Chapter 7 Skeletal System

Chapter 7 Skeletal System
Bone Classification Long Bones Short Bones Flat Bones Irregular Bones Sesamoid (Round) Bones

Skeletal System Functions Support Protection Movement facilitation
internal organs Movement facilitation Bones act as the levers Articulations as the fulcrums Muscles provide the force

Skeletal System Functions Mineral Storage Storage of Energy
calcium and phosphorous Storage of Blood Cell Producing Cells red bone marrow Storage of Energy lipids stored in yellow bone marrow are important source of chemical energy

Bone Function Support, Movement & Protection gives shape to head, etc.
supports body’s weight protects lungs, etc. bones and muscles interact when limbs or body parts move Inorganic Salt Storage calcium phosphate magnesium sodium potassium Blood Cell Formation hematopoiesis red marrow

Cells and Histology of Bone
Cartilage, Osseous and Dense CT Osseous Tissue (4 cell types) Osteoprogenitor Found throughout the bone Have mitotic potential May differentiate into osteoblast

Osseous Tissue (4 cell types) Osteoblast No mitotic potential Found on the surface of the bone Secrete mineral salts and organic components for bone formation

Osseous Tissue (4 cell types) Osteocytes No mitotic potential Found within the bone Maintain daily cellular activities of bone tissue Osteoclast Found on the surface of bone Function in the re-absorption of bone

Parts of a Long Bone Epiphysis proximal end Articular Cartilage
distal end proximal end Articular Cartilage Covers each epiphysis Hyaline cartilage Diaphysis Shaft Metaphysis Area between diaphysis and epiphysis in mature bone

Parts of a Long Bone Periosteum
Contains nerves, blood vessels, osteo cells Attachment point for ligaments and tendons Medullary cavity contains yellow marrow Endosteum lines the medullary cavity

Parts of a Long Bone Spongy Bone
Irregular lattice work of bone-trabeculae Spaces filled with red marrow produces RBCs

Parts of a Long Bone Compact Bone Tightly packed tissue Parts
Concentric Lamellae Concentric circles of tightly packed tissue Volkmann’s Canals Penetrate compact bone Allow blood vessels and nerves into medullary cavity and other Haversian Canals

Parts of a Long Bone Compact Bone Haversian Canals
Run longitudinally through the compact bone Concentric lamellae surround the canals Lacunae Open spaces between the concentric lamellae that contain osteocytes Look like “little lakes”

Parts of a Long Bone Compact Bone Canaliculi Osteon (Haversian System)
Tiny canals that radiate away from the lacunae Osteon (Haversian System) Central canal, surrounding lamellae, lacunae, osteocytes and canaliculi

Bone Development Intramembranous Ossification
bones originate within sheetlike layers of connective tissues broad, flat bones skull bones (except mandible) intramembranous bones Endochondral Ossification bones begin as hyaline cartilage form models for future bones most bones of the skeleton endochondral bones

Endochondral Ossification
hyaline cartilage model primary ossification center secondary ossification centers epiphyseal plate osteoblasts vs. osteoclasts

Hyaline cartilage model “bone” created by chondroblast Actual ossification of this “bone” starts 6-7 weeks after conception

Interstitial and Oppositional Growth Chondrocytes burst and trigger calcification Capillaries and bone cells invade dying cartilage Bone starts to calcify

Primary Ossification Center Blood vessels in mid-region produce ossification center Osteoblast form spongy bone in the area of calcified cartilage, this causes the center to enlarge Spongy bone is destroyed by osteoclast-forms medullary cavity

Secondary Ossification Centers When blood vessels enter the epiphysis Spongy bone created here will stay Epiphyseal plate Layer of hyaline cartilage between the 2 areas of growth Stays until you reach maturity

Remnants of hyaline cartilage on the epiphysis becomes articulating cartilage

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

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 extracellular matrix

Homeostasis of Bone Tissue
Bone Re-absorption – action of osteoclasts and parathyroid hormone Bone Deposition – action of osteoblasts and calcitonin

Factors Affecting Bone Development, Growth, and Repair
Deficiency of Vitamin A – retards bone development Deficiency of Vitamin C – results in fragile bones Deficiency of Vitamin D – rickets, osteomalacia Insufficient Growth Hormone – dwarfism Excessive Growth Hormone – gigantism, acromegaly Insufficient Thyroid Hormone – delays bone growth Sex Hormones – promote bone formation; stimulate ossification of epiphyseal plates Physical Stress – stimulates bone growth

Superficial Bone Anatomy
Process bony prominence “bump” Condyle rounded or knuckle like process Tubercle small process Tuberosity large process (tibial tuberosity) Trochanter huge process (located on the proximal end of the femur)

Crest narrow ridge of bone Spine sharp slender process (holes and/or depressions) Fissure narrow slit through which blood vessels or nerves pass Foramen opening through which blood vessels and nerves pass

Meatus tubelike passageway running within a bone Sulcus or groove furrow that accommodates a soft structure such as blood vessels, nerves or tendons Fossa depression in or on the surface of a bone

Skeletal Organization
Axial Skeleton head neck trunk Appendicular Skeleton upper limbs lower limbs pectoral girdle pelvic girdle

Hyoid Bone Supports tongue Attachment point for muscles that move tongue

Cranium Frontal (1) Forehead Roof of nasal cavity
Roofs of optical orbits Frontal sinuses Supraorbital foramen Blood vessels and nerve Coronal suture Develops in two parts Completely fused by age 5 or 6

Cranium Parietal (2) Side walls of cranium Roof of cranium
sagittal suture Fuses two parietal bones together Coronal suture Fuses parietal bones to frontal bone

Cranium Occipital (1) back of skull base of cranium foramen magnum
Inferior part of brain stem connects with spinal cord occipital condyles Either side of foramen magnum lambdoid suture Fuses parietal bones with occipital bone

Cranium Temporal (2) side walls of cranium external acoustic meatus
floor of cranium floors and sides of orbits squamous suture Fuses parietal with temporal external acoustic meatus Leads to inner ear mandibular fossa Where mandible meets temporal bone mastoid process Neck muscle attachment styloid process Tongue and pharynx attachment zygomatic process

Cranium Sphenoid (1) base of cranium sides of skull
floors and sides of orbits sella turcica Indentation along midline within cranial cavity Contains pituitary gland sphenoidal sinuses

Cranium Ethmoid (1) roof and walls of nasal cavity floor of cranium
wall of orbits cribriform plates Join two parts of ethmoid on either side of nasal cavity perpendicular plate Forms most of nasal septum superior and middle nasal conchae Support mucous membranes of nasal cavity ethmoidal sinuses crista galli Projects upward into cranial cavity Attaches brain membranes

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

Facial Skeleton

Facial Skeleton Palatine (2)
L shaped bones located behind the maxillae posterior section of hard palate floor of nasal cavity lateral walls of nasal cavity

Facial Skeleton Zygomatic (2) prominences of cheeks
lateral walls of orbits floors of orbits temporal process Extends posteriorly to join zygomatic process of temporal bone

Facial Skeleton Lacrimal (2) Nasal (2) medial walls of orbits
groove from orbit to nasal cavity Nasal (2) bridge of nose

Facial Skeleton Vomer (1) inferior portion of nasal septum

Facial Skeleton Inferior Nasal Conchae (2)
extend from lateral walls of nasal cavity

Facial Skeleton Mandible (1) Lower jaw Body Ramus Mandibular condyle
Horseshoe shaped portion Ramus Flat, upward projections Mandibular condyle Fits into mandibular fossa Coronoid process Chewing muscle attachment alveolar process mandibular foramen mental foramen

Infantile Skull Fontanels – fibrous membranes

Vertebral Column cervical vertebrae (7) thoracic vertebrae (12)
lumbar vertebrae (5) sacrum coccyx

Vertebral Column cervical curvature thoracic curvature
Smallest vertebrae Most dense bone tissue thoracic curvature lumbar curvature sacral curvature rib facets vertebra prominens Long spinous process on 7th vertebra intervertebral discs intervertebral foramina

Cervical Vertebrae Atlas – 1st; supports head
Axis – 2nd; dens pivots to turn head transverse foramina Blood vessels leading to the brain pass through bifid spinous processes Muscle attachment vertebral prominens useful landmark

Thoracic Vertebrae long spinous processes rib facets

Lumbar Vertebrae large bodies thick, short spinous processes
Support weight thick, short spinous processes Nearly horizontal

Sacrum five fused vertebrae median sacral crest
Fuse between age 15 and 30 median sacral crest Fused spinous processes posterior sacral foramina posterior wall of pelvic cavity sacral promontory Body of the 1st sacral vertebra

Coccyx tailbone four fused vertebrae Fuse by age 25

Thoracic Cage Ribs Sternum Thoracic vertebrae Costal cartilages
Supports shoulder (pectoral) girdle and upper limbs Protects viscera Role in breathing

Ribs True ribs (7) False ribs (5)
Attach to sternum by costal cartilage False ribs (5) Costal cartilage does not reach sternum Top 3 join cartilage of 7th True rib Bottom 2 don’t attach at all floating (2)

Rib Structure Shaft Head posterior end articulates with vertebrae
Tubercle Costal cartilage hyaline cartilage

Sternum Manubrium Body Xiphoid process

Appendicular Skeleton
Comprised of 2 parts Pectoral girdle and upper extremity Shoulders and arms Pelvic girdle and lower extremity Hips and legs

Pectoral Girdle attach bones of the upper extremities to the axial skeleton Shoulder Girdle clavicles - anterior scapulae - posterior supports upper limbs

Clavicles Long slender bone with double curvature Sternal end
Rounded end articulates with manubrium Acromial end Broad flat end articulates with scapula (acromion process)

Scapulae Triangular flat bone Posterior part of the thorax
Between the 2nd and the 7th rib Medial boarder 5 centimeters from the vertebral column spine Runs diagonally across body supraspinous fossa infraspinous fossa

Scapulae acromion process part of the spine that expands past the body
coracoid process located at the lateral end of the superior ridge glenoid cavity fossa inferior to the acromian process Articulates with the head of the humerus to make a ball and socket joint

Scapulae

Upper Limb Consists of 60 bones Each side contains 30 bones 1 humerus
1 radius 1 ulna 8 carpals 5 metacarpals 14 phalanges

Upper Limb Humerus Articulates proximally with the scapula and distally with both the radius and the ulna Largest bone in the upper extremity

Humerus rounded proximal end, articulates with glenoid cavity
Head rounded proximal end, articulates with glenoid cavity Anatomical neck Slight groove below head Epiphyseal plate Greater tubercle large lateral process below the anatomical neck

Humerus lesser tubercle anterior side Intertubercular groove
Surgical neck Constricted portion inferior to tubercles Fractures likely here Deltoid tuberosity Slight bump on the anterior surface Insertion point for deltoid muscle

Humerus Capitulum rounded knob articulates with head of radius
Trochlea Pulley-like surface that articulates with ulna Coronoid fossa Receives part of the ulna when elbow is flexed On anterior, distal surface

Humerus Olecranon fossa posterior side
receives olecranon process of ulna when elbow is extended Medial and Lateral Epicondyles Found on either side of distal end of humerus Serve as attachments of most forearm muscles

Humerus Ulnar nerve Lies over the posterior surface of the medial epicondyle Can be rolled between the finger and the medial epicondyle

Ulna medial forearm bone trochlear notch Curved area between olecranon and coronoid process Articulates with trochlea of humerus Allows for flexion and extension of elbow

Ulna Olecranon process posterior projection proximal end
Coronoid process anterior projection- lateral Styloid process posterior side of the head of the ulna Head distal end of the ulna

Radius lateral forearm bone Head Disc like structure that articulates with capitulum of humerus and radial notch of ulna Radial tuberosity Proximal end inferior to head Anterior surface Styloid process Distal end Articulates with scaphoid bone

Wrist and Hand Carpals (16) Metacarpals (10) Phalanges (28) trapezium
trapezoid capitate scaphoid pisiform triquetrum hamate lunate Metacarpals (10) Phalanges (28) proximal phalanx middle phalanx distal phalanx

Pelvic Girdle Provide a strong support for the lower extremities
Coxae (2) Each is 3 bones fused together Os coxa (1) Sacrum supports trunk of body protects viscera

Coxae Acetabulum iliac crest hip bones
lateral fossa of the os coxa where 3 pelvic bones merge Ilium Superior to other 2 portions iliac crest superior border serves as insertion point for abdominal wall muscles

Coxae Ilium Iliac fossa Greater sciatic notch
internal surface seen from the medial side gives the pelvis a bowl shape appearance Greater sciatic notch Inferior to iliac crest Posterior to acetabulum Allows for major nerves and blood vessels to travel from sacrum to legs

Coxae Ischium lesser sciatic notch ischial tuberosity
inferior, posterior portion of the coxal bone ischial spines Posterior, superior to ischial tuberosity lesser sciatic notch Inferior to ischial spine ischial tuberosity tuberosity that we sit on

Coxae Pubis Joins with other pubic bone at symphysis pubis
orbturator foramen between ischium, pubic bone and acetabulum symphysis pubis Joins with other pubic bone at symphysis pubis Hormone, relaxin, is released during child birth that allows greater flexibility of the fibrocartilage

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

Male and Female Pelvis Female iliac bones more flared broader hips
pubic arch angle greater more distance between ischial spines and ischial tuberosities sacral curvature shorter and flatter lighter bones

Lower Limb Femur (2) Patella (2) Tibia (2) Fibula (2) Tarsals (14)
Metatarsals (10) Phalanges (14)

Femur Body of femur angles toward the midline
Longest & heaviest bone of body Body of femur angles toward the midline makes knees closer than hips Degree is greater in females

Femur Head Neck rounded end articulates with acetabulum
Distal to the head Elderly people break this area often Greater trochanter & Lesser trochanter large processes below the neck serve attachment points for some thigh and buttock muscles

Femur Shaft Medial & Lateral epicondyles diaphysis Linea aspera
Posterior side of shaft Serves as insertion point for adductor muscles of the leg Medial & Lateral epicondyles Distal end of femur Articulates with proximal end of tibia

Femur Intercondylar fossa Patellar surface
important area for the ligaments in the knee Patellar surface distal anterior surface between the condyles that forms a gliding joint with the patella

Patella Inferior end is called the Apex anterior surface of knee
kneecap Inferior end is called the Apex anterior surface of knee flat sesamoid bone located in a tendon

Tibia shin bone Large, medial, weight bearing bone of the lower extremity Lateral & Medial Condyles Articulate with epicondyles of femur Inferior surface of the lateral condyle articulates with the fibula

Tibia Tibial tuberosity Anterior surface of the tibia
Surface serves as attachment point for the patellar ligaments and tendons anterior crest Extends downward from tibial tuberosity

Tibia Intercondylar Eminence
Upward projection between the condyles of the tibia Cruciate ligaments attach here Medial malleolus Medial projection on the distal end of the tibia Provides medial supports to the hinge joint of your ankle

Fibula Non weight-bearing Long, slender proximal end more rounded
Lateral to tibia Non weight-bearing Long, slender Head proximal end more rounded Lateral malleolus Distal end articulates with the tibia and talus Lateral support to the ankle Longer pointier end

Ankle and Foot Largest and strongest tarsal Supports body weight
Calcaneus Largest and strongest tarsal Supports body weight Serves as lever attachment for gastrocnemius

Ankle and Foot Talus Uppermost tarsal
Only bone that articulates with the tibia and fibula Initially bares all body weight, then transfers half to the calcaneus and half to the other tarsals

Ankle and Foot Navicular intermediate cuneiform medial cuneiform
just anterior to the talus cuboid Lateral side of the foot Articulates with calcaneus, the 4th and 5th metatarsal lateral cuneiform intermediate cuneiform medial cuneiform Each cuneiform that articulates with the corresponding metatarsal

Ankle and Foot Metatarsals (10)
numbered from the medial to the lateral side Phalanges (28) proximal middle distal

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

Clinical Application Types of Fractures fissured comminuted transverse
green stick fissured comminuted transverse oblique spiral

Clinical Application: Fractures
Impacted one fragment is firmly driven into the other Displaced anatomical alignment is NOT preserved Non-displaced anatomical alignment is preserved Stress partial fracture resulting in bones inability to withstand forces About 25% involve distal end of the fibula

Clinical Application: Fractures
Pathologic caused by weakening of the bone due to a disease Pott’s fracture of the distal end of the fibula with serious injury to the distal tibial articulation Severe eversion sprain may lead to this Colle’s fracture at the distal end of the radius in which the distal end is displaced posteriorly Occurs frequently when you try to stop yourself from falling

Clinical Application: Fracture Repair
Fracture breaks blood vessels found in the Haversian system Blood clot forms at the site of the break within 6 to 8 hours (fracture hematoma) Fracture hematoma serves as the focus for cellular invasion

Callus forms New bone tissue developed around the fracture Site of osteoblast activity

Remodeling Dead bone is absorbed by osteoclast Compact bone replaces spongy bone in the fractured area

Clinical Application: Disorders
Osteoporosis Age related disease characterized by decreased bone mass an increased chance of fractures Decreased levels of estrogen (sex hormones that stimulate osteoblast)

Osteoporosis White women more than men and people of color Other factors linked to osteoporosis Body build short people have less bone mass Weight thin people have less adipose, which stores estrogen Smokers- low estrogen levels Calcium deficiency and mal-absorption Vitamin D deficiency Certain drugs- alcohol, cortisone, etc. Premature menopause

Osteoporosis Prevention Exercise muscle action stimulates blood flow to bone tissue Estrogen pills- for post menopause women Calcium supplements/ vitamins Prescription anabolic steroids- increase hormone levels Sodium Fluoride stimulates oteoblast

Osteogenic Sarcoma Malignant bone tumor that affects osteoblast People between ages of 10-25 Left untreated it will metasticize and lead to death Treatment includes chemotherapy following amputation of affected area

Rickets Vitamin D deficiency in children Body can’t transport Ca+2 and P-3 from GI tract to blood Osteoblasts in diaphysis don’t calcify causing bones to stay soft Weight of body causes the legs to bow Cure and prevention Dietary- add vitamin D, calcium and phosphorus in large amounts Exposing the skin to ultraviolet rays of light

Chapter 7 Skeletal System

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