Download Appendicular Skeleton

A&P – Appendicular Skeleton Notes
Appendicular Skeleton
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Bones of limbs and their girdles
– Pectoral girdle
• Attaches upper limbs to body trunk
– Pelvic girdle
• Attaches lower limbs to body trunk
Pectoral Girdle (Shoulder Girdle)
•
________________________________
– Attach upper limbs to axial skeleton
– Provide attachment sites for muscles that move upper limbs
Clavicles (Collarbones)
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Cone-shaped sternal end articulates with ______________________ medially
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Flattened acromial end articulates laterally with ____________________
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Anchor muscles
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Act as braces to hold the scapulae and arms out
laterally
Scapulae (Shoulder Blades)
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On dorsal surface of rib cage, between ribs _____
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Flat and triangular, with three borders and three
angles
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Several large fossae named according to location
The Upper Limb
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30 bones form skeletal framework of each upper limb
– Arm
• ______________________
– Forearm
• _______________________
– Hand
• 8 __________________ bones in the wrist
• 5 ___________________ bones in the palm
• 14 ____________________ in the fingers
Humerus
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Largest, longest bone of upper limb
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Articulates superiorly with glenoid cavity of scapula
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Articulates inferiorly with radius and ulna
Bones of the Forearm
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Ulna
– Medial bone in forearm
– Forms major portion of elbow joint with humerus
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Radius
– Lateral bone in forearm
– Head articulates with capitulum of humerus and radial
notch of ulna
– ____________________________ connects radius and ulna along their entire length
Hand: Carpus, Metacarpus, and Phalanges
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Carpus (Wrist)
– Eight bones in two rows
• Proximal row—lateral to medial
–
Scaphoid, lunate, triquetrum, and pisiform
• Distal row—lateral to medial
–
Trapezium, trapezoid, capitate, and hamate
– Only scaphoid, lunate, and triquetrum form wrist joint
Hand: Metacarpus and Phalanges
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Metacarpus (Palm)
– Five metacarpal bones (I to V from thumb to little finger) form the palm
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Phalanges (Fingers)
– Fingers numbered I to V starting at thumb (_____________________)
– Digit I (Pollex) has 2 bones - no middle phalanx
– Digits II to V have 3 bones—distal, middle, and proximal phalanx
Pelvic (Hip) Girdle
• Two hip bones (_______________________ or os coxae) and sacrum
– Attach lower limbs to axial skeleton with strong ligaments
– Transmit weight of upper body to lower limbs
– ___________________________________
• Less mobility but more stable than shoulder joint
• Three fused bones form coxal bone
– Ilium, ischium, and pubis
• Bony pelvis formed by coxal bones, sacrum, and
coccyx
Hip Bone
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Three regions
1._____________________
• Superior region of coxal bone
• Auricular surface articulates with sacrum
(sacroiliac joint)
2._____________________
• Posteroinferior part of hip bone
3._____________________
• Anterior portion of hip bone
• Pubis joins at pubic symphysis joint
Comparison of Male and Female Pelves
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Female pelvis
– Adapted for ____________________________
– True pelvis (inferior to pelvic brim) defines birth canal
– Cavity of true pelvis is ___________________, shallow, and has greater capacity
Comparison of Male and Female Pelves
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Male pelvis
– Tilted less far forward
– Adapted for support of male's ___________________________________________
– Cavity of true pelvis is ____________________ and deep
The Lower Limb
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Carries entire weight of erect body
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Subjected to exceptional forces if jump or run
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Three segments of lower limb
– Thigh
– Leg
– Foot
Bones Of The Thigh
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_______________________
– Largest and strongest bone in the body
– Length ______________ of person's height
– Articulates proximally with acetabulum of hip and distally with tibia and patella
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Patella
– Sesamoid bone in quadriceps tendon
Bones Of The Leg
• ____________________
– Medial leg bone
– Receives weight of body from femur; transmits to
foot
• ____________________
– Not weight bearing; no articulation with femur
– Several muscles originate from fibula
– Articulates proximally and distally with tibia
• Tibia and fibula connected by interosseous membrane
Foot: Tarsus, Metatarsus, Phalanges
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Tarsus
– Seven tarsal bones form posterior half of foot
– Body weight carried primarily by talus and calcaneus
– Other tarsal bones: cuboid, navicular, and medial, intermediate, and lateral
cuneiform bones
Foot: Metatarsals and Phalanges
• Metatarsals:
– Five metatarsal bones (I to V from hallux to little toe)
– Enlarged head of metatarsal I forms "ball of the foot"
• Phalanges
– 14 bones of toes
– Digit I (____________________) has 2 bones - no middle phalanx
– Digits II to V have 3 bones—distal, middle, and proximal phalanx
Arches Of The Foot
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Maintained by interlocking foot bones, ligaments, and tendons
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Allow foot to bear weight
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Three arches
– Lateral longitudinal
– Medial longitudinal
– Transverse
Developmental Aspects: Fetal Skull
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Infant skull has more bones than adult skull
– Skull bones such as mandible and frontal bones are unfused
– Skull bones connected by _______________________
• Unossified remnants of fibrous membranes
• Ease birth and allow brain growth
• Four fontanelles
–
Anterior, posterior, mastoid, and sphenoidal
Congenital Abnormalities Of Skull
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Cleft palate
– No medial fusion of right and left halves of palate
Developmental Aspects: Growth Rates
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At birth, cranium huge relative to face
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At 9 months, cranium is _______________________
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Mandible and maxilla are foreshortened but lengthen with age
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Arms and legs grow at faster rate than head and trunk, leading to _____________________
Developmental Aspects: Spinal Curvature
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Primary thoracic and sacral curvatures obvious at birth
– Give spine a ________________________
– Convex posteriorly
Developmental Aspects: Spinal Curvature
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Secondary curvatures
– Cervical and lumbar—convex anteriorly
– Appear as child develops (e.g., lifts head, learns to walk)
Developmental Aspects: Old Age
• Intervertebral discs thin, less hydrated, and less elastic
– Risk of _________________________ increases
• Several centimeter ______________________common by 55
• Costal cartilages ossify
– Rigid thorax causes shallow breathing and less efficient gas exchange
• All bones lose mass, so _______________________ increases