131, t4, ch7 axial skeleton _14

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Axial Skeleton Chapter 7

IB 131 Instructor: Tom Carlson

Department of Integrative Biology University of California, Berkeley

1

The Skeleton Consists of:

bones joints cartilage ligaments

Composed of 206 named bones grouped into two divisions axial skeleton: 80 bones appendicular skeleton: 126 bones

2

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 3

The Axial

Skeleton (in green)

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

4

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

5

Skull Bodys most complex bony structure Skull: formed by cranial and facial bones 8 Cranial bones: ethmoid, frontal, occipital,

sphenoid, parietal (2), temporal (2) 14 Facial bones: mandible, vomer, inferior

nasal conchae (2), lacrimal (2), maxilla (2), nasal (2), palantine (2), zygomatic (2)

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The cranial & facial bones Bones of cranium (cranial vault)

Lambdoid suture

Facial bones

Squamous suture

(a) Cranial and facial divisions of the skull

Coronal suture

Figure 7.2a 7

Skull Facial bones

Form framework of face Form cavities for sense organs of sight, taste,

and smell Provide opening for passage of air and food Hold teeth Anchor facial muscles

The cranium (cranial bones) Encloses and protects brain Provides attachment for head and neck

muscles 8

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

Cranial Fossae Internally, prominent bony ridges divide skull into

distinct fossae Anterior cranial fossa: frontal lobe of cerebrum Middle cranial fossa: temporal lobe of cerebrum Posterior cranial fossa: cerebellum

Figure 7.2b, c 9

Small Cavities of Skull

Middle and inner ear cavitiesin lateral aspect of cranial base

Nasal cavitylies in and posterior to the nose

Orbitshouse the eyeballs Air-filled sinusesoccur in several

bones around the nasal cavity

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Skull contains approximately 85 named openings

Foramina, canals, and fissures Provide openings for important structures

Spinal cord Blood vessels serving the brain Cranial nerves

11

Lateral aspect of skull

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Cranial Bones Formed from eight bones

Paired bones include Temporal bones Parietal bones

Unpaired bones include Frontal bone Occipital bone Sphenoid bone Ethmoid bone

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Figure 7.6a

The Skull Formed by cranial and facial bones

Parietal bone


Maxilla

Mandible


Mental foramen


Mental protuberance

Frontal bone

Glabella

Frontonasal suture



Middle nasal concha


Vomer

Optic canal


14

Cranial cavity floor

15


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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 17

Parietal Bones & associated Sutures Parietal bones form superior and lateral parts

of skull Coronal sutureruns in the coronal plane

and is located where parietal bones meet frontal bone

Squamous sutureoccurs where each parietal bone meets a temporal bone inferiorly

Sagittal sutureoccurs where right and left parietal bones meet superiorly

Lambdoid sutureoccurs where parietal bones meet the occipital bone posteriorly

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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 19

Sutural Bones

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

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Frontal Bone

Forms the forehead and roofs of orbits Supraorbital marginsuperior margin

of orbits Glabellasmooth part of frontal bone

between superciliary (eyebrow) arches Frontal sinuses within frontal bone Contributes to anterior cranial fossa

21

Figure 7.6a

Cranial & Facial Bones of Skull

Parietal bone


Maxilla

Mandible


Mental foramen


Mental protuberance

Frontal bone

Glabella

Frontonasal suture



Middle nasal concha


Vomer

Optic canal


22

Cranial and Facial Bones of Skull

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Occipital Bone

Forms the posterior portion of the cranium and cranial base

Articulates with the temporal bones and parietal bones

Forms the posterior cranial fossa

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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 25

Inferior Aspect of Skull

26




Sutural bone


Occipital condyle


Parietal bone

Sagittal suture The Skull Posterior View

Figure 7.5 27

Occipital Bone structures

Superior and inferior nuchal lines Occipital condyles Hypoglossal canal through which CN XII

runs Foramen magnum located at its base

28


29

Temporal Bones Lie inferior to parietal bones Contributes to the middle and

posterior cranial fossae Form the inferolateral portion of the

skull

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(b) Photograph of right side of skull

Sphenoid bone (greater wing)

Coronal suture

Parietal bone Squamous suture

Zygomatic process

Temporal 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 31


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Regions of Temporal Bones Squamous region flat area of bone which

contains bar-like zygomatic process; zygomatic process projects anteriorly to meet zygomatic bone of face and contributions of these two bones to make up the zygomatic arch

Tympanic region surrounds the external acoustical meatus (= external ear canal)

Styloid process extends down from inferior temporal bone and is muscle attachment site

Mastoid region Petrous region 33

The Temporal Bone

Figure 7.8

Mastoid region

External acoustic meatus

Mastoid process

Styloid process Tympanic region

Mandibular fossa

Zygomatic process

Squamous region

34


35

The Temporal Bone Mastoid region/mastoid process

Site for neck muscle attachment Contains air sinuses

Petrous region Projects medially, contributes to cranial base Appears as a boney wedge between

occipetal bone posteriorly and sphenoid bone anteriorly

Houses cavities of middle and internal ear

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Hard palate

Zygomatic bone

Incisive fossa





Foramen magnum



Mandibular fossa

Vomer

Styloid process




Foramen spinosum


Figure 7.7a 37

Foramina of Temporal Bone Carotid canal Jugular foramen (at boundary with

occipital bone) Foramen lacerum (at boundary with

sphenoid bone and occipital bone) Internal & external acoustic meatus

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39


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Inferior Aspect of Skull

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The Sphenoid Bone Spans the width of the cranial floor Resembles a butterfly or bat Has a body Has three pairs of processes Contains five important openings Is the keystone of the cranium and forms

a central wedge that articulates with multiple other cranial bones

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The Sphenoid Bone Body

The superior part of the body bears a saddle-shaped prominence called a sella turcica

The seat of this saddle contains the hypophyseal fossa, which holds the pituitary gland (= hypophysis)

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The Sphenoid Bone Processes

Greater wings Lesser wings Pterygoid processes

45

Greater wing

Body of sphenoid

Superior orbital fissure

Lesser wing

Pterygoid process

(b) Posterior view

Sphenoid Bone posterior view

Figure 7.10b 46

(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

Sphenoid Bone superior view

Figure 7.10a 47

Sphenoid Bone Openings Superior orbital fissure: long slit between

greater and lesser wings Optic canal: lies just anterior to sella tursica Foramen rotundum: in medial part of greater

wing Foramen ovale: posteriolateral to foramen

rotundum Foramen spinosum: posteriolateral to foramen

ovale (at boundary with temporal bone) Foramen lacerum (at boundary with temporal

bone and occipital bone) 48

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50

Figure 7.6a


Parietal bone


Maxilla

Mandible


Mental foramen


Mental protuberance

Frontal bone

Glabella

Frontonasal suture



Middle nasal concha


Vomer

Optic canal


51

The Ethmoid Bone

Lies between nasal and sphenoid bones

Forms most of the medial bony region between the nasal cavity and orbits

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Midsagittal section through skull

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Figure 7.6a


Parietal bone


Maxilla

Mandible


Mental foramen


Mental protuberance

Frontal bone

Glabella

Frontonasal suture



Middle nasal concha


Vomer

Optic canal


55

Midsagittal section through skull

56

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, anterior view

57

The Ethmoid Bone Cribriform platesuperior surface of the

ethmoid bone Contain olfactory foramina

Crista galliattachment for falx cerebri, the large vertical sheet of connective tissue which lies in between cerebral hemispheres

Perpendicular plateforms superior part of nasal septum

Lateral massescontain air cells 58

Partitions of dura mater in the cranial cavity and the dural venous sinuses

Figure 13.27a

Falx cerebri

Superior sagittal sinus

Straight sinus Crista galli of the ethmoid bone

Pituitary gland Falx cerebelli

(a) Midsagittal view

Tentorium cerebelli

59

The Ethmoid Bone

Superior and middle nasal conchae Extend medially from lateral masses

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Left lateral wall of nasal cavity

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Bones of Nasal Cavity

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Parietal bone


Maxilla

Mandible


Mental foramen


Mental protuberance

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


Middle nasal concha

Inferior nasal concha Vomer

Optic canal


Skull Bones

Figure 7.6a 63

The Facial Bones 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

64

Facial Bones Unpaired bones

Mandible Vomer

Paired bones Maxillae Zygomatic Nasal Lacrimal Inferior nasal conchae Palatine 65

Mandible

The lower jawbone is the largest and strongest facial bone

Composed of two main parts Horizontal body Two upright rami

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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 67

Mandible Mandibular condyle Temporomandibular joint: interface of mandibular

condyle with mandibular fossa of temporal bone Mandibular notch Coronoid process Ramus of mandible Mandibular angle Body of mandible Alveolar margin Mental foramen Mandibular foramen

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Maxillary Bones

Figure 7.13b

Frontal process

Articulates with frontal bone

Anterior nasal spine


Alveolar margin

(b) Maxilla, right lateral view

Orbital surface

Zygomatic process (cut)

70

Maxillary Bones Articulate with all other facial bones except

the mandible Are the keystone bones of the face Contain maxillary sinuseslargest

paranasal sinuses Forms part of the inferior orbital fissure Alveolar margin Inferiomedial surface of orbit Infraorbital foramen

71

Parietal bone


Maxilla

Mandible


Mental foramen


Mental protuberance



Middle nasal concha


Optic canal


Skull Bones, anterior view

Figure 7.6a 72

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Hard palate

Zygomatic bone

Incisive fossa





Foramen magnum



Mandibular fossa

Vomer

Styloid process




Foramen spinosum

Skull Bones, inferior view

Figure 7.7a 73

Skull bones, lateral view

74

Paired Bones of the Face Maxilla bone Zygomatic bones: form lateral wall of

orbits Lacrimal bones: located in the medial

orbital walls Nasal bones: form bridge of nose Inferior nasal conchae: thin, curved

bones that project medially and form the lateral walls of the nasal cavity

Palatine bones: complete the posterior part of the hard palate 75

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)


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

76


Hard palate

Zygomatic bone

Incisive fossa





Foramen magnum



Mandibular fossa

Vomer

Styloid process




Foramen spinosum

Skull Bones, inferior view

Figure 7.7a 77

Other Bones of the Face

Vomer: forms the inferior part of the nasal septum and is an unpaired bone

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Parietal bone


Maxilla

Mandible


Mental foramen


Mental protuberance



Middle nasal concha


Optic canal



Figure 7.6a 79

Special Parts of the Skull

Orbits Nasal cavity Paranasal sinuses

80

Nasal septum

Perpendicular plate of ethmoid bone Vomer bone Septal cartilage

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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 82

Paranasal Sinuses

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

Lined with mucous membrane

83

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 84

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Orbit walls

Roof Lateral wall Medial wall Floor

85

Orbit walls formed by parts of seven bones

Frontal Sphenoid Zygomatic Maxillary Palatine Lacrimal Ethmoid

86

Orbits

87

Orbit

88

Orbit wall openings

Superior orbital fissures Inferior orbital fissures Optic canals

89

Parietal bone


Maxilla

Mandible


Mental foramen


Mental protuberance



Middle nasal concha


Optic canal



Figure 7.6a 90

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Figure 7.17

The Hyoid Bone Associated with skull

but not directly in contact with any other bone

Lies inferior to the mandible in anterior neck

The only bone with no direct articulation with any other bone

Acts as a movable base for the tongue

Greater horn

Lesser horn

Body

91

The Vertebral Column

Formed from 26 bones in the adult Transmits weight of trunk to the lower

limbs Surrounds and protects the spinal cord Serves as attachment sites for muscles

of the neck and back

92

Five Major Regions of Vertebral Column

7 cervical vertebrae of the neck region 12 thoracic vertebrae 5 lumbar vertebrae 1 sacrum (5 fused bones = 1 bone) 1 coccyxinferior to sacrum

93

Normal Curvatures of Vertebral Columns

Cervical and lumbar curvatures: concave posteriorly

Thoracic and sacral curvatures: convex posteriority

94

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

95

Ligaments which Stabilize The Vertebral Column

Anterior longitudinal ligaments: wide and attach strongly to both boney vertebrae and intervertebral discs and prevents hyperextension of back

Posterior longitudinal ligaments: narrow, relatively weak, and attaches only to intervertebral discs and prevents hyperflexion of back

Ligamentum flavum: contains elastic connective tissue and connects lamina of adjacent vertebrae

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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


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 97

Intervertebral Discs: cushion-like pads between vertebrae

Nucleus pulposus

Gelatinous inner sphere Absorbs compressive stresses

Anulus fibrosus Outer rings formed of ligament Inner rings formed of fibrocartilage These rings function to contain the nucleus

pulposus 98

Intervertebral Discs of Spine Herniated Intervertebral Disc

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

99

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)

100

Common Structures of Vertebrae Body Vertebral arch Vertebral foramen Spinous process Transverse process Superior and inferior articular processes Intervertebral foramena: between every pair

of vertebrae are two apertures (openings) which allow for the passage of the spinal nerve root, dorsal root ganglion

101

Vertebral Region Characteristics Specific regions of the spine perform

specific functions Types of movement that may occur

between vertebrae Flexion and extension Lateral flexion Rotation in the long axis

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Posterior 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


Intervertebral foramen Posterior longitudinal ligament

Anulus fibrosus Nucleus pulposus

Sectioned body of vertebra

Transverse process

Sectioned spinous process

Ligamentum flavum

Interspinous ligament


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

Figure 7.19a, b 103

Cervical Vertebrae

Seven cervical vertebrae (C1 C7) are the lightest vertebrae in the spine

104

Dens of axis Transverse ligament of atlas C1 (atlas) C2 (axis) C3

Bifid spinous process Transverse processes

C7 (vertebra prominens)

(a) Cervical vertebrae


Cervical Vertebrae

Figure 7.22a 105

Cervical Vertebrae

Table 7.2a 106

The Atlas, C1

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

107

The Atlas C1, superior view

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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Sutural bone


Occipital condyle


Parietal bone

Sagittal suture Occipital condyles at base of skull

Figure 7.5 109


Hard palate

Zygomatic bone

Incisive fossa





Foramen magnum



Mandibular fossa

Vomer

Styloid process




Foramen spinosum


Figure 7.7a 110

The Atlas C1, Inferior View

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

111

The Axis, C2 Has a body and a spinous process Dens (odontoid process tooth) is a

knoblike structure which projects superiorly from the body of axis (C2) and is cradled in the anterior arch of the atlas

112

The Axis, C2 Dens acts as a pivot for rotation of the atlas

and skull Dens participates in rotating the head from

side to side The name axis for the 2nd cervical vertebral

body is appropriate since its dens allows the head to rotate on the necks axis.

113

The Axis

Figure 7.21c

C2 Posterior

Dens (c) Superior view of axis (C2)


Body

Superior articular facet Transverse process

Pedicle

Lamina Spinous process

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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


Cervical Vertebrae

Figure 7.22a 115

Cervical Vertebrae C3 C7 Body: small and wide laterally (side to side) Spinous process: short and bifid (except C7) and

project posteriorally Vertebral foramen: triangular and large Transverse processes contain foramina Superior facets directed superposteriorly Inferior facets directed inferoanteriorly Spine region with the greatest range of motion

with the following movement allowed: flexion & extension, lateral flexion, rotation

116

Cervical, Thoracic, & Lumbar Vertebrae Superior View

117

Cervical, Thoracic, & Lumbar Vertebrae Right Lateral View

118

Cervical, Thoracic, & Lumbar Vertebrae

119

Thoracic vertebrae

120

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Thoracic Vertebrae All articulate with ribs Body: larger than cervical bodies and heart-

shaped from superior view Spinous processes are long and point

inferiorly Vertebral foramen are circular

121


122


123

Costal Facets of Thoracic Vertebrae which interface with ribs

Inferior costal facet for head of rib Superior costal facet for head of rib Transverse costal facet for tubercle of rib (except

for T11 T12) Each of these above three facets are present on

both sides of vertebrae, so each vertebrae has a total of six facets which interface with ribs

Usually, the head of a rib is attached to the bodies of two vertebrae, the inferior costal facet of the superior vertebra and the superior costal facet of the inferior vertebra

124


125

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 126

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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 127

Connections between Thoracic Vertebral Bodies

Laterally each side of the vertebral body bears two facets (demifacets), one at the superior edge and one at the inferior edge

These demifacets interface with vertebral bodies above and below

Superior articular facets point posteriorly Inferior articular processes point anteriorly Allows rotation and limits flexion and

extension 128

Thoracic vertebrae

129

Thoracic Vertebrae

Table 7.2b 130


131


132

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The Thoracic Cage Forms the framework of the chest Components

Thoracic vertebraeposteriorly Ribslaterally Sternum and costal cartilageanteriorly

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

133

Intercostal spaces

True ribs (17

False ribs (812)

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 134

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

135

Sternum Formed from three sections

Manubriumsuperior section Articulates with medial end of clavicles and

rib 1 Bodybulk of sternum

Sides are notched at articulations for costal cartilage of ribs 27

Xiphoid processinferior end of sternum Ossifies around age 40

136

Intercostal spaces

True ribs (17

False ribs (812)



L1 Vertebra


Sternum


The Thoracic Cage

Figure 7.24a 137

Sternum Anatomical landmarks

Jugular notch Central indentation at superior border of

the manubrium Sternal angle

A horizontal ridge where the manubrium joins the body of the sternum

Xiphisternal joint Where sternal body and xiphoid process

fuse Lies at the level of the 9th thoracic

vertebra 138

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Ribs attach to vertebral column posteriorly

Rib pairs 1-7 (vertebrosternal ribs) - superior seven pairs of ribs which attach to sternum by costal cartilage

Rib pairs 8-10, (vertebrochondral ribs) pairs of ribs which attach to the sternum indirectly

Ribs pairs 1112 (floating ribs) are not attached to the sternum

Ribs 8-12 are sometimes called false ribs because they attach to the sternum indirectly (ribs 8-10) or not at all (ribs 11-12)

139

Intercostal spaces

True ribs (17

False ribs (812)



L1 Vertebra


Sternum


The Thoracic Cage

Figure 7.24a 140

Superior articular process

Transverse process

Spinous process

Intervertebral disc

Body


(c) Lumbar vertebrae

Lumbar Vertebrae

Figure 7.22c 141

Lumbar Vertebrae (L1L5) Bodies are thick and robust Transverse processes are thin and tapered and

nearly perpendicular to spinous process Spinous processes are thick, blunt, and point

posteriorly Vertebral foramina are triangular Superior articular facets face posteromedially or

medially Inferior articular facets face anterolaterally or

laterally Allows flexion and extensionrotation prevented

142


143


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Sacrum (S1S5) Shapes the posterior wall of pelvis Formed from 5 fused vertebrae Superior surface articulates with L5 Inferiorly articulates with coccyx

145

Sacrum (S1S5) Anterior View Sacral promontory: Where the

anterosuperior margin of the first sacral vertebrae bulges into pelvic cavity

Human bodys center of gravity is 1 cm posterior to sacral promontory

Four transverse ridges cross the anterior surface of the sacrum, marking the lines of fusion of sacral vertebrae

sacral spinal nerves pass through the sacral foramina

146

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

147

Sacrum (S1S5) Posterior View Facets of superior articular processes On the posterior surface in the midline is the bumpy

median sacral crest which represents the fused spinous processes of the sacral vertebrae

Lateral to the medial sacral crest are the sacral foramina through which sacral spinal nerves pass

Just lateral to these is the lateral sacral crest Ala (wing) are in superior lateral part of sacrum The alae articulate with the hip bones and form the

sacroiliac joints which are sites where the axial skeleton bone (sacrum) interfaces with an appendicular skeleton bone (ileum of coxal)

148

The Axial

Skeleton (in green)

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

149

Bones of the Pelvic Girdle

Figure 8.8a

PLAY Pelvis

Coxal bone (os coxae or hip bone)

llium

Sacroiliac joint

Iliac fossa

Pubis

Ischium

Sacrum

Base of sacrum

Sacral promontory

Pelvic brim Acetabulum

Pubic crest Pubic symphysis

Iliac crest

Coccyx

Pubic arch

Anterior inferior iliac spine

Anterior superior iliac spine

Pubic tubercle

(a) Pelvic girdle

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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

151

Coccyx

Is the tailbone Formed from 35 fused vertebrae Offers only slight support to pelvic

organs Long filament of connective tissue (filum

terminale) attaches to coccyx which helps anchor spinal cord in place

152

Fontanelles Fontanelles are unossified remnants of

membranes present at birth Anterior, posterior, mastoid, and sphenoidal

fontanelles Allows skull to be safely compressed and molded

as infant passes through narrow birth canal A visible arterial pulse may be seen in the

fontanelles and can look like a fountain Fontanelles tend to be replaced by bone by the

end of the 1st year, however, the anterior fontanelle may take 1.5 to 2 years to ossify and close 153

Fontanelles

Figure 7.28a

Occipital bone

Parietal bone

Anterior fontanelle

Frontal suture Frontal bone

Ossification center

(a) Superior view

Posterior fontanelle

154

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)

155

Skull and face growth

9 months of age: skull adult size 2 years of age: skull adult size 8-9 years: cranium almost adult size 6-13 years: accelerated growth of jaws,

cheekbones, large permanent teeth, nose, and paranasal sinuses

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The Axial Skeleton Throughout Life

Water content of the intervertebral discs decreases with age

By age 55, loss of a few centimeters in height is common

Thorax becomes more rigid as costal cartilage gradually ossifies

Bones lose mass with age

157

131, t4, ch7 axial skeleton _14

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