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7-1
The Skeletal System
7-2
Figure 7.1b The Axial Skeleton
Figure 7.1b
7-3
THE AXIAL SKELETON
• The axial skeleton consists of 80 bones in
three regions:
– The skull
– The vertebral column
– The bony thorax
• The axial skeleton supports the head and
trunk and protects important organs.
– Brain
– Heart
– Lungs
7-4
THE SKULL
• The skull is the most complex skeletal
structure consisting of 22 bones.
– The cranium protects the brain
– The facial bones:
• Form the facial features
• Place for special sense organs
• Passages for air and food
• Secure the teeth
• Attachment sites for facial muscles
• With the exception of the mandible, all skull
bones are connected to each other thru
sutures.
7-5
• Consists of the cranium and the bones of the face
– The cranium encloses cranial cavity
– Facial bones surround and protect the entrances to the
respiratory and digestive tracts
• Superficial landmarks include the sutures
– Lambdoid
– Coronal
– Sagittal
– Squamous
The skull
7-6
Figure 7.2 Cranial and Facial
Subdivisions of the Skull
7-7
Figure 7.3 The Adult Skull
Figure 7.3a, b
7-8
Figure 7.3 The Adult Skull
Figure 7.3c
7-9
Figure 7.3 The Adult Skull
Figure 7.3d
****Only
movable joint
on skull bone
is attachment
between
mandible and
cranium.
7-10
• one occipital bone
– foramen magnum
• two parietal bones
• one frontal bone
– frontal sinuses
Focus: The Individual Bones of the
Skull Cranial Bones
• two temporal bones
– auditory ossicles
• one sphenoid
• one ethmoid
7-11
Infant Skull
• Contains cartilaginous soft spots called
fontanelles.
• What function do fontanelles serve?
7-12
The Hyoid Bone
• The hyoid bone is the
“adam’s apple”
• It serves as a point of
attachment for
muscles that perform
the act of swallowing,
or deglutition.
7-13
The Vertebral Column
7-14
The Rib Cage
7-15
Appendicular Skeleton
• Girdles
– Pectoral or shoulder
– Pelvic
• Upper Limbs
– Arm (brachial)
– Forearm (_antebrachium_)
– Wrist (carpal)
– Hand (manual)
• Lower Limbs
– Thigh (femoral)
– Leg (__crural_)
– Foot (pedal)Fig. 7.1
7-16
THE PECTORAL GIRDLE
• The pectoral girdle is formed by the clavicle
and the scapula.
• Only the clavicle actually attaches to the
thorax.
• The scapula “floats” on the back of the ribs.
• The humerus attaches loosely to the sockets
formed by the scapula and clavicle.
– This is good for freedom of movement.
– This is not as good for stability.
7-17
VIEW OF THE PECTORAL
GIRDLE
7-18
Pectoral Girdle• Scapula (2)
– Acromion process
• Forms protective cover
• Attachment for clavicle
• Attachment for muscles
– Coracoid process
• Attachment for muscles
– ____Clavicle___
• Articulates with humerus
• Clavicle (2)
Fig. 7.29
7-19
THE UPPER LIMB
• The upper limb consists of the:
– Arm
– Forearm
– Hand
• The upper limb contains 30 bones.
7-20
VIEW OF THE UPPER LIMB
7-21
Arm• Humerus
– Head
– Tubercles
• Greater and lesser
– Intertubercular groove
– Capitulum
– Trochlea
– Epicondyles
• Attachment of forearm
muscles
Fig. 7.30
7-22
Forearm
• Radius
– Thumb side
– ___radial tuberosity_____ (biceps brachii muscle)
• Ulna
– Little finger side
– Trochlear notch
– Olecranon process
– Radial notchFig. 7.31
7-23
Wrist and Hand
• Wrist
– 8 carpal bones
• Metacarpals: hand
bones
• Phalanges: finger
bones
Fig. 7.32
7-24
THE PELVIC GIRDLE
• The pelvic girdle attaches the lower limbs to
the axial skeleton.
• The attachment of the pelvis to the sacrum
is an incredibly stable and strong
attachment, unlike the pectoral girdle.
• The socket for the femur (acetabulum) is
deep & holds the femur extremely well.
– Less mobile ball & socket joint than the
shoulder.
• Each wing of the pelvic girdle is formed
from a bone called the coxal bone.
7-25
Pelvis
• Coxae: Right and Left
– Ilium- larger
– Ischium- smaller
– Pubis
• _pubic arch or pubic
symphisis______
• Acetabulum
• Obturator foramen
• Sacrum
Fig. 7.35
7-26
Coxa
Fig. 7.36
7-27
FEMALE VS. MALE PELVIS
7-28
Female vs. Male Pelvic Girdle
• What purpose do the differences between
the female and male pelvic girdles serve?
7-29
THE LOWER LIMB
• The bones of the lower limb must support
the weight of the entire body, thus, these are
the largest and heaviest of the bones.
• The lower limb consists of:
– The thigh
– The leg
– The foot
• The lower limb is formed by 30 bones.
– 1 patella
– -1 tarsal vs carpal
7-30
Thigh
• Femur
– Head
– Neck
– Trochanters
• Greater and lesser
– Condyles
• Medial and lateral
– Epicondyles
• Medial and lateral
• _____Patella_____ or kneecap
Fig. 7.39
7-31
Leg
• Tibia
– Larger and supports
most of weight
– Tibial tuberosity
– Medial malleolus
• Fibula
– Articulates with tibia
not femur
– Lateral malleolus
Fig. 7.41
7-32
Foot
• Tarsals (7)
– _Talus___
(ankle bone)
– _Calcaneus__
(heel)
• Metatarsals:
foot bones
• Phalanges: toe
bones
Fig. 7.43
7-33
Points to Remember
• Appendicular skeleton includes bones of upper and lower limbs and pectoral and pelvic girdles
• Pectoral girdle and upper limb held in place largely by muscles
• Pelvic girdle has strong articulation with sacrum to help support weight of body
7-34
Practice Question 1
Each of the following bones contributes to
forming the orbit except the
A. ethmoid bone.
B. nasal bone.
C. lacrimal bone.
D. sphenoid bone.
E. frontal bone.
******
7-35
Practice Question 2
Each of the following bones is part of the
pelvic girdle except the
A. femur.
B. ischium.
C. pubis.
D. ilium.
E. coxa.
*****
7-36
Practice Question 3
In the true female pelvis, as compared to the true male pelvis,
A. the bones are heavier and thicker with prominent markings.
B. the distance between the anterior superior iliac spines is greater.
C. the ischium, ilium, and pubis remain unfused in adulthood.
D. the angle formed at the junction of the pubic bones is narrow.
E. the dimensions of the pelvic outlets are smaller.
*****
7-37
Practice Question 4
The eleventh and twelfth ribs are called floating ribs
because they lack
A. a posterior attachment to thoracic vertebrae.
B. an anterior attachment to lumbar vertebrae.
C. an vertebral attachment anteriorly.
D. an anterior attachment to the sternum.
E. an vertebral attachment posteriorly.
*****
7-38
Practice Question 5
The bones of the forearm include the
A. humerus.
B. fibula.
C. radius.
D. tibia.
E. femur.
*****
7-39
Practice Question 6
The medial bulge at your ankle is a projection
from the
A. femur.
B. fibula.
C. calcaneus.
D. talus.
E. tibia. *****
7-40
Practice Question 7
Which of the following is not a part of the
axial division of the skeletal system?
A. Vertebral column
B. Hyoid bone
C. Skull
D. Auditory ossicles
E. Pectoral girdle *****
7-41
Practice Question 8
At its distal end the femur articulates with
the
A. fibia
B. tibia.
C. acetabulum.
D. tibia and fibula.
*****
7-42
Practice Question 9
A common injury in the winter are falls in which someone hits the back of their head on the ice. What bone is most likely to be involved in this type of fall?
A. Zygomatic
B. Frontal
C. Temporal
D. Occipital *****
7-43
Practice Question 10
• As you proceed from the head down the
vertebral column, the vertebrae become
larger and heavier.
True
False
*****
7-44
Practice Question 11
• Damage to the temporal bone would most
likely affect the sense of hearing.
True
False
*****
7-45
Practice Question 12
• Differences in the skeleton of males and
females can best be seen in the
characteristics of the pelvis.
True
False
*****
7-46
Practice Question 13
• Ribs that have no connection to the sternum
are called the false ribs.
True
False *****
7-47
Practice Question 14
• The axial skeleton includes the bones of the
upper and lower extremities and the
girdles.
True
False *****
7-48
Practice Question 15
• The bones of the forearm are also called
antebrachium.
True
False*****
7-49
Practice Question 16
• The sacrum is composed of 5 fused
vertebrae.
True
False*****
7-50
Practice Question 17
• At its proximal end the humerus articulates
with the ulna and radius.
True
False *****
7-51
Practice Question 18
• An injury to the lateral side of your ankle
would involve the tibia.
True
False *****
7-52
Practice Question 19
The clavicle is part of the axial skeleton.
True
False *****
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