presentation on skeleton system

The Skeletal System

PowerPoint ® Lecture Slide Presentation

by Patty Bostwick-Taylor, �Florence-Darlington Technical College

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings

• Overview of the Skeletal System
• Skeleton (Greek) = “dried up body”
• Two subdivisions of the skeleton
• Axial skeleton – longitudinal axis of body
• Appendicular skeleton – limbs & girdles
• Parts of the skeletal system:
• Bones (skeleton)
• Functions of Bones
• Form internal framework: supports body & cradles soft organs
• Ex: skull bones fused to enclose the brain
• Ex: vertebrae surround spinal cord
• Ex: rib cage encloses thoracic organs
• Skeletal muscles attached to bone via tendons, move body and its parts
• Results in full body locomotion, fine movements, internal movements

Functions of Bones, continued…

• Fat (marrow) in medullary cavities
• Bones store minerals: calcium & phosphorus
• Ca 2+ needed for nervous impulses, muscle contraction, blood clotting
• Hormones control movement of calcium to and from bones and blood
• Blood cell formation
• AKA hematopoesis
• Within marrow/medullary cavities

Classification of Bones

• The adult skeleton has 206 bones
• Two basic types of bone tissue:
• Compact bone
• Dense, smooth, homogeneous
• Spongy bone
• AKA cancellous bone
• Small needle-like �pieces of bone, called trabeculae
• Many open spaces
• Site of hematopoesis
• Filled with red marrow

Figure 5.2b

Structure of Cancellous Bone

Structure of Compact Bone

Classification of Bones on the basis of Shape

• Classification of bones on the basis of shape
• 4 shapes of bone: long, short, flat, irregular
• Longer than they are wide
• Shaft with heads at both ends
• Contain mostly compact bone
• All the bones of the limbs (except patella, ankle & wrist)

Classification of Bones, continued…

• Short bones
• Generally cube-shaped
• Contain mostly cancellous bone
• Bones of the wrist (carpal) & ankle (tarsal)
• Sesamoid bones – bones which form within tendons; e.g. patella
• Thin, flattened, and usually curved
• Two thin layers of compact bone surround a layer of cancellous bone
• Irregular bones
• Irregular shape
• Do not fit into other bone classification categories
• Pelvic bones
• Facial bones

Answer “Did You Get It?” Questions #1-2

Figure 5.1d

• Anatomy of a Long Bone

Gross Anatomy

• Diaphysis/es
• Length of the bone
• Composed of compact bone
• Outside covering of the diaphysis
• Fibrous connective tissue membrane

Anatomy of a Long Bone, continued…

• Perforating/Sharpey’s fibers
• Connective tissue fibers
• Secure periosteum to underlying bone
• Epiphysis/es
• Ends of the bone
• Thin layer of compact bone enclosing cancellous bone
• Articular cartilage
• Covers the external surface of the epiphyses
• Made of hyaline cartilage
• Decreases friction at joint surfaces
• Supply bone cells with nutrients
• Epiphyseal line
• Remnant of the epiphyseal plate
• Seen in adult bones
• Epiphyseal plate
• Flat plate of hyaline cartilage seen in young, growing bone
• Hormones inhibit long bone growth by the end of puberty
• Epiphyseal plate is replaced by bone, leaving epiphyseal line behind

Proximal End of a Long Bone

Epiphyseal Plate

• Medullary cavity
• Cavity inside of the shaft
• Contains yellow marrow (mostly adipose tissue) in adults
• In infants, contains red marrow (for blood cell formation)
• In adults, red marrow is in cavities of cancellous bone (flat bones) and in epiphyses (long bones)

Bone Markings

• Surface features of bones
• Sites of attachments for muscles, tendons, and ligaments
• Passages for nerves and blood vessels
• Categories of bone markings
• Projections or processes—grow out from the bone surface
• All begin with T
• Depressions or cavities—indentations
• All begin with F (except facet)

Table 5.1 (1 of 2)

Table 5.1 (2 of 2)

Bone Markings – Major Features

• Body/shaft/diaphysis
• Humerus, femur
• Femoral neck
• Distal femur, posterior mandible, occipital condyles
• Thoracic vertebral bodies
• Sagittal crest
• Mastoid process (temporal), styloid process (distal radius & ulna)
• Tubercle/tuberosity
• Tubercle: greater & lesser tubercle on humerus, conoid tubercle (inferior edge of lateral clavicle)
• Tuberosity: radial tuberosity, tibial tuberosity, deltoid tuberosity (humerus)
• Greater & lesser trochanters on proximal femur
• Lateral epicondyle of humerus
• Foramen/foramina
• Mental foramen (lateral mandible)
• Canal/meatus
• Canal: carotid canal (base of skull)
• Meatus: external auditory meatus
• Superior orbital fissure, inferior orbital fissure
• Frontal sinus
• Olecranon fossa (posterior, distal humerus)
• Fovea capitus on femoral head (fovea smaller than fossa)

Microscopic Anatomy of Bone

• Osteocytes – mature bone cells
• Lacunae – tiny cavities housing osteocytes
• Lamellae – concentric circles (layers) of lacunae & matrix
• Central (Haversian) canals – passageway for blood vessels & nerves
• Canaliculi – tiny canals
• Radiate from the central canal to lacunae
• Form a transport system connecting all bone cells to nutrient supply
• Perforating (Volkman’s) canals
• Canal perpendicular to the central canal
• Carries blood vessels and nerves

Figure 5.3b–c

Answer “Did You Get It?” Questions #3-4

• Bone Formation, Growth, and Remodeling
• In embryos, the skeleton is primarily hyaline cartilage
• During development, much of this cartilage is replaced by bone
• Cartilage remains in isolated areas
• Bridge of the nose
• Parts of ribs

Bone starting�to replace�cartilage

Epiphyseal�plate�cartilage

Articular�cartilage

Spongy�bone

In an embryo

New bone�forming

Growth�in bone�width

Growth�in bone�length

Epiphyseal�plate cartilage

Blood�vessels

Hyaline�cartilage

New center of�bone growth

Medullary�cavity

Bone collar

Hyaline�cartilage�model

Bone Growth (Ossification)

• Ossification = process of bone formation
• Flat bones form on fibrous membranes
• Other bones develop from hyaline cartilage models
• Two phases:
• Hyaline cartilage model covered with bone matrix
• Done by osteoblasts = bone-forming cells
• Hyaline cartilage model digested away, forming a medullary cavity
• Two locations remain as cartilage after birth: articular cartilages (covering ends of bones) and epiphyseal plates

Long Bone Formation and Growth

Figure 5.4a

• Growth in Bone Length
• New cartilage is continuously formed on external surface of articular cartilage and epiphyseal plate
• Older cartilage becomes ossified
• Cartilage is broken down
• Enclosed cartilage is digested away, opening up a medullary cavity
• Bone replaces cartilage through the action of osteoblasts
• Growth in Bone Width; AKA appositional growth
• Osteoblasts (from periosteum) add bone to outside of diaphysis
• Osteoclasts (in endosteum) remove bone from inside of diaphysis
• Both occur at approximately the same rate, resulting in larger diameter
• Long-bone growth controlled by hormones; ends in puberty
• Growth hormone
• Sex hormones
• Bones are continually remodeled in response to two factors
• Blood calcium levels
• Pull of gravity and muscles on the skeleton

Types of Bone Cells

• Osteocytes — mature bone cells
• Osteoblasts — bone-forming cells
• Osteoclasts — bone-destroying cells
• Break down bone matrix for remodeling and release of calcium in response to parathyroid hormone
• Bone remodeling is performed by both osteoblasts & osteoclasts

Bone & Calcium Homeostasis

• Parathyroid hormone (PTH): releases Ca 2+ in blood
• ↑’s blood Ca 2+ by ↑’g osteoclast activity
• ↑ Ca resorption from urine in kidney back into blood
• Stimulates vitamin D production
• Stimulated by ↓ blood Ca 2+
• Calcitonin – stores Ca 2+ in bone
• Hypercalcemia = high blood calcium, decreases osteoclast activity
• ↓’s Ca 2+ by ↓’g osteoclast activity
• Stimulated by ↑ Ca 2+

Bone Remodeling

• Bone Remodeling = depositing new bone matrix in a mature bone
• In order to retain normal proportions & strength during long-bone growth
• In order to form projections where muscles attach
• Atrophy in bedridden or physically inactive people
• Homeostatic Imbalances

Growth & Development

• Giantism: abnormally increased size, excessive endochondral growth @ epiphyseal plates
• Dwarfism: person is abnormally small, improper growth @ epiphyseal plates
• Osteogenesis imperfecta: (bone + production + imperfect) – genetic disorders causing brittle bones with insufficient collagen; easily fractured, especially in fetus; poor healing/misalignment
• Failure of bones to calcify
• Softening & bowing of bones
• Children with lack of calcium or Vitamin D in diet

Homeostatic Imbalance

Bacterial Infection

• Osteomyelitis: bone marrow inflammation, can be caused by Stapholococcus (type of bacterium) through wounds or tuberculosis

Decalcification

• Osteomalacia: (bone softness) – due to calcium depletion from bones; pregnancy or “Adult Rickets” from vitamin D deficiency
• Bone Fractures – Homeostatic Imbalance
• Fracture — break in a bone
• Types of bone fractures
• Closed (simple) fracture — break that does not penetrate the skin
• Open (compound) fracture — broken bone penetrates through the skin
• Bone fractures are treated by reduction and immobilization: realignment of the broken bone ends
• Closed reduction : bones realigned via external means
• Open reduction : bones realigned via internal surgery and secured with pins/wires/plates

Common Types of Fractures

More on Fractures

complete – two bone fragments are separate

incomplete – two bone fragments are not separated

comminuted - > 2 fragments

impacted – 1 fragment pushed into cancellous portion of another fragment

oblique /spiral – at an angle other than perpendicular

greenstick – partly broken and partly bent

linear – parallel to long axis of bone

transverse – perpendicular to long axis

More Fracture Pics…

• Incomplete/Greenstick
• Longitudinal
• Dislocation

A Few More Notes on Fractures…

• Note: joint immobilization during mid-late bone healing results in 3x decrease in strength
• Muscles lose mass (atrophy)
• Bone not subject to the stresses that helps it form
• Solution = walking cast
• Repair of Bone Fractures
• Hematoma (blood-filled swelling) forms
• Blood vessels rupture when bone breaks
• Bone cells die due to lack of nutrition
• Break is splinted by fibrocartilage to form a callus
• New capillaries grow into clot
• Phagocytes remove dead tissue
• Fibrocartilage callus forms; contains cartilage matrix, bony matrix, collagen fibers
• Callus “splints” the bone
• Fibrocartilage callus is replaced by a bony callus
• Osteoclasts remove fibrocartilage callus
• Osteoblasts build bony callus
• Bony callus is remodeled to form a permanent patch
• Done in response to mechanical stresses
• Occurs over next few weeks-months

Answer “Did You Get It?” Questions #5-8

Stages in the Healing of a Bone Fracture

External�callus

Bony�callus of�spongy�bone

Healed�fracture

New�blood�vessels

Internal�callus�(fibrous�tissue and�cartilage)

Spongy�bone�trabecula

Hematoma�formation

Fibrocartilage�callus formation

Bony callus�formation

Bone remodeling

• The Axial Skeleton
• Forms the longitudinal axis of the body
• Divided into three parts
• Vertebral column
• Bony thorax

Axial Skeleton

• Skull (28 bones including auditory ossicles)
• Hyoid bone (1 bone)
• Vertebral column (26 bones)
• Cervical (7 vertebrae)
• Thoracic (12 vertebrae)
• Lumbar (5 vertebrae)
• Sacrum (1 – 5 fused vertebrae)
• Coccyx (1 -~4 fused vertebrae)
• Thoracic Cage (25 bones)
• Sternum (1 – 3 parts)

80 total bones in axial skeleton

• Two sets of bones: cranium & facial bones
• Bones are joined by sutures : interlocking, immovable joints
• Only the mandible is attached by a freely movable joint
• Braincase – encloses cranial cavity
• Surrounds & protects brain
• 6 bones, 8 when paired
• Facial bones – forms facial structure
• 8 bones, 14 when paired
• Auditory ossicles – form the middle ear
• These bones transmit vibration to eardrum
• Malleus, incus, & stapes

Braincase bones – 8 bones

• 2 parietals
• 2 temporals
• 1 occipital

The Skull, continued…

• Cranium: encloses & protects brain
• Frontal bone
• Parietal bones ( wall) – sagittal & coronal sutures
• Most of sides & roof of cranial cavity
• Joined to temporal by squamous suture (scale-like)
• Joined to frontal by coronal suture (crown)
• Joined to occipital by lambdoid suture (λ)
• Sagittal suture joins two parietals
• Temporal bones (time) – squamous sutures
• Inferior part of cranium & part of cranial floor
• Joined to occipital and parietal by squamous suture
• External acoustic (auditory) meatus – sound waves travel through to eardrum
• Styloid process– muscle attachment for tongue, hyoid, & pharynx movement
• Zygomatic process– articulates with zygomatic
• Mastoid process– neck muscle attachment for head rotation
• Jugular foramen
• Internal acoustic meatus
• Carotid canal
• Other landmarks:
• Mandibular Fossa – articulates with mandible
• Occipital bone (back of the head)
• Lambdoid suture - joined to parietals by lambdoid suture
• Foramen magnum– passage of spinal cord (connects to brain)
• Occipital condyles– articulate with vertebral column
• Posterior part & prominent portion of the base of the cranium
• Sphenoid bone (wedge-shaped)
• Sella turcica – contains pituitary gland
• Foramen ovale
• Optic canal
• Superior orbital fissure
• Sphenoid sinuses
• Connects to all other cranial bones
• Ethmoid bone
• Crista galli
• Cribriform plate
• Superior nasal concha & middle nasal concha – form lateral walls of nasal cavity
• Light, spongy bone that increases surface area of nasal cavity
• Moistens & warms inhaled air
• Anterior floor of the cranium between the orbits
• Composes much of nasal cavity & part of nasal septum
• Perpendicular Plate – part of nasal septum (with vomer)

Human Skull, Lateral View

Human Skull, Superior View

Human Skull, Inferior View

Human Skull, Anterior View

Figure 5.11

• Facial bones: holds eyes & support facial muscles
• Maxillae/maxilla
• Maxillary bones
• Alveolar margin
• Palatine processes
• Paranasal sinuses
• Hollow portions of bones surrounding the nasal cavity
• Functions of paranasal sinuses
• Lighten the skull
• Give resonance and amplification to voice

Facial Bones, continued…

• Palatine bones
• Zygomatic bones
• Lacrimal bones
• Nasal bones
• Inferior nasal conchae

Paranasal Sinuses

Figure 5.10a

Figure 5.10b

• The Hyoid Bone
• Not really part of the skull
• The only bone that does not articulate with another bone
• Serves as a moveable base for the tongue
• Attachment point for neck muscles that raise/lower the larynx during swallowing and speech

The Fetal Skull

• Infant’s face is very small compared to cranium size
• Fetal skull is large compared to the infant’s total body length
• Fontanels — fibrous membranes connecting the cranial bones; AKA soft spots
• Allow skull to be compressed during child birth
• Allow the brain to grow during latter pregnancy and early infancy
• Convert to bone within 22-24 months after birth

Answer “Did You Get It?” Questions #9-13

Figure 5.13a

Figure 5.13b

The Vertebral Column (Spine)

• Axial support for the body
• Extends from skull (support) to pelvis (transmits body weight to lower limbs)
• Surrounds and protects the spinal cord
• Allows spinal nerves to exit spinal cord
• Site for muscle attachment
• Permits head & trunk movement

Composition:

• Composed of 26 irregular bones, connected by ligaments, creating a flexible and curved structure
• 33 vertebrae before birth
• 9 fuse to become the sacrum and coccyx
• 24 vertebral bones
• Neck: 7 cervical vertebrae
• Chest/thorax: 12 thoracic vertebrae
• Lower back: 5 lumbar vertebrae
• Intervertebral discs: pads of fibrocartilage in between vertebrae
• Absorb shock
• Provide flexibility
• Loses function with age

The Vertebral Column

• Homeostatic Imbalance: Herniated (slipped) discs
• Drying of discs
• Weakening of ligaments of vertebral column
• Exceptional twisting forces
• If disc presses on spinal cord or spinal nerves, can cause numbness and pain

Vertebral Column Damage

• “Broken Tailbone”
• Fractured coccyx
• Can occur during childbirth and from falls
• Spinal curvatures
• S-shaped curve
• Prevents shock to head
• Make body trunk flexible
• Primary curvatures are the spinal curvatures of the thoracic and sacral regions
• Present from birth
• Produce C-shape in newborns’ spine
• Secondary curvatures are the spinal curvatures of the cervical and lumbar regions
• Develop after birth
• Lumbar curvature provides ability to center body weight on lower limbs; develops as a baby begins to walk
• Cervical curvature develops as a baby begins to raise its head

Figure 5.16

• Homeostatic Imbalance: Abnormal Spine Curvatures
• Scoliosis : abnormal lateral curvature
• Kyphosis: abnormal posterior curvature
• Usually upper thoracic
• Lordosis: abnormal anterior curvature
• Causes : congenital, due to disease, poor posture, unequal muscle pull on spine

Vertebral Column Defects

• Vertebral Anatomy
• Body/centrum – bears weight; faces anteriorly
• Vertebral arch – created by posterior extensions; forms vertebral foramen
• Lamina – extend from transverse process to spinous process
• Pedicle – extend from body to transverse process (feet)
• Vertebral foramen – houses spinal cord
• Transverse process – extend laterally from the vertebral arch between pedicle & lamina
• Spinous process - project dorsally from laminae; can feel externally
• Articular processes – area of vertebral articulation
• Superior and inferior
• Lateral to vertebral foramen
• Articular facet – smooth surface articulates with ribs
• Intervertebral foramina - notches formed by adjacent vertebrae; spinal nerves exit here
• Vertebral canal – formed by all vertebral foramina; spinal cord passage/protection

Vertebral Anatomy, continued…

Differences in Vertebrae

• Cervical (7: C 1 -C 7 )
• Atlas (C 1 )
• Large articular facets that articulate with occipital condyles (holds head up)
• Axis (C 2 )
• Pivot for rotation of atlas & skull
• Dens – large upright process
• Shake your head “no”

Cervical Vertebrae, continued…

• Smallest, lightest vertebrae
• Short spinous processes; some have branched spinous processes
• Transverse processes contain foramina for vertebral arteries going to brain; only present in cervical vertebrae
• Small bodies (except atlas)
• Thoracic (12: T 1 -T 12 )
• Only vertebrae that articulate with the ribs
• ~Heart-shaped body
• 2 lateral articular facets for rib articulation
• Transverse processes articulate with rib tubercles
• Long, thick spinous processes hooks sharply down: giraffe head
• Lumbar (5: L 1 -L 5 )
• Large, thick bodies
• Heavy, rectangular spinous process; moose head
• Medially facing superior articular facets (“locks” vertebrae together for stability)

A Typical Vertebrae, Superior View

Figure 5.17

• 5 fused vertebrae
• Articulates with L 5 superiorly and coccyx inferiorly
• Alae articulate with ilia (hip bones) laterally at the sacroiliac (SI) joint
• Forms posterior wall of pelvis
• Median sacral crest – fused spinous processes of the sacral vertebrae
• Sacral foramina: posterior & anterior
• Sacral canal – continuation of vertebral canal
• Sacral hiatus – large inferior opening
• Site of anesthetic injection prior to childbirth
• Sacral promontory – bulge in anterior edge of body of 1 st vertebra in sacrum
• Palpated before childbirth to determine pelvic opening size
• Formed from the fusion of three to five vertebrae
• “Tailbone,” or remnant of a tail that other vertebrates have
• Reduced vertebral bodies
• No foramina or processes
• The Bony Thorax
• Consists of three parts:
• Thoracic vertebrae
• AKA thoracic cage
• Forms a cage to protect heart, lungs, and major vessels

The Bony Thorax, continued…

• Sternum, AKA breastbone
• Fusion of manubrium, body, and xiphoid (sword) process
• Attached to 1 st 7 pair of ribs
• Jugular notch – concave superior border of manubrium; @ T 3
• Sternal angle – junction of manubrium & body; @ 2 nd intercostal space (heart valve auscaultation @ heart’s apex )
• Xiphisternal joint – junction of body & xiphoid process; @ T 9
• 12 pair form walls of bony thorax
• Articulate posteriorly with vertebrae, then curve downward anteriorly
• True ribs: pairs 1-7; attach to sternum via costal cartilages
• False ribs: pairs 8–12; attach indirectly to sternum or not at all
• Floating ribs: pairs 11–12; no sternal attachment
• Intercostal spaces – spaces between ribs are filled with muscles that air in breathing

Answer “Did You Get It?” #14-17

• The Appendicular Skeleton
• Composed of 126 bones
• Pectoral girdle
• Limbs (appendages)
• Pelvic girdle

Appendicular = “to hang something on”

• The Pectoral (Shoulder) Girdle
• Composed of two bones
• Clavicle—collarbone
• Scapula—shoulder blade
• Doubly curved
• Articulates with the manubrium medially an with the scapula laterally
• Forms shoulder joint with scapula
• Braces arm away from top of thorax

Pectoral Girdle

Bones of the Shoulder Girdle, continued…

Figure 5.21c–d

• Acromion process : enlarged end of scapula’s spine
• Connects with clavicle laterally at acromioclavicular joint
• Coracoid process : beaklike
• Points over top of shoulder; anchors some arm muscles
• Suprascapular notch : nerve passageway

Scapulae, continued…

• Scapula not attached directly to skeleton
• Held in place by trunk muscles
• Superior, medial (vertebral), and lateral (axillary)
• Glenoid cavity : receives head of humerus (forms lateral angle)
• Shoulder girdle is light and provides free movement:
• One attachment point to axial skeleton at sternoclavicular joint
• Scapula slides back and forth over the thorax
• Glenoid cavity is shallow and shoulder is poorly reinforced by ligaments
• BUT, shoulder is easily dislocated
• Bones of the Upper Limbs
• 30 bones form each upper limb
• Upper limb: arm, forearm, hand

Bones of the Upper Limbs, continued…

• Humerus (makes up arm)
• Head of humerus articulates with glenoid cavity of scapula
• Anatomical neck: slight constriction of humerus
• Intertubercular sulcus lies between greater and lesser tubercles: sites of muscle attachment
• Surgical neck: distal to tubercles; commonly fractured
• Deltoid tuberosity: roughened area of attachment of deltoid muscle

Arm, continued…

• Radial groove: runs obliquely down posterior aspect of diaphysis; site of radial nerve
• Trochlea: spool-like structure on the medial aspect of distal end of humerus; articulates with forearm (medial condyle)
• Capitulum: ball-like structure on lateral aspect of distal end of humerus; articulates with forearm (lateral condyle)
• Coronoid fossa: depression superior to trochlea on anterior surface; articulates with ulna
• Olecranon fossa: depression superior to trochlea on posterior surface; articulates with ulna
• Medial and lateral epicondyles: lie superior to condyles
• Lateral bone in anatomical position (thumb side)
• Articulates with ulna at radioulnar joint proximally and distally
• Connected to ulna via interosseous membrane along the lengths of the bones
• Styloid process at distal end
• Articulates with capitulum of humerus with disc-shaped head
• Radial tuberosity: site of attachment of biceps muscle

Forearm, continued…

• Medial bone in anatomical position (little finger side)
• Coronoid process on anterior surface of proximal end; articulates with trochlea of humerus (coronoid fossa)
• Olecranon process on posterior surface of proximal end; articulates with trochlea of humerus (olecranon fossa)
• Trochlear notch separates coronoid and olecranon processes

Elbow Bone Landmarks

• Carpals — AKA wrist
• 8 bones arranged in 2 irregular rows of 4 bones each
• Form the carpus (wrist)
• Ligaments bind carpals together and limit movement
• Scaphoid, lunate, triquetrum, pisiform, hamate, capitate, trapezoid, trapezium

Hand, continued…

• Metacarpals — AKA palm
• Numbered 1-5 from thumb toward pinky
• Heads of metacarpals form knuckles
• Digit – one finger or thumb, composed of 2-3 phalanges
• Numbered 1-5 from thumb
• Phalanges — bones of the fingers
• 14 phalanges per hand
• 3 phalanges per finger; 2 phalanges per thumb
• Distal, middle, & proximal phalanx
• Thumb lacks the middle phalanx

Answer “Did You Get It?” Questions # 18-21

• Bones of the Pelvic Girdle
• Formed by two coxal (ossa coxae) bones, AKA hip bones
• Bony pelvis = coxal bones, sacrum, coccyx
• Pelvic girdle = coxal bones
• Large, heavy bones
• Strong attachments to axial skeleton (@ SI joint)
• Femur firmly attached to pelvic girdle by ligaments

Bones of the Pelvic Girdle, continued…

Functions :

• Total weight of the upper body rests on the pelvis
• It protects several organs:
• Reproductive organs
• Urinary bladder
• Part of the large intestine
• Composed of three pairs of fused bones
• Ilium: large, flaring bone; forms most of hip bone
• Connects posteriorly to the sacrum at the sacroiliac joint
• Alae: wing-like portion of the ilia
• Iliac crest: upper edge of the ala
• Anterior superior iliac spine: anterior edge of iliac crest
• Posterior superior iliac spine: posterior edge of iliac crest
• Ischium: “sit down” bone
• Most posterior part of coxal bone
• Ischial tuberosity: origin of your hamstring muscles ; receives body weight in sitting position
• Ischial spine: superior to ischial tuberosity; narrow portion of pelvic outlet (birth canal)
• Greater sciatic notch: passageway for blood vessels and sciatic nerve from posterior pelvis to thigh; avoid injections
• Pubis/Pubic Bone
• Most anterior part of coxal bone
• Obturator foramen: formed by fusion of pubis rami anteriorly and ischium posteriorly
• Passageway for blood vessels and nerves toward anterior thigh
• Pubic symphysis: anterior cartilaginous (fibrocartilage) joint between pubic bones
• AKA “vinegar cup”
• Fusion of ilium, ischium, and pubis
• Deep socket which receives head of femur
• False pelvis – superior to true pelvis; area medial to alae
• True pelvis – inferior to alae and pelvic brim; forms birth canal
• Pelvic outlet: inferior opening between ischial spines
• Pelvic inlet: superior opening between left & right sides of pelvic brim
• Gender Differences of the Pelvis
• Female inlet is larger and more circular
• Female pelvis is shallower; bones are lighter and thinner
• Female ilia flare more laterally

Gender Differences of the Pelvis, continued…

• Female sacrum is shorter and less curved
• Female ischial spines are shorter and farther apart; thus the outlet is larger
• Female pubic arch is more rounded because the angle of the pubic arch is greater

Answer “Did You Get It?” Questions #22-23

• Bones of the Lower Limbs
• Carry total body weight
• Lower limb bones much thicker and stronger than upper limb bones

Bones of the Lower Limbs, continued…

• Thigh (1 bone only)
• Heaviest, strongest bone in the body
• Proximal epiphysis:
• Ball-like head
• Neck (commonly fractured)
• Sites of muscle attachment:
• Greater and Lesser trochanters
• Intertrochanteric line
• Intertrochanteric crest
• Gluteal tuberosity
• Slants medially toward knee; more so in women with wider pelvis

Femur, continued…

• Lateral and medial condyles on distal epiphysis articulate with tibia
• Intercondylar fossa separates the condyles
• Patellar surface on anterior aspect of distal epiphysis; forms joint with patella
• Tibia and fibula connected along their lengths by interosseous membrane

Composition :

• AKA Shinbone
• Larger and medially oriented
• Medial and lateral condyles at proximal epiphysis; articulate with femoral condyles to form knee joint
• Intercondylar eminence separates condyles

Tibia, continued…

• Tibial tuberosity: site of attachment for patellar ligament
• Medial malleolus on medial aspect of distal epiphysis; forms inner ankle bulge
• Anterior border: sharp ridge on anterior surface; unprotected by muscles
• Lateral to tibia
• Forms joints with tibia proximally and distally
• Thin, stick-like
• Not involved with knee joint
• Lateral malleolus on lateral aspect of distal epiphysis forms outer ankle bulge
• Support body weight
• Act as lever to propel body forward during locomotion
• Posterior half of foot
• 7 tarsal bones
• Calcaneus, talus, navicular, cuboid, lateral cuneiform, intermediate cuneiform, medial cuneiform
• Most weight carried by calcaneus and talus; talus articulates with tibia

Foot, continued…

• Metatarsals (5)
• Form the sole
• Phalanges (14)
• Form the toes
• 3 phalanges per toe; great toe has 2 phalanges
• Distal, middle, and proximal phalanx
• Arches of the Foot
• Bones are arranged to form three arches
• 2 longitudinal: medial and lateral
• 1 transverse
• Ligaments and tendons keep bones in place while allowing springiness
• “Fallen arches” or “flat feet” are caused by weak arches

Answer “Did You Get It?” Question #’s 24-26

• Articulation/joint = point where two bones meet
• Functions of joints:
• Hold bones together
• Allow for mobility
• Ways joints are classified:
• Functionally – based an amount of movement
• Structurally – based on type of tissue between the bones

Functional Classification of Joints

• Synarthroses
• Immovable joints
• Axial skeleton
• Some cartilaginous & fibrous joints
• Amphiarthroses
• Slightly moveable joints
• Cartilaginous & some fibrous joints
• Diarthroses
• Freely moveable joints
• Common in the limbs
• Synovial joints

Structural Classification of Joints

• Fibrous joints
• Generally immovable
• Cartilaginous joints
• Immovable or slightly moveable
• Freely moveable
• Fibrous Joints
• Bones united by fibrous tissue
• Connective tissue fibers binding skull bones
• Syndesmoses :
• Allows more movement than sutures
• Distal end of tibia and fibula
• Cartilaginous Joints
• Bone ends covered by cartilage
• Amphiarthrotic Examples (slightly movable):
• Pubic symphysis (fibrocartilage)
• Intervertebral joints (fibrocartilage discs between)
• Synarthrotic Examples (immovable):
• Epiphyseal plates (hyaline cartilage) of long bones
• Costal cartilages between first ribs and sternum (hyaline)
• Synovial Joints
• Articulating bones are separated by a joint cavity filled with synovial fluid
• All the joints of the limbs
• Features of synovial joints:
• Articular cartilage (hyaline) covers the ends of bones
• A fibrous articular capsule encloses joint surfaces; lined with synovial membrane
• Joint cavity is filled with synovial fluid
• Ligaments reinforce the joint

Synovial Joints, continued…

• Structures Associated with the Synovial Joint
• Bursae (AKA purses) – flattened fibrous sacs
• Act like ball bearings by reducing friction
• Lined with synovial membranes
• Filled with synovial fluid
• Not actually part of the joint
• Common where ligaments, muscles, skin, tendons, or bones rub together
• Tendon sheath
• Elongated bursa that wraps around a tendon

Summary of Joint Classes

[Insert Table 5.3 here]

• Dislocation – bone forced out of normal position in the joint cavity
• Reduction – process of returning the bone to its proper position

Types of Synovial Joints

• Plane Joint
• Flat articular surfaces
• Short slipping or gliding movements
• Nonaxial movements
• Intercarpal joints of wrist
• Hinge Joint
• Cylindrical end of one bone fits into trough-shaped surface of another bone
• Angular movement in one plane (hinge)
• Uniaxial (one axis)
• Elbow, ankle, phalanges
• Pivot Joint
• Rounded end of one bone fits into sleeve or ring of bone
• Uniaxial – one long axis
• Proximal radioulnar joint and joint between atlas and dens of axis
• Condyloid Joint
• AKA knuckle-like
• Egg-shaped surface of one bone fits into oval concavity of another bone
• Allow moving bone to travel
• Side to side, or
• Back and forth
• Biaxial = movement around two axes; but, not around long axis
• Knuckle (metacarpophalangeal) joints
• Saddle Joint
• Articular surfaces have convex and concave surfaces
• Biaxial – similar movements as condyloid joints
• Carpometacarpal joints in thumb
• Ball-and-Socket Joint
• Spherical head of one bone fits into round socket of another
• Multiaxial joint – movement in all axes, including rotation
• Most freely moving synovial joints
• Shoulder and hip

Figure 5.30d–f

• Homeostatic Imbalances of Joints
• Bursitis (AKA “water on the knee”): inflammation of a bursa or synovial membrane usually caused by a blow or friction
• Sprains: ligaments or tendons of joint are damaged by excessive stretching or are torn from bone
• Heal slowly due to poor vascular supply
• Tendonitis – inflammation of tendon sheaths

Homeostatic Imbalances of Joints, continued…

• Arthritis: inflammatory or degenerative diseases of joints
• arth = joint; itis = inflammation
• Over 100 different types; most widespread crippling disease in the United States
• Pain, stiffness, swelling of joint
• Acute arthritis caused by bacterial infection; treated with antibiotics
• Chronic arthritis: osteoarthritis, rheumatoid arthritis, gouty arthritis
• Chronic forms of arthritis
• Osteoarthritis (OA)
• Most common chronic arthritis
• Chronic degenerative condition related to normal aging processes
• Erosion of articular cartilages, formation of bone spurs, restricts joint movement, crepitus, painful
• Rheumatoid arthritis (RA)
• Chronic inflammatory disorder occurring between the ages of 40-50; affects more women than men
• Mostly in hand, wrist, foot, and ankle joints (symmetrical)
• An autoimmune disease—the immune system attacks the joints
• Symptoms begin with inflammation of synovial membranes, accumulation of synovial fluid; inflammatory cells destroy tissues
• Often leads to deformities
• Gouty arthritis (AKA Gout)
• Inflammation of joints is caused by a deposition of uric acid crystals from the blood
• Extremely painful
• Typically affects a single joint, such as the great toe
• More common in men; after age of 30; probably genetic
• Can usually be controlled with diet

Answer “Did You Get It?” Question #’s 27-30

• Developmental Aspects of the Skeletal System
• Fetal Changes
• First long bones made of hyaline cartilage
• Earliest flat bones are fibrous membranes
• During fetal development both are converted to bone
• Fontanels remain upon birth to allow for brain growth, but ossify by 2 years of age

12-week old fetus

• Skeletal Changes Throughout Life
• Adolescence
• Epiphyseal plates become ossified and long bone growth ends
• Size of cranium in relationship to body
• 2 years old—skull is ¾ of adult size
• 8 or 9 years old—skull is near adult size and proportion
• Between ages 6 and 11, the face grows out from the skull
• Jaws increase in size
• Cheekbones & nose become prominent
• Respiratory passages expand
• Permanent teeth develop

Skeletal Changes Throughout Life, continued…

• Curvatures of the spine
• Primary curvatures are present at birth and are convex posteriorly
• Secondary curvatures are convex anteriorly and are associated with a child’s later development
• Result from reshaping of the intervertebral disks
• Abnormal spinal curvatures (scoliosis and lordosis) are often congenital, but can result from injuries
• Skeletal growth changes body proportions
• Birth—head & trunk = 1.5x longer than lower limbs
• Lower limbs grow faster than trunk; reach ~= length as head & trunk by age of 10
• Puberty—female pelvis broadens; male skeleton becomes more robust
• Osteoporosis
• Bone-thinning disease afflicting
• 50% of women over age 65
• 20% of men over age 70
• Disease makes bones fragile and bones can easily fracture
• Especially vertebrae and neck of femur
• Vertebral collapse results in kyphosis (AKA dowager’s hump)
• Estrogen aids in health and normal density of a female skeleton after menopause
• Other contributing factors: diet low in calcium and protein, low vitamin D, smoking, insufficient weight-bearing exercise
• Elderly often suffer from pathologic fractures by avoiding doing anything too physical
• Osteoarthritis also occurs in weight-bearing joints

Answer “Did You Get It?” Question #’s 31-34

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14.2: Introduction to the Skeletal System

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• Page ID 16803

• Suzanne Wakim & Mandeep Grewal
• Butte College

Skull and Cross-Bones

The skull and cross-bones symbol has been used for a very long time to represent death, perhaps because after death and decomposition, bones are all that remain. Many people think of bones as being dead, dry, and brittle. These adjectives may correctly describe the bones of a preserved skeleton, but the bones of a living human being are very much alive. Living bones are also strong and flexible. Bones are the major organs of the skeletal system.

The skeletal system is the organ system that provides an internal framework for the human body. Why do you need a skeletal system? Try to imagine what you would look like without it. You would be a soft, wobbly pile of skin containing muscles and internal organs but no bones. You might look something like a very large slug. Not that you would be able to see yourself — folds of skin would droop down over your eyes and block your vision because of your lack of skull bones. You could push the skin out of the way if you could only move your arms, but you need bones for that as well!

Components of the Skeletal System

In adults, the skeletal system includes 206 bones, many of which are shown in Figure \(\PageIndex{2}\). Bones are organs made of dense connective tissues, mainly the tough protein collagen. Bones contain blood vessels, nerves, and other tissues. Bones are hard and rigid due to deposits of calcium and other mineral salts within their living tissues. Locations, where two or more bones meet, are called joints. Many joints allow bones to move like levers. For example, your elbow is a joint that allows you to bend and straighten your arm.

Besides bones, the skeletal system includes cartilage and ligaments.

• Cartilage is a type of dense connective tissue, made of tough protein fibers. It is strong but flexible and very smooth. It covers the ends of bones at joints, providing a smooth surface for bones to move over.
• Ligaments are bands of fibrous connective tissue that hold bones together. They keep the bones of the skeleton in place.

Axial and Appendicular Skeletons

The skeleton is traditionally divided into two major parts: the axial skeleton and the appendicular skeleton, both of which are pictured in Figure \(\PageIndex{3}\).

• The axial skeleton forms the axis of the body. It includes the skull, vertebral column (spine), and rib cage. The bones of the axial skeleton, along with ligaments and muscles, allow the human body to maintain its upright posture. The axial skeleton also transmits weight from the head, trunk, and upper extremities down the back to the lower extremities. In addition, the bones protect the brain and organs in the chest.
• The appendicular skeleton forms the appendages and their attachments to the axial skeleton. It includes the bones of the arms and legs, hands and feet, and shoulder and pelvic girdles. The bones of the appendicular skeleton make possible locomotion and other movements of the appendages. They also protect the major organs of digestion, excretion, and reproduction.

Functions of the Skeletal System

The skeletal system has many different functions that are necessary for human survival. Some of the functions, such as supporting the body, are relatively obvious. Other functions are less obvious but no less important. For example, three tiny bones (hammer, anvil, and stirrup) inside the middle ear transfer sound waves into the inner ear.

Support, Shape, and Protection

The skeleton supports the body and gives it shape. Without the rigid bones of the skeletal system, the human body would be just a bag of soft tissues, as described above. The bones of the skeleton are very hard and provide protection to the delicate tissues of internal organs. For example, the skull encloses and protects the soft tissues of the brain, and the vertebral column protects the nervous tissues of the spinal cord. The vertebral column, ribs, and sternum (breast bone) protect the heart, lungs, and major blood vessels. Providing protection to these latter internal organs requires the bones to be able to expand and contract. The ribs and the cartilage that connects them to the sternum and vertebrae are capable of small shifts that allow breathing and other internal organ movements.

The bones of the skeleton provide attachment surfaces for skeletal muscles. When the muscles contract, they pull on and move the bones. The figure below, for example, shows the muscles attached to the bones at the knee. They help stabilize the joint and allow the leg to bend at the knee. The bones at joints act like levers moving at a fulcrum point, and the muscles attached to the bones apply the force needed for movement.

Hematopoiesis

Hematopoiesis is the process in which blood cells are produced. This process occurs in a tissue called red marrow, which is found inside some bones, including the pelvis, ribs, and vertebrae. Red marrow synthesizes red blood cells, white blood cells, and platelets. Billions of these blood cells are produced inside the bones every day.

Mineral Storage and Homeostasis

Another function of the skeletal system is storing minerals, especially calcium and phosphorus. This storage function is related to the role of bones in maintaining mineral homeostasis. Just the right levels of calcium and other minerals are needed in the blood for the normal functioning of the body. When mineral levels in the blood are too high, bones absorb some of the minerals and store them as mineral salts, which is why bones are so hard. When blood levels of minerals are too low, bones release some of the minerals back into the blood. Bone minerals are alkaline (basic), so their release into the blood buffers the blood against excessive acidity (low pH), whereas their absorption back into bones buffers the blood against excessive alkalinity (high pH). In this way, bones help maintain acid-base homeostasis in the blood.

Another way bones help to maintain homeostasis is by acting as an endocrine organ. One endocrine hormone secreted by bone cells is osteocalcin, which helps regulate blood glucose and fat deposition. It increases insulin secretion and also the sensitivity of cells to insulin. In addition, it boosts the number of insulin-producing cells and reduces fat stores.

• What is the skeletal system? How many bones are there in the adult skeleton?
• Describe the composition of bones.
• Besides bones, what other organs are included in the skeletal system?
• Identify the two major divisions of the skeleton.
• List several functions of the skeletal system.
• Discuss sexual dimorphism in the human skeleton.
• Bones, cartilage, and ligaments are all made of types of ____________ tissue.
• True or False. Bones contain living tissue and can affect processes in other parts of the body.
• True or False. Bone cells contract to pull on muscles in order to initiate a movement.
• If a person has a problem with blood cell production, what type of bone tissue is most likely involved? Explain your answer.
• Are the pelvic girdles part of the axial or appendicular skeleton?
• What are three forms of homeostasis that the skeletal system regulates? Briefly explain how each one is regulated by the skeletal system.
• What do you think would happen to us if we did not have ligaments? Explain your answer.

b. How is cartilage related to joints?

c. Identify one joint in the human body and describe its function.

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Attributions.

• Fighter squadron 84 by US Navy , public domain via Wikimedia Commons
• Human skeleton front by LadyofHats Mariana Ruiz Villarreal, public domain via Wikimedia Commons
• Axial skeleton by LadyofHats Mariana Ruiz Villarreal, public domain via Wikimedia Commons
• Appendicular skeleton by LadyofHats Mariana Ruiz Villarreal, public domain via Wikimedia Commons
• Knee anatomy by Blausen.com staff (2014). " Medical gallery of Blausen Medical 2014 ". WikiJournal of Medicine 1 (2). DOI : 10.15347/wjm/2014.010 . ISSN 2002-4436 . CC BY 3.0 via Wikimedia Commons
• Text adapted from Human Biology by CK-12 licensed CC BY-NC 3.0

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High school biology

Course: high school biology   >   unit 8, skeletal structure and function.

• Ligaments, tendons, and joints
• Three types of muscle
• Anatomy of a skeletal muscle cell
• LeBron Asks: What muscles do we use when shooting a basket?
• The musculoskeletal system review
• The musculoskeletal system

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The Skeletal System

May 20, 2012

1.53k likes | 1.9k Views

5. The Skeletal System. The Skeletal System. Parts of the skeletal system Bones (skeleton) Joints Cartilages Ligaments Two subdivisions of the skeleton Axial skeleton Appendicular skeleton. Functions of Bones. Support the body Protect soft organs

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• bone growth
• compact bone
• bone replaces cartilage
• width called appositional growth

Presentation Transcript

5 The Skeletal System

The Skeletal System Parts of the skeletal system Bones (skeleton) Joints Cartilages Ligaments Two subdivisions of the skeleton Axial skeleton Appendicular skeleton

Functions of Bones Support the body Protect soft organs Skull and vertebrae for brain and spinal cord Rib cage for thoracic cavity organs Allow movement due to attached skeletal muscles Store minerals and fats Calcium and phosphorus Fat in the internal marrow cavity Blood cell formation (hematopoiesis)

Bones of the Human Body The adult skeleton has 206 bones Two basic types of bone tissue Compact bone Homogeneous Spongy bone Small needle-like pieces of bone Many open spaces

Spongy bone Compact bone Figure 5.1

Classification of Bones on the Basis of Shape Bones are classified as: Long Short Flat Irregular

Classification of Bones Long bones Typically longer than they are wide Shaft with heads situated at both ends Contain mostly compact bone All of the bones of the limbs (except wrist, ankle, and kneecap bones) Example: Femur Humerus

Figure 5.2a

Classification of Bones Short bones Generally cube-shaped Contain mostly spongy bone Includes bones of the wrist and ankle Sesamoid bones are a type of short bone which form within tendons (patella) Example: Carpals Tarsals

Figure 5.2d

Classification of Bones Flat bones Thin, flattened, and usually curved Two thin layers of compact bone surround a layer of spongy bone Example: Skull Ribs Sternum

Figure 5.2c

Classification of Bones Irregular bones Irregular shape Do not fit into other bone classification categories Example: Vertebrae Hip bones

Figure 5.2b

Anatomy of a Long Bone Diaphysis Shaft Composed of compact bone Epiphysis Ends of the bone Composed mostly of spongy bone

Articular cartilage Proximal epiphysis Spongy bone Epiphyseal line Periosteum Compact bone Medullary cavity (lined by endosteum) Diaphysis Distal epiphysis (a) Figure 5.3a

Anatomy of a Long Bone Periosteum Outside covering of the diaphysis Fibrous connective tissue membrane Perforating (Sharpey’s) fibers Secure periosteum to underlying bone Arteries Supply bone cells with nutrients

Endosteum Yellow bone marrow Compact bone Periosteum Perforating (Sharpey’s) fibers Nutrient arteries (c) Figure 5.3c

Anatomy of a Long Bone Articular cartilage Covers the external surface of the epiphyses Made of hyaline cartilage Decreases friction at joint surfaces

Articular cartilage Compact bone Spongy bone (b) Figure 5.3b

Anatomy of a Long Bone Epiphyseal plate Flat plate of hyaline cartilage seen in young, growing bone Epiphyseal line Remnant of the epiphyseal plate Seen in adult bones

Anatomy of a Long Bone Marrow (medullary) cavity Cavity inside of the shaft Contains yellow marrow (mostly fat) in adults Contains red marrow for blood cell formation in infants In adults, red marrow is situated in cavities of spongy bone and epiphyses of some long bones

Bone Markings Surface features of bones Sites of attachments for muscles, tendons, and ligaments Passages for nerves and blood vessels Categories of bone markings Projections or processes—grow out from the bone surface Terms often begin with “T” Depressions or cavities—indentations Terms often begin with “F”

Microscopic Anatomy of Compact Bone Osteon (Haversian system) A unit of bone containing central canal and matrix rings Central (Haversian) canal Opening in the center of an osteon Carries blood vessels and nerves Perforating (Volkmann’s) canal Canal perpendicular to the central canal Carries blood vessels and nerves

Osteon (Haversian system) Lamellae Blood vessel continues into medullary cavity containing marrow Spongy bone Perforating fibers Compact bone Periosteal blood vessel Central (Haversian) canal Periosteum Perforating (Volkmann’s) canal (a) Blood vessel Figure 5.4a

Microscopic Anatomy of Bone Lacunae Cavities containing bone cells (osteocytes) Arranged in concentric rings called lamellae Lamellae Rings around the central canal Sites of lacunae

Lamella Osteocyte Canaliculus Lacuna (b) Central (Haversian) canal Figure 5.4b

Osteon Lacuna (c) Central canal Interstitial lamellae Figure 5.4c

Microscopic Anatomy of Bone Canaliculi Tiny canals Radiate from the central canal to lacunae Form a transport system connecting all bone cells to a nutrient supply

Formation of the Human Skeleton In embryos, the skeleton is primarily hyaline cartilage During development, much of this cartilage is replaced by bone Cartilage remains in isolated areas Bridge of the nose Parts of ribs Joints

Bone Growth (Ossification) Epiphyseal plates allow for lengthwise growth of long bones during childhood New cartilage is continuously formed Older cartilage becomes ossified Cartilage is broken down Enclosed cartilage is digested away, opening up a medullary cavity Bone replaces cartilage through the action of osteoblasts

Bone Growth (Ossification) Bones are remodeled and lengthened until growth stops Bones are remodeled in response to two factors Blood calcium levels Pull of gravity and muscles on the skeleton Bones grow in width (called appositional growth)

Articular cartilage Hyaline cartilage Spongy bone New center of bone growth New bone forming Epiphyseal plate cartilage Growth in bone width Medullary cavity Bone starting to replace cartilage Invading blood vessels Growth in bone length New bone forming Bone collar Hyaline cartilage model Epiphyseal plate cartilage In an embryo In a child In a fetus Figure 5.5

Bone starting to replace cartilage Bone collar Hyaline cartilage model In an embryo Figure 5.5, step 1

Hyaline cartilage New center of bone growth Medullary cavity Invading blood vessels Growth in bone length In a fetus Figure 5.5, step 2

Articular cartilage Spongy bone New bone forming Epiphyseal plate cartilage Growth in bone width Invading blood vessels New bone forming Epiphyseal plate cartilage In a child Figure 5.5, step 3

Bone growth Bone remodeling Growing shaft is remodeled as: Bone grows in length because: Articular cartilage 1 Cartilage grows here. Epiphyseal plate 2 Cartilage is replaced by bone here. 1 Bone is resorbed here. 3 2 Cartilage grows here. Bone is added by appositional growth here. 4 Cartilage is replaced by bone here. 3 Bone is resorbed here. Figure 5.6

Types of Bone Cells Osteocytes—mature bone cells Osteoblasts—bone-forming cells Osteoclasts—giant bone-destroying cells Break down bone matrix for remodeling and release of calcium in response to parathyroid hormone Bone remodeling is performed by both osteoblasts and osteoclasts

Bone Fractures Fracture—break in a bone Types of bone fractures Closed (simple) fracture—break that does not penetrate the skin Open (compound) fracture—broken bone penetrates through the skin Bone fractures are treated by reduction and immobilization

Common Types of Fractures Comminuted—bone breaks into many fragments Compression—bone is crushed Depressed—broken bone portion is pressed inward Impacted—broken bone ends are forced into each other Spiral—ragged break occurs when excessive twisting forces are applied to a bone Greenstick—bone breaks incompletely

Repair of Bone Fractures Hematoma (blood-filled swelling) is formed Break is splinted by fibrocartilage to form a callus Fibrocartilage callus is replaced by a bony callus Bony callus is remodeled to form a permanent patch

Hematoma External callus Bony callus of spongy bone New blood vessels Internal callus (fibrous tissue and cartilage) Healed fracture Spongy bone trabecula 1 4 Hematoma forms. Fibrocartilage callus forms. Bony callus forms. Bone remodeling occurs. 2 3 Figure 5.7

Hematoma Hematoma forms. 1 Figure 5.7, step 1

Hematoma External callus New blood vessels Internal callus (fibrous tissue and cartilage) Spongy bone trabecula 2 Hematoma forms. Fibrocartilage callus forms. 1 Figure 5.7, step 2

Hematoma External callus Bony callus of spongy bone New blood vessels Internal callus (fibrous tissue and cartilage) Spongy bone trabecula 2 Hematoma forms. Fibrocartilage callus forms. Bony callus forms. 1 3 Figure 5.7, step 3

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