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1 PowerPoint ® Lecture Slides prepared by Leslie Hendon University of Alabama, Birmingham C H A P T E R Copyright © 2011 Pearson Education, Inc. Part 1 7 Bones, Part 1: The Axial Skeleton Copyright © 2011 Pearson Education, Inc. The Skeleton Consists of: Bones, cartilage, joints, and ligaments Composed of 206 named bones grouped into two divisions Axial skeleton (80 bones) Appendicular skeleton (126 bones) Copyright © 2011 Pearson Education, Inc. The Axial Skeleton(in green) Formed from 80 named bones Consists of skull, vertebral column, and bony thorax Figure 7.1a Skull Thoracic cage (ribs and sternum) (a) Anterior view Facial bones Cranium Sacrum Vertebral column Clavicle Scapula Sternum Rib Humerus Vertebra Radius Ulna Carpals Phalanges Metacarpals Femur Patella Tibia Fibula Tarsals Metatarsals Phalanges Copyright © 2011 Pearson Education, Inc. The Axial Skeleton Figure 7.1b (b) Posterior view Cranium Clavicle Bones of pectoral girdle Bones of pelvic girdle Upper limb Scapula Rib Humerus Vertebra Radius Ulna Carpals Phalanges Metacarpals Femur Lower limb Tibia Fibula Copyright © 2011 Pearson Education, Inc. Figure 7.6a The Skull Formed by cranial and facial bones Parietal bone Squamous part of frontal bone Nasal bone Sphenoid bone (greater wing) Temporal bone Ethmoid bone Lacrimal bone Zygomatic bone Maxilla Mandible Infraorbital foramen Mental foramen (a) Anterior view of skull Mental protuberance Frontal bone Glabella Frontonasal suture Supraorbital foramen (notch) Supraorbital margin Superior orbital fissure Inferior orbital fissure Middle nasal concha Inferior nasal concha Vomer Optic canal Perpendicular plate Ethmoid bone Copyright © 2011 Pearson Education, Inc. The Cranium Is the body’s most complex bony structure Formed by cranial and facial bones The cranium Encloses and protects brain Provides attachment for head and neck muscles

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Page 1: Bones, Part 1: The Axial Skeletonstreaming.missioncollege.org/dlamkin/media/BIOSC_047_38282/47ch_0… · Bones, Part 1: The Axial Skeleton ... • Appendicular skeleton (126 bones)

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PowerPoint® Lecture Slides prepared by Leslie Hendon University of Alabama, Birmingham

C H A P T E R

Copyright © 2011 Pearson Education, Inc.

Part 1

7 Bones, Part 1: The Axial Skeleton

Copyright © 2011 Pearson Education, Inc.

The Skeleton

•  Consists of: •  Bones, cartilage, joints, and ligaments

•  Composed of 206 named bones grouped into two divisions •  Axial skeleton (80 bones) •  Appendicular skeleton (126 bones)

Copyright © 2011 Pearson Education, Inc.

The Axial Skeleton(in green)

•  Formed from 80 named bones

•  Consists of skull, vertebral column, and bony thorax

Figure 7.1a

Skull

Thoracic cage (ribs and sternum)

(a) Anterior view

Facial bones Cranium

Sacrum

Vertebral column

Clavicle Scapula Sternum Rib Humerus Vertebra Radius Ulna

Carpals

Phalanges Metacarpals Femur Patella Tibia Fibula

Tarsals Metatarsals Phalanges

Copyright © 2011 Pearson Education, Inc.

The Axial Skeleton

Figure 7.1b (b) Posterior view

Cranium

Clavicle Bones of pectoral girdle

Bones of pelvic girdle

Upper limb

Scapula

Rib Humerus Vertebra Radius Ulna

Carpals Phalanges Metacarpals Femur

Lower limb

Tibia Fibula

Copyright © 2011 Pearson Education, Inc. Figure 7.6a

The Skull

•  Formed by cranial and facial bones

Parietal bone

Squamous part of frontal bone Nasal bone Sphenoid bone (greater wing) Temporal bone Ethmoid bone Lacrimal bone Zygomatic bone

Maxilla

Mandible

Infraorbital foramen

Mental foramen

(a) Anterior view of skull

Mental protuberance

Frontal bone

Glabella

Frontonasal suture

Supraorbital foramen (notch) Supraorbital margin Superior orbital fissure

Inferior orbital fissure

Middle nasal concha

Inferior nasal concha

Vomer

Optic canal

Perpendicular plate Ethmoid bone

Copyright © 2011 Pearson Education, Inc.

The Cranium

•  Is the body’s most complex bony structure •  Formed by cranial and facial bones •  The cranium •  Encloses and protects brain •  Provides attachment for head and neck

muscles

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The Face

•  Facial bones serve to •  Form framework of the face •  Form cavities for the sense organs of sight,

taste, and smell •  Provide openings for the passage of air and

food •  Hold the teeth in place •  Anchor muscles of the face

Copyright © 2011 Pearson Education, Inc.

The Cranium Bones of cranium (cranial vault)

Lambdoid suture

Facial bones

Squamous suture

(a) Cranial and facial divisions of the skull

Coronal suture

Figure 7.2a

Copyright © 2011 Pearson Education, Inc.

Anterior cranial fossa

Middle cranial fossa

Posterior cranial fossa

(b) Superior view of the cranial fossae

Frontal lobe of cerebrum

Temporal lobe of cerebrum Cerebellum

Posterior Middle Anterior

Cranial fossae

(c) Lateral view of cranial fossae showing the contained brain regions

Overview of Skull Geography

•  Facial bones form anterior aspect •  Cranium is divided into cranial vault and the

base •  Internally, prominent bony ridges divide skull

into distinct fossae

Figure 7.2b, c Copyright © 2011 Pearson Education, Inc.

Overview of Skull Geography

•  The skull contains smaller cavities •  Middle and inner ear cavities—in lateral

aspect of cranial base •  Nasal cavity—lies in and posterior to the

nose •  Orbits—house the eyeballs •  Air-filled sinuses—occur in several bones

around the nasal cavity

Copyright © 2011 Pearson Education, Inc.

Overview of Skull Geography

•  The skull contains approximately 85 named openings •  Foramina, canals, and fissures •  Provide openings for important structures • Spinal cord • Blood vessels serving the brain • 12 pairs of cranial nerves

Copyright © 2011 Pearson Education, Inc.

Cranial Bones

•  Formed from eight large bones •  Paired bones include • Temporal bones • Parietal bones

•  Unpaired bones include • Frontal bone • Occipital bone • Sphenoid bone • Ethmoid bone

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Parietal Bones and Sutures

•  Parietal bones form superior and lateral parts of skull

•  Four sutures of the cranium •  Coronal suture—runs in the coronal plane • Located where parietal bones meet the

frontal bone •  Squamous suture—occurs where each

parietal bone meets a temporal bone inferiorly

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Parietal Bones and Sutures

•  Four sutures of the cranium (continued) •  Sagittal suture—occurs where right and left

parietal bones meet superiorly •  Lambdoid suture—occurs where the parietal

bones meet the occipital bone posteriorly

Copyright © 2011 Pearson Education, Inc.

Sutural Bones

•  Small bones that occur within sutures •  Irregular in shape, size, and location •  Not all people have sutural bones

Copyright © 2011 Pearson Education, Inc.

Lambdoid suture Occipital bone

Superior nuchal line

External occipital protuberance

Sutural bone

Inferior nuchal line

Occipital condyle

External occipital crest Occipitomastoid suture

Parietal bone

Sagittal suture The Skull— Posterior View

Figure 7.5

Copyright © 2011 Pearson Education, Inc.

Maxilla (palatine process)

Hard palate

Zygomatic bone

Incisive fossa

Median palatine suture Intermaxillary suture

Infraorbital foramen Maxilla Sphenoid bone (greater wing)

Foramen ovale Pterygoid process

Foramen lacerum Carotid canal External acoustic meatus Stylomastoid foramen Jugular foramen

Foramen magnum

Occipital condyle Inferior nuchal line Superior nuchal line

Temporal bone (zygomatic process)

Mandibular fossa

Vomer

Styloid process

External occipital crest External occipital protuberance (a) Inferior view of the skull (mandible removed)

Mastoid process Temporal bone (petrous part) Basilar part of the occipital bone Occipital bone

Palatine bone (horizontal plate)

Foramen spinosum

Inferior Aspect of the Skull

Figure 7.7a Copyright © 2011 Pearson Education, Inc.

(b) Photograph of right side of skull

Sphenoid bone (greater wing)

Coronal suture

Parietal bone Squamous suture

Zygomatic process

Temporal bone

Lambdoid suture Occipital bone

External occipital protuberance Occipitomastoid suture External acoustic meatus Mastoid process Styloid

process Mandibular ramus Mandibular angle

Mental foramen

Frontal bone

Ethmoid bone Lacrimal bone Nasal bone Lacrimal fossa Zygomatic bone

Maxilla

Mandible

Coronoid process

Alveolar margins

Mandibular condyle

Mandibular notch

Lateral Aspect of the Skull

Figure 7.4b

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The Temporal Bone

Figure 7.8

Mastoid region

External acoustic meatus

Mastoid process

Styloid process Tympanic region

Mandibular fossa

Zygomatic process

Squamous region

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(a) Superior view, as in Figure 7.9

Optic canal

Greater wing Sella turcica

Lesser wing

Foramen rotundum Foramen ovale Foramen spinosum

Body of sphenoid

The Sphenoid Bone

Figure 7.10a

Copyright © 2011 Pearson Education, Inc.

Greater wing

Body of sphenoid

Superior orbital fissure

Lesser wing

Pterygoid process

(b) Posterior view

The Sphenoid Bone

Figure 7.10b Copyright © 2011 Pearson Education, Inc.

Orbital plate

Ethmoidal air cells

Perpendicular plate

Middle nasal concha

Cribriform plate Olfactory

foramina

Crista galli

Left lateral mass

Figure 7.12

The Ethmoid Bone

Copyright © 2011 Pearson Education, Inc.

Facial Bones

•  Unpaired bones •  Mandible and vomer

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

Copyright © 2011 Pearson Education, Inc.

Parietal bone

Squamous part of frontal bone Nasal bone Sphenoid bone (greater wing) Temporal bone Ethmoid bone Lacrimal bone Zygomatic bone

Maxilla

Mandible

Infraorbital foramen

Mental foramen

(a) Anterior view of skull

Mental protuberance

Frontal bone Glabella Frontonasal suture Supraorbital foramen (notch) Supraorbital margin Superior orbital fissure

Inferior orbital fissure

Middle nasal concha

Inferior nasal concha Vomer

Optic canal

Perpendicular plate Ethmoid bone

Facial Bones

Figure 7.6a

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Coronoid process

Mandibular foramen

Mental foramen

Mandibular angle

Ramus of mandible

Mandibular condyle

Mandibular notch

Mandibular fossa of temporal bone

Body of mandible

Alveolar margin

(a) Mandible, right lateral view

Temporomandibular joint

Mandible

Figure 7.13a Copyright © 2011 Pearson Education, Inc.

Maxillary Bones

Figure 7.13b

Frontal process

Articulates with frontal bone

Anterior nasal spine

Infraorbital foramen

Alveolar margin

(b) Maxilla, right lateral view

Orbital surface

Zygomatic process (cut)

Copyright © 2011 Pearson Education, Inc.

Maxilla (palatine process)

Hard palate

Zygomatic bone

Incisive fossa

Median palatine suture Intermaxillary suture

Infraorbital foramen Maxilla Sphenoid bone (greater wing)

Foramen ovale Pterygoid process

Foramen lacerum Carotid canal External acoustic meatus Stylomastoid foramen Jugular foramen

Foramen magnum

Occipital condyle Inferior nuchal line Superior nuchal line

Temporal bone (zygomatic process)

Mandibular fossa

Vomer

Styloid process

External occipital crest External occipital protuberance (a) Inferior view of the skull (mandible removed)

Mastoid process Temporal bone (petrous part) Basilar part of the occipital bone Occipital bone

Palatine bone (horizontal plate)

Foramen spinosum

Maxillary Bones

Figure 7.7a Copyright © 2011 Pearson Education, Inc.

Other Bones of the Face

•  Zygomatic bones •  Form lateral wall of orbits

•  Nasal bones •  Form bridge of nose

•  Lacrimal bones •  Located in the medial orbital walls

•  Palatine bones •  Complete the posterior part of the hard palate

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Other Bones of the Face

•  Vomer •  Forms the inferior part of the nasal septum

•  Inferior nasal conchae •  Thin, curved bones that project medially form

the lateral walls of the nasal cavity

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Special Parts of the Skull

•  Orbits •  Nasal cavity •  Paranasal sinuses •  Hyoid bone

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Nasal Cavity

Figure 7.14a

Frontal sinus Superior nasal concha Middle nasal concha

Ethmoid bone

Inferior nasal concha Nasal bone

Maxillary bone (palatine process)

Palatine bone (perpendicular plate)

Palatine bone (horizontal plate)

Pterygoid process

(a) Bones forming the left lateral wall of the nasal cavity (nasal septum removed)

Sphenoid sinus

Sphenoid bone

Superior, middle, and inferior meatus

Anterior nasal spine

Copyright © 2011 Pearson Education, Inc.

Vomer

Crista galli Cribriform plate

Ethmoid bone Frontal sinus

Nasal bone

Septal cartilage

Alveolar margin of maxilla

Perpendicular plate of ethmoid bone

Sella turcica

Sphenoid sinus

Palatine bone

Palatine process of maxilla

(b) Nasal cavity with septum in place showing the contributions of the ethmoid bone, the vomer, and septal cartilage

Hard palate

Nasal Septum

Figure 7.14b

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Paranasal Sinuses

•  Air-filled sinuses are located within •  Frontal bone •  Ethmoid bone •  Sphenoid bone •  Maxillary bones

•  Lined with mucous membrane •  Lighten the skull

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Paranasal Sinuses

Figure 7.15a, b

Frontal sinus Ethmoidal air cells (sinus)

Maxillary sinus

Sphenoid sinus

(a) Anterior aspect

Frontal sinus Ethmoidal air cells

Maxillary sinus

Sphenoid sinus

(b) Medial aspect

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Orbits

Figure 7.16b

Roof of orbit

Medial wall

Orbital plate of ethmoid bone

Sphenoid body

Supraorbital notch Optic canal

Floor of orbit Orbital process of palatine bone Orbital surface of maxillary bone

Lacrimal bone Nasal bone

Frontal process of maxilla

Lateral wall of orbit Zygomatic process of frontal bone Greater wing of sphenoid bone Orbital surface of zygomatic bone

Zygomatic bone

Zygomatic bone

Inferior orbital fissure Infraorbital groove

Infraorbital foramen

Superior orbital fissure

(b) Contribution of each of the seven bones forming the right orbit

Lesser wing of sphenoid bone Orbital plate of frontal bone

Copyright © 2011 Pearson Education, Inc. Figure 7.17

The Hyoid Bone

•  Lies inferior to the mandible

•  The only bone with no direct articulation with any other bone

•  Acts as a movable base for the tongue

Greater horn

Lesser horn

Body

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The Vertebral Column

•  Formed from 26 bones in the adult •  Transmits weight of trunk to the lower limbs •  Surrounds and protects the spinal cord

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The Vertebral Column

•  Serves as attachment sites for muscles of the neck and back

•  Held in place by ligaments •  Anterior and posterior longitudinal ligaments •  Ligamentum flavum

Copyright © 2011 Pearson Education, Inc.

The Vertebral Column

Figure 7.18

Cervical curvature (concave)

7 vertebrae, C1 – C7

Thoracic curvature

(convex) 12 vertebrae,

T1 – T12

Lumbar curvature (concave)

5 vertebrae, L1 – L5

Sacral curvature

(convex) 5 fused vertebrae sacrum

Coccyx 4 fused vertebrae Anterior view Right lateral view

C1

T 1 2 3 4 5 6 7 8 9

10 11 12

L 1 2 3 4 5

2 3 4 5 6 7

Spinous process Transverse processes

Intervertebral discs Intervertebral foramen

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Regions and Normal Curvatures

•  The Vertebral column has five major regions •  7 cervical vertebrae of the neck region •  12 thoracic vertebrae •  5 lumbar vertebrae •  Sacrum—five fused bones •  Inferior to lumbar vertebrae

•  Coccyx—inferior to sacrum

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Regions and Normal Curvatures

•  Curvatures of the spine •  Cervical and lumbar curvatures • Concave posteriorly

•  Thoracic and sacral curvatures • Convex posteriority

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Regions and Normal Curvatures

•  Curvatures increase resilience of spine •  Thoracic and sacral curvatures •  Primary curvatures • Present at birth

•  Lumbar curvature •  Develops when baby begins to walk

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Ligaments of the Spine

•  Major supporting ligaments •  Anterior longitudinal ligament • Attaches to bony vertebrae and

intervertebral discs • Prevents hyperextension

•  Posterior longitudinal ligament • Narrow and relatively weak • Attaches to intervertebral discs

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Posterior longitudinal ligament

Anterior longitudinal ligament

Body of a vertebra

Intervertebral disc

(b) Anterior view of part of the spinal column

Ligaments of the Spine

Supraspinous ligament Intervertebral disc Anterior longitudinal ligament

Intervertebral foramen Posterior longitudinal ligament

Anulus fibrosus

Nucleus pulposus

Sectioned body of vertebra

Transverse process

Sectioned spinous process

Ligamentum flavum

Interspinous ligament

Inferior articular process

(a) Median section of three vertebrae, illustrating the composition of the discs and the ligaments

Figure 7.19a, b

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Ligaments of the Spine

Figure 7.19c, d

Vertebral spinous process (posterior aspect of vertebra)

Spinal nerve root

Anulus fibrosus of disc

Herniated portion of disc

Nucleus pulposus of disc

Spinal cord

(c) Superior view of a herniated intervertebral disc

Transverse process

(d) MRI of lumbar region of vertebral column in sagittal section showing normal and herniated discs

Nucleus pulposus of intact disc

Herniated nucleus pulposus

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Intervertebral Discs

•  Are cushion-like pads between vertebrae •  Composed of • Nucleus pulposus • Anulus fibrosus

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Intervertebral Discs

•  Nucleus pulposus •  Gelatinous inner sphere •  Absorbs compressive stresses

•  Anulus fibrosus •  Outer fings formed of ligament •  Inner rings formed of fibrocartilage •  Contain the nucleus pulposus

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General Structure of Vertebrae

PLAY Spine (horizontal)

Figure 7.20

Posterior

Anterior

Lamina

Superior articular process and facet

Transverse process

Pedicle

Spinous process

Vertebral arch

Vertebral foramen

Body (centrum)

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General Structure of Vertebrae

•  Common structures to all regions •  Body •  Vertebral arch •  Vertebral foramen •  Spinous process •  Transverse process •  Superior and inferior articular processes •  Intervertebral foramina

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Regions Vertebral Characteristics

•  Specific regions of the spine perform specific functions

•  Types of movement that occur between vertebrae •  Flexion and extension •  Lateral flexion •  Rotation in the long axis

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Cervical Vertebrae

•  Seven cervical vertebrae (C1–C7)—smallest and lightest vertebrae

•  C3–C7 are typical cervical vertebrae •  Body is wider laterally •  Spinous processes are short and bifid (except

C7) •  Vertebral foramen are large and triangular •  Transverse processes contain transverse

foramina •  Superior articular facets face

superoposteriorly

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Cervical Vertebrae

Table 7.2a

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Dens of axis

Transverse ligament of atlas C1 (atlas) C2 (axis)

C3

Bifid spinous process

Transverse processes

C7 (vertebra prominens)

(a) Cervical vertebrae

Inferior articular process

Cervical Vertebrae

Figure 7.22a Copyright © 2011 Pearson Education, Inc.

The Atlas

•  C1 is termed the atlas •  Lacks a body and spinous process •  Supports the skull •  Superior articular facets receive the occipital

condyles •  Allows flexion and extension of neck •  Nodding the head “yes”

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The Atlas

Figure 7.21a

Anterior arch

Superior articular facet

Transverse foramen

Posterior arch

Posterior tubercle

Anterior tubercle

Posterior

Lateral masses

(a) Superior view of atlas (C1)

C1

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The Atlas

Figure 7.21b

Facet for dens

Transverse process Lateral

masses

Transverse foramen

Posterior arch

Posterior tubercle Posterior

Anterior tubercle

Anterior arch

(b) Inferior view of atlas (C1)

Inferior articular facet

C1

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The Axis

•  Has a body and spinous process •  Dens (odontoid process) projects superiorly •  Formed from fusion of the body of the atlas

with the axis •  Acts as a pivot for rotation of the atlas and

skull •  Participates in rotating the head from side to

side

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The Axis

Figure 7.21c

C2 Posterior

Dens

(c) Superior view of axis (C2)

Inferior articular process

Body

Superior articular facet Transverse

process

Pedicle

Lamina Spinous process

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Thoracic Vertebrae (T1—T12)

•  All articulate with ribs •  Have heart-shaped bodies from the superior

view •  Each side of the body of T1–T10 bears

demifacts for articulation with ribs •  T1 has a full facet for the first rib •  T10–T12 only have a single facet

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Thoracic Vertebrae

Table 7.2b

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Thoracic Vertebrae

•  Spinous processes are long and point inferiorly

•  Vertebral foramen are circular •  Transverse processes articulate with

tubercles of ribs •  Superior articular facets point posteriorly •  Inferior articular processes point anteriorly •  Allows rotation and prevents flexion and

extension

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Lumbar Vertebrae (L1—L5)

•  Bodies are thick and robust •  Transverse processes are thin and tapered •  Spinous processes are thick, blunt, and point

posteriorly •  Vertebral foramina are triangular •  Superior and inferior articular facets directly

medially •  Allows flexion and extension—rotation

prevented

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Lumbar Vertebrae

Table 7.2c Copyright © 2011 Pearson Education, Inc.

Superior articular process

Transverse process

Spinous process

Intervertebral disc

Body

Inferior articular process

(c) Lumbar vertebrae

Lumbar Vertebrae

Figure 7.22c

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Sacrum (S1—S5)

•  Shapes the posterior wall of pelvis •  Formed from 5 fused vertebrae •  Superior surface articulates with L5 •  Inferiorly articulates with coccyx •  Sacral promontory •  Where the first sacral vertebrae bulges into

pelvic cavity •  Center of gravity is 1 cm posterior to sacral

promontory •  Ala—develops from fused rib elements

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Sacrum

•  Sacral foramina •  Ventral foramina • Passage for ventral rami of sacral spinal

nerves •  Dorsal foramina • Passage for dorsal rami of sacral spinal

nerves

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Sacrum

Figure 7.23

Body of first sacral vertebra

Transverse ridges (sites of vertebral fusion)

Coccyx Coccyx

Anterior sacral foramina Apex

Posterior sacral foramina

Median sacral crest

Sacral promontory Sacral canal

Sacral hiatus

Body Facet of superior articular process

Lateral sacral crest

Auricular surface

Ala

(a) Anterior view (b) Posterior view

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Coccyx

•  Is the “tailbone” •  Formed from 3—5 fused vertebrae •  Offers only slight support to pelvic organs

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The Thoracic Cage

•  Forms the framework of the chest •  Components •  Thoracic vertebrae—posteriorly •  Ribs—laterally •  Sternum and costal cartilage—anteriorly

•  Protects thoracic organs •  Supports shoulder girdle and upper limbs •  Provides attachment sites for muscles

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Intercostal spaces

True ribs (1–7

False ribs (8–12)

Jugular notch Clavicular notch

Manubrium Sternal angle Body Xiphisternal joint Xiphoid process

L1 Vertebra

Floating ribs (11, 12) (a) Skeleton of the thoracic cage, anterior view

Sternum

Costal cartilage Costal margin

The Thoracic Cage

Figure 7.24a

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The Thoracic Cage

Figure 7.24b

Xiphisternal Xiphisternal joint

Heart

Sternal angle

Jugular notch

(b) Midsagittal section through the thorax, showing the relationship of surface anatomical landmarks of the thorax to the vertebral column

T2

T4

T3

T9

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Sternum

•  Formed from three sections •  Manubrium—superior section • Articulates with medial end of clavicles

•  Body—bulk of sternum • Sides are notched at articulations for costal

cartilage of ribs 2–7 •  Xiphoid process—inferior end of sternum • Ossifies around age 40

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Sternum

•  Anatomical landmarks •  Jugular notch • Central indentation at superior border of the

manubrium •  Sternal angle • A horizontal ridge where the manubrium

joins the body •  Xiphisternal joint • Where sternal body and xiphoid process

fuse • Lies at the level of the 9th thoracic vertebra

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Ribs

•  All ribs attach to vertebral column posteriorly •  True ribs - superior seven pairs of ribs • Attach to sternum by costal cartilage

•  False ribs—inferior five pairs of ribs •  Ribs 11–12 are known as floating ribs

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Ribs

Figure 7.25a, b

Junction with costal cartilage

Shaft Head Neck Articular facet on tubercle

Costal angle Costal groove

Facets for articulation with vertebrae

(a) A typical rib (rib 6, right), posterior view

Transverse costal facet (for tubercle of rib) Superior costal facet

(for head of rib) Body of vertebra Head of rib

Intervertebral disc

Tubercle of rib Neck of rib

Shaft Sternum

Angle of rib

Cross- section of rib Costal groove

(b) Vertebral and sternal articulations of a typical true rib Costal cartilage

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Spinous process Articular facet on tubercle of rib

Shaft

Ligaments

Neck of rib

Head of rib Body of thoracic vertebra

Transverse costal facet (for tubercle of rib)

Superior costal facet (for head of rib)

(c) Superior view of the articulation between a rib and a thoracic vertebra

Ribs

Figure 7.25c

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Disorders of the Axial Skeleton

•  Cleft palate •  A common congenital disorder •  Right and left halves of palate fail to fuse

medially •  Stenosis of the lumbar spine •  Narrowing of the vertebral canal •  Can compress roots of spinal nerves

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Disorders of the Axial Skeleton

•  Abnormal spinal curvatures •  Scoliosis—an abnormal lateral curvature •  Kyphosis—an exaggerated thoracic

curvature •  Lordosis—an accentuated lumbar curvature;

“swayback”

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The Axial Skeleton Throughout Life

•  Membrane bones begin to ossify in second month of development

•  Bone tissue grows outward from ossification centers

•  Fontanels •  Unossified remnants of membranes

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Fontanelles

Figure 7.28a

Occipital bone

Parietal bone

Anterior fontanelle

Frontal suture

Frontal bone

Ossification center

(a) Superior view

Posterior fontanelle

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Fontanelles

Figure 7.28b

Frontal bone

Sphenoidal fontanelle

(b) Lateral view

Posterior fontanelle

Mastoid fontanelle

Parietal bone

Ossification center

Occipital bone

Temporal bone (squamous portion)

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The Axial Skeleton Throughout Life

•  Many bones of the face and skull form by intramembranous ossification

•  Endochondral bones of the skull •  Occipital bone •  Sphenoid •  Ethmoid bones •  Parts of the temporal bone

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The Axial Skeleton Throughout Life

•  Aging of the axial skeleton •  Water content of the intervertebral discs

decreases •  By age 55, loss of a few centimeters in height

is common •  Thorax becomes more rigid •  Bones lose mass with age