Transcript Chapter 8

Chapter 8
Lecture
Outline
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8-1
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The Skeletal System
• Overview of the skeleton
• The skull
• The vertebral column
and
thoracic cage
• The pectoral girdle and
upper limb
• The pelvic girdle and
lower limb
8-2
Overview of the Skeleton
• Regions of the skeleton
– axial skeleton = central axis
• skull, vertebral column, ribs, sternum and sacrum
– appendicular skeleton = limbs and girdles
• Number of bones
– 206 in typical adult skeleton
• varies with development of sesamoid bones (patella)
– start at 270 at birth, decreases with fusion
• Surface markings defined in Table 8.2
8-3
Surface Features of Bones
8-4
Axial and Appendicular Skeleton
• Axial skeleton in
tan
– skull, vertebrae,
sternum, ribs,
sacrum and hyoid
• Appendicular
skeleton in green
–
–
–
–
pectoral girdle
upper extremity
pelvic girdle
lower extremity
8-5
Major Skull Cavities
8-6
The Skull
• 22 bones joined together by sutures
• Cranial bones surround cranial cavity
– 8 bones in contact with meninges
• frontal, parietal,
– calvaria (skullcap) forms roof and walls
• Facial bones support teeth and form
nasal cavity and orbit
– 14 bones with no direct contact with brain
or meninges
– attachment of facial and jaw muscles
8-7
Cranial Fossa
• 3 basins that comprise the cranial floor or base
– anterior fossa holds the frontal lobe of the brain
– middle fossa holds the temporal lobes of the brain
– posterior fossa contains the cerebellum
• Swelling of the brain may force tissue through foramen
8-8
magnum resulting in death
Frontal Bone
• Forms forehead and
part of the roof of the
cranium
• Forms roof of the
orbit
• Contains frontal
sinus
8-9
Parietal Bone
• Cranial roof and part
of its lateral walls
• Bordered by 4 sutures
– coronal, sagittal,
lambdoid and
squamous
Temporal lines
• Temporal lines of
temporalis muscle
8-10
Temporal Bone
• Lateral wall and part of
floor of cranial cavity
– squamous part
• zygomatic process
• mandibular fossa and
TMJ
– tympanic part
• external auditory meatus
• styloid process
– mastoid part
• mastoid process
– mastoiditis from ear
infection
• mastoid notch
– digastric muscle
8-11
Petrous Portion of Temporal Bone
• Part of cranial floor
– separates middle from
posterior cranial fossa
• Houses middle and inner
ear cavities
– receptors for hearing and
sense of balance
– internal auditory meatus
= opening for CN VII
(vestibulocochlear nerve)
8-12
Right Temporal Bone
8-13
Openings in Temporal Bone
• Carotid canal
– passage for internal
carotid artery
supplying the brain
• Jugular foramen
– irregular opening
between temporal and
occipital bones
– passageway for
drainage of blood
from brain to internal
jugular vein
8-14
Occipital Bone
• Rear and base of skull
• Foramen magnum holds
spinal cord
• Skull rests on atlas at
occipital condyles
• Hypoglossal canal transmits
hypoglossal nerve (CN XII)
supplying tongue muscles
• External occipital
protuberance for nuchal
ligament
• Nuchal lines mark neck
muscles
8-15
Sphenoid Bone
• Lesser wing
• Greater wing
• Body of sphenoid
• Medial and lateral
pterygoid processes
8-16
Sphenoid Bone
• Body of the sphenoid
– sella turcica contains
hypophyseal fossa
– houses pituitary gland
• Lesser wing
– optic foramen
• Greater wing
– foramen rotundum and
ovale for brs. trigeminal
nerve
– foramen spinosum for
meningeal artery
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Sphenoid Bone
• Sphenoid
sinus
8-18
Ethmoid Bone
• Between the orbital cavities
• Lateral walls and roof nasal
cavity
• Cribriform plate and crista
galli
• Ethmoid air cells form
ethmoid sinus
• Perpendicular plate forms
part of nasal septum
• Concha (turbinates) on
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lateral wall
Ethmoid Bone
• Superior and middle
concha
• Perpendicular plate of
nasal septum
8-20
Maxillary Bones
• Forms upper jaw
– alveolar processes are bony points
between teeth
– alveolar sockets hold teeth
• Forms inferomedial wall of orbit
– infraorbital foramen
• Forms anterior 2/3’s
of hard palate
– incisive foramen
– cleft palate
8-21
Locations of Paranasal
Sinuses
• Maxillary sinus fills maxillae bone
• Other bones containing sinuses are frontal,
ethmoid and sphenoid.
8-22
Palatine Bones
• L-shaped bone
• Posterior 1/3 of the
hard palate
• Part of lateral nasal
wall
• Part of the orbital
floor
8-23
Zygomatic Bones
• Forms angles of the
cheekbones and part
of lateral orbital wall
• Zygomatic arch is
formed from temporal
process of zygomatic
bone and zygomatic
process of temporal
bone
8-24
Lacrimal Bones
• Form part of medial
wall of each orbit
• Lacrimal fossa
houses lacrimal sac
in life
– tears collect in
lacrimal sac and drain
into nasal cavity
8-25
Nasal Bones
• Forms bridge of
nose and supports
cartilages of nose
• Often fractured by
blow to the nose
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Inferior Nasal Conchae
• A separate bone
• Not part of ethmoid
like the superior and
middle concha or
turbinates
8-27
Vomer
• Inferior half of the
nasal septum
• Supports cartilage
of nasal septum
8-28
Mandible
• Only movable bone
– jaw joint between mandibular fossa
and condyloid process
• Holds the lower teeth
• Attachment of muscles of mastication
– temporalis muscle onto coronoid process
– masseter muscle onto angle of mandible
• Mandibular foramen
• Mental foramen
8-29
Ramus, Angle and Body of
Mandible
8-30
Bones Associated With Skull
• Auditory ossicles
– malleus, incus, and
stapes
• Hyoid bone
– suspended from
styloid process of
skull by muscle and
ligament
– greater and lesser
cornua
8-31
Skull in Infancy and
Childhood
• Spaces between unfused
bones called fontanels
– filled with fibrous
membrane
– allow shifting of bones
during birth and growth of
brain
• 2 frontal bones fuse by
age six (metopic suture)
• Skull reaches adult size
by 8 or 9
8-32
The Vertebral Column
• 33 vertebrae and
intervertebral discs of
fibrocartilage
• Five vertebral groups
–
–
–
–
–
7 cervical in the neck
12 thoracic in the chest
5 lumbar in lower back
5 fused sacral
4 fused coccygeal
• Variations in number of
lumbar and sacral
vertebrae
8-33
Newborn Spinal Curvature
• Spine exhibits one
continuous Cshaped curve
• Known as primary
curvature
8-34
Adult Spinal Curvatures
• S-shaped vertebral
column with 4
curvatures
• Secondary curvatures
develop after birth
– lifting head as it begins
to crawl develops
cervical curvature
– walking upright
develops lumbar
curvature
8-35
Abnormal Spinal Curvatures
• From disease,
posture, paralysis or
congenital defect
• Scoliosis from lack
of proper
development of one
vertebrae
• Kyphosis is from
osteoporosis
• Lordosis is from
weak abdominal
8-36
muscles
General Structure of Vertebra
• Body
• Vertebral foramen
form vertebral canal
• Neural arch
– 2 lamina
– 2 pedicles
• Processes
– spinous, transverse
and articular
8-37
Intervertebral Foramen and
Discs
• Intervertebral foramen
– Notches between
adjacent vertebrae
– passageway for nerves
• Intervertebral discs
– bind vertebrae together
– absorb shock
– gelatinous nucleus
pulposus surrounded by
anulus fibrosus (ring of
fibrocartilage)
– herniated disc pressures
spinal nerve or cord 8-38
Typical Cervical Vertebrae
• Small body and larger vertebral foramen
• Transverse process short with transverse
foramen for protection of vertebral arteries
• Bifid or forked spinous process in C2 to C6
• C7 vertebra prominens
8-39
The Unique Atlas and Axis
• Atlas (C1) supports the skull
– concave superior articular facet
• nod your head in “yes” movement
– ring surrounding large vertebral
foramen
• anterior and posterior arch
• no vertebral body
• Axis (C2)
– dens or odontoid process is held in
place inside the vertebral foramen of
the atlas by ligaments
– allows rotation of head -- “no”
8-40
Atlas and Axis Articulation
8-41
Typical Thoracic Vertebrae
• Larger body than cervical but smaller than lumbar
• Spinous processes pointed and angled downward
• Superior articular facets face posteriorly permitting
some rotation between adjacent vertebrae
• Rib attachment
– costal facets on vertebral body and at ends of transverse
processes for articulation of ribs
8-42
Lumbar Vertebrae
• Thick, stout body and blunt, squarish
spinous process
• Superior articular processes face medially
– lumbar region resistant to twisting movements
8-43
Sacrum (Anterior View)
• 5 sacral vertebrae
fuse by age 26
• Anterior surface
– smooth and concave
– sacral foramina were
intervertebral
foramen
• nerves and blood
vessels
– 4 transverse lines
indicate line of
fusion of vertebrae
8-44
Sacrum (Posterior View)
• Median sacral crest
• Lateral sacral crest
• Posterior sacral
foramina
• Sacral canal ends as
sacral hiatus
• Auricular surface is
part of sacroiliac joint
8-45
Coccyx
• Single, small bone
– 4 vertebrae fused by 30
– Co1 to Co4
• Attachment site for
muscles of pelvic floor
• Cornua
– hornlike projections on Co1
for ligaments attach coccyx
to sacrum
• Fractured by fall or during
childbirth
8-46
Thoracic Cage
• Consists of thoracic
vertebrae, sternum and
ribs
• Attachment site for
pectoral girdle and many
limb muscles
• Protects many organs
• Rhythmically expanded
by respiratory muscles
to draw air into the lungs
8-47
Rib Structure
Tubercle
Head
• Flat blade called a shaft
– inferior margin has costal
groove for nerves and vessels
• Proximal head and tubercle
are connected by neck
• Articulation
– head with body of vertebrae
– tubercle with transverse process
8-48
Numbered Rib Articulations
8-49
True and False Ribs
• True ribs (1 to 7)
attach to sternum
with hyaline
cartilage
• False ribs (8-12)
– 11-12 are floating
and not attached to
sternum
• 12 pairs of ribs in
both sexes
8-50
Pectoral Girdle
• Attaches upper extremity to the body
• Scapula and clavicle
• Clavicle attaches medially to the
sternum and laterally to the scapula
– sternoclavicular joint
– acromioclavicular joint
• Scapula articulates with the humerus
– humeroscapular or shoulder joint
– easily dislocated due to loose attachment8-51
Clavicle
• S-shaped bone, flattened dorsoventrally
• Inferior - marked by muscle and ligament
• Sternal end rounded -- acromial end flattened
8-52
Scapula
•
•
•
•
•
Triangular plate overlies ribs 2 to 7
Spine ends as acromion process
Coracoid process = muscle attachment
Subscapular, infraspinous and supraspinous fossa
Glenoid fossa = socket for head of humerus
8-53
Scapular Features
8-54
Upper Limb
• 30 bones per limb
• Brachium (arm) = humerus
• Antebrachium (forearm) = radius and
ulna (radius on thumb side)
• Carpus (wrist) = 8 small bones(2 rows)
• Manus (hand) = 19 bones(2 groups)
– 5 metacarpals in palm
– 14 phalanges in fingers
8-55
Humerus
• Hemispherical head
• Anatomical neck
• Greater and lesser tubercles
and deltoid tuberosity
• Intertubercular groove holds
biceps tendon
• Rounded capitulum articulates
with radius
• Trochlea articulates with ulna
• Olecranon fossa holds
olecranon process of ulna
• Forearm muscles attach to
medial and lateral epicondyles
8-56
Ulna and Radius
• Radius
– head = disc rotates during
pronation and supination
• articulates with capitulum
– radial tuberosity for biceps
muscle
• Ulna
– olecranon and trochlear notch
– radial notch holds ulna
• Interosseous membrane
– ligament attaches radius to
ulna along interosseous
margin of each bone
8-57
Carpal Bones
• Form wrist
– flexion, extension,
abduction and
adduction
• 2 rows (4 bones each)
– proximal row =
scaphoid, lunate,
triquetrum and pisiform
– distal row = trapezium,
trapezoid, capitate and
hamate
8-58
Metacarpals and Phalanges
• Phalanges are
bones of the fingers
– thumb or pollex has
proximal and distal
phalanx
– fingers have
proximal, middle and
distal phalanx
• Metacarpals are
bones of the palm
– base, shaft and head
8-59
Sesamoid Bone
8-60
Pelvic Girdle
• Girdle = 2 hip bones
• Pelvis = girdle and sacrum
• Supports trunk on the legs
and protects viscera
• Each os coxae is joined to
the vertebral column at the
sacroiliac joint
• Anteriorly, pubic bones are
joined by pad of fibrocartilage
to form pubic symphysis
8-61
Pelvic Inlet and Outlet
• False and true pelvis separated at pelvic brim
• Infant’s head passes through pelvic inlet and
8-62
outlet
Os Coxae (Hip Bone)
• Acetabulum is hip joint socket
• Ilium
– iliac crest and iliac fossa
– greater sciatic notch contains
sciatic nerve
• Pubis
– body, superior and inferior ramus
• Ischium
– ischial tuberosity bears body weight
– ischial spine
– lesser sciatic notch between ischial
spine and tuberosity
– ischial ramus joins inferior pubic
ramus
8-63
Comparison of Male and
Female
• Female lighter, shallower pubic arch( >100 degrees), and
pubic inlet round or oval
• Male heavier, upper pelvis nearly vertical,
coccyx more vertical, and pelvic inlet heart-shaped
8-64
Femur and Patella (Kneecap)
• Nearly spherical head and
constricted neck
– ligament to fovea capitis
• Greater and lesser
trochanters for muscle
attachment
• Posterior ridge called linea
aspera
• Medial and lateral condyles
and epicondyles found
distally
• Patella = triangular
8-65
sesamoid
Tibia
• Tibia is thick, weightbearing bone (medial)
• Broad superior head with
2 flat articular surfaces
• medial and lateral condyles
– roughened anterior surface
palpated below patella
(tibial tuberosity)
– distal expansion = medial
malleolus
8-66
Fibula
• Slender lateral strut
stabilizes ankle
• Does not bear any
body weight
– spare bone tissue
• Head = proximal end
• Lateral malleolus =
distal expansion
• Joined to tibia by
interosseous
8-67
membrane
The Ankle and Foot
• Tarsal bones are shaped and
arranged differently from carpal
bones due to load-bearing role of the
ankle
• Talus is most superior tarsal bone
– forms ankle joint with tibia and fibula
– sits upon calcaneus and articulates
with navicular
• Calcaneus forms heel (achilles
tendon)
• Distal row of tarsal bones
– cuboid, medial, intermediate and
lateral cuneiforms
8-68
The Foot
• Remaining bones of foot are
similar in name and
arrangement to the hand
• Metatarsal I is proximal to
the great toe (hallux)
– base, shaft and head
• Phalanges
– 2 in great toe
• proximal and distal
– 3 in all other toes
• proximal, middle and distal
8-69
Embryonic Limb Rotation
• Rotation of upper and lower limbs in opposite
directions
– largest digit medial in foot and lateral in hand
– Elbow flexes posteriorly and knee flexes anteriorly
8-70
Foot Arches
• Sole of foot not flat on ground
• 3 springy arches absorb stress
– medial longitudinal arch from
heel to hallux
– lateral longitudinal arch from heel
to little toe
– transverse arch across middle of
foot
• Arches held together by short,
strong ligaments
– pes planis (flat feet)
8-71
Bipedalism and Limb
Adaptations
8-72
Bipedalism and Upright
Stance
8-73
Bipedalism and Head Position
8-74