Skeletal System Functions

• Support - provides hard framework for soft tissue

• Protection of underlying organs• Brain, Eyes, Inner ear structures, heart & lungs,

kidneys

• Movement - skeletal muscles use bones as levers

• Storage. • Calcium and Phosphorous

• Stored then released as needed.

• Fat stored in marrow cavities

• Blood cell production (Hematopoiesis). Bone marrow that gives rise to blood cells and platelets

Bone Shapes

• Long• Ex. Upper and

lower limbs• Short

• Ex. Carpals and tarsals

• Flat• Ex. Ribs, sternum,

skull, scapulae• Irregular

• Ex. Vertebrae, facial

Classification of Bones

· Long bones

· Typically longer than wide

· Have a shaft with heads at both ends

· Contain mostly compact bone

• Examples: Femur, humerus

Classification of Bones

Slide 5.4bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

· Short bones

· Generally cube-shape

· Contain mostly spongy bone

· Examples: Carpals, tarsals

Classification of Bones

Slide 5.5aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

· 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

Slide 5.5bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

· Irregular bones

· Irregular shape

· Do not fit into other bone classification categories

· Example: Vertebrae and hip

• Axial skeleton• Skull• Vertebral column• Thoracic cage

• Appendicular skeleton

• Pectoral and pelvic girdles• Upper and lower limbs

Skeletal system includes both:

The Axial Skeleton

Figure 7.1b

Figure 7.2

Cranial and Facial Subdivisions of the Skull

The Adult Skull(ant view)

Figure 7.3d

The Adult Skull(sup & post view)

Figure 7.3a, b

The Adult Skull(lateral view)

Figure 7.3c

The Adult Skull( inf view)

Skull(cranial fossa)

Figure 7.4b

Newborn vs. Adult

Major Differences Fontanelles

Pos & sphenoidal=2-3month after birth

Mastoid=1year Ant=1-2 year

Unfused Structures Sutures

Unfused Structures frontal parietal occipital

Paranasal Sinuses· Functions:

· lightening the weight of the head· Give resonance and amplification to voice· humidifying and heating inhaled air· serving as a crumple zone to protect vital structures in the

event of facial trauma

Remember that the Axial skeleton includes:

SkullVertebral columnThoracic cage

Axial skeleton is shown in green

Cervical Vertebrae (7)Thoracic Vertebrae (12)Lumbar Vertberae (5)SacrumCoccyx

Cervical Vertebrae (7)Thoracic Vertebrae (12)Lumbar Vertberae (5)SacrumCoccyx

The Vertebral Column

The Vertebral Column

The Vertebral Column

• Fetus and infant: 33 separate bones, or vertebrae

• Adult: 24 vertebrae• Inferior 9 have fused

forming• The sacrum (5) and• The coccyx (4)

• Four spinal curves• Primary

(accommodation) curves = thoracic and sacral

• Secondary (compensation) curves = lumbar and cervical

Curvatures of the Spine• Scoliosis

side-to-side, lateral curve

Lordosis

• Abnormal inward curve of the lumbar region

Kyphosis

Abnormal curvatures

Structure of a typical vertebra

• Typically has a body and vertebral arch• Superior and inferior articular processes • Separated by intervertebral discs

Vertebral Anatomy

• Cervical• Has small body• Large relative size of vertebral foramen• Costal processes with transverse foramina• Notched spinous processes

Vertebral regions

The Cervical Vertebrae

C1 (atlas)

• Without body• Have lateral masses

with tow arc post and ant

• Have an post tubercle

C2 (axis)

Thoracic vertebrae

The Thoracic Vertebrae• Heart-shaped body• Long slender spinous processes• Articulations for ribs

Lumbar Vertebrae• Most massive• Least mobile• Subjected to great

stresses

sacrum

• Fusion of 5 sacral vertebra• Surfaces:• Anterior(pelvic)• Posterior• Lateral

• Base• apex

The Sacrum and Coccyx

• Protects reproductive, digestive and urinary organs

• Thoracic vertebrae• Ribs• Sternum

• Ribs and sternum forms the rib cage

Thoracic cage

Sternum

• Three parts• Manubrium• Body• Xiphoid process

Ribs

• 12 Pairs• True ribs

• First 7 pairs• Attach to thoracic

vertebrae and sternum

• False ribs• Next 8,9,10 pairs• Attach to the cartilage

of the ribs above• Floating ribs

• Last 2 pairs of false ribs• Have no attachment in

the front

The Thoracic Cage

The Thoracic Cage

Typical rib

• Has a head, neck, tubercle and a body

Vertebral and Sternal Articulations

Appendicular Skeleton

Appendicular Skeleton: Pectoral Girdle (Shoulder)

Appendicular Skeleton: Pelvic Girdle

• Hip bones• Composed of three pair of fused bones

• Ilium• Ischium• Pubic bone

• The total weight of the upper body rests on the pelvis

• Protects several organs• Reproductive organs• Urinary bladder• Part of the large intestine

Hip Bone

Ilium

Pubis

Ischium

Next

Back

Appendicular Skeleton: Pelvic Girdle

The sacrum and coccyx are part of the axial skeleton not appendicular skeleton.

Appendicular Skeleton: Pelvic GirdleCoxal Bone Structure

Appendicular Skeleton: Pelvic GirdleMale and Female Pelvis Comparison

Femur Bone

Proximal End

Distal End

Shaft or Body

Head and Neck

Trochanter (Greater & Lesser)

Intertrochanteric Line & Crest

3 Borders: Lateral, Medial &

Posterior (Linea Aspera)

3 Surfaces: Anterior, Lateral

& Medial

2 Condyle: Lateral & Medial

1 Notch: Intercondylar Notch

1 Surface: Patellar

Appendicular Skeleton: Femoral Region

· The thigh has one bone

· Femur – thigh bone

Proximal End

Back

Proximal End

Back

Shaft or Body

Distal End

Review

Next

Appendicular Skeleton: Patellar and Crural Regions

· The leg has two bones

· Tibia

· Fibula

Appendicular Skeleton: Tarsal, Pes, and Digits Regions

· The foot

· Tarsus – ankle

· Metatarsals – sole

· Phalanges – toes

Articulations: Joints

• A joint is a location where two or more bones meet.

• Functions of joints• Hold bones together• Allow for mobility

• Ways joints are classified• Functionally• Structurally

Types of Joints

• Fibrous joints• Generally immovable (sutures of skull)

• Cartilaginous joints• Immovable or slightly moveable (vertebral

disc)

• Synovial joints• Freely moveable (shoulder, pelvis, knee,

elbow, digits)• Articulating bones are separated by a joint

cavity• Synovial fluid is found in the joint cavity

Structure of a Synovial Joint

Figure 5.28

Type of Synovial Joints

Types of Synovial Joints

perpendicular plate of ethmoid

Med part of labyrinth

Appendicular Skeleton: Brachium Region

· The arm is formed by a single bone

· Humerus

Appendicular Skeleton: Antebrachium Region

• The forearm has two bones

• Ulna (side adjacent to little finger)

• Radius (side adjacent to thumb)

Appendicular Skeleton: Carpus, Manus, and Digits Region

· The hand

· Carpals – wrist

· Metacarpals – palm

· Phalanges – fingers