The Skeletal System

The Skeletal System

Objectives

• Identify and describe the five functions of the skeletal system

• Distinguish between long bones, short bones, flat bones, and irregular bones; provide examples of each

• Identify parts of a typical long bone

Skeletal System

• Bones are made of several tissues

• About 206 bones in the human body

Functions of Skeletal System

• SUPPORT: Hard framework that supports and anchors the soft organs of the body.

• PROTECTION: Surrounds organs such as the brain and spinal cord.

• MOVEMENT: Allows for muscle attachment therefore the bones are used as levers.

• STORAGE: Minerals and lipids are stored within bone material.

• BLOOD CELL FORMATION: The bone marrow is responsible for blood cell production.

Parts of the Skeletal System

• Axial skeleton– Skull and bones that support it– Includes vertebra and ribs– 80 bones

• Appendicular skeleton– Limbs– 126 bones

Parts of the Skeletal System

• 206 bones• 4 TYPES BONE

– Long bones– Short bones– Flat bones– Irregular bones

• 2 TYPES BONE TISSUE– Compact– Cancellous (spongy)

Classification of Bones: By Shape

• Long bones – longer than they are wide (e.g., humerus)

• Designed to absorb stress

Classification of Bones: By Shape

• Short bones– Cube-shaped bones

of the wrist and ankle

– Equal in length and width

Classification of Bones: By Shape

• Flat bones – thin, flattened, and a bit curved (e.g., sternum, ribs, and most skull bones)

Classification of Bones: By Shape

• Irregular bones – bones with complicated shapes (e.g., vertebrae, face bones, hip bones)

Features of a Long Bone:

Epiphysis: Ends of the bone.

Diaphysis: The shaft of the bone which surrounds the medullary cavity.

Articular Cartilage: Cushions the ends of the bones and allows for smooth movement.

Epiphyseal Plate:Areas made of cartilage allowing for the growth of the bone.

Objectives

• Describe the inorganic and organic components of bone tissue

• Distinguish between the 3 types of bone cells on the basis of their functions

• Understand the role of calcium and phosphorus for bone growth

• List the axial skeleton components• Identify the 8 cranium bones and the

13 facial bones

Bone Composition

• Bone tissue( 10), cartilage, dense connective tissue, blood-forming tissue, BVs, nerves

• Bone tissue– Inorganic materials (salts form crystals –hydroxyapatite)• Crystals 2/3 total bone weight• Provide hardness

– Organic materials (collagen)• Reinforce/strengthen matrix

Types of Bone Cells - 3

• Osteoblasts– Arise from embryonic cells– Produce matrix ( mineral salts and collagen)– Contributes to new bone

• Osteocytes– Mature bone cells– Move nutrients/waste through bone matrix

Types of Bone Cells cont.

• Osteoclasts– ‘Wandering’ bone cells– Secrete substance that dissolves bone matrix

back into original components: calcium, phosphorus work their way into circulatory system

– Activity controlled by hormones hence osteoporosis is linked to hormonal changes

Types of Bone Cells cont.

• Osteoblasts giveth.Osteoclasts taketh away.Osteocytes maintaineth.

• Work together to not only build new bone but to strengthen existing bone– Cracks, fractures

Types of Bone Cells cont.

– Osteoporosis: rate of bone loss exceeds bone regrowth• Osteoclasts reasborbing more bone tissue

than osteoblasts are replacing

Bone Growth and Minerals

Calcium• Most common mineral

found in body• Contributes to bone

strength• A component in

hydroxyapatite• Phosphorus

codependency• 206 bones contain 3

lbs of calcium

Phosphorus• Second most common

mineral found in body• Other major

component in hydroxyapatite

• Bones/teeth store 85% of body’s total

• Calcium codependency

The Axial Skeleton

• Made up of bones that roughly form the body’s “head to toe” vertical axis– Skull– Vertebral column (backbone)– Ribs– Sternum (breastbone)

The Skull: Protection for the Brain

• Set of bones of the head region– Bones of cranium

• 8 bones– Frontal bone, Parietal bones(2), occipital bone,

temporal bones(2), sphenoid bone, ethomoid bone

– Facial bones• 13 immovable bones

– Maxillary bones (2), palatine bones (2), zygomatic bones (2), nasal bones (2), lacrimal bones (2), vomer bone, inferior nasal conchae

• 1 movable lower jaw– Mandible

Bones of the Skull

Human Skull, Superior ViewHuman Skull, Superior View

Slide 5.23Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 5.8

The Skull

Skull – Inferior View

Objectives

• Name and identify the regions of the vertebral column and give the number of vertebrae in each segment

• Distinguish between three types of ribs• Name and identify the components of the

pectoral girdle and pelvic girdle• List the primary subdivisions of the

appendicular skeleton

Objectives

• Compare and contrast pectoral girdle and pelvic girdle– Structure– Purpose– Male vs. female

• Identify the components of the lower limbs and upper limbs

• Compare and contrast bones of the arm and forearm with the bones of the thigh and leg

Vertebral Column

• Vertebrae separated by intervertebral discs

• Spine has normal curvature• Each vertebrae is given a name

according to location

Vertebral Column

• 7 Cervical vertebrae• 12 thoracic• 5 lumbar• 1 sacrum (5 fused)• 1 coccyx (4 fused)

Structure of a Typical Vertebrae

Ribs, Sternum and Thoracic Vertebrae

• Ribs– True ribs (1st seven pairs)– False ribs – Floating ribs

• Sternum• Thoracic Vertebrae• Coastal cartilage

Ribs, Sternum and Thoracic Vertebrae

Appendicular Skeleton

• Pectoral girdle• Limbs (appendages)• Pelvic girdle

Appendicular Skeleton

The Pectoral (Shoulder) Girdle

• Composed of two bones– Clavicle (collarbone)– Scapula (shoulder blade)

• These bones allow the upper limbs to have exceptionally free movement

Bones of the Shoulder Girdle

Bones of the Upper Limb

• The arm is formed by a single bone– Humerus

Bones of the Upper Limb

• The forearm has two bones– Ulna– Radius

Bones of the Upper Limb

• The hand– Carpals

• Wrist

– Metacarpals• Palms

– Phalanges• Fingers

Bones of the Pelvic Girdle

• Hip bones• Composed of three pair of fused bones

– Ilium– Ischium– Pubic bone

• Total weight of upper body rests on pelvis

• Protects reprod. organs, urinary bladder, part of large intestine

The Pelvis

Gender Differences of the Pelvis

Bones of the Lower Limbs

• The thigh has one bone– Femur

• Thigh

Bones of the Lower Limbs

• The leg has two bones– Tibia– Fibula

Bones of the Lower Limbs

• Foot– Talsus

• Ankle

– Metatarsals• Sole

– Phalanges• Toes

• Intro to Skeleton

Objectives

• Define joint and the two classifications of joints • Distinguish between functional classification and

structural classification of joints• Identify where in the body the 3 types of

functional joints are located• Define the 6 types of synovial joints,

distinguishing between each in terms of plane movement and example locations

Joints

• Region where two or more bones (or parts of bone) unify articulation

• Functions– Holds bone together– Allow for mobility

• Classified by– Function – how much movement permitted– Structure – diff type of material/mechanism

by which bone surfaces interact

Functional Classification of Joints

• 3 Types1. Synarthrosis

– Immovable joints– Ex: Joints between skull bones, tooth in

socket

2. Amphiarthrosis– Slightly movable joints– Ex: Joints between tibia and fibula,

discs between vertebrae

Functional Classification of Joints

3. Diarthrosis– Freely movable joints– Ex: Hip joint, elbow

Structural Classification of Joints

• 3 Types1. Fibrous joints

– United by fibrous tissue– Generally immovable (synarthrosis)

2. Cartilaginous joints– United by cartilage– Immovable or slightly movable

(amphiarthrosis)

Structural Classification of Joints

3. Synovial joints– Contains joint cavity which contains

fluid allowing bones to slide over one another without grinding

– Freely movable (diarthrosis)

Synovial Joints

• Classified further according to shape of articular surfaces or movement – Plane joints– Hinge joints– Saddle joints– Condyloid joints– Ball and socket joints– Pivot joints

Synovial Joints: Range of Motion

• Nonaxial – slipping/gliding movement only

• Uniaxial – movement in one plane• Biaxial – movement in two planes• Multiaxial – movement in or around

all three planes

Synovial Joints

• Plane Joints – gliding and sliding movement due to the flat articular surface; allow movement in a single plane (nonaxial)– Ex: shoulder blade and collar bone

• Hinge Joints – Allow movement in a single plane (uniaxial)– Ex: Elbow

Synovial Joints

• Saddle Joints– Shaped like a saddle. Permit movement in two separate

planes (biaxial)– Back and forth movement, side – to –side, and some

pivotal– Ex: Thumb joint

• Condyloid(Ellipsoid) Joints– Back and forth movement,

circular movement– Joints are biaxial.– Ex: Knuckle

Synovial Joints

• Ball and socket Joints– Consist of spherical head articulating with a

dome shaped cup. Allows for movement on multiple planes. (Multiaxial)

– Ex: Hip joint

• Pivot Joints– Allow rotation on one plane. (Uniaxial)– Movement limited to rotation about a

central axis– Ex: Joint between 1st and 2nd vertebrae

Objectives

• Distinguish between gliding, angular, rotation and misc. categories of movement

• Define each of the above• Provide body examples of each misc.

category movement

Movements• Gliding• Angular

– Flexion/Extension– Abduction/Adduction– Circumduction

• Rotation– Medial/Lateral

• Misc– Elevation/depression– Protraction/retraction– Inversion/Eversion– Pronation/Supination– Dorsiflexion/Plantar flexion

Gliding

• Linear motion• One plane of motion• 2 opposing surfaces pass one

another• Ex:

– Clavicle and sternum

Angular

• Changes in longitudinal position of bone

• Flexion/Extension/Hyperextension– Flexion: decrease in angle btw bones– Extension: increase in angle btw bones– Hyperextension: extension beyond the

standard anatomical position

Angular continued

• Abduction/Adduction/Circumduction– Abduction: movement away from

midline– Adduction: movement toward the

midline– Circumduction: combination

Rotation

• Spin along a longitudinal axis • Medial

– Rotation towards the midline

• Lateral– Rotation away from the midline

Misc.

• Elevation/Depression– Superior & inferior bone movement– Ex: Scapula, mandible

• Protraction/Retraction– Anterior & Posterior bone movement– Ex: Mandible

Misc. cont.

• Inversion– Inward movement of functional surface;

toward midline of the body– Ex: Sole of foot

• Eversion– Outward movement of functional

surface; away from midline of the body– Ex: Sole of foot

• Inversion/Eversion

Misc. cont.

• Pronation– Eversion of the foot, medial rotation of

forearm( toward midline)

• Supination– Inversion of the foot, lateral rotation of

forearm

• Video

Misc. cont.

• Dorsiflexion– Movement of the foot upward

• Plantar flexion– Movement of the foot downward

• Summary video