Download The Axial Skeleton

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The Axial Skeleton
PowerPoint® Lecture Presentations prepared by
Leslie Hendon
University of Alabama, Birmingham
© 2014 Pearson Education, Inc.
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I. The Skeleton
A. Bones, cartilage, joints, and ligaments
1. joints - also called articulations
B. 206 named bones grouped into two divisions
1. Axial skeleton (80 bones)
► skull, vertebral column, and thoracic cage
2. Appendicular skeleton (126 bones)
► upper and lower limbs
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II. The Cranium (Skull)
A. The cranium is formed by cranial and facial bones
1. enclose and protect the brain
2. provide attachment sites for muscles of the head and neck
B. Facial bones
1. Form framework of the face
2. Form cavities for sense organs of sight, taste, and smell
3. Provide openings for passage of air and food
4. Hold the teeth in place
5. Anchor muscles of the face
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C. Internally bony ridges divide skull into distinct fossae (surfaces)
1. anterior
2. middle
3. posterior
D. Brain sits within the cranial fossae
1.brain occupies cranial cavity
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Anterior cranial
fossa
Middle cranial
fossa
Posterior cranial
fossa
Superior view of the cranial fossae
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E. The skull contains smaller cavities
1. middle & inner ear cavities—in lateral aspect of cranial base
2. nasal cavity—lies in and posterior to the nose
3. orbits—house the eyeballs
4. sinuses — air-filled spaces in bones around the nasal cavity
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Sinuses of the cranium
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F. The skull contains approximately 85 named openings
1. foramina, canals, and fissures
2. provide openings for important structures
a. spinal cord
b. blood vessels serving the brain
c. 12 pairs of cranial nerves
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IV. Cranial Bones
A. Formed from eight large bones
1. paired bones
a. temporal bones
b. parietal bones
2. unpaired bones
a. frontal bone
b. occipital bone
c. sphenoid bone
d. ethmoid bone
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V. Sutures
A. Four sutures of the cranium
1. coronal suture - runs in the coronal plane
2. squamous suture - parietal bone meets temporal bone
3. sagittal suture - where right and left parietal bones
4. lambdoid suture – parietal bones meet the occipital bone
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Cranium
right side of the skull
Coronal suture
Frontal bone
Parietal bone
Sphenoid bone
Squamous suture
Ethmoid bone
Lambdoid suture
Lacrimal bone
Lacrimal fossa
Occipital bone
Nasal bone
Temporal bone
Zygomatic bone
Maxilla
Zygomatic process
External acoustic meatus
Mastoid process
Styloid process
Mandible
Condylar process
Mental foramen
Mandibular notch
Mandibular ramus
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Mandibular
angle
Coronoid process
right side of the skull
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Frontal bone
Parietal bone
Supraorbital foramen
Nasal bone
Sphenoid bone
Superior orbital fissure
Temporal bone
Optic canal
Ethmoid bone
Inferior orbital fissure
Lacrimal bone
Ethmoid
bone
Zygomatic bone
Infraorbital foramen
Maxilla
Mandible
Mental
foramen
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Vomer
Ethmoid
bone
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Parietal bone
Sagittal suture
Lambdoid
suture
Occipital bone
Superior nuchal line
External occipital
protuberance
Inferior nuchal line
Occipital
condyle
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© 2014 Pearson Education, Inc.
Maxilla
Hard
palate Palatine bone
Infraorbital foramen
Maxilla
Zygomatic bone
Sphenoid bone
Vomer
zygomatic process
Styloid process
External acoustic meatus
Mastoid process
Temporal bone
Jugular foramen
Occipital condyle
Occipital bone
External occipital
protuberance
Inferior view of the skull (mandible removed)
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Foramen magnum
Inferior view of the skull (mandible removed)
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External
acoustic
meatus
Zygomatic
process
Mastoid process
Styloid
process
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Optic
canal
Lesser wing
Foramen
rotundum
Greater
wing
Foramen ovale
Sella
turcica
Body of sphenoid
Superior view
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Foramen
spinosum
Crista galli
Cribriform plate
with cribriform
foramina
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The Holes in the Head
Optic foramen
Foramen rotundum
Foramen ovale
Foramen spinosum
Foramen lacerum
Internal acoustic
meatus
Jugular foramen
Hypoglossal canal
Foramen magnum
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▲
View
Crista galli
Cribriform plate
Ethmoid
bone
Sphenoid
Frontal bone
Lesser wing
Optic canal
Greater wing
Foramen rotundum
sella turcica
Foramen ovale
Foramen spinosum
Foramen lacerum
Temporal bone
Internal acoustic
meatus
Jugular foramen
Parietal bone
Occipital bone
Foramen magnum
Superior view of the skull, calvaria removed
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Hypoglossal canal
View
Superior view of the skull, calvaria removed
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The Sphenoid Bone
Optic
canal
Lesser wing
Foramen
rotundum
Greater
wing
Foramen ovale
Sella
turcica
Body of sphenoid
Superior view
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Foramen
spinosum
Parietal bone
Coronal suture
Frontal bone
Sphenoid bone
Squamous
suture
Temporal bone
Crista galli
Nasal bone
Lambdoid suture
Occipital bone
Ethmoid bone
Vomer
External occipital
protuberance
Maxilla
Internal acoustic
meatus
Mandibular
foramen
Palatine bone
Midsagittal section showing the internal anatomy of the left half of skull
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Mandible
Midsagittal section showing the internal anatomy of the left half of skull
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Mandible
Temporomandibular
joint
Coronoid
process
Mandibular notch
Condylar
process
Mandibular foramen
Ramus
of
mandible
Mental foramen
Mandibular
angle
Body of mandible
Mandible, right lateral view
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Mandible
Mandible, right lateral view
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Figure 7-15a Paranasal sinuses.
Frontal
sinus
Ethmoidal
air cells
(sinus)
Sphenoidal
sinus
Maxillary
sinus
Anterior aspect
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Hyoid Bone
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Figure 7.17 The hyoid bone.
Greater horn
Lesser horn
Body
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XIII. Thoracic Cage
Jugular notch
Clavicular notch
Manubrium
Sternal angle
Body
True
ribs
(17)
Xiphoid
process
False
ribs
(812)
Costal
cartilage
Floating
ribs (11, 12)
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L1
Vertebra
Sternum
XIII. Thoracic Cage
L1
Vertebra
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Vertebral Column
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The Vertebral Column
A. In the adult, is formed from 26 bones
B. Transmits weight of trunk to the lower limbs
C. Surrounds and protects the spinal cord
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Regions and Normal Curvatures
A. The vertebral column has five major regions
► 7 cervical vertebrae of the neck region
► 12 thoracic vertebrae
► 5 lumbar vertebrae
► Sacrum - five fused bones
► Coccyx - inferior to sacrum
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C1
2
Cervical curvature (concave)
7 vertebrae, C1  C7
3
4
5
6
7
T1
Spinous
process
2
3
Transverse
processes
4
5
6
7
Thoracic curvature
(convex)
12 vertebrae,
T1  T12
8
9
Intervertebral
discs
10
11
Intervertebral
foramen
12
L1
2
3
Lumbar curvature
(concave)
5 vertebrae, L1  L5
4
5
Sacral curvature
(convex)
5 fused vertebrae
sacrum
Coccyx
4 fused vertebrae
Anterior view
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Right lateral view
Regions and Normal Curvatures
A. Curvatures of the spine
1. Cervical and lumbar curvatures
► Concave posteriorly
2. Thoracic and sacral curvatures
► Convex posteriority
kyphosis – exagerated curvature in thoracic region (humpback)
lordosis – exaggerated curvature in the lumbar region
scoliosis – S-shaped curvature of the whole vertebral column
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Supraspinous ligament
Intervertebral
disc
Transverse process
Anterior longitudinal
ligament
Sectioned
spinous process
Intervertebral foramen
Ligamentum flavum
Posterior longitudinal
ligament
Anulus fibrosus
Interspinous
ligament
Nucleus pulposus
Inferior articular process
Sectioned body of vertebra
Median section of three vertebrae, illustrating the composition
of the discs and the ligaments
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Posterior longitudinal
ligament
Anterior longitudinal
ligament
Body of a vertebra
Intervertebral disc
Anterior view of part of the spinal column
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Intervertebral Discs
A. Are cushion-like pads between vertebrae
1. Nucleus pulposus
a. gelatinous inner sphere
b. absorbs compressive stresses
2. Anulus fibrosus
a. outer rings formed of ligament
b. inner rings formed of fibrocartilage
c. contains the nucleus pulposus
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Vertebrae
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Posterior
Lamina
Spinous
process
Transverse
process
Superior
articular
process
and
facet
Vertebral
arch
Vertebral
foramen
Pedicle
Body
Anterior
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Posterior
Anterior
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Cervical Vertebrae
A. Cervical
1. C1 (atlas) no body, no spine
2. C2 (axis) bifid spine, dens (head)
3. C3-6 bifid spine
4. C7 non-bifid spine, first bulge in lower neck
5. transverse foramen (vessel+nerve)
6. bodies get larger in descending fashion
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© 2014 Pearson Education, Inc.
Dens of axis
Transverse ligament
of atlas
C1 (atlas)
C2 (axis)
C3
Inferior articular process
Bifid spinous process
Transverse processes
C7 (vertebra prominens)
Cervical vertebrae
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C1 – The Atlas
Posterior
C1
Posterior tubercle
Posterior arch
Transverse
foramen
Lateral
masses
Superior articular
facet
Anterior arch
Anterior tubercle
Superior view of atlas (C1)
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C1 – Axis
C2
Posterior
Spinous process
Inferior
articular
process
Lamina
Pedicle
Superior
articular
facet
Transverse
process
Dens
Body
Superior view of axis (C2)
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Thoracic Vertebrae
A. Thoracic
1. long, inferior-directed spinous processes
2. transverse processes are long and heavy
3. T1 superior whole facet : inferior demifacet
4. T2-8 two demifacets; superior large / inferior small
5. T9 single superior demifacet
6. T10-12 whole facet for individual rib articulation
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© 2014 Pearson Education, Inc.
Lumbar Vertebrae
A. Lumbar
1. all have largest, thickest bodies
2. spinous processes are oblong and heavy
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Superior
articular
process
Transverse
process
Body
Intervertebral
disc
Spinous
process
Lumbar vertebrae
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Inferior
articular
process
The Sacrum
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Sacral promontory
Sacral
canal
Ala
Body of
first
sacral
vertebra
Body
Facet of superior
articular process
Auricular
surface
Median
sacral
crest
Transverse ridges
(sites of vertebral
fusion)
Apex
Anterior
sacral
foramina
Coccyx
Anterior view
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Lateral
sacral
crest
Posterior
sacral
foramina
Coccyx
Posterior view
Sacral
hiatus
Coccyx
A. Is the “tailbone”
B. Formed from 3–5 fused vertebrae
C. Offers only slight support to pelvic organs
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The Thoracic Cage
A. Forms the bony framework of the chest
B. Components
1. thoracic vertebrae—posteriorly
2. ribs - laterally
3. sternum and costal cartilage - anteriorly
C. Protects thoracic organs
D. Supports shoulder girdle and upper limbs
E. Provides attachment sites for many muscles of the back
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Ribs
A. All ribs attach to vertebral column posteriorly
1. true ribs—superior seven pairs of ribs
► Attach to sternum by costal cartilage
2. false ribs—inferior five pairs of ribs
3. floating ribs – ribs 11 and 12
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Jugular notch
Clavicular notch
Manubrium
Sternal angle
Body
Xiphisternal
joint
True
ribs
(17)
Xiphoid
process
False
ribs
(812)
Intercostal
spaces
Costal
cartilage
Floating
ribs (11, 12)
L1
Vertebra
Skeleton of the thoracic cage, anterior view
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Costal
margin
Sternum
Superior costal facet
(for head of rib)
Angle
of rib
Body of vertebra
Head of rib
Intervertebral disc
Neck of rib
Tubercle of rib
Shaft
Sternum
Crosssection
of rib
Costal cartilage
Vertebral and sternal articulations of a typical true rib
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Figure 7.25c Ribs.
Articular facet
on tubercle of rib
Spinous process
Shaft
Ligaments
Transverse
costal facet
(for tubercle
of rib)
Neck of rib
Head of rib
Body of
thoracic
vertebra
Superior view of the articulation between a rib and a
thoracic vertebra
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Sternum
A. Formed from three sections
1. Manubrium—superior section
► clavicular notches articulate with medial end of clavicles
2. Body—bulk of sternum
► sides are notched at joints for costal cartilage of ribs 2–7
3. Xiphoid process—inferior end of sternum
► ossifies around age 40
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Jugular notch
Clavicular notch
Manubrium
Body
True
ribs
(17)
Xiphoid
process
False
ribs
(812)
Intercostal
spaces
Costal
cartilage
Floating
ribs (11, 12)
L1
Vertebra
Skeleton of the thoracic cage, anterior view
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Costal
margin
Sternum
Fetal Skeleton
A. Fontanelles
1. unossified remnants of membranes
2. soft spots in infant cranium
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Fontanelles
Frontal suture
Frontal bone
Anterior
fontanelle
Ossification
center
Parietal bone
Posterior fontanelle
Superior view
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Occipital
bone
Infant Cranium
Parietal bone
Ossification
center
Frontal bone
Sphenoidal
fontanelle
Posterior
fontanelle
Mastoid
fontanelle
Occipital bone
Lateral view
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Temporal bone
(squamous part)