Transcript The Skeletal System: The Appendicular Skeleton

The Skeletal System: The
Appendicular Skeleton
Divisions of the Skeletal System
Axial skeleton—protects and supports the
internal organs
 Appendicular skeleton—facilitates
movement
 The appendicular skeleton consists of 126
bones; it includes bones of the limbs and the
girdles
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Pectoral (Shoulder) Girdles
Attach the bones of the upper limbs to the
axial skeleton
 Each consists of 2 bones: clavicle and
scapula
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Clavicle
Collarbone
 An s-shaped bone that articulates with the
manubrium of the sternum and with the
scapula
 One of the most frequently fractured bones
of the body
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Fig. 08.02
Scapula
Shoulder blade
 A triangular-shaped flat bone that articulates
with the clavicle
 The acromion is a process of the scapula
that can be felt as the high point of the
shoulder
 The glenoid cavity is a depression of the
scapula that articulates with the humerus to
form the shoulder joint
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Upper Limbs
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Each upper limb has 30 bones:
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Humerus (1)
Radius (1)
Ulna (1)
Carpals (8)
Metacarpals (5)
Phalanges (14)
Humerus
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Upper arm bone
The longest and largest bone of the upper limb
Articulates proximally with the scapula and
distally at the elbow with the radius and ulna of
the forearm
The head articulates with the glenoid cavity of the
scapula
The capitulum articulates with the head of the
radius; the trochlea articulates with the ulna
Radius and Ulna
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Long bones of the forearm
The ulna is longer than the radius and is located on the
“little-finger” side of the forearm
The olecranon of the ulna forms the prominence of the
elbow
The radius is located on the thumb side of the forearm
The elbow joint is formed by 2 articulations:
– The trochlear notch of the ulna with the trochlea of the humerus
– The head of the radius with the capitulum of the humerus
Carpals
The wrist consists of 8 small bones called
carpals
 These bones are arranged in two rows of
four bones each
 In most carpal fractures, only the scaphoid
carpal bone is broken
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Metacarpals
The palm of the hand consists of 5 long
bones called metacarpals
 Each of these bones consists of a base,
shaft, and head
 The metacarpals are numbered 1 through 5,
starting with the thumb
 The “knuckles” are the heads of the
metacarpals
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Phalanges
The long bones of the fingers (digits)
 There are 14 phalanges in each hand
 Each phalanx consists of a base, shaft, and
head
 There are 2 phalanges in the thumb, or
pollex, and 3 phalanges in each of the other
four digits
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Pelvic (Hip) Girdles
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Consist of 2 hip bones, called coxal bones
These 2 bones unite anteriorly at a joint called the pubic
symphysis and posteriorly with the sacrum at the sacroiliac
joints
The 2 coxal bones and the sacrum form the pelvis; the
pelvis supports the vertebral column and pelvic organs and
attaches the lower limbs to the axial skeleton
In an adult, each coxal bone consists of three bones that
fused together after birth:
– Ilium
– Ischium
– Pubis
Pelvic (Hip) Girdles (continued)
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The ilium is the largest and most superior of the three hip
bone components; it articulates with the sacrum to form the
sacroiliac joint
The ischium is located inferior and posterior; the pubis is
located inferior and anterior; together, they surround the
obturator foramen, the largest foramen of the skeleton
All three of these bones make up the acetabulum, a deep
fossa that accepts the round head of the femur
The two coxal bones meet anteriorly at a joint called the
pubic symphysis; this joint contains a cartilage disc that
gives the joint flexibility
The pelvis of a female is wider and shallower than that of a
male to allow for childbirth
Lower Limbs
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Each lower limb has 30 bones:
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Femur (1)
Patella (1)
Tibia (1)
Fibula (1)
Tarsals (7)
Metatarsals (5)
Phalanges (14)
Femur
Thigh bone
 Longest, heaviest, and strongest bone in the
body
 Its proximal end consists of a head that
articulates with the hip bone at the
acetabulum; its distal end articulates with
the tibia and patella
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Patella
Kneecap
 A small, triangular bone located anterior to
the knee joint
 It is a sesamoid bone, which develops in the
tendon of the “quadriceps” muscle
 Articulates with the femur
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Tibia and Fibula
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The tibia is the shinbone
It is the larger, medial, weight-bearing bone of the
lower leg
At is proximal end, the tibia articulates with the
femur and fibula; at its distal end, it articulates
with the fibula and the talus bone of the ankle
The fibula is the smaller bone of the lower leg
It lies parallel and lateral to the tibia
Tarsals
The ankle consists of 7 bones called tarsals
 The calcaneus is the largest and strongest
tarsal bone; it is located in the posterior heel
part of the foot
 The talus is the uppermost tarsal bone; it
articulates with the fibula and tibia
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Metatarsals
The main part of the foot consists of 5 long
bones called metatarsals
 Each of these bones consists of a base,
shaft, and head
 The metatarsals are numbered 1 through 5,
from the medial to lateral position
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Phalanges
The long bones of the toes
 There are 14 phalanges on each foot
 Each phalanx consists of a base, shaft, and
head
 There are 2 phalanges in the big toe, or
hallux, and 3 phalanges in each of the other
four digits
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