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Anatomy of Skeletal System
SKELETAL SYSTEM

COMPOSED OF:
-Bones
-Cartilage
-Joints
-Ligaments
Functions of Skeletal System

SUPPORT: Hard framework that supports and anchors
the soft organs of the body.

PROTECTION: Surrounds organs such as the brain and
spinal cord.

MOVEMENT: Allows for muscle attachment therefore
the bones are used as levers.

STORAGE: Minerals and lipids are stored within bone
material.

BLOOD CELL FORMATION: The bone marrow is
responsible for blood cell production.
Bone Markings
 Bone Surface is not smooth, but shows:
 Bone markings which reveal where:
-muscles, tendons, and ligaments attatched
-nerves and blood vessels pass
*bone marking may be:
1-projections or processes or
2-depressions or cavities
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 5.9
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Compact bone
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Structure
Outer layer of bone, very hard and dense.
Its structural unit is called Haversian systems or
osteon.
Matrix is composed of Ca salts (Ca carbonate and Ca
phosphate)
Osteocytes – living bone cells that live in matrix.
Porous (Spongy) bone


Sponge-like , located in the ends of long bones.
Needle-like threads of bone that surround spaces..
These spaces are filled with red bone marrow which
produces blood cells.
Classification of Bones
 Long bones
 Typically longer than wide
 Have a shaft with heads at both ends
 Contain mostly compact bone
• Examples: Femur, humerus
 Short bones
 Generally cube-shape
 Contain mostly spongy bone
 Examples: Carpals, tarsals
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 5.4a
Classification of Bones on the
Basis of Shape
Figure 5.1
Slide 5.4c
 Flat bones
 Thin and flattened
 Usually curved
 Thin layers of compact bone around a layer of
spongy bone
 Examples: Skull, ribs, sternum
 Irregular bones
 Irregular shape
 Do not fit into other bone classification
categories
 Example: Vertebrae and hip
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 5.5a
Gross Anatomy of a Long Bone
 Diaphysis
 Shaft,Composed of
compact bone
 Epiphysis
 Ends of the long bone,
composed mostly of
spongy bone
 A plate of cartilage
separates epiphyses
from diaphysis for
bone longitudinal
growth.
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.2a
Slide 5.6
 Periosteum
Outside
covering of the
diaphysis
Fibrous
connective
tissue
membrane
 Sharpey’s fibers
secure
periosteum to
underlying bone
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.2c
Slide 5.7
Structures of a Long Bone
 Articular cartilage
 Covers the external surface
of the epiphyses (inside the
joints )
 Made of hyaline cartilage
 Decreases friction at joint
surfaces
Figure 5.2a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 5.8a
 Medullary cavity
 Cavity of the shaft
 Contains yellow
marrow (mostly fat)
in adults
 Contains red marrow
(for blood cell
formation) in infants
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.2a
Slide 5.8b
Microscopic Anatomy of Bone
 Osteon (Haversian System) is the unit of bone
structure which is composed of:
 Central (Haversian) canal
 Present in the center of an osteon
 Carries blood vessels and nerves
 Perforating (Volkman’s) canal
 Perpendicular to the central canal
 Carries blood vessels and nerves
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
5.10a
Microscopic Anatomy of Bone
Figure 5.3
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
5.10b
Microscopic Anatomy of Bone( cont.)
 Lacunae
 Cavities containing
bone cells
(osteocytes)
 Arranged in
concentric rings
called Lamellae
around the central
canal
Figure 5.3
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
5.11a
Microscopic Anatomy of
Bone(cont.)
 Canaliculi
 Tiny canals
 Radiate from the
central canal to
lacunae to transport
nutrients.
Figure 5.3
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
5.11b
 Between the ages of 16 and 25 years
(influenced by estrogen or testosterone), all of
the cartilage of the epiphyseal discs is replaced
by bone. This is called closure of the epiphyseal
discs (or we say the discs are closed) and a
line appears instead seen in x-ray, and the
bone lengthening process stops.
 NOTICE:
- bones grow in width through periosteum.
- bone change shape continuously by gravity
&muscle pull.
Slide
5.13a
Long Bone Formation and Growth
Figure 5.4a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
5.14a
Long Bone Formation and Growth
Figure 5.4b
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
5.14b
Homeostatic Imbalance
Rickets is a disease of children in which
the bones fail to calcify due to deficiency of
calcium in the diet or vitamin D . As a result
bone soften leading to bowing of legs and
deformities of the pelvis, skull, and rib cage.
Because the epiphyseal plates cannot be
calcified, they continue to widen, and the
ends of long bones become visibly enlarged
and broad.
Types of Bone Cells
 Osteocytes
 Mature bone cells present inside lacunae
 Osteoblasts
 Bone-forming cells
 Osteoclasts
 Break down bone matrix for remodeling and
release of calcium.
 Bone remodeling is a process of balance
between both osteoblasts and osteoclasts
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 5.15
Fractures
Closed fracture (simple): skin is intact
 Open fracture (compound): skin is open
 Fracture reduction :
1-closed reduction ,no surgery is needed
2-open reduction ,surgery is needed

Repair of fracture
Healing time for simple fracture is 6-8 weeks
(longer in elderly people) .It occurs in
FOUR major events
 1-hematoma formation
 2-fibrocartilage callus formation
 3-bony callus formation
 4-bone remodelling
**Groth of long bones
Long bones are first made of cartilage
model , and ossification begins in the third
month of gestation. Osteoblasts produce
bone matrix in the center of the diaphyses
(center of ossification)of the long bones
and in the center of short, flat, and
irregular bones. Bone matrix gradually
replaces the original cartilage.
The long bones also develop centers of
ossification in their epiphyses.
At birth, ossification is not yet complete and
continues throughout childhood.
Cartilage remains in isolated areas as bridge
of the nose , parts of ribs and joints .
Increase in bone length occurs in the epiphyseal
discs(plates) at the junction of the diaphysis with
each epiphysis. Bone grows in length as more
cartilage is produced on the epiphysis side.
On the diaphysis side, osteoblasts produce bone
matrix to replace the cartilage.
PARTS OF THE SKELETON
1- Axial skeleton
- Skull and associated bones
 Auditory ossicles
 Hyoid bones
- Vertebral column
- Thoracic cage(Ribs+ sternum)
2- Appendicular skeleton
-Pectoral girdle +upper limb
-Pelvic girdle + lower limb
The Axial Skeleton
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Skull and associated
bones:
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Auditory ossicles
Hyoid bone
Vertebral column
Thoracic cage
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Ribs + sternum
The Skull and Associated Bones
The Adult Skull
•skull = 22 bones
•cranium = 8 bones: frontal, occipital, 2 temporals, 2 parietals, sphenoid and
ethmoid
•facial bones = 14 bones: nasals, maxillae, zygomatics, mandible, lacrimals,
palatines, inferior nasal conchae, vomer.
•skull forms a larger cranial cavity
-also forms the nasal cavity, the orbits, paranasal sinuses
- mandible and auditory ossicles are the only movable skull bones
•cranial bones also: attach to membranes called meninges
-stabilize positions of the brain, blood vessels
-outer surface provides large areas for muscle attachment that
move the head or provide facial expressions
Sutures
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All of the joints between cranial bones are
immovable joints called sutures. It may
seem strange to refer to a joint without
movement, but the term joint (or
articulation) is used for any junction of two
bones.
Four sutures are important:
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Coronal – between parietal and frontal
Sagittal– between parietal bones
Lambdoid – between the parietal and occipital
Squamous – between the parietal and temporal.
Figure 6.4 Sectional Anatomy
of the Skull, Part I
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Frontal bone
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Forms the forehead
Roof of the orbit
articulates with
parietal, sphenoid,
lacrimal, nasal,
ethmoid, zygomatic
and maxilla
superior and lateral
to glabellar region –
frontal sinuses
inferior portion –
supraorbital ridges
with supraorbital
notch (supraorbital
nerve and artery)
•Parietal bones
-Part of the superior and lateral surfaces of the cranium
-articulate with each other in
sagittal suture
-articulate with occipital, frontal,
temporal and sphenoid bones
•Temporal bone shows:mastoid process , styloid process,external
acoustic meatus and temperomandibular joint .
-
Occipital bone
 Part
of the base of
the skull
 articulates with
parietal, temporal
and sphenoid
 Surrounds the
foramen magnum
 projections =
occipital condyles
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Sphenoid bone
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Contributes to floor
of cranium
The body of the bat
has a depression
called the sella
turcica,which
encloses the
pituitary gland.
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Ethmoid bone
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Irregularly shaped bone
Forms part of orbital wall
Forms roof of nasal cavity
two lateral masses – contain the
ethmoid sinuses
Two projections' called the superior
and middle nasal conchae
Cribiform plate: perforations
for olfactory nerve,
midline is the crista galli
14 Facial Bones
Nasal (2)
Mandible (1)
Inferior nasal conchae (2)
Maxillae (2)
Lacrimal (2)
Zygomatic (2)
Palatine (2)
Vomer (1)
Bones of the Face

Maxillae
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Paired bone
Largest of facial
bones
Form upper jaw
body contains the
maxillary sinuses
Zygomatic Bones
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Cheekbones
Lateral wall of orbit

Palatine bones
Form posterior
portion of hard
palate
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Inferior nasal concha
Located on each side of nasal septum
 Increase epithelial surface
 Create turbulence in inspired air

 Lacrimal
 Smallest
bones
bones in skull
 Forms nasolacrimal groove
leading to nasolacrimal canal
 Delivers tears to nasal cavity
Palatine & Vomer
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Vomer
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posterior part of nasal septum
Forms inferior portion of nasal septum
Articulates with maxillae and palatines
Mandible
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lower jaw
only freely movable bone of the skull
moving articulations with temporal
bone in temperomandibular joint.
The Hyoid Bone
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Suspended by stylohyoid ligaments
Consists of a body, greater horns and
lesser horns.
Base for muscles of the tongue and
larynx
Paranasal Sinuses
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Paired cavities in ethmoid, sphenoid, frontal and maxillary
bones.
Lined with mucous membranes and open into nasal cavity
though openings called ostia
Resonating chambers for voice,
and lighten the skull.
Sinusitis is inflammation of
the sinuses leads to headache
Infection can easily spread
from the nose to the sinuses
and from one sinus to the
other as mucous membranes
are continuous.
Growth in human skull
**The cranial and facial bones are first made of
fibrous connective tissue. In the third month of
fetal development, fibroblasts (spindle-shaped
connective tissue cells) become more specialized
and differentiate into osteoblasts, which produce
bone matrix. From each center of ossification,
bone growth radiates outward as calcium salts
are deposited. This process is not complete at
birth; a baby has areas of fibrous connective
tissue remaining between the bones of the skull.
These are called fontanels
fontanels permit:
- Compression of the baby’s head during
birth without breaking the still thin cranial
bones.
- The growth of the brain after birth.
Fontanels are “ soft spots,”. A baby’s skull
is quite fragile and must be protected from
trauma.
By the age of 2 years, all the fontanels
have become ossified, and the skull
becomes a more effective protective
covering for the brain.
Homeostatic Imbalance
Several congenital abnormalities may
distort the skull. Most common is cleft
palate, a condition in which the right and left
halves of the palate fail to fuse medially
(Figure 7.34). The persistent opening
between the oral and nasal cavities
interferes with sucking and can lead to
aspiration (inhalation) of food into the lungs
and aspiration pneumonia
The Vertebral Column
http://www.wisc-online.com/objects/index.asp?objID=AP12104
Adult Vertebral Column
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26 vertebrae
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24 individual vertebrae
Sacrum
Coccyx
Seven cervical vertebrae
Twelve thoracic vertebrae
Five lumbar vertebrae
Sacrum and coccyx are
Fused together.
Typical Vertebrae  Body
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Vertebral arch
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weight bearing
pedicles
laminae
Vertebral
foramen
Seven processes
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2 transverse
1 spinous
4 articular
The vertebrae are separated by discs of fibrous
cartilage that act as cushions to absorb shock. An
intervertebral disc has a tough outer covering and
a soft center called the nucleus pulposus.
Extreme pressure on a disc may rupture the outer
layer and force the nucleus pulposus out.This is
called DISC PROLAPSE .
This may occur when a person lifts a heavy
object improperly, that is, using the back rather
than the legs and jerking upward, which puts
sudden, intense pressure on the spine.
Most often this affects discs in the lumbar region.
Typical Cervical Vert. (C3-C7)
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Smaller bodies
Larger spinal canal
Transverse processes
are shorter and has
transverse foramen for
vertebral artery
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Spinous processes of
C2 to C6 often bifid
1st and 2nd cervical
vertebrae are unique

atlas & axis
Atlas & Axis (C1-C2)
The Atlas
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C1 is termed the atlas
Lacks a body and spinous process
Supports the skull
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Superior articular facets receive the
occipital condyles
Allows flexion and extension of neck

Nodding the head “yes”
The Atlas
Figure 7.16a
The Axis
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Has a body and spinous process
Dens (odontoid process) projects
superiorly
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Acts as a pivot for rotation of the atlas and
skull
Participates in rotating the head from side
to side ,as if we refuse.
The Axis
Thoracic Vertebrae
(T1-T12)
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All articulate with
ribs
Have heart-shaped
bodies from the
superior view
Each side of the
body bears
demifacts for
articulation with
ribs
Thoracic Vertebrae
 Spinous
processes are long and
point inferiorly
 Vertebral foramen are circular
 Transverse processes articulate
with tubercles of ribs
 Allows
rotation and prevents
flexion and extension
Lumbar Vertebrae
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Bodies are thick and
strong
Transverse processes
are thin and tapered
Spinous processes
are thick, blunt, and
point
Vertebral foramina
are triangular
Allows flexion and
extension –
No rotation
Sacrum (S1 – S5)
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Forms the posterior wall of pelvis
Formed from 5 fused vertebrae
Superior surface articulates with L5
Inferiorly articulates with coccyx
Sacral promontory

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Where the first sacral vertebrae bulges into pelvic
cavity
Center of gravity is 1 cm posterior to sacral
promontory
Sacrum

Sacral foramina

Ventral foramina

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Passage for ventral rami of sacral spinal nerves
Dorsal foramina

Passage for dorsal rami of sacral spinal nerves
Sacrum
Figure 7.18a, b
Coccyx
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Is the “tailbone”
Formed from 3 – 5 fused vertebrae
Offers only slight support to pelvic organs
Bony Thorax
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Forms the framework of the chest
Components of the bony thorax
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Thoracic vertebrae – posteriorly
Ribs – laterally
Sternum and costal cartilage – anteriorly
Protects thoracic organs
Supports shoulder girdle and upper
limbs
Provides attachment sites for muscles
The Bony Thorax
Figure 7.19a
The Bony Thorax
Figure 7.19b
Sternum

Formed from three parts :

Manubrium – superior part

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Body – bulk of sternum
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Articulates with medial end of clavicles
Sides are notched as articulations for costal
cartilage of ribs .
Xiphoid process – inferior end of sternum

Ossifies around age 40
Sternum

Anatomical landmarks

Jugular notch
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Central indentation at superior border of the
manubrium
Sternal angle

A horizontal ridge where the manubrium joins the
body
Ribs

All ribs attach to vertebral column
posteriorly

True ribs - superior seven pairs of ribs


Attach to sternum by costal cartilage
False ribs – inferior five pairs of ribs ,attatch
indirectly to the sternum
 floating ribs ribs 11–12 are short and
free anteriuorly.
Ribs
Figure 7.20a
Ribs
Figure 7.20b
Disorders of the Axial Skeleton

Abnormal spinal curvatures
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Scoliosis – an abnormal lateral curvature
Kyphosis – an exaggerated thoracic
curvature
Lordosis – an accentuated lumbar curvature
– “swayback”
Stenosis of the lumbar spine

A narrowing of the vertebral canal
The Appendicular Skeleton
Allows us to move and manipulate
objects
 Includes all bones other than axial
skeleton, it includes:

the limbs (upper & lower limbs)
 the supportive girdles (pectoral &pelvic
girdles)

th
Figure 8–1
The Pectoral Girdle
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Also called the shoulder girdle
Connects the arms to the body
Positions the shoulders
Provides a base for arm movement
The Pectoral Girdle
Figure 8–2a
The Pectoral Girdle
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Consists of:
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2 clavicles
2 scapulae
Connects with the axial skeleton only at
the manubrium(claviculosternal joint)
The Clavicles
Figure 8–2b, c
The Clavicles

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Also called collarbones
Long, S-shaped bones
Originate at the manubrium (sternal end)
Articulate with the scapulae (acromial
end)
The Scapulae
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Also called shoulder blades
Broad, flat and triangular
Articulate with arms and collarbone
Anatomy of
The scapula
Figure 8–3a
The Upper Limbs

Arms, forearms, wrists, and hands
Note: arm (brachium) = 1 bone, the
humerus
ANATOMY OF
The Humerus
Figure 8–4
The Humerus


The bone of the arm
Articulates with the glenoid cavity (fossa )
of the scapula above and with the
trochlear notch of the ulna below
The Forearm
Figure 8–5
The Forearm
 Also
called the
antebrachium
 Consists
 ulna
of 2 long bones:
(medial)
 radius (lateral)
Interosseous Membrane


A fibrous sheet provides strength
Connects lateral margin of ulnar shaft to
radius
The Wrist
Figure 8–6
The Wrist
8
carpal bones:
4
proximal carpal bones
4 distal carpal bones
allow wrist to bend and
twist
Homeostatic Imbalance
The arrangement of carpal bones is concave anteriorly
forming the carpal tunnel. Besides the median nerve
(which supplies the lateral side of the hand), several
long muscle tendons crowd into this tunnel. Overuse and
inflammation of the tendons cause them to swell,
compressing the median nerve, which causes tingling
and numbness of the areas served. Pain is greatest at
night. Those who repeatedly flex their wrists and fingers,
such as those who work at computer keyboards all day,
are particularly susceptible to this nerve impairment,
called carpal tunnel syndrome. This condition is
treated by splinting the wrist during sleep or by surgery
Metacarpus (Palm)
Five metacarpal bones radiate from the wrist to form the
palm of the hand (meta = beyond). These are numbered
1 to 5 from thumb to little finger. The bases of the
metacarpals articulate with the carpals proximally Their
bulbous heads articulate with the proximal phalanges of
the fingers. When you clench your fist, the heads of the
metacarpals become prominent as your knuckles.
Metacarpal 1, associated with the thumb, is the
shortest and most mobile. It occupies a more anterior
position than the other metacarpals. The joint between
metacarpal 1 and carpals allows opposition, the action of
touching your thumb to the tips of your other fingers.
Phalanges (Fingers)
The fingers, or digits of the
upper limb, are numbered 1
to 5 beginning with the
thumb, or pollex (pol′eks). In
most people, the third finger
is the longest. Each hand
contains 14 miniature long
bones called phalanges (fahlan′jēz). Except for the
thumb, each finger has three
phalanges: distal, middle, and
proximal. The thumb has no
middle phalanx. [Phalanx is
the singular term for
phalanges.]
The Pelvic girdle
 Consists
of 2 ossa coxae,
the sacrum, and the coccyx

It attaches the lower limbs to the
axial skeleton, transmits the weight of
the upper body to the lower limbs,
and supports the visceral organs of
the pelvis
The OSSA COXAE
Also called hipbones
 Strong to bear body weight &stress of
movement
 Each is made up of 3 fused bones:

ilium (articulates with sacrum)
 ischium
 pubis

The Acetabulum (vinegar cup)
called the hip socket
 Is the meeting point of the
ilium, ischium, and pubis
 Articulates with head of the
femur (Hip joint)
 Also
landmarks of the Pubis

Pubic symphysis:
gap between pubic tubercles
 padded with fibrocartilage

landmarks of the Ischium
• Ischial tuberosity:posterior
projection you sit on
• Ischeal spine,superior to the
tuberosity ,important during
labour
Divisions of the Pelvis
Figure 8–9
Comparing the Male
and Female Pelvis

Female pelvis:
 The inlet is larger and more circular
 As a whole is shallower and bones are lighter and
thinner
 Ilia flare more laterally
 Sacrum is shorter and less curved
 Ischial spines are shorter and farther apart ,thus the
outlet is larger.
 Pupic arch is more rounded because the angle of the
pupic arch is greater.
Comparing the Male
and Female Pelves
Figure 8–10
The Lower Limbs
 Functions:
 weight
 motion
bearing
Bones of the Lower Limbs
 Femur
(thigh)
 Patella (kneecap)
 Tibia and fibula (leg)
 Tarsals (ankle)
 Metatarsals (foot)
 Phalanges (toes)
The Femur(longest, heaviest )
Figure 8–11
The Patella


Also called the kneecap
Formed within tendon of quadriceps
femoris to decrease friction.
The Tibia and Fibula
Figure 8–13
The Tibia




Also called the shinbone
Supports body weight
Larger than fibula
Medial to fibula, form medial malleolus
The Fibula
• Attaches muscles of feet and toes
• Smaller than tibia
• Lateral to tibia, form lateral malleolus
The Ankle

Also called the tarsus:



consists of 7 tarsal
bones ,of them are:
Talus, receives the end
of tibia
& Calcaneus (heel
bone):


transfers weight to
ground
attaches Achilles tendon
Figure 8–14a
Feet: Metatarsal Bones
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5 long bones of foot
Numbered 1-5, from medial to lateral
Articulate with toes
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Phalanges:
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Hallux:
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bones of the toes
big toe, 2 phalanges (distal &proximal)
Other 4 toes:
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3 phalanges (distal, middle & proximal
phalanx)
Shock absorption :occurs due to
1-Intervertebral discs
2- S-shaped vertebral column
3- Arches of the Foot
Feet Arches
Arches of the Foot :bones of the foot are
arranged to form THREE strong arches,
2 longitudinal (medial & lateral)&
1 transverse
 Ligaments & tendons help to hold the
bones firmly in the arched position but still
allow a certain amount of sprigness
 Week arches are referred to as flat foot
Figure 8–14b
Articulations (Joints)
Function
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Holds bones together
Allows bones to move
All bones articulate with at least one other
bone except the hyoid.
Classification of joints
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Functional classification: focuses on the
amount of movement (synarthrosis,
amphiarthrosis and diarthrosis)
Structural classification : based on
whether Fibrous, Cartilage or a joint cavity
separates the bon ends at the joint.
As a general rule, fibrous joints are
immovable and synovial joints are freely
movable .
Types
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Synarthroses
No movements
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Primarily in axial
skeleton
Bones connected
with fibrous
tissue ligament
Examples : Skull
sutures
Types
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Amphiarthroses
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Slightly
movable
In axial
skeleton
Connected by
cartilage
Intervertebral
joints, pubic
symphysis
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Diarthroses – freely movable
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Also called synovial (fluid filled joint cavity)
Primarily found in the limbs
Plane of movement depends on the joint
Synovial Joints have 4 features
1. Articular cartilage: hyaline
2. Joint Cavity: space filled with lubricating fluid
3.Fibrous Capsule: fibrous CT lined with a smooth
synovial membrane
4. Reinforcing Ligament: can be inside or outside
the joint capsule
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Synovial Fluid: viscous and lubricating
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Bursae: fluid filled sacs ,see later
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Tendons sheath an elongated bursa that rapes
around a tendon subjected to friction.
Types of synovial joints based on
shape
 Plane(nonaxial)
-Slipping or gliding
movements
-Intercarpel joints are best
examples
Hinge joints( uniaxial)
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Angular movement is allowed in only one
plane like a hinge
Examples :elbow,ankle and
interphalangeal joints
Ball-and-socket joints
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A spherical head of one bone fits into a
round socket in another
These Multiaxial joints allow movements in
all axes including rotation
Shoulder and Hip are examples
Bursae
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Flattened fibrous sac lined with synovial
membrane with thin synovial fluid
Acts as bags of lubricant to reduce friction
where ligaments, muscle, skin, tendon or
bones rub together
Disorders of joints
Dislocation:Bone is forced out of its
position.
Reduction is done by experts only
 Bursitis: example falling on the knee
 Sprain: excessive stretch on a ligament
 Arthritis: inflammation of joints, may be
-Acute: usually bacterial
-Chronic: Rheumatoid
,Osteoarthritis and
Gouty arthritis
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Developmental aspects
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Long bones are formed of Hyaline cartilage
Flat bones of skull are formed of fibrous
membranes
At birth , some fontanels still remain
By end of adolescence, the epiphyseal plates are
fully ossified
Adult skull is 1/8 & infant skull is 1/4 of the
total body length
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At birth , cranium is huge relative to face , it
is related to rapid growth of brain
By 2 years skull is 3/4 adult size
By 9 years , skull become nearly of adult size
At birth, the spine is arched and convex
posteriorly
Secondary curvature which are convex
anteriorly appear, with raising the head
(cervical) & with start of walking(lumber)
Primary curvatures still present in thorasic and
sacral regions leading to S-shaped spine in adult
At birth the UL(upper/lower) ratio is 1.7 to 1
 At 10, UL is 1 to 1
 Bones become stronger with pull of gravity &muscle
contractions
 Osteoporosis, thin and fragile bones occurs in totally
inactive persons. It occurs in half women after 65 and
in20% of men after70(estrogen maintain healthy bones)
Causes of Osteoporosis:
- estrogen deficiency
- diet poor in calcium & protein
- lack of vitamin D
- smoking
- lack of exercise
* pathologic fracture is the result
END of Sk. system
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