The Appendicular Skeleton

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The Appendicular Skeleton
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THE SKELETAL SYSTEMThe Appendicular Skeleton

• 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 leg
• Thigh
• Leg
• Foot

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Pectoral Girdle(Shoulder Girdle)

• Clavicle anterior collar bone
• Sternal end attaches to the manubrium medially
• Acromial end articulates with the scapula
  laterally
• Scapula posterior shoulder blade

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Scapulae triangular, paired, but dont connect
in back (adds thoracic flexibility)
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Scapula

• Glenoid cavity articulates with the humerus
• Acromium articulates with clavicle
• Coracoid process projects anteriorly

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Upper extremity

• Arm or Brachium upper arm
• Between shoulder and elbow (humerus)
• Forearm or Antebrachium
• Radius ulna
• Hand includes
• Wrist (carpus)
• Palm (metacarpus)
• Fingers (phalanges)

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Arm

• 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

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Right humerus, anterior view
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Right humerus, posterior view
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Forearm
Radius is thinner proximally, like a spool of
thread, and wide distally ulna is slightly
longer and looks like a monkey wrench
(supposedly!)

• 2 bones articulate with each other proximally
  and distally
• Interosseous membrane between them
• Ulna
• Olecranon hinges with the humerus forming elbow
• Styloid process distally
• Radius
• Contributes to wrist joint
• Styloid process anchors a ligament to wrist
  (thumb side)

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Right forearm bones, anterior view
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Right forearm bones, posterior view
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• In the anatomical position, the radius is
  lateral (thumb side) with pronation the palm
  faces posteriorly and the bones cross

Left forearm
Prone body lying face down Suppine body lying
face up
Anatomical position
prone
(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
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Proximal and distal joints of the forearm
proximal ulna
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Hand

• 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
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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
• Bony pelvis is basin-like structure hip bones
  plus the axial sacrum and coccyx

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Hip bone (os coxae) 3 separate bones in
childhood which fuse

• Ilium
• Ischium
• Pubis

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Ilium
ilium

• Iliac crest
• Anterior superior iliac spine
• Greater sciatic notch
• Forms part of acetabulum
• (hip socket) which receives ball-shaped head of
  femur

ilium
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Ischium

• Body
• Ramus
• Ischial spine
• Ischial tuberosity
• Part of socket

ischium
ischium
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Pubis

• Joins medially in pubic symphysis
• Forms obturator foramen (large hole) with
  ischium
• Part of socket

pubis
pubis
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Hip bones with labels
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False (greater) and true (lesser) pelvis
Ligaments
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Pelvis and childbearing

• 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
• 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

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Lower limb

• Thigh femur
• Leg (lower leg)
• Tibia
• Fibula
• Foot

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Thigh

• 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

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Right femur, anterior view
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Right femur, posterior view
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Leg

• Tibia shin bone
• Medial and lateral condyles
• Tibial tuberosity
• Distal medial malleolus (medial ankle)
• Fibula
• Distal lateral malleolus (lateral ankle)
• Interosseous membrane

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Right lower leg, anterior view
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Foot

• 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)
• 5 metatarsals
• 14 phalanges
• Great toe is hallux

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Right foot, superior (dorsal) view and inferior
(plantar) view
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Right foot, lateral and medial views
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Arches