SKELETAL
SYSTEM
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Illustrations and References
• Gray’s Anatomy of the Human Body at
www.bartleby.com
• Dynamic Anatomy and Physiology, by L.L. Langley, 3rd
edition, McGrawHill
• Principles of Anatomy and Physiology, Gerald Tortora and
Bryan Derrickson, Wiley, 12th Edition
• Principles of Anatomy and Physiology, Gerald Tortora and
Bryan Derrickson, Wiley, 11th Edition
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Functions
Support – gives the body its shape and allows the body to
maintain an erect posture
Protection – protects the brain, spinal cord and thoracic
structures
Leverage – muscles attach to some bones and function as
levers to produce movement
Storage – store calcium and phosphorous
Blood Cell Production – contain bone marrow where
hematopoietic cells are found
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Bones
• Bones appear to be solid structures however, bone tissue is
actually porous. The pores are filled with bone cells and blood
vessels that supply the cells with nutrients.
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Principles of Anatomy and Physiology, 12th Edition
Types of Bones
• Long Bones
• Greater length than width
• Divided into diaphysis in the middle and two
epiphyes at the ends
• Slightly curved to help distribute weight and
stress along the length of the bone
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Principles of Anatomy and Physiology, 12th Edition
Types of Bones
• Short Bones
• cube-shaped
• Flat Bones
• Thin and flat in shape
• Irregular Bones
• Complex shapes
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Principles of Anatomy and Physiology, 12th Edition
Types of Bones
• Sesamoid Bones
• Usually small bones with the exception of the patella in the knee
joint which is larger than other sesamoid bones
• Found in tendons that may be subjected to compression and
tension
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Principles of Anatomy and Physiology, 12th Edition
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Axial and Appendicular Skeleton
• The 206 bones of the adult human skeleton are divided into 2
groups, the axial skeleton and the appendicular skeleton
Axial Skeleton
Appendicular Skeleton
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Principles of Anatomy and Physiology, 11th Edition
Axial Skeleton
• The axial skeleton contains 80 bones that form the axis or
center of the human body.
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Cranial bones (8)
Facial bones (14)
Hyoid (1)
Bones of ears (6 –[ 3 each side])
Vertebral column (26)
Sterum (1)
Ribs (24)
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Principles of Anatomy and Physiology, 11th Edition
Appendicular Skeleton
• The appendicular skeleton contains 126 bones that for the
upper and lower extremities
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Clavicle (2)
ulna (2)
metacarpals (10)
Pelvic bone (2)
Tibia (2)
Metatarsus (10)
scapula (2)
humerus (2)
radius (2)
carpals (16)
upper phalanges (28)
femur (2)
fibula (2)
patella (2)
tarsus (2)
lower phalanges (28)
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Joints
• Are points of contact between bones or between cartilage and
bones
• Are surrounded by a fibrous joint capsule and held together by
ligaments
• Are classified by their degree of motion
• Immovable
• Slightly movable
• Freely movable
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Synovial Joints
• Are classified by the type of movement possible:
• Hinge joint (elbow) has one concave and one convex
articulating surface and movement can take place in
only one direction
• Pivot joint (elbow that allows you to turn your hand
over ) moves only in the vertical plane
• Gliding joint (wrist) has essentially flattened articular
surfaces allowing for sliding movement in all directions
• Ball and socket joint (hip/shoulder) has extensive
movement in almost any direction or plane
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Synovial Joints
• The shoulders, elbows, hips and knees are examples of
synovial joints
• Synovial joints contain bursae which are sac-like structures
that are filled with synovial fluid which provides a cushion.
Bursae are found between skin and bones, tendons and
bones, muscles and bones and ligaments and bones
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Principles of Anatomy and Physiology, 11th Edition
Henry Gray (1825–1861). Anatomy of the Human Body. 1918.
Wrist
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Wrist
• The movements consist of rotation of the lower end of the
radius around an axis which passes through the center of the
head of the ulna. When the radius rotates forward, pronation
of the forearm and hand is the result; and when rotated
backward, supination.
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Henry Gray (1825–1861). Anatomy of the Human Body. 1918.
hip
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Henry Gray (1825–1861). Anatomy of the Human Body. 1918.
Elbow
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Henry Gray (1825–1861). Anatomy of the Human Body. 1918.
Shoulder
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Henry Gray (1825–1861). Anatomy of the Human Body. 1918.
Knee
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Fibrous Joints
• Have little or no movement
• Lack a joint cavity
• Are tightly joined by fibrous tissue
• Example: the articulation between the proximal tibia and
fibula (the bones are alittle further apart than a suture but are
still tightly joined by fibrous tissue
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Intervertebral Disks
• The central portion of the intervertebral disk is formed by a
gelantinous substance, the nucleus pulposis.
• If this disk is displaced or damaged, the nucleus pulposis may
herniate and protrude into the vertebral canal or
intervertebral foramen. The disk may press upon the spinal
nerve, causing pain or paralysis in the area of the nerve’s
distribution.
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Appendicular Skeleton
• The extremities attach to the axial skeleton by the pectorial
girdle (formed by the clavical and scapula at the shoulder) and
the pelvic girdle (consisting of the innominate bones of the
hips)
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Principles of Anatomy and Physiology, 11th Edition
Upper Extremity
• Scapula – shoulder blade; is the site of the attchment
ofsuperficial muscles of the back and certain muscles of the
shoulder and arm
• Clavicle – collarbone;extends from the sterum to the acromion
and is the only bony attachment between the trunk and the
upper extremity
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Lower Extremity
• The pelvic girdle is formed by the two innominate bones
which attach the lower extremity to the axial skeleton at the
sacroiliac articulation. This is a strong and stable joint that
transmits the weight of the torso to the lower extremity.
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Congratulations !
• You have completed the first unit on the review of the
Skeletal System.
• You may review this unit as many times as you wish.
• When you are ready, go to the quiz marked Skeletal
System Quiz 1 under the Quiz tab in D2L.
• You must earn a 70% or better on each quiz to
successfully complete the unit. You have 3 attempts to
earn a 70% or better.
• When you have completed both quizzes for the Skeletal
System with a 70% or better you will be issued a
certificate of completion and be awarded 2 CEs.
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