3. Functions of Skeletal System
1)Support – provides
solid axis for muscles
to act against,
creating motion.
2)Protection- bones
such as skull provide
barrier of protection
from external forces
3)Hematopoiesis-
production of red
blood cells
4. Types of Bones
Bones are divisible
into 5 class.
Long
Short
Flat
Irregular
Sesamoid
5. Long Bones
Found in the limbs
Each bone is made of
a body (diaphysis)
and two extremities
(epiphyses)
Wall consists of
dense tissue
Central canal called
medullary canal is
filled with marrow
6. Short Bones
Found in skeleton
where strength,
compactness, and
limited movement are
desired
2 main examples
Tarsus
Carpus
7. Flat Bones
Used in spots where
protection or
muscular attachment
is desired
Main locations are
skull and scapula
8. Irregular Bones
Bones which don’t fit
into other categories
due to irregular
shapes
Examples:
vertebrae;sphenoid;
hyoid
15. Nutrition (contd)
Decrease in calcium
triggers release of
Parathyroid hormone
Triggers osteoclasts
to break down bone,
releasing calcium
into blood
16. Exposure to Sunlight
UV light on the skin causes Vitamin D
production
Promotes proper absorption of calcium in
the SI
19. Bone maintenance
Osteoblasts-
constantly producing
new bone tissue
Osteoclasts – clean
out old bone tissue
Causes holes or
tunnels in bone which
osteoblasts then fill in
with calcium and
phosphate compounds
29. Repairing Fractures
Closed reduction = bones
are eased back into
alignment and “reset”
Open reduction = bones are
surgically reset using
screws or wires
After either, a cast is
usually applied to
immobilize the bone;
healing begins
30. Internal Bone Repair
1)Hematoma forms from
ruptured blood vessels.
2)After new capillaries
form, fibrocartillage callus
“splints” broken bone
using cartilage and bony
matrix.
3)Osteoblasts migrate to
area, forming bone
“patch” over break.
Fibrocartilage is replaced
by bony callus.
32. Divisions of the Skeletal System
Skeletal system is
divided into two main
division
Axial – central skeleton
that protects and
supports vital organs
Appendicular – skeleton
of the extremities
33. Axial Skeleton
Composed of skull and
vertabrae
Mainly flat and irregular
bones
Serve to protect organs
such as brain, heart,
and lungs
Also helps to support
body along central axis
(backbone)
34. Parts of the axial skeleton
Skull – protects brain
Vertebrae – protect
spinal chord ;also serves
to keep skeleton upright
Ribs – protect lungs and
heart ; gives intercostal
muscles a hard surface
to move against for
breathing
35. Divisions of the skull
Skull is divided into 2
sets of bones
Cranium – collection of
8 bones which hold and
protect brain
Facial bones – 14
bones that make up the
face; all but 2 are
paired
36. Cranium
Frontal Bone – makes up
forehead, eyebrows, and
superior section of eye orbital
Parietal Bone – form most of
the superior and lateral walls
of cranium
Temporal bones – lie inferior
to parietal bones
Occipital bone – forms back
and floor of cranium; foramen
magnum (large hole) allows
spinal chord to meet brain
37.
38. Facial Bones
Mandible- lower jaw
bone
Maxillary bones
(maxillae) fuse
together to form
upper jaw
Palatine processes –
directly posterior to
maxillae; forms rear
of hard palate
39. Facial Bones Contd.
Zygomatic bones – cheekbones
Lacrimal bones – inferior section of orbital
bones; provides passageway for tears
Ethmoid bone- forms roof of nasal cavity
40. More Facial Bones
Nasal bones- form
bridge of nose
Vomer – divides nasal
cavity in half
Inferior conchae- thin
curved bones which
project from interior of
nasal cavity
42. Intervertebral Discs
Pads of cartilage
between each vertebrae
Provide cushioning;
reduce shock
High water content
As you age, water
content lowers, drying
discs
Can cause herniated
(slipped) disc; where
disc protrudes from
spine
43. Bony Thorax
Made of bones which
connect and protect
heart and lungs
Ribs, Costal
Cartilage, and
Sternum
44. Ribs
12 pairs of ribs, each
connects to a thoracic
vertebrae
First 7 pairs = true ribs;
attach directly to
sternum
Last 5 pairs = false ribs;
indirect or no
attachment; last two are
floating (no sternal
45. Sternum
Fusion of three bones
1) Manubrium (top)
2) Body (middle)
3) Xiphoid Process
(bottom)
Location for rib
attachment
Surrounded by costal
cartilage
46. Sternal Puncture
Process by which
marrow is removed
from sternum
Good location
because of proximity
to body surface
48. Intro
Supports body
Connects skull to
pelvis
Sends weight down to
pelvis, where it is
transmitted through
the legs
Surrounds and
protects spinal cord
26 total bones
49. Divisions of the Spinal Column
4 main divisions
1) Cervical curvature
2)Thoracic curvature
3)Lumbar curvature
4)Pelvic
Sacrum
Thorax
50. Cervical curvature
Begins where skull
meets spine
Composed of 7
vertebrae
Labeled C1-C7,
starting at skull
First two vertebrae
(C1 and C2)are
different
51. C1 and C2
Perform different jobs
than other vertebrae
C1 (atlas) has
depressions that
accept the occipital
codyles (“yes nod”)
C2 (axis) acts as pivot
point for skull (“no”
head shake)
53. Lumbar Vertebrae
5 vertebrae
(L1-L5)
Sturdiest because
under the most stress
54. Sacrum
1 bone composed of
5 fused vertebrae
“wing-like” alae
connect laterally with
hip bones (forms
sacroiliac joints)
Makes up posterior
wall of pelvis
55. Coccyx
1 bone formed by
fusion of 3 vertebrae
Tailbone
Thought to be left
over from when our
ancestors had tails
58. Pelvis
Juncture point for axial
skeleton and lower
body
Holds internal organs
Distributes weight
down legs
3 fused bones
Obturator foramen-
large hole through
which nerves and
muscles pass
59. Bones of the Pelvis
Ilium
Ischium
Pubis
Become fused
into “pelvis” at
puberty
60. Ilium
Makes up top of hip
(iliac crest)
Lateral portions of
the pelvis
Contains hip socket
61. Features of the Ilium
Iliac crest – rounded
projection on superior
surface; makes up “hip”
Acetabulum- joint
between femure and
pelvis
Width from crest to crest
= false pelvis
Width of actual inlet =
true pelvis
69. Shoulder Girdle
Also called pectoral
girdle
Composed of only
two bones
Clavicle
Scapula
70. Clavicle
Collar bone
Double-curved
Attaches medially to manubrium
of sternum
Attaches laterally to scapula
Acts as a brace, keeping arm
away from thorax
Also prevents shoulder
dislocation
71. Scapula
Shoulder Blade
Main function is
attachment of shoulder
Major point of muscle
attachment for movement
of arms
Weakly attached to
thorax, so moves easily
72. Major Processes of the Scapulae
1)Acromion – extends
from spine of
scapulae
Point of attachment of
clavicle
2)Coracoid- main site
of arm muscle
attachment
73. Glenoid Cavity
Socket of arm joint
Shallow
Allows for great range
of motion
Also dislocates easily
74. Movement in the Shoulder Girdle
Very free moving because
1)Only attaches at one point to axial
skeleton
2)Loose attachment of scapula allows it to
slide
3)Glenoid cavity very shallow
75. Arm Bones
Arms composed of
long bones
Humerus (upper arm)
Radius and Ulna
(forearm)
76. Humerus
Simple long bone
Greater and lesser
tubercle allow for
muscle attachment
Deltoid tuberosity-
place of attachment
for deltoid muscle
77. Attachment to the forearm
Trochlea articulates
against bones of
forearm
Olecranon fossa
shaped like spoon
82. Intro
Any point where bones
meet
Also called
articulations
Every bone (except
hyoid) articulates with
at least 1 other bone
83. Classifications of Joints
Can be classified by
mobility, or by the
type of tissue which
connects the bones
84. Joint classification by Mobility
Can be one of three
types.
1) Synarthroses –
immovable joint
2)amphiarthroses- slightly
moveable joint
3)diarthroses- freely
movable
85. Classification by connective tissue
type
Joints are connected by
either fibrous, cartilage,
or synovial connective
tissue.
Fibrous is usually
synarthroses,
Synovial – diarthroses
86. Fibrous Joints
Fibrous tissue
Example= sutures of
the skull
Tight fibrous tissue
allows for essentially no
movement
88. Synovial Joints
Bones separated by
synovial cavity
Empty pocket serves to
reduce friction between
moving bones
Usually located in
extremities, where
movement is necessary
89. So… What does it mean to be
double-jointed?
Usually not actually
two joint cavities
Ligaments are simply
less taut than
normal, allowing for
more flexibility
Can be indicative of
serious genetic
defects
90. Joint Problems
Osteoarthritis –
general break-down
of joints, leading to
ossification, and
then pain.
Rheumatoid Arthritis
– autoimmune
disease where body
attacks its own
tissues; cause
unknown
92. Sutures of the cranium
Suture – location
where flat bones of
the cranium meet and
fuse
Squamous- fuses
temporal and parietal
Coronal – fuses frontal
to parietal
Saggital – fuses plates
of parietal bones
Lambdoid – fuses
occipital to parietal
93. Bone markings of the Temporal Bones
1) external auditory
meatus – canal which
leads to inner ear
2) styloid process – sharp,
needlelike projections
inferior to the
e.a.m.;location of muscle
attachment
3) zygomatic process-
forms cheek bones;forms
large hole which allows
jaw muscles to pass
through to mandible
94. Temporal bone markings (contd.)
4) mastoid process –
posterior and inferior to
e.a.m.;location of muscle
attachment for muscles of
the neck
5) jugular foramen- at
junction of occipital and
temporal bones; allows
jugular vein to pass
through from brain
6) carotid canal – anterior
to j.f. Allows carotid
artery to pass to brain
95. Occipital Condyles
Lie lateral to the
foramen magnum
Rest upon the spinal
column
Provides point of
attachment for skull to
spinal column
96. Cribriform Bones
Cribriform bones –
“holey” bone plates
which make up roof of
nasal cavity;allow for
olfactory sensors to
pass from nose to brain
97. Sinuses
Empty pocket inside
bones which are lines
with mucous
membranes
Paranasal sinus-
surrounds nasal
cavity
Lighten skull, and
thought to amplify
sounds when
speaking
98. Deformations
Cleft palate = when
palatine bones fail to
properly or completely
fuse.
Leads to inability to
nurse, due to failure
to form a vacuum.
100. In general
Male skeleton is larger, with thicker bones
Female bones maintain many
characteristics of prepubescent skeleton
Male features change at puberty (usually
at points of muscular attachment)
101. Skull
Male mastoid process
more pronounced
Superior portion of
female orbital (brow
ridge) less pronounced
Female mandible is
pointed, while male is
squared
102. Facial Differences
Female face wider than
male
Females have more
pointed nose, while
males are more blunt
Female forehead less
sloping
Eyebrows positioned
higher in females
103. Pelvis
Female Pelvis wider
and more shallow
Male iliac crests more
pointed
Male pelvis more
narrow
105. Forensic anthropology
Most will say that there is no exact way to
determine sex from skeleton (not exact
science)
Pelvis is probably most reliable feature to
analyze, followed by mandible