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SKELETAL SYSTEM
Chapter 5
VERTEBRAE
Consists of 26 irregular bones that surround and
protect the spinal cord
 Before birth, the spine consists of 33 separate
vertebrae, but nine fuse to form the scrum and
coccyx
 The spine is arranged into three curvatures

Cervical (7 vertebrae)
 Thoratic (12 vertebrae)
 Lumbar (5 vertebrae)
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VERTEBRAE
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When referring to individual vertebra, use the
first letter of the curvature where it is located
followed by the numbered location in the
curvature (numbered superior  inferior)
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For Example: Vertebra C4 is the 4th vertebra in the
cervical curvature
The sacrum consists of 5 fused vertebrae while
the coccyx consists of 4.
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The coccyx is commonly referred to as the tailbone
VERTEBRAE
Primary curvatures are the thoratic and sacral
because they are present at birth
 Secondary curvatures develop later in life

Cervical when a baby lifts its head
 Lumbar when a baby begins to walk
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There are several types of abnormal curvatures
Scoliosis is lateral movement of the spine
 Kyphosis is an exaggerated thoratic curvature
 Lordosis is an exaggerated lumbar curvature
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VERTEBRAE
The single vertebrae are separated by pads of
flexible fibrocartilage called intervertebral disks.
 Function of the disks is to cushion the vertebrae
and absorb shocks
 Disks are more spongy and compressible early in
life and become harder with age.

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Herniated or slipped disks: Become more common
with age. Occur because disks dry out and ligaments
weaken. Occasionally the protruding disk presses on
the spinal cord causing immense pain.
VERTEBRAE

Anatomy of an individual vertebrae includes the
following structures:
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Body – anterior portion of vertebra that bears the
weight
Vertebral foramen – canal that holds the spinal cord
Transverse processes – lateral projections (2)
Spinous process – single posterior projection
Vertebral arch – arch formed from the joining of the
two transverse processes and spinous process
Superior and inferior articular processes – form
joints with adjoining vertebrae, lateral to the
vertebral foramen
VERTEBRAE
Spinous
Process
Vertebra
l arch
Transverse
Process
Vertebra
l
foramen
Body
VERTEBRAE
Cervical vertebrae (C1-C7) form the neck region of
the spine
 First two vertebrae are the atlas and axis

Atlas has no body and allows you to nod “yes”
 Axis acts as a pivot for the atlas and skull
 Joint between the two allows you to indicate “no”

The remaining cervical vertebrae are the
smallest and lightest vertebrae.
 Transverse process on cervical vertebrae have
foramina (openings) that allow vertebral arteries
to pass into your brain.
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VERTEBRAE

Cervical Vertebrae
Foramina of
Transverse
Process
VERTEBRAE

Atlas and Axis
VERTEBRAE
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Thoratic vertebrae (12) are larger than the
cervical vertebrae
Body is slightly heart shaped and have facets where
ribs attach
 The spinous process is long and hooks downward

Lumbar vertebrae (5) have massive bodies with
hatchet shaped spinous processes
 Since the lumbar region bears most of the weight
on the spine, lumbar vertebrae are the sturdiest.

VERTEBRAE
The sacrum is composed of 5 fused vertebrae. It
is inferior to L5 and superior to the coccyx.
 The coccyx is formed from three to five
irregularly shaped vertebrae.
 Common name is the tailbone

THORATIC CAGE
Thoratic cage or bony thorax consists of the
sternum, ribs and thoratic vertebrae
 Sternum is a flat bone separated into three
sections

Superior manubrium
 Middle body
 Inferior xiphoid process
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Ribs form the walls of the cage.
First seven pairs are “true” ribs because they attach
to the sternum directly
 Next five pairs are “false” ribs because they attach to
the sternum indirectly
 Last two pairs are floating ribs because they do not
attach at all
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APPENDICULAR SKELETON

The arm and shoulder
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The shoulder girdle consists of the clavicle and
scapula
Clavicle acts as a brace to prevent shoulder
dislocation.
Scapula is not directly attached to the axial skeleton,
rather it is held in place by muscles
It’s loose attachment allows it to slide back and forth
as muscles contract.
Forearm consists of the radius and ulna
In the anatomical position, the radius is the lateral
bone attaching to the thumb.
APPENDICULAR SKELETON

The hand
Consists of the carpals, metacarpals, and phalanges
 8 carpal bones, 5 metacarpals, and 14 phanlanges
 Each phalange has 3 bones: proximal, middle and
distal
 Exception is the thumb, which only has 2: proximal
and distal
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APPENDICULAR SKELETON
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Pelvic Girdle
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Formed by two coxal bones, commonly called hip
bones
Each hip bone is made by the fusion of three bones:
ilium, ischium, and pubis.
When you put your hands on your hips, they are
resting on the ilia.
The ischium is the “sit down bone” because it receives
the body’s weight when sitting
The pubis is the anterior portion of the hip
False pelvis measures from ilium to ilium and the
true pelvis and is inferior to the false pelvis.
APPENDICULAR SKELETON
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Male vs. Female pelvis

Individual pelvis structures vary, but there are noted
differences between the male and female pelvis
The female true pelvis is larger and more circular
 Female pelvis is shallower and the bones are lighter and
thinner
 The ilia flare more laterally than a male pelvis
 Female sacrum is shorter and less curved
 Female pubic arch is greater than 90 degrees, while the
male arch is less than 90 degrees

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The dimensions of the true pelvis are very important
for childbirth, because they need to be large enough
to allow the baby’s head to pass during childbirth