The Appendicular Skeleton

THE APPENDICULAR SKELETON Composed of 126 bones

Limbs (appendages) Pectoral girdle Pelvic girdle

THE APPENDICULAR SKELETON

Figure 5.6a

acromion

THE APPENDICULAR SKELETON

Figure 5.6b

THE PECTORAL (SHOULDER) GIRDLE Composed of two bones

Clavicle—collarbone –slender bone; at risk to fracture

Scapula—shoulder blade These bones allow the upper limb to have

exceptionally free movement The clavicle serves as a brace to hold the

arm away from the top of the thorax…so there is no problem with the arm clearing the wides dimension of the thoracic cage.

BONES OF THE SHOULDER GIRDLE

Figure 5.21a

Coracoid processgreater tubercle

BONES OF THE SHOULDER GIRDLE

Figure 5.21b

CLAVICLE (#2)

BONES OF THE SHOULDER GIRDLE

Figure 5.21c–d

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SCAPULA (#1)

BONES OF THE UPPER LIMBS Humerus

Forms the arm Single bone

BONES OF THE UPPER LIMBS

Figure 5.22a–b

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Humerus (#3)

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BONES OF THE UPPER LIMBS The forearm has two bones

Ulna Medial bone in anatomical position

Radius Lateral bone in anatomical position

BONES OF THE UPPER LIMBS

Figure 5.22c

Radius (#4) & Ulna (#5) *

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BONES OF THE UPPER LIMBS The hand

Carpals—wrist 8 bones Metacarpals—palm Phalanges—fingers 14 bones

BONES OF THE UPPER LIMBS

Figure 5.23

Carpal (#6), Metacarpals (#7), Phalanges (#8)

BONES OF THE PELVIC GIRDLE Formed by two coxal (ossa coxae) bones Composed of three pairs of fused bones

Ilium Ischium Pubis

Pectoral Girdle is more flexiblePelvic Girdle is more secure and better able to bear

weight

BONES OF THE PELVIC GIRDLE The total weight of the upper body rests on

the pelvis…therefore, must be massive It protects several organs

Reproductive organs Urinary bladder Part of the large intestine

People instinctively curl over to protect internal organs

THE PELVIS

Figure 5.24a

More massive than 4 legged creatures because it has to bear more weight.

THE PELVIS: RIGHT COXAL BONE

Figure 5.24b

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Illium = yellow bone #1Ischium = Purple bone #2Pubis = Red bone #3

GENDER DIFFERENCES OF THE PELVIS The female inlet is larger and more circular The female pelvis as a whole is shallower,

and the bones are lighter and thinner The female ilia flare more laterally The female sacrum is shorter and less curved The female ischial spines are shorter and

farther apart; thus the outlet is larger The female pubic arch is more rounded

because the angle of the pubic arch is greater

GENDER DIFFERENCES OF THE PELVIS

Figure 5.24c

TRUE VS FALSE PELVIS The greater or FALSE pelvis is located above

the pelvic brim- SUPERIOR; supports the abdominal viscera the organs contained within the abdominal cavity; they include the stomach, intestines, liver, spleen, pancreas, and parts of the urinary and reproductive tracts

The lesser or TRUE pelvis below the brim- INFERIOR; limits delivery of baby

BONES OF THE LOWER LIMBS The thigh has one bone

Femur The heaviest, strongest bone in the body

BONES OF THE LOWER LIMBS FEMUR #4

Figure 5.25a–b

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Anterior view of right femur

Posterior view of right femur

Patella # 5

BONES OF THE LOWER LIMBS The lower leg has two bones

Tibia Shinbone Larger and medially oriented

Fibula Thin and sticklike

BONES OF THE LOWER LIMBS

Figure 5.25c

Fibula #6Tibia #7

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BONES OF THE LOWER LIMBS The foot

Tarsals Two largest tarsals

Calcaneus (heelbone) Talus

Metatarsals—sole Phalanges—toes

BONES OF THE LOWER LIMB

Figure 5.26

Talus #8Calcaneus #9Metatarsals #10Phalanges #11

ARCHES OF THE FOOT Bones of the foot are arranged to form three

strong arches Two longitudinal One transverse

ARCHES OF THE FOOT

Figure 5.27

FALLEN ARCHESThe ligament and tendons are weakend, allowing bones to “fall”