Transcript THE APPENDICULAR SKELETON

The Appendicular Skeleton
THE SKELETAL SYSTEM
The Appendicular Skeleton
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2 pairs of limbs and 2 girdles
Pectoral (shoulder) girdle attaches upper limbs
Pelvic (hip) girdle secures lower limbs
3-Segmented limbs
 Upper = arm
 Arm
 Forearm
 Hand
 Lower =
 Thigh
 Leg
 Foot
leg
Pectoral
Girdle
(Shoulder Girdle)
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Clavicle – anterior: collar bone
 Sternal
end attaches to the manubrium
medially
 Acromial end articulates with the scapula
laterally
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Scapula – posterior: shoulder blade
Scapulae: triangular, paired, but don’t
connect in back (adds thoracic flexibility)
Scapula
Glenoid cavity
articulates with
the humerus
 Acromium
articulates with
clavicle
 Coracoid
process projects
anteriorly
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Upper extremity
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Arm or Brachium =
upper arm
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Forearm or
Antebrachium
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Between shoulder
and elbow (humerus)
Radius & ulna
Hand includes:
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Wrist (carpus)
Palm (metacarpus)
Fingers (phalanges)
Arm
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Humerus is the only
bone
 Head of humerus fits
into glenoid cavity of
scapula
 Distal & medially,
trochlea articulates
with the ulna
 Distal & laterally
capitulum articulates
with the radius
 Medial & lateral
epicondyles
Right
humerus,
anterior view
Right
humerus,
posterior view
Forearm
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2 bones: articulate with each
other proximally and distally
Interosseous membrane
between them
Ulna
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Olecranon hinges with the
humerus forming elbow
Styloid process distally
Radius
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Contributes to wrist joint
Styloid process anchors a
ligament to wrist (thumb side)
Radius is thinner proximally, like a spool
of thread, and wide distally; ulna is
slightly longer and looks like a monkey
wrench (supposedly!)
Right forearm bones,
anterior view
Right forearm bones,
posterior view
Left forearm
prone
Anatomical
position
In the anatomical
position, the radius is
lateral (thumb side); with
pronation the palm
faces posteriorly and the
bones cross
Prone: body lying face down
Suppine: body lying face up
(you can remember prone if you think
about how you would fall forward onto
your face if you passed out)
pronation moves the forearm into the
prone position and supination moves
it back to the anatomical position
Proximal and distal joints of the forearm
proximal ulna
Hand
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Proximal is “wrist” – 8 carpal bones
Palm of hand - 5 metacarpals
Fingers (or digits) consist of miniature long bones called
phalanges: thumb (“pollex”) has 2; fingers have 3:
proximal, middle, distal
Right hand, 2 views:
Pelvic Girdle
(Hip Girdle)
Strongly attached to axial skeleton (sacrum)
 Deep sockets
 More stable than pectoral (shoulder) girdle
 Less freedom of movement
 Made up of the paired hip bones
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 “Bony
pelvis” is basin-like structure: hip bones
plus the axial sacrum and coccyx
Hip bone (os coxae): 3 separate
bones in childhood which fuse
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Ilium
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Ischium
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Pubis
Ilium
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Iliac crest
Anterior
superior iliac
spine
Greater sciatic
notch
Forms part of
“acetabulum”
(hip socket)
which receives
ball-shaped
head of femur
ilium
ilium
Ischium
Body
 Ramus
 Ischial spine
 Ischial
tuberosity
 Part of socket
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ischium
ischium
Pubis
Joins
medially in
pubic
symphysis
 Forms
“obturator
foramen”
(large hole)
with ischium
 Part of socket
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pubis
pubis
Hip bones with labels
False (greater) and
true (lesser) pelvis
Ligaments
Pelvis and childbearing
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Male/female differences
 Large
& heavy vs light & delicate
 Heart shaped pelvic inlet vs oval
 Narrow deep true pelvis vs wide & shallow
 Narrow outlet vs wide
 Less than 90 degree pubic arch vs more than 90
degree
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Birth canal changes shape as baby descends:
head turns ¼
 Higher:
pelvic inlet (brim) - side to side largest
 Lower: pelvic outlet - largest in AP direction
Lower limb
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Thigh: femur
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Leg (lower
leg)
 Tibia
 Fibula
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Foot
Thigh
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Femur is largest, longest
and strongest bone in the
body
Head fits in socket
(acetabulum) of pelvis
Neck is weakest
Greater trochanter
Distal: lateral & medial
condyles and epicondyles
Patella: sesmoid bone
Right femur,
anterior view
Right femur,
posterior view
Leg
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Tibia: shin bone
 Medial
and lateral
condyles
 Tibial tuberosity
 Distal medial malleolus
(medial ankle)
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Fibula
 Distal
lateral malleolus
(lateral ankle)
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Interosseous
membrane
Right lower leg,
anterior view
Foot
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Tarsus: 7 tarsal bones
 Talus:
articulates with
tibia and fibula anteriorly
and calcaneus posteriorly
 Calcaneus: heel bone
 Smaller cuboid,
navicular, and 3
cunieforms (medial,
intermediate and lateral)
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5 metatarsals
14 phalanges
 Great
toe is hallux
Right foot, superior (dorsal) view and inferior (plantar) view
Right foot,
lateral and
medial views
Arches