The organs of the skeletal system including the bones and the structures, including ligaments,...

The organs of the skeletal system including the bones and the structures , including

ligaments, tendons, and cartilage.

Chapter 7Skeletal System

Bone Function

1. Support and ProtectionSupport and Protection• gives shape to head, etc.• supports body’s weight• protects lungs, etc.

2. Body MovementBody Movement• interacts with muscles• bones act as rigid bar of a lever

3. Blood Cell FormationBlood Cell Formation• hemapoiesis• red marrow

4. Inorganic Salt StorageInorganic Salt Storage• calcium • phosphate• magnesium• sodium• potassium

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Bone Classification

Name Description Location

1. Long bones 2 epiphysis and 1 diaphysis Extremities

2. Short bones cube shaped (6-7 sides) Wrist, ankle bones

3. Flat bones 2 layers of compact, Skull (cranium) with spongy inside Sternum

4. Irregular bones very irregular shape Facial, Vertebral column

5. Sesamoid Bones develop within a tendon.

6. Wormian Bones – are tiny bones within the skull that lie between major skull bones.7-2

Bones are classified by their shape:

Bone Classification

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Bones are classified by their shape:

Parts of a Long Bone

• EpiphysisEpiphysis – expanded end of the bone (distal & proximal)

• consists mainly of spongy bone• surrounded by a thin layer of compact bone

• DiaphysisDiaphysis – shaft • consist of a central medullary cavity (yellow marrow)• surrounded by a thick collar of compact bone.

• CompactCompact bone bone – solid, dense, and smooth• SpongySpongy bone bone – has canals and open spaces filled with marrow

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Compact and Spongy Bone

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• ArticularArticular cartilage cartilage – pad of cartilage on the epiphyses where bones articulate or join.

• Shock absorber

• PeriosteumPeriosteum – outer, fibrous, protective covering of diaphysis

• richly supplied with blood lymph vessels•contains bone forming and destroying cells• serves as insertions for tendons and ligament

• EndosteumEndosteum – inner lining of the medullary cavity. • contains layer of osteoblasts and osteoclasts

• Medullary cavityMedullary cavity – cavity of the diaphysis • contains marrow (red when young and yellow when older)

• TrabeculaeTrabeculae – spongy bone consisting of branching bony plates.

• MarrowMarrow – specialized type of soft connective tissue (red and yellow)

Red Marrow – formation of red/white blood cellsYellow MarrowYellow Marrow – replaces red marrow when it

becomes depleted• Epiphyseal lineEpiphyseal line – junction of the growth plate.

Parts of a Long Bone• epiphysis

• distal• proximal

• diaphysis• compact bone• spongy bone• articular cartilage• periosteum• endosteum• medullary cavity• trabeculae• marrow

• red• yellow 7-3

• Osteon (Haversian system) – basic unit of bone• Central canal (Haversian canal)– center of an

osteon that contains blood vessels• Volkmann’s canal – (transverse canals) –

contain larger blood vessels.• Lacuna – hollow cavity in bone.• Bone matrix – made of collagen that adds

strength, which enables a bone to bend increasing flexibility.

Microscopic Structureof Compact Bone

Types of Bone Cells

1. Osteocyte – is a mature bone cell that transports nutrients/wastes.

2. Osteoblasts – A bone forming cell.

3. Osteoclasts – a cell responsible for eroding bone.

Once a bone has been formed, it is continuously Once a bone has been formed, it is continuously remodeled throughout life. This process involves the remodeled throughout life. This process involves the action of osteoblasts, osteoclasts, and specific action of osteoblasts, osteoclasts, and specific hormones.hormones.

Bone Cells

• Your distal femurdistal femur is replaced every four months

• Diaphysis of the femur may not be fully replaced during one’s life

• Bone maturation and remodeling continue until the age of 21 in both sexes.

Did You Know!!!

• OssificationOssification – formation of bone by osteoblasts.• OsteogenesisOsteogenesis – the development of membranelike

connective tissue into bone.• The “skeleton” of an embryo is composed of

fibrous CT membranes that are loosely shaped like bones.

• The “skeleton” provides supporting structures for ossification to begin

• At about 6-7 weeks gestation, ossification begins and continues throughout adulthood.

Bone Development and Growth

Two Types of Ossification

Intramembranous Ossification• bones form on or within a fibrous CT membrane• flat bones (clavicles and skull bones)• happens mainly in the skull • complete ossification does occur until a few months after birth. WHY?

Endochondral Ossification (endo = inside, chondro = cartilage)• bones begin as hyaline cartilage• most bones of the skeleton• endochondral bones

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Endochondral Ossification

• hyaline cartilage model• primary ossification center• secondary ossification centers

• epiphyseal plate• osteoblasts vs. osteoclasts

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Growth at the Epiphyseal Plate

First layer of cells• closest to the end of epiphysis• resting cells• anchors epiphyseal plate to epiphysis

Second layer of cells• many rows of young cells• undergoing mitosis

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Epiphyseal plate (line) – place where longitudinal growth

of bone takes place.

Growth at the Epiphyseal Plate

Third layer of cells• older cells• left behind when new cells appear• cells enlarging and becoming calcified

Fourth layer of cells• thin• dead cells• calcified intercellular substance

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Bone Repair

Four Steps of RepairFour Steps of Repair

1. Hematoma – 6-8 hours a blood clot forms

2.2. Fibrocartilagious CallusFibrocartilagious Callus – fibrocartilage fills the space between the ends of the broken bone.

3.3. Bony CallusBony Callus – Osteoblasts produce trabeculae of spongy bone which joins the broken bones together. (3-4 months)

4.4. RemodelingRemodeling – Osteoblasts build new compact bone. Osteoclasts reabsorb the spongy bone, creating a new medullary cavity. 7-10

Fractures

Types of Fractures

1. green stick2. fissured3. comminuted4. transverse5. oblique6. spiral

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• A number of factors influence bone development, growth, and repair.

• Nutrition, exposure to sunlight, and hormonal secretions are all examples.

1.1. MineralsMinerals – needed for bone remodeling1. Calcium2. Phosphorus 3. Magnesium4. Boron

Factors Affecting Bone Development, Growth, and Repair

2. VitaminsVitamins – growth, remodeling, and repair

Vit D – increased intestinal absorption

of calcium.

Vit C – help maintain bone matrix.

Vit A – controls osteoblasts and clasts activity.

Vit B12 – role in osteoblasts activity

Factors Affecting Bone Development, Growth, and Repair

3. HormonesHormones – needed for bone growth and remodeling.

1. Human Growth Hormone (hGH)

- secreted by pituitary.

- responsible for the general growth of all tissue.

- Stimulates reproduction of cells at epiphyseal plate.

Factors Affecting Bone Development, Growth, and Repair

2. Sex Hormone – Testosterone

- promotes new bone growth

3. Thyroid hormone

- Stimulates replacement of cartilage by bone in epiphyseal plate.

- parathyroid and calcitonin.

4. ExerciseExercise - increases bone growth.

Factors Affecting Bone Development, Growth, and Repair

Disorders Affecting Bone Development, Growth, and Repair

• Deficiency of Vitamin A – retards bone development• Deficiency of Vitamin C – results in fragile bones • Insufficient Growth Hormone – dwarfism• Excessive Growth Hormone – gigantism• Insufficient Thyroid Hormone – delays bone growth• Rickets – lack of vitamin D, calcium, or phosphate. It leads to softening and weakening of the bones• Osteopenia – bone mineral density (BMD) that is lower than normal peak BMD• Osteomalasia – softening of the bones due to a lack of vitamin D or a problem with the body's ability to break down and use this vitamin 7-11

Levers

Four Basic Components1. rigid bar – bones2. fulcrum – point on which bar moves;joint3. object moved against resistance4. force – supplies energy for movement; muscles

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Levers and Movement

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Skeletal Organization

Axial Skeleton• head • neck • trunk

Appendicular Skeleton• upper limbs• lower limbs• pectoral girdle• pelvic girdle

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Skeletal Organization

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The skull, composed of 22 bones, consists of the cranial bones (cranium) and the facial bones (face)

• 8 Cranial bones– protect brain & house ear ossicles

– muscle attachment for jaw, neck & facial muscles

• 14 Facial bones– protect delicate sense organs -- smell, taste, vision

– support entrances to digestive and respiratory systems

Skull

Skull

Frontal (1)• forehead• roof of nasal cavity• roofs of orbits• frontal sinuses• supraorbital foramen• coronal suture

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Skull

Parietal (2)• side walls of cranium• roof of cranium• sagittal suture

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Skull

Temporal (2)• wall of cranium• floor of cranium• floors and sides of orbits• squamosal suture• external acoustic meatus• mandibular fossa• mastoid process• styloid process• zygomatic process

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Skull

Occipital (1)• back of skull• base of cranium• foramen magnum• occipital condyles• lambdoidal suture

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Skull

Sphenoid (1)• base of cranium• sides of skull• floors and sides of orbits• sella turcica• sphenoidal sinuses

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Skull

Ethmoid (1)• roof and walls of nasal cavity• floor of cranium• wall of orbits• cribiform plates• perpendicular plate• superior and middle nasal conchae• ethmoidal sinuses• crista gallis

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Facial Skeleton

Maxillary (2)• upper jaw• anterior roof of mouth• floors of orbits• sides of nasal cavity• floors of nasal cavity• alveolar processes• maxillary sinuses• palatine process

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Facial Skeleton

Palatine (2)• posterior roof of mouth• floor of nasal cavity• lateral walls of nasal cavity

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Facial Skeleton

Zygomatic (2) • prominences of cheeks• lateral walls of orbits• floors of orbits• temporal process

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Facial Skeleton

Lacrimal (2)• medial walls of orbits• groove from orbit to nasal cavity

Nasal (2)• bridge of nose

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Facial Skeleton

Vomer (1)• inferior portion of nasal septum

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Facial Skeleton

Mandible (1)• lower jaw• body• ramus• mandibular condyle• coronoid process• alveolar process• mandibular foramen• mental foramen

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Infantile Skull

Fontanels – fibrous membranes

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Functions of the Vertebral Column

1. Protects the spinal cord.

2. Absorbs Shock

3. Holds body in upright position

Vertebral Column

Vertebral Column

• cervical vertebrae (7)• thoracic vertebrae (12)• lumbar vertebrae (5)• sacrum (5) – are fused• coccyx (4) – are fused

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Vertebral Column

Four Curvatures of the VC 1. cervical curvature2. thoracic curvature3. lumbar curvature4. pelvic curvature

Other Parts of the VC

• rib facet• intervertebral discs• intervertebral foramina

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Cervical Vertebrae

• Atlas – 1st; supports head

• Axis – 2nd; dens pivots to turn head

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Common Parts of a Vertebrae

Thoracic Vertebrae

• long spinous processes• rib facets

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Lumbar Vertebrae

• large bodies

• thick, short spinous processes

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Sacrum

• five fused vertebrae

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Coccyx

• tailbone

• four fused vertebrae

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• KyphosisKyphosis – improper curvature of the upper thoracic region of the VC.

• LordosisLordosis – abnormal curvature of the lumbar region of the VC.

• ScoliosisScoliosis – abnormal lateral curvature of the spine.

Disorders of the VC

KyphosisKyphosis

LordosisLordosis

ScoliosisScoliosis

Thoracic Cage

• Ribs• Sternum

• Thoracic vertebrae• Costal cartilages

Functions of Thoracic Cage• Supports shoulder girdle

• Protects viscera• Role in breathing

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Ribs• Articulate anteriorly with sternum• Articulate posteriorly with thoracic vertebrae

Three Types of Ribs•True – upper pair ribs (7) - articulate with sternum• False – remaining pair ribs (5) - Do not articulate•Floating – 11th and 12th pair (2)

- These ribs do not articulate anteriorly7-39

Rib Structure

• Shaft• Head – posterior end; articulates with vertebrae• Tubercle – articulates with vertebrae• Costal cartilage – hyaline cartilage

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Sternum

Parts of the SternumParts of the Sternum •Manubrium

• articulates with clavicle

• Body – middle portion

• Xiphoid process• lower extension

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Pectoral Girdle

• shoulder girdle • clavicles• scapulae• supports upper limbs

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Clavicles

• articulate with manubrium• articulate with scapulae (acromion process)

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Scapulae

• spine• supraspinous fossa• infraspinous fossa

• acromion process• coracoid process• glenoid cavity

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Upper Limb

• Humerus• Radius• Ulna• Carpals• Metacarpals• Phalanges

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Humerus

• head• greater tubercle• lesser tubercle• anatomical neck• surgical neck• deltoid tuberosity• capitulum• trochlea• olecranon fossa

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ForearmThe forearm consists of two bones:

1. RADIUS - Thumb side

2. ULNA – pinky side

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OTHER STRUCTURES:

OLECRANON PROCESS

RADIAL TUBEROSITY

Radius and Ulna

• medial forearm bone• trochlear notch• olecranon process• coronoid process• styloid process

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Wrist and Hand

• Carpals (16)• trapezium• trapezoid• capitate• scaphoid• pisiform• triquetrum• hamate• lunate

• Metacarpals (10)

• Phalanges (28)• proximal phalanx• middle phalanx• distal phalanx

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Pelvic Girdle

• Coxae (2)• supports trunk of body• connects lower limbs to to the vertebral column

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Coxae

• hip bones• ilium

• iliac crest• iliac spines• greater sciatic notch

• ischium• ischial spines• lesser sciatic notch• ischial tuberosity

• pubis• obturator foramen• acetabulum

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Greater and Lesser Pelvis

Greater Pelvis• lumbar vertebrae posteriorly• iliac bones laterally• abdominal wall anteriorly

Lesser Pelvis• sacrum and coccyx posteriorly• lower ilium, ischium, and pubis bones laterally and anteriorly

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Male and Female Pelvis

Female• iliac bones more flared• broader hips• pubic arch angle greater• more distance between ischial spine and ischial tuberosity• sacral curvature shorter and flatter• lighter bones

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Lower Limb

• Femur• Patella• Tibia• Fibula• Tarsals• Metatarsals• Phalanges

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Femur

• longest bone of body• head• fovea capitis• neck• greater trochanter• lesser trochanter• linea aspera• condyles• epicondyles

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Patella

• kneecap• anterior surface of knee• flat seasmoid bone located in a tendon

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Tibia

• shin bone• medial to fibula• condyles• tibial tuberosity (Osgood- Schlatter)• anterior crest• medial malleolus• bears weight

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Fibula

Insert figure 7.54

• lateral to tibia• long, slender• head• lateral malleolus• does not bear any body weight

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Ankle and Foot

• Tarsals (14)• calcaneus• talus• navicular• cuboid• lateral cuneiform• intermediate cuneiform• medial cuneiform

• Metatarsals (10)

• Phalanges (28)• proximal• middle• distal

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Ankle and Foot

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Ankle and Foot

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Life-Span Changes

• decrease in height at about age 30• calcium levels fall• bones become brittle• osteoclasts outnumber osteoblasts• spongy bone weakens before compact bone• bone loss rapid in menopausal women• hip fractures common• vertebral compression fractures common

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• Overall frailty

• Decreased muscle strength

• Side effects of medication

• Slowed reaction time due to stiffening joints

• Poor vision and/or hearing

• Disease (cancer, infection, arthritis)

REASONS FOR FALLS