Chapter 5:The Skeletal System—

Part B

Fracture - A break in a bone Types of bone fractures

Closed (simple) fracture – break that does not penetrate the skin

Open (compound) fracture – broken bone penetrates through the skin

Bone fractures are treated by reduction (realignment of bone ends) and immobilization (cast)6-8 weeks healing

Bone Fractures

Common Types of Fractures

Table 5.2

Bone fractures

Hematoma (blood-filled swelling) is formed Break is splinted by fibrocartilage to form a

callus of cartilage, bone, & collagen Fibrocartilage callus is replaced by a bony

callus formed of spongy bone Bony callus is remodeled to form a

permanent patch

Repair of Bone Fractures

Stages in the Healing of a Bone Fracture

Figure 5.5, step 1

Hematoma

Hematomaformation

Stages in the Healing of a Bone Fracture

Figure 5.5, step 2

HematomaExternalcallus

Newbloodvessels

Internalcallus(fibroustissue andcartilage)

Spongybonetrabecula

Hematomaformation

Fibrocartilagecallus formation

Stages in the Healing of a Bone Fracture

Figure 5.5, step 3

HematomaExternalcallus

Bonycallus ofspongybone

Newbloodvessels

Internalcallus(fibroustissue andcartilage)

Spongybonetrabecula

Hematomaformation

Fibrocartilagecallus formation

Bony callusformation

Stages in the Healing of a Bone Fracture

Figure 5.5, step 4

HematomaExternalcallus

Bonycallus ofspongybone

Healedfracture

Newbloodvessels

Internalcallus(fibroustissue andcartilage)

Spongybonetrabecula

Hematomaformation

Fibrocartilagecallus formation

Bony callusformation

Bone remodeling

Forms the longitudinal part (central line) of the body

Divided into three partsSkullVertebral columnBony thorax

The Axial Skeleton

The Axial Skeleton

Figure 5.6

Two sets of bonesCranium (encloses brain)8 bones

Facial bones14 bones

Bones are joined by sutures--interlocking immovable joints

Only the mandible is attached by a freely movable joint

The Skull

8 large flatbonesParietal & temporal – pairedParietal – superior & lateral

Meet midline at sagittal sutureMeet frontal bone at coronal suture

Temporal – meet parietal at squamous sutureExternal auditory meatus – canal to eardrumMastoid & styloid processes – attach neck

musclesFrontal – foreheadOccipital – posteriorMeets parietal at lambdoid suture

Cranium

Sphenoid - eye orbits & floor of cranial cavityOptic canal – nerve to eye

Ethmoid – roof of nasal cavity & medial eye orbitsCrista galli = cock’s comb; attaches brainCribriform plates – holes for olfactory nerves

Bones of the Skull

The Skull

Figure 5.7

Bones of the Skull

Figure 5.11

Sphenoid boneSella turcica = Turk’s saddle

Holds pituitary glandForamen ovale – cranial nerves

Between temporal & occipitalJugular foramen – junction of occipital & temporal

bonesPassage of jugular vein

Temporal boneInternal acoustic meatus – cranial nerves VII & VIICarotid canal

For carotid artery Occipital bone

Foramen magnum – spinal cord to brain

Bone Markings

Human Skull, Superior View

Figure 5.8

Lacrimal – 2; contain tear ducts Mandible – 1; largest & strongest face bone Maxilla – 2; fuse = upper jaw Zygomatic – 2; cheek bones & eye sockets Palatine – 2;

Hard palate – maxilla & palatine bonesCleft palate if not fused

Vomer – 1; forms nasal septum Inferior nasal conchae – 2 Nasal - 2

Facial Bones (14)

Human Skull, Inferior View

Figure 5.9

Paranasal Sinuses Hollow portions of bones surrounding the nasal cavity

HobanFigure 5.10

Paranasal Sinuses Functions of paranasal sinuses

◦Lighten the skull◦Give resonance and amplification to voice

HobanFigure 5.10

2006Hoban

Note how the sinuses drain into the nasal cavity…

SinusitisRecall that “-itis” means inflammation of◦Sinuses are continuous with nasal passages and throat◦Infections can travel up to sinuses

The Hyoid Bone The only bone that

does not articulate with another bone

Serves as a moveable base for the tongue

Aids in swallowing and speech

Figure 5.12

The Fetal Skull The fetal skull is large compared to the infant’s

total body length◦Adult skull – 1/8 body length

Newborn skull – ¼ body length Fontanelles – fibrous membranes connecting

the cranial bones◦Allow fetal skull to be compressed during birth◦Allow the brain to grow◦Convert to bone within 24 months after birth

Figure 5.13

The Fetal Skull

Figure 5.13

Fetal SkeletonNote how large the head is compared to the rest of the body…

Checkpoint:What is the advantage of a larger head area to the developing baby?

More area for the brain to develop properly…