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.

Principles of Anatomy and Physiology, 12th Edition

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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

Principles of Anatomy and Physiology, 12th Edition

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Types of Bones

• Short Bones

• cube-shaped

• Flat Bones

• Thin and flat in shape

• Irregular Bones

• Complex shapes

Principles of Anatomy and Physiology, 12th Edition

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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

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

Principles of Anatomy and Physiology, 11th Edition

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Axial Skeleton

• The axial skeleton contains 80 bones that form the axis or center of the human body.

• Cranial bones (8)

• Facial bones (14)

• Hyoid (1)

• Bones of ears (6 –[ 3 each side])

• Vertebral column (26)

• Sterum (1)

• Ribs (24)

Principles of Anatomy and Physiology, 11th Edition

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Appendicular Skeleton

• The appendicular skeleton contains 126 bones that for the upper and lower extremities

• Clavicle (2) scapula (2) humerus (2)

• ulna (2) radius (2) carpals (16)

• metacarpals (10) upper phalanges (28)

• Pelvic bone (2) femur (2) fibula (2)

• Tibia (2) patella (2) tarsus (2)

• Metatarsus (10) 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

Principles of Anatomy and Physiology, 11th Edition

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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)

Principles of Anatomy and Physiology, 11th Edition

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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. 32