The Skeletal System: The Appendicular Skeleton
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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
Pectoral (Shoulder) Girdles
Attach the bones of the upper limbs to the
axial skeleton
Each consists of 2 bones: clavicle and
scapula
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
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
Upper Limbs
Each upper limb has 30 bones:
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–
–
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Humerus (1)
Radius (1)
Ulna (1)
Carpals (8)
Metacarpals (5)
Phalanges (14)
Humerus
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
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
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
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
Pelvic (Hip) Girdles
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)
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
Each lower limb has 30 bones:
–
–
–
–
–
–
–
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
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
Tibia and Fibula
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
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
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