Download Frontal bone

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
Structure

Compact bone
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Outer layer of bone, very hard and dense.
Organized in structural units called Haversian
systems.
Matrix is composed of Ca salts (Ca carbonate and Ca
phosphate)
Osteocytes – living bone cells that live in matrix.
Porous (Spongy) bone


Located in the ends of long bones.
Many spaces that are filled with red bone marrow
which produces bone cells.
Structure

Spongy bone (cont’d)


Trabeculae – needle-like threads of spongy
bone that surround the spaces. Add strength
to this portion of the bone.
Cartilage

Matrix is a firm gel with chondrocytes
suspended in the matrix.
Classification of Bones
 Long bones
 Typically longer than wide
 Have a shaft with heads at both ends
 Contain mostly compact bone
• Examples: Femur, humerus
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 5.4a
Classification of Bones
 Short bones
 Generally cube-shape
 Contain mostly spongy bone
 Examples: Carpals, tarsals
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 5.4b
Classification of Bones on the
Basis of Shape
Figure 5.1
Slide 5.4c
Classification of Bones
 Flat bones
 Thin and flattened
 Usually curved
 Thin layers of compact bone around a layer
of spongy bone
 Examples: Skull, ribs, sternum
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 5.5a
Classification of Bones
 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 5.5b
Gross Anatomy of a Long Bone
 Diaphysis
 Shaft
 Composed of
compact bone
 Epiphysis
 Ends of the bone
 Composed mostly of
spongy bone
Figure 5.2a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 5.6
Structures of a Long Bone
 Periosteum
 Outside covering of
the diaphysis
 Fibrous connective
tissue membrane
 Sharpey’s fibers
 Secure periosteum to
underlying bone
 Arteries
 Supply bone cells
with nutrients
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
 Made of hyaline
cartilage
 Decreases friction
at joint surfaces
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.2a
Slide 5.8a
Structures of a Long Bone
 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)
 A unit of bone
 Central (Haversian) canal
 Opening in the center of an osteon
 Carries blood vessels and nerves
 Perforating (Volkman’s) canal
 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
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Slide
5.10b
Microscopic Anatomy of Bone
 Lacunae
 Cavities containing
bone cells
(osteocytes)
 Arranged in
concentric rings
 Lamellae
 Rings around the
central canal
 Sites of lacunae
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.3
Slide
5.11a
Microscopic Anatomy of Bone
 Canaliculi
 Tiny canals
 Radiate from the
central canal to
lacunae
 Form a transport
system
Figure 5.3
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
5.11b
Changes in the Human Skeleton
 In embryos, the skeleton is primarily hyaline
cartilage
 During development, much of this cartilage
is replaced by bone
 Cartilage remains in isolated areas
 Bridge of the nose
 Parts of ribs
 Joints
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 5.12
Bone Growth
 Epiphyseal plates allow for growth of
long bone during childhood
 New cartilage is continuously formed
 Older cartilage becomes ossified
 Cartilage is broken down
 Bone replaces cartilage
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
5.13a
Bone Growth
 Bones are remodeled and lengthened
until growth stops
 Bones change shape by gravity &muscle
pull
 Bones grow in width through periostium
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
5.13b
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
Types of Bone Cells
 Osteocytes
 Mature bone cells
 Osteoblasts
 Bone-forming cells
 Osteoclasts
 Bone-destroying cells
 Break down bone matrix for remodeling and
release of calcium
 Bone remodeling is a process by 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
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Repair of fracture
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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
Skeletal system includes

Axial division
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•
Skull and associated bones
 Auditory ossicles
 Hyoid bones
Vertebral column
Thoracic cage(Ribs+ sternum)
Appendicular division
-Pectoral
girdle
-Pelvic girdle
The Axial Skeleton

Axial division
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Skull and associated
bones:
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Auditory ossicles
Hyoid bones
Vertebral column
Thoracic cage

Ribs + sternum
The Skull and Associated Bones
Sutures
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Sutures – Immovable joints that join skull
bones together
Form boundaries between skull bones
Four sutures:
Coronal – between parietal and frontal
 Sagittal– between parietal bones
 Lambdoid – between the parietal and occipital
 Squamous – between the parietal and
temporal
 Fontanels – usually ossify by 2 years of age

Sagittal
Frontal
(Coronal)
Squamous
Lambdoid
Sutures
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
Bones of the Cranium
Frontal View
Frontal
Frontal View
Parietal
Frontal View
Temporal
Frontal View
Nasal
Frontal View
Vomer
Frontal View
Zygoma
Frontal View
Maxilla
Frontal View
Mandible
Frontal View
Frontal
Parietal
Temporal
Nasal
Vomer
Zygoma
Maxilla
Mandible
Frontal View
Lateral View
Frontal
Lateral View
Parietal
Lateral View
Temporal
Lateral View
Nasal
Lateral View
Zygoma
Lateral View
Maxilla
Lateral View
Mandible
Lateral View
Occipital
Lateral View
Mastoid Process
Lateral View
External Auditory Meatus
Lateral View
Parietal
Frontal
Sphenoid
Temporal
Occipital
Mastoid Process
Nasal
Zygoma
Maxilla
Mandible
External Auditory Meatus
Lateral View
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 – sagittal suture
-articulate with occipital, frontal,
temporal and sphenoid bones
•Temporal bone
-Forms wall of jugular foramen
-Petrous part: posterior portion
-Tympanic part: associated with ear canal
-Squamous part: anterior portion, fan-shaped
-zygomatic process
-forms cranial portion of the TMJ joint
-inferior to zygo. process – mandibular fossa (mandibular condyle)
•Temporal bone – petrous portion
•houses the inner ear
-inferior aspect – mastoid
process (air spaces that
communicate with the middle
ear)
-also for attachment of
sternocleidomastoid muscle
-inferior to mastoid process –
mastoid foramen
-anterior to mastoid process –
external acoustic meatus
-inferior and medial to the MP
– styloid process (muscle
attachment)
-stylomastoid foramen
(7th cranial)
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Occipital bone
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Part of the base of the skull
articulates with parietal,
temporal and sphenoid
Surrounds the foramen magnum
lateral to the FM – hypoglossal
canal (12th cranial)
projections = occipital
condyles
Forms part of the jugular
foramen
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Sphenoid bone
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Contributes to floor of
cranium
articulates with the
frontal, ethmoid,
temporal
zygomatic, parietal
maxillary, palatine,
vomer & occipital bones
Bridges cranial and facial
bones
Optic canal allows
passage of optic nerve
Ethmoid bone
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Irregularly shaped bone
Forms part of orbital wall
Forms roof of nasal cavity
articulates with: frontal,
sphenoid, lacrimal and maxillary
bones
connects with the vomer
two lateral masses – contain the
ethmoid sinuses

projections called the superior
and middle nasal conchae
two plates: perpendicular
plate
& the cribiform plate
 Cribiform plate: perforations
for olfactory nerve, midline is the
crista galli
 Perpendicular plate = upper
part of nasal septum

14 Facial Bones
Nasal (2)
Zygomatic (2)
Mandible (1)
(2)
Maxillae (2)
Lacrimal (2)
Palatine
Bones of the Face

Maxillae
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Paired bone
Largest of facial
bones
Form upper jaw
body = orbital,
nasal,
infratemporal and
facial surfaces
body contains the
maxillary sinuses
Maxillary bones: Anterior
View
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frontal process – articulates with frontal bone and nasal bones & forms
medial orbital rim
facial surface – body of maxilla
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infraorbital foramen – landmark for local
inferior to this IF – canine fossa
inferior portion of the maxilla – alveolar processes of the teeth (contains
the roots of the maxillary teeth
Zygomatic Bones
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Cheekbones
Lateral wall of orbit along with sphenoid
Part of zygomatic arch along with part of
temporal

Palatine bones
Small, L-shaped
 link between maxilla and
sphenoid
 Form posterior portion of hard
palate
 Contribute to floor of orbit
 made up of horizontal
plate and a vertical plate
+ orbital process

-two

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
Mandible: Inferior
surface
-visible are the genial tubercles – or mental spines
-muscle attachment area
-two fossas: 1) sublingual (sublingual salivary gl.)
2) submandibular (submandibular gl.)
-divided by the mylohyoid line (mylohyoid m.)
-mandibular foramen – opening of the mandibular canal
-for the exit of the alveolar nerve and vessels
-can be lost with alveolar process reabsorption
-overhanging the foramen – lingula (attachment of sphenomandibular
ligament – TMJ)
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
part of the nasal complex
 Paired cavities in ethmoid,
sphenoid, frontal and
maxillary
 Lined with mucous
membranes and open into
nasal cavity though openings
called ostia
 Resonating chambers for
voice, lighten the skull
frontal sinuses: frontal bone, separated by a  Sinusitis is inflammation of
the membrane (allergy)
septum
 connects with nasal cavity – frontonasal duct
 infection can easily spread
sphenoid sinuses: body of the sphenoid bone
from one sinus to the other
through the nasal cavity
 also drain into nasal cavity
ethmoid sinuses: or ethmoid air cells, located in can also spread to other
the lateral masses
tissues
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anterior, middle and posterior sinuses
maxillary: body of the maxilla
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size varies with individual and age
largest of the sinuses
close proximity to alveolar processes –
periodontal tissues may be in direct contact with
sinus’ mucus membranes

secondary sinusitis
The Vertebral Column
http://www.wisc-online.com/objects/index.asp?objID=AP12104
Adult Vertebral Column

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
Typical Cervical Vert. (C3-C7)

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Smaller bodies
Larger spinal canal
Transverse
processes

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shorter
transverse foramen
for vertebral artery
Spinous processes
of C2 to C6 often
bifid
1st and 2nd
cervical vertebrae
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


Has a body and spinous process
Dens (odontoid process) projects
superiorly


Acts as a pivot for rotation of the atlas and
skull
Participates in rotating the head from side
to side
The Axis
Thoracic Vertebrae
(T1-T12)
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
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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 rocesses
are thick, blunt,
and point
Vertebral
foramina are
triangular
Allows flexion and
extension –
rotation
prevented
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


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


Articulates with medial end of clavicles
Sides are notched as articulations for costal
cartilage of ribs 2–7
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
What are the bones of
the pectoral girdle, their
functions, and features?
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

Consists of:



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



Also called shoulder blades
Broad, flat and triangular
Articulate with arms and collarbone
Anatomy of
The scapula
Figure 8–3a
What are the bones of
the upper limbs, their
functions, and features?
The Upper Limbs

Arms, forearms, wrists, and hands
Note: arm (brachium) = 1 bone, the
humerus
ANATOMY OF
The Humerus
Figure 8–4
The Humerus



Also called the arm
The long, upper armbone
Articulates with the pectoral girdle
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
Metacarpal Bones
 The
5 long bones of the hand
 Numbered I–V from lateral
(thumb) to medial
 Articulate with proximal
phalanges
Phalanges of the Hands
 Pollex
(thumb):
2
phalanges (proximal,
distal)
 Fingers:
3
phalanges (proximal,
middle, distal)
What are the bones of
the pelvic girdle, their
functions, and features?
The Pelvis
 Consists
of 2 ossa coxae,
the sacrum, and the coccyx
 Stabilized by ligaments of
pelvic girdle, sacrum, and
lumbar vertebrae
The Pelvic Girdle
Figure 8–7
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
Marks of the Pubis

Pubic symphysis:
gap between pubic tubercles
 padded with fibrocartilage

Marks of the Ischium
• Ischial tuberosity:posterior
projection you sit on
• Ischeal spine,superior to the
tuberosity ,important during
labour
The Pelvis
Figure 8–8
Divisions of the Pelvis
Figure 8–9
The Pelvis

Perineum region:



inferior edges of true pelvis
forms pelvic outlet
perineal muscles support organs of pelvic
cavity
What are the structural
and functional differences
between the male and
female pelvis?
Comparing the Male
and Female Pelvis
 Female
pelvis:
 smoother
 lighter
 less
prominent muscle and
ligament attachments
Comparing the Male
and Female Pelvis
Figure 8–10
Pelvis Modifications
for Childbearing
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Enlarged pelvic outlet
Broad pubic angle (> 100°)
Less curvature of sacrum and coccyx
Wide, circular pelvic inlet
Broad, low pelvis
Ilia project laterally, not upwards
What are the bones of
the lower limbs, their
functions, and features?
The Lower Limbs
 Functions:
 weight
bearing
 motion
Note: leg = lower leg; thigh =
upper leg
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
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Also called the kneecap
Formed within tendon of quadriceps
femoris
The Tibia and Fibula
Figure 8–13
The Tibia
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Also called the shinbone
Supports body weight
Larger than fibula
Medial to fibula
The Fibula
• Attaches muscles of feet and toes
• Smaller than tibia
• Lateral to tibia
Bones of the Ankle
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Talus:
Calcaneus (heel bone):
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transfers weight to ground
attaches Achilles tendon
The Ankle
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Also called the tarsus:
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consists of 7 tarsal
bones
Figure 8–14a
Feet: Metatarsal Bones
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5 long bones of foot
Numbered I–V, medial to lateral
Articulate with toes
Feet: Phalanges
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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, medial, proximal)
Feet: Arches
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Arches transfer weight from 1 part of the
foot to another
Figure 8–14b
Arches of the Foot
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Bones are arranged to form THREE strong
arches, 2 longitudinal (medial & lateral)&
1 transverse
Ligaments & tendons help to hgold the
bones firmly in the arched position but still
allow a certain amount of spriginess
Week arches are referred to as flat foot
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 bony regions 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 axial
skeleton
Bones connected
with fibrous
tissue ligament
Examples:Skull
sutures and distal
Tibia/Fibula
Types
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Amphiarthroses
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Slightly movable
Axial skeleton
Connected by
cartilage
Intervertebral
joints, pubic
symphysis
Types
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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 - Structure
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
5.Synovial Fluid: viscous and lubricating
6. Bursae: fluid filled sacs ,see later
7. Tendons sheath an elongated bursa that rapes
around a tendon subjected to friction.
8. Menisci: cartilaginous discs
Synovial Joint
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
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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
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 epiphysial 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 (primary) and
convex posteriorly
Secondary curvature are convex anteriorly,
cervical with raising the head & lumber
with start of walking
S-shaped spine in adult
At birth the UL 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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