulae
and scalenes).
• The anterior rami of the cervical
spinal nerves course initially on
the transverse processes in
grooves for spinal nerves between
the tubercles.
By Addis T. 25

26. Cervical Vertebrae
• There are 4 typical
– (C3-C6) and
• 3 atypical
– C1(atlas), C2(axis) and C7
• Typical cervical vertebra
– Has a bifid spine
– Have foramina in their transverse
processes.
– Transverse process has an anterior
tubercle and a posterior tubercle.
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By Addis T.

27. C1 (Atlas)
• The Atlas is ring-shaped and supports the
skull
• No a body & spinous process
• has paired lateral masses that serve the
place of a body by bearing the weight of
the cranium
• superior articular surfaces articulate with
two large cranial protuberances called the
occipital condyles and form atlanto-
occipital joint
• Inferior articular surfuces articulate with
below vertebra and form atlanto axial
joint
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By Addis T.

28. C2 (Axis)
• is the strongest of the cervical
vertebrae
• C1, carrying the cranium, rotates on
C2 (e.g., when a person turns the
head to indicate “no”).
• Has superior articular facets, on
which the atlas rotate
• Has blunt tooth-like dens (odontoid
process) which projects superiorly
from its body.
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By Addis T.
• Both the dens and the spinal cord are encircled by the atlas.
• The dens lies anterior to the spinal cord transverse
ligament of the atlas is a ligament which passes between the
dens and spinal cord
• It has a large bifid spinous process

29. Atypical Cervical vertebrae
C7
 long spinous process.
 Small transverse foramen
 Has prominent unbifid spinous used to count
vertebrae
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By Addis T.

30. 30
By Addis T.

31. The thoracic vertebrae
• are in the upper back and provide attachment for the ribs
• the primary characteristic features of thoracic vertebrae are
– the costal facets on the body of the vertebrae for
articulation with ribs.
– The middle four thoracic vertebrae (T5–T8) demonstrate
all the features typical of thoracic vertebrae.
– The articular processes of thoracic vertebrae extend
vertically
– This arc permits rotation and some lateral flexion of the
vertebral column in this region.
– The T1–T4 vertebrae share some features of cervical
vertebrae, eg. horizontal spinous process that may be
nearly as prominent as that of the C7.
– T1 also has a complete costal facet for the 1st rib and a
demifacet for the 2nd rib
By Addis T. 31

32. Thoracic Vertebrae…
• Body
– Heart shaped
– one or two costal facets for
articulation with head of rib
• Vertebral foramen
– Circular and smaller than those
of cervical and lumbar vertebrae
• Transverse processes
– Long and strong and extend
posterolaterally
– length diminishes from T1 to
T12
– have facets for articulation with
tubercle of rib
By Addis T.
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33. Thoracic Vertebrae
• Articular processes
– Superior facets directed
posteriorly and slightly
laterally
– inferior facets directed
anteriorly and slightly
medially
• Spinous processes
– Long, slope
posteroinferiorly
– tips extend to level of
vertebral body below
By Addis T. 33

34. Thoracic Vertebrae
Typical: T5-T8
– Body is larger than
cervical; heart shaped
– Spinous process is long
and sharp, projects
inferiorly
– Vertebral foramen is
circular
– Contains all the features
typical of thoracic
vertebrae
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By Addis T.

35. Lumbar Vertebrae
• The lower back between the thorax & sacrum.
• Large and kidney shaped body when viewed superiorly
• Vertebral foramen is triangular; larger than in thoracic
vertebrae and smaller than in cervical vertebrae
• The transverse processes project posterosuperiorly as well
as laterally.
• On the posterior surface of the base of each transverse
process is a small accessory process, which provides an
attachment for the intertransversarii muscles.
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By Addis T.

36. Lumbar Vertebrae…
• Articular processes - The superior articular process directed
medially and the inferior articular facets directed laterally.
• On the posterior surface of the superior articular processes
are mammillary processes, which give attachment to both
the multifidus and intertransversarii muscles of the back.
• Spinous processes is short thick, and broad
• Vertebra L5 - is the largest of all vertebra.
• It has massive body and transverse processes
By Addis T. 36

37. Sacrum
• Triangular bone
• Formed by the union of 5 sacral
vertebrae
• Indicated as a S1-S5.
• The fusion of the sacral
vertebrae begins ages 20yrs.
• It provides strength and stability
to the pelvis
• Transmits the weight of the body
to the pelvic girdle
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By Addis T.

38. Sacrum
• Contains Sacral canal is the
continuation of the vertebral
canal in the sacrum.
• Sacral canal contains the bundle
of spinal nerve roots known as
the cauda equina
• Sacrum also contains four pairs
of sacral foramina for the exit of
the posterior and anterior rami of
the spinal nerves
By Addis T. 38

39. Sacrum
• The pelvic surface of the
sacrum (ventral surface) is
smooth and concave
• Four transverse lines on this
surface from adults indicate
where fusion of the sacral
vertebrae occurred.
By Addis T. 39

40. Sacrum
• The base of the sacrum is
formed by the superior surface
of the S1 vertebra
• The anterior projecting edge of
the body of the S1 vertebra is the
sacral promontory
• The apex of the sacrum, its
tapering inferior end, has an
oval facet for articulation with
the coccyx.
• Female sacrum are shorter,
wider and more curved between
S2 and S3 than a male sacrum
• But the body of the S1 vertebra
is usually larger in males.
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By Addis T.

41. Sacrum
• Dorsal surface which is rough
and convex
• Contains:- median sacral crest,
intermediate sacral crest & lateral
sacral crest
• the median sacral crest,
represents the fused rudimentary
spinous processes of S1-S4; S5 has
no spinous process.
• The intermediate sacral crests
represent the fused articular
processes
• The lateral sacral crests are the
tips of the transverse processes of
the fused sacral vertebrae.
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By Addis T.

42. Coccyx (Tail bone )
• Triangular bone formed by fusion of the four
rudimentary coccygeal vertebrae.
• The pelvic surface is concave and relatively
smooth
• Coccygeal cornua is rudimentary articular
process which articulate with the sacral
cornua.
• Co1 is the largest and broadest of all the
coccygeal vertebrae
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By Addis T.
Rudmentery
transverse proces
• Not Participate in support of the body weight during standing.
• Provides attachments for muscle and ligaments.

43. Curvatures of the Vertebral Column
• Vertebral column in adults has
four curvatures: cervical,
thoracic, lumbar, and sacral.
• During fetal development, the
vertebral column shows a C-
shaped concavity to the ventral
• This persists in adults only in the
thoracic and sacral regions
• Two type of curvature
– Primary curvature
– Secondary curvature 43
By Addis T.

44. Curvatures of the Vertebral Column
 Primary curvatures
• Seen in the thoracic and sacral
curvatures .
• They are primary curvatures that
develop during the fetal period in
relationship to the fetal position
• the primary curvatures are in the same
direction as the main curvatures of the
fetal vertebral column and they retained
throughout life 44
By Addis T.

45. Curvatures of the Vertebral Column
 Secondary curvatures
• Occur after birth on the cervical and
lumbar vertebrae
• that result from extension from the flexed
fetal position.
• Cervical curvature begins to appear when
the infant starts to raise the head.
• The lumbar curvature observed when the
infant starts to walk
• The secondary curvatures begin to appear
before birth but well observed after birth 45
By Addis T.

46. Pelvic Girdle
• Basin-shaped ring of bones that connects the vertebral
column to the femurs in the thighs
• Functions
Bear the weight of the upper body when sitting and
standing
Transfer the weight of the upper body from the axial
to the lower appendicular skeleton for standing and
walking
Provide attachment for the powerful muscles
Contain and protect the pelvic viscera and the inferior
abdominal viscera
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47. The bony pelvis is formed by 4 bones united by 4 joints
Bones: 2 hip bones, sacrum and coccyx
Joints: 2 sacroiliac joints, pubic symphysis and
sacrococcygeal joint
47

48. Hip bones
The two hip bones are joined at the pubic symphysis
anteriorly and to the sacrum posteriorly at the sacroiliac
joints to form a bony ring, the pelvic girdle
Each hip bone is formed by 3 bones fusing at the
acetabulum (a cup-like articular depression on lateral
aspect for the head of the femur) by a y-shaped cartilage
Begin to fuse at 15-17 years and complete at 20-25 years
of age
• The 3 bones are:
 Ilium
 Ischium
 Pubis 48

49. 49

50. Ilium
 The superior, flattened, fan-shaped part of the hip bone
 Located superior to the acetabulum
Body
forms the superior part of the acetabulum
joins ischium and pubis at acetabulum
Ala (wing)
bordered superiorly by iliac crest
dorsum feature:- anterior, posterior and inferior
gluteal lines (origins of gluteus minimus, medius and
maximus muscles)
50

51. Landmarks of ilium:
Anterior superior
iliac spine
Anterior inferior
iliac spine
Posterior superior
iliac spine
Posterior inferior
iliac spine
Greater sciatic
notch
51

52. Ischium
• posteroinferior part of hip bone
• has a body and a ramus
• Body
– forms the posterior part of the acetabulum
– joins ilium and superior ramus of pubis to form
acetabulum
• Ramus
– fuses with the inferior ramus of pubis
– forms part of the inferior boundary of the obturator
foramen
52

53. • Landmarks
 ischial tuberosity
• large posteroinferior
protuberance of the
ischium
• supports body during
sitting
ischial spine
• small pointed
posterior projection
near the junction of
the ramus and body
lesser sciatic notch
53

54. Pubis
• anteromedial part of hip bone
• Forms anterior part of the acetabulum
• angulated bone; has two rami (inferior & superior) and body
Body
– has a symphyseal surface for articulation with the
contralateral pubis
Rami
– superior pubic ramus: forms anterior part of acetabulum
– inferior pubic ramus: forms part of the inferior boundary
of the obturator foramen
54

55. Landmarks
Pubic crest
• thickening on the anterior part of the body
of the pubis
• ends laterally as a swelling - pubic tubercle
Pubic arch (sub pubic angle)
• formed by the ischiopubic rami (conjoined
inferior rami of the pubis and ischium) of the
two sides
• these rami meet at the pubic symphysis
• their inferior borders define the subpubic angle
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