The Skeletal The Skeletal SystemSystem

Functions of Bones

Support of the body Protection of soft organs Movement due to attached skeletal

muscles Storage of minerals and fats Blood cell formation

The Skeletal System

Parts of the skeletal system Bones (skeleton) Joints Cartilages Ligaments

Divided into two divisions Axial skeleton Appendicular skeleton

Bones of the Human Body

The adult skeleton has 206 bones Two basic types of bone tissue

Compact bone Spongy bone

Figure 5.2b

Classifications of Bones

Figure 5.1Page 144

Classification of Bones

Long bones Typically longer than wide Have a shaft with heads at both ends Contain mostly compact bone

Examples: Femur, humerus

Long Bone Anatomy

Diaphysis Shaft Composed mostly of

compact bone Epiphysis

Ends of the bone Composed mostly of

spongy bone

Figure 5.2aPage 145

Long Bone Anatomy

Periosteum Outside covering

of the diaphysis Fibrous

connective tissue membrane

Endosteum Lines the inner

marrow cavity Red marrow Yellow marrow

Figure 5.2c

Classification of Bones

Short bones Generally cube-shaped Contain mostly spongy

bone Examples: Carpals, tarsals

Classification of Bones

Flat bones Thin and flattened Usually curved Thin layers of compact bone around a layer

of spongy bone Examples: Skull, ribs, sternum

Classification of Bones

Irregular bones Irregular shape Do not fit into other bone classification

categories Example: Vertebrae and hip

Skeletal Divisions Axial Skeleton

Bones of the skull and cranium

Bones of the Vertebral Column

Bones of the ribs and sturnum

Appendicular Skeleton Bones of the appendages

and pectoral and pelvic girdles

The Axial Skeleton

Forms the longitudinal part of the body

Skull: 8 cranial bones, 14 facial

Vertebral column Thorax

The Cranium

Frontal Bone Forms the forehead

and superior surface of each eye socket (orbital)

Frontal sinuses are air filled pockets that produce mucus that cleans and moistens the nasal cavities

The Cranium

Parietal Bones

Posterior to the frontal bones, located on each side

Forms the roof and superior walls of the cranium

The Cranium

Occipital Bone Posterior and inferior portions of the

cranium Surrounds the foramen magnum

(opening that connects the cranial cavity

with the spinal cavity)

The Cranium

Temporal Bones

Lie below the parietal bones and contribute to the sides and base of the cranium

The Cranium

Sphenoid Bone Forms part of the

floor of the cranium Unites the cranial

and facial bones “Bat” shaped Contains sphenoidal

sinuses

The Cranium

Ethmoid Bone Consists of two

“honeycombed” masses of bone

Forms part of the cranial floor

Two projections Superior conchae Middle conchae

The Skull

Figure 6-14

Zygomatic Bones

Found on both sidesof the face

Bone curves laterally to form the cheek bone

Forms lateral walls of the orbits

The Skull

Mandible Bone of the lower

jaw

Articulates with the temporal bone at the mandibular fossa

Mobile

The Skull

Figure 6-14

Maxillary Bone Articulates will all bones

of the face, except the mandible

Forms: The floor and medial

portions of the rims of the orbits

The walls of the nasal cavity

The anterior roof of the mouth

The Skull

Figure 6-14

Nasal

Articulate with the frontal bone and maxillary bone

Form a bridge midway between the orbits

The Skull

Figure 6-14

Lacrimal Bones Located within the orbits,

on the medial surfaces

Articulate with the frontal, ethmoid, and maxillary bones

Provide a passageway for the lacrimal (tear) ducts

The Skull

Figure 6-14

Palatine Bone Paired bones of the

bony (hard) palate

Roof of the mouth

Contribute to the floor of the nasal cavity

The Skull

Figure 6-14

Foramen Magnum

Connects the cranial cavity with the spinal cavity

The spinal cord passes through this opening and connects to the inferior portion of the brain

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Figure 5.7

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Figure 5.11

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Figure 5.9