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Skeletal system
Axial skeleton: The bones that form the
longitudinal axis of the body.
Appendicular skeleton: Is the bones of
limbs, and girdles.
Skeletal system includes cartilages,
ligaments, and bones.
Functions of the bones
Support
Protection
Movement
Storage
Blood cell formation
Classification of bones
Compact bones
Sponge bones
Long bones
Short bones
Flat bones
Irregular bones
Structure of long bones
Diaphysis body, or shaft, covered by
periosteum.
Epiphyses are the ends of long bones,
covered by articular cartilage
Epiphyseal line: is the remnant of the
epiphyseal plate which makes bone
grow. In adults the cavity of the shaft is
yellow marrow, in children red marrow.
Axial skeleton
•
It forms the longitudinal axis of the body.
•
Skull,verteberal column, and bony thorax.
•
Skull: Is formed of two sets of bones.
•
Cranium, and mandible.
Cranium:
Is composed of eight ,large, flat bones.
• Frontal bone: Forms the fore head,
bony projections under eye brow,
superior part of each orbit.
• Parietal bones: forms the superior,
and lateral wall of the skull.
• The meet in the midline at sagittal
suture, and forms the coronal suture,
where they meet frontal bone.
• Temporal bone: Lie inferior to the
parietal bone, join them at squamous
suture
Bone marking of temporal bones
1. External auditor meatus.
2. Styloid process
3. Zygomatic process
4. Mastoid process
5. Jugular foramen
6. Carotid canal
Occipital bone
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Most posterior bone of the body.
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It forms the back, and floor of the skull.
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Joins the parietal bone Anteriorly, at
lambdoid suture.
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Has foramen magnum, and occipital
condyles
Sphenoid bone
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Butterfly shaped bone
In middle depression called sella
turcica, for pituitary gland.
Foramen ovale, for branches of 5th
cranial nerve.
Has sphenoid sinus.
Ethmoid bone
• Irregular shape, anterior to sphenoid.
• Roof the nose.
•
Has projection called crista galli.
• Lateral has cribriform plates, for nerve
fibers of olfactory nerve.
Facial bones
14 bone form the face,12 paired.
2 Single ,mandible, and vomer.
Maxillary bones
• Two fuse ,to form upper jaw.
• All bones join it.
• Pallatine process, form the hard palate.
• Contain maxillary sinuses.
Palatine bones: form part of hard palate
Zygomatic bones: check bones
Lacrimal bones: Fingernail size bone
Nasal bones
Vomer bone
Inferior conchae.
Mandible or lower jaw
Strongest bone of the face.
Join the temporal bone at tempero mandibular joint.
Horizontal part form the chin.
Lower teeth lie in it
Hyoid bone
Does not articulate with other bones.
Lies two cm above larynx.
Horseshoe shape, has body and two horns.
Rise larynx during speak, and swallow.
Fetal skull
One forth of fetal size.
Two fontanelles, large diamond shape anterior one.
small triangular posterior one.
They connect skulls bones.
Anterior one close at 18-24 month.
Vertebral column (spine)
 Axial support from the
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skull to the pelvis.
The spine is formed of 33
vertebrae, before birth.
9 fuse after birth to form
two composite bones the
sacrum and the coccyx.
There are seven cervical,
twelve thoracic, five
lumbar vertebrae.
The vertebrae are
separated by intervertebral
discs
intervertebral discs.
 The disc is composed of 90%


water.
It is fibrocartilage.
They absorb shock.
Drying of the disc and weakness
of the ligaments predispose to
herniated disc, if it press on
spinal cord or spinal nerves it
cause severe pain, and
numbness.
The vertebral column is S shape.
The spinal curvatures in the thoracic and sacral
region are called primary curvatures.
Since they are present since birth.
Secondary curvatures, in cervical and
lumbar vertebrae.
Cervical convexity forward at 3rd month, lumbar
convexity forward at 12th month.
Length of vertebral column 3/4from bone 1/4
from disc.
Typical vertebra is
composed of
Body: is the anterior weight
bearing part of vertebra.
Vertebral arch: is formed by the
joining of all posterior
extensions,lamina,pedicle.
Vertebral foramen: canal
through which spinal cord
pass.
Transverse process: two lateral
projections.
Spinous process: single
projection from posterior part
of the arch
Superior and inferior articular
processes: paired projections
lateral to vertebral canal to
form joints with adjacent
vertebrae.
Cervical vertebrae
Seven cervical vertebrae
First is the Atlas, second is the axis.
Atlas has no body, no spinous process, look
like a ring, superior surface has articular
surface for the occipital condyles .
AXIS,2ND CERVICAL VERTEBRAE
Act as pivot for rotation of atlas and skull.
It has odontoid process, which is upright
process.
Rotation occur at atlanto-axial joint.
.
Typical cervical
vertebraeC3-C7
•They are the smallest
,lightest vertebrae.
•Spinous process are short,
and divided.
•Transverse process has
foramina, through which
vertebral artery pass
• Thoracic vertebrae
• 12 thoracic vertebrae.
• All are typical, larger than cervical
vertebrae.
• Body are heart shaped.
• Has articular facet for head of ribs.
• Spinous process are long.
Lumbar vertebrae
Strongest vertebrae
Most common site
for disc is
L4-5 L5-S1
Thoracic lumbar vertebrae
Sacrum
 Formed by union of five vertebrae.
 Superiorly articulate with L5.
 Inferiorly with coccyx.
 Wing like ala articulate with pelvis in
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sacroiliac joint.
It forms the posterior part of the pelvis.
Has dorsal sacral crest, and dorsal sacral
foramina.
Vertebral canal continue as sacral canal.
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COCCYX
• Formed by fusion of 3-5 small vertebrae.
Sacrum
Bony Thorax [thoracic cage]
Sternum, ribs and thoracic vertebrae form the
bony thorax.
Sternum
Formed by fusion of three
bones,(Manubrium,Body,and Xiphoid
process).
Attached to first seven pair of ribs.
Sternum has three important bony
land marks.
Jugular notch: at
level 3rd thoracic
vertebra.
Concave upper border of manubrium.
Sternal angle: :(angle of Louis)
manubrium and body meet.
Slight transverse elevation.
Level of 2nd rib. .(T4/T5)
Xiphisternal joint: body and Xiphoid meet
at level of 9th thoracic vertebra
Ribs
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Twelve pairs of ribs form the walls of
thoracic cage.
All ribs articulate with thoracic
vertebrae.
True ribs articulate with sternum, by
costal cartilage.
False ribs, are attached indirectly to
sternum, or not attached at all, last two
are called floating ribs.
• The intercostals space is below rib filled by
intercostals muscles, help in respiration.
• Fracture rib at weakest area, which is the
angle of the rib.
• The first two and last two ribs are difficult
to be fractured.
• Pain during inspiration, unable to cough, is
symptoms of rib fracture.
Upper limb
Is divided into
Shoulder region
Arm
Elbow
Forearm
Wrist
Hand
Bones of shoulder region
Clavicle and scapula
Clavicle is attached medially to
sternum, and laterally to scapula
at acromioclavicular joint.
It is the commonest bone to be
fractured, by fall on out stretched
hand, or direct hit, weakest point
is junction of medial two thirds
and lateral third.
Scapula
Triangular
in
shape,
has
two
important
processes,acromiom,and coracoid.
Scapula has three borders superior,lateral,medial,and
three angles,superior,inferior,and lateral. The glenoid
cavity receive head of humerous to form shoulder joint.
 The glenoid cavity is shallow.
 The shoulder girdle is light.
 The shoulder girdle is attached to axial skeleton at one
point.
 It has very wide range of movement, so it is easily
dislocated.
Arm is formed by single bone the humerus,it is a
typical long bone, has upper end ,shaft, lower end.
Upper end has head, two
tuberosities,greater,and lesser tuberosity,and neck.
In the middle of the shaft(body), deltoid
tuberosity,and radial groove.
The lower end, medial trochlea,and lateral
capitulum,above trochlea a depression coronoid
fossa anteriorly,and posteriorly, olecranon fossa,and
medial and lateral epicondyles.
Forearm bones
Radius and ulna
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Radius is the lateral bone, on the
thumb side.
Both radius and ulna articulate by
superior and inferior radio-ulnar joint.
Both are connected by interosseous
membrane.
Head of radius,trochlear notch of
ulna forms the elbow joint.
Radial tuberosity is for insertion of
biceps muscle.
Hand
The skeleton of the hand
Carpals,metacarpals and phalanges.
There is eight carpal bones arranged in two
rows.Carpus form the wrist, metacarpus forms the
palm,phalynges form the fingers.
Carpus bones arranged in two rows
Proximal row scaphoid,lunate,triquetral,and pisiform.
Distal row
Trapezium trapezoid,capitate,and hamate.
Five metacarpals each has base, body and head.
Phalynges have,proximal,middle,and distal phalynx
,except thumb.
Bones of the pelvic girdle
Right, and left hip bones, and sacrum.
Large, and heavy bones.
Functions of the pelvis
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Bearing weight.
Protect Large intestine, reproductive
organs, and urinary bladder, which lie
in pelvis.
Provide attachments for muscles.
Rotatory movement during walking.
Each hip bone is formed by fusion of
three bones.
Ilium ,ischium ,pubis.
Ilium
 connect posteriorly with sacrum at
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sacroiliac joint.
Iliac crest is the curved highest part of
iliac bone.
Iliac crest ends Anteriorly by anterior
superior iliac spine, and posteriorly by
posterior superior iliac spine.
Ischium
is the sitting bone;ischial tuberosity is
part which receive body weight.
Ischial spine, narrows the outlet of pelvis
through which baby must pass.
Greater sciatic notch, allow blood
vessels, and sciatic nerve to pass to
thigh.
Pubis
is the most anterior part of hip bone.
Pubic bones fuse anteriorly to form, a
cartilaginous joint called symphysis
pubis.
The three bones, ilium,ischium,pubis,fuse
at acetabulum, which receive head of
femur bone, in hip joint.
True pelvis and lie inferior to the ilia,is
the part which allow baby's head to
pass. False pelvis is above true pelvis.
Pelvic outlet is the inferior opening of the
pelvis.
Differences between male
and female pelvis
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The FM inlet is larger and
more circular.
The FM pelvis is shallower
and bones are lighter.
The FM ilia flare more
laterally.
FM sacrum is shorter, and
less curved.
FM ischial spines are shorter,
and further apart.
FM pubic arch is more
rounded,
Differences between male and female pelvis
Bones of the lower limbs
FEMUR
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Is the longest bone of the body.
It is 45cm long, and forms 1/4 of stature.
It has upper, shaft, and lower end.
Upper end has head,neck,greater trochanter,lesser
trochanter.
Anteriorly Intertrochanteric line
Posteriorly Intertrochanteric crest are sites for
muscle attachments
Head articulate with accetabulum in hip joint.
Angle between neck, and shaft is smaller in females
than in males, because they have wide pelvis.
Blood supply of head of femur
Blood ascending from shaft.
Blood from capsule of hip joint.
Blood from ligamentum teres.
Types of fracture neck femur
Sub capital
Transcervical
Basal
Intertrochanteric
Femur
Distal end
Medial and lateral condyles
Intercondylar notch.
Smooth patellar surface for patella
at knee joint
Tibia and fibula
Are the two bones of the leg, connected by interosseus
membrane.
Tibia is the shin bone, medial bone.
Has upper end,shaft,and lower end.
Upper end has medial,lateral condyles,inter condylar
eminence, to form with distal femur the knee joint.
Patellar ligament
attached to tibial tuberosity
,a rough area on anterior Tibial surface.
Medial malleolus is the inner bulge
of the ankle.
Anterior crest is felt under the skin
Fibula
 Very thin and long bone
 Has upper end,neck,shaft,and lower
end.
 Forms with tibia, joints ,proximal and
distal.
 Lower end is lateral malleolus,form
outer part of the ankle.
Patella
 Large flat sesamoid bone
 Triangular in shape, base
above, apex below.
 Anterior surface is
rough,posterior surface is
smooth.
 No function of patella,
function of knee joint
return100% after removal
Tarsal,metatarsal,and phalynges
Function of the foot
Support our body weight
Serve as levers that propel our body, during
walking, and running.
The tarsus form the posterior half of the foot.
Tarsus is formed of seven bones.
Calcaneus or heel bone
Talus between, tibia and calcaneus
Navicular,cuboid, three cuneiform bones.
Five metatarsal bones
14 phalynges,five to each toe ,except two
for big toe.
The bones in the foot, form three arches.
Two longitudinal arches,one
medial,one lateral,one transverse.
Tendons and ligaments bind bones
together.
Fallen arches are called flat feet.
The arches are the bones which do
not touch the ground
• Medial arch responsible for
walking
• Lateral arch support body weight.
Para nasal sinuses
• There are eight Para nasal sinuses
• Frontal, maxillary, sphenoid, and ethmoid sinuses
all are paired sinuses
• Maxillary sinus is the most important sinus
Functions of para nasal sinuses
• Resonance of voice
• Make bones of skull lighter
• Humidification of air
• Warming of air
• Barrier to infection
• Inflammation in them is called sinusitis
Para nasal sinuses
BONE
• Cells
• Osteocytes
• Osteoblasts
• Osteoclasts
• Bone matrix
• Organic
• Collagen type 1
• Ground substance
• Proteoglycans
• Glycoproteins
• Inorganic
• Hydroxyapatite
• Ca Po4, magnesium, bicarbonate, citrate, sodium &
potassium
Bone Tissue
• Osteoblasts
• Secrete organic part of bone matrix
• Osteocytes
• Mature bone cells
• Sit in lacunae
• Maintain bone matrix
• Osteoclasts
• Degrade and reabsorb bone
• Periosteum
• External layer of CT that surrounds bone
• Outer: Dense irregular CT
• Inner: Osteoblasts, osteoclasts
• Endosteum
• Internal layer of CT that lines cavities and covers trabeculae
• Contains osteoblasts and osteoclasts
Compact Bone
External layer
Osteon (Haversian system)
Parallel to the long axis of the bone
Groups of concentric tubules (lamella)
Lamella = layer of bone matrix where all fibers run in
the same direction
Adjacent lamella fibers run in opposite directions
Haversian Canal runs through center of osteon
Contains blood vessels and nerves
Connected to each other by perforating (Volkman)
canals
Interstitial lamellae fills spaces and forms periphery
Bone Anatomy: Spongy bone
• Spongy bone (cancellous bone): internal layer
• Trabeculae: small, needle-like pieces of
bone form honeycomb
• each made of several layers of lamellae +
osteocytes
• no canal for vessels
• space filled with bone marrow
• not as dense, no direct stress at bone’s
center
Shapes of Bones
• Flat = skull, sternum, clavicle
•
Irregular = pelvis, vertebrae
•
Short = carpals, patella
•
Long = femur, phalanges,
metacarpals, humerus
TYPES OF BONE
(GROSS OBSERVATION)
• JOINTS
• All bones form joints with at least one
other bone, except hyoid bone.
• Functions of joints
• They hold bone together securely.
• They give rigid bones mobility.
• Functional classification
• Based on amount of movement
• Imobile,slightly mobile,and freely mobile.
Category
Type and Description
Examples
Synarthrosis (immovable)
Suture—fibrous connective
tissue between bone
surfaces
Between cranial bones;
between facial bones
Amphiarthrosis (slightly
movable)
Symphysis—disc of fibrous
cartilage between bones
• Between vertebrae;
between pubic bones
Diarthrosis (freely movable)
Ball and socket—movement Scapula and humerus;
in all planes
pelvic bone and femur
Hinge—movement in one
plane
Humerus and ulna; femur
and tibia; between
phalanges
Condyloid—movement in
one plane with some lateral
movement
Temporal bone and
mandible
Pivot—rotation Gliding—
side-to-side movement
Atlas and axis; radius
&ulna. Betweencarpals