Skeletal System

CHAPTER 6

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Skeletal System

• Human skeleton consists of 206 bones– Serves as supporting framework of body– Protects vital internal organs– Important role in movement = attachments for

muscles– Reservoir for storing minerals– Red bone marrow = blood cell formation

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Bone Structure

• Diaphysis– Main shaft-like portion of a long bone– Compact bone

• Epiphysis– Located at each end of a long bone

• Epiphyseal line– Separates diaphysis from epiphysis

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Bone Structure

• Periosteum– Covers the surface of the long bone

• Articular cartilage– Covers joint surfaces

• Medullary (marrow) cavity– Contains yellow marrow

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Bone Structure

• Spongy bone (trabeculae)– Also called cancellous bone

• Red bone marrow– Site for blood cell production

• Yellow marrow– Stores fat

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Bone Structure

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Bone Markings

• Bone markings = specific features of bones– Enlargements that extend out from the bone– Openings within the bone– Hollow regions within the bone– Points of attachment for muscles and tendons– Points for joining one bone to another– Cavities and passage for nerves and blood

vessels

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• Concave areas or openings in a bone– Help form joints– Serve as points of attachment for muscle

• Sulcus– Groove or depression in a bone

• Example = fissure

• Sinus– Opening or hollow space in a bone

• Example = frontal sinus

Bone Depressions

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• Fossa– Hollow or shallow concave depression in bone

• Example = fossa of the iliac (hip) bone

• Foramen– Hole within a bone for blood vessels or nerves

to pass through• Example = Foramen magnum of the skull

Bone Depressions

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Cranial Bones

• Cranium = bony skull – Envelops brain

• Composed of eight bones– Immovable bones

• Borders meet to form immovable joints – Immovable joints = sutures

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Cranial Bones

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Facial Bones

• Two bones provide distinctive shape to face– Maxillae (upper jaw bones)– Mandible (lower jaw bone)

• All facial bones connected by immovable joints (sutures)– One exception (mandible)

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Facial Bones

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Vertebral Bones

• Form long axis of the body– Referred to as spinal column or backbone– 24 vertebrae + sacrum + coccyx– Offer protection to spinal cord

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• Cervical vertebrae– Vertebrae of the neck (cervic/o = neck)– Identified as C1 – C7

• Thoracic vertebrae– Vertebrae of the chest (thorac/o = chest)– Identified as T1 – T12

• Lumbar vertebrae– Vertebrae of lower back (lumb/o = lower back, loins)– Identified as L1-L5

Vertebral Bones

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Vertebral Bones

• Sacrum– Singular, triangular shaped bone– Resulted from fusion of five individual sacral

bones in the child

• Coccyx– Also called “tailbone”– Resulted from fusion of four individual

coccygeal bones in the child

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• True ribs (Ribs 1-7)– Attach to sternum in front and vertebrae in

back

• False ribs (Ribs 8-10)– Attach to vertebrae in back but attach to

cartilage of 7th rib in front – not the sternum

• Floating ribs (Ribs 11-12)– Attach to vertebrae in back– Completely free of attachment in front

Bones of the Thorax

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Bones of the Upper Extremities

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Pelvic Bones

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• Femur– Thigh bone

• Patella– Knee bone or kneecap

• Tibia– Larger and stronger of the two lower leg

bones

• Fibula– More slender of the two lower leg bones

Bones of the Lower Extremities

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• Ankle bones (Tarsals)– Calcaneus – Talus bone

• Foot bones– Metatarsals– Phalanges

Bones of the Ankle and Foot

PATHOLOGICAL CONDITIONS

Skeletal System

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Osteomalacia

• Pronounced– (oss-tee-oh-mah-LAY-she-ah)

• Defined– Abnormal softening of the bones due to a

deficiency of calcium and phosphorus in the blood

• Which is necessary for bone mineralization

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Osteomyelitis

• Pronounced– (oss-tee-oh-my-ell-EYE-tis)

• Defined– A local or generalized infection of the bone

and bone marrow– Resulting from a bacterial infection that has

spread to the bone tissue through the blood

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Osteoporosis

• Pronounced– (oss-tee-oh-poh-ROW-sis)

• Defined– Porous bones– Bones that were once strong become fragile

due to loss of bone density

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Osteoporosis

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Ewing’s Sarcoma

• Pronounced– (YOO-wings sar-KOH-mah)

• Defined– Malignant tumor of the bones common to

young adults, particularly adolescent boys

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Osteogenic Sarcoma

• Pronounced– (oss-tee-oh-JEN-ic sar-KOH-mah)

• Defined– Malignant tumor arising from bone– Also known as osteosarcoma

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Osteochondroma

• Pronounced– (oss-tee-oh-kon-DROH-mah)

• Defined– Most common benign bone tumor– Most frequently involves the femur and tibia

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Paget’s Disease

• Pronounced– (PAJ-ets dih-ZEEZ)

• Defined– Nonmetabolic disease of the bone– Characterized by excessive bone destruction

and unorganized bone formation by the osteoblasts

• Bone is weak and prone to fractures

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Spinal Stenosis

• Pronounced– (SPIGH-nal stin-OH-sis)

• Defined– Narrowing of the vertebral canal, nerve root

canals, or intervertebral foramina • Openings of the lumbar spinal canal

– Causes pressure on nerve roots prior to their exit from the foramina

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Talipes Equinovarus

• Pronounced– (TAL-ih-peez eh-kwine-oh-VAIR-us)

• Defined– Clubfoot

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Talipes

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Abnormal Curvature of the Spine

• Kyphosis– Outward curvature = humpback or hunchback

• Lordosis– Inward curvature = swayback

• Scoliosis– Lateral (sideward) curvature

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Abnormal Curvature of the Spine

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Fracture: Broken Bone

• Closed fracture– Break in the bone but no open wound in skin– Simple fracture

• Open fracture– Break in the bone, as well as an open wound

in skin– Compound fracture

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• Complete fracture– Break extends through the entire thickness of

bone

• Incomplete fracture– One side of bone is broken and one side of

bone is bent considerably but not broken– Greenstick fracture

Fracture: Broken Bone

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• Compression fracture– Caused by bone surfaces being forced

against each other

• Impacted fracture– Direct force causes bone to break– Forces broken end of smaller bone into

broken end of larger bone

Fracture: Broken Bone

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• Colle’s fracture– Break occurs at lower end of the radius– Within one inch of connecting with wrist bones

• Hairline fracture– Minor fracture in which the bone continues to

be in perfect alignment– Also known as a stress fracture

Fracture: Broken Bone

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• Pathological fracture– Bone is weakened by a preexisting disease– Break is in response to a force that would

not cause a normal bone to break

• Treatment of fractures– Closed reduction– Open reduction

Fracture: Broken Bone

DIAGNOSTIC TECHNIQUES, TREATMENTS

AND PROCEDURES

Skeletal System

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Diagnostic Techniques, Treatments, and Procedures

• Bone scan– Intravenous injection of a radioisotope, which

is absorbed by bone tissue– Followed by scanning of the skeleton

approximately three hours later to detect areas where the bone absorbs the isotope

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Diagnostic Techniques, Treatments, and Procedures

• Bone marrow aspiration– Removal of a small sample of bone marrow

from a selected site with a needle– Specimen is examined under a microscope– Sterile technique

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Diagnostic Techniques, Treatments, and Procedures

• Noninvasive procedures for evaluating bone density– Dual Photon Absorptiometry– Dual Energy X-Ray Absorptiometry