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THE SKELETON. CHAPTER 7 9/30/2007. Introduction . A strong, yet light, internal support for the human body The skeleton is adapted for the protection, locomotor, and manipulative functions The upright stance increases the ability of the skeletal muscle to resist gravity. Introduction .

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the skeleton

THE SKELETON

CHAPTER 7

9/30/2007

introduction
Introduction
  • A strong, yet light, internal support for the human body
  • The skeleton is adapted for the protection, locomotor, and manipulative functions
  • The upright stance increases the ability of the skeletal muscle to resist gravity
introduction3
Introduction
  • The skeleton maintains its upright position through a series of compensating curves
  • The skeleton accounts for approximately 20% of the body mass
  • The 206 bones of the body are grouped into the axial and appendicular skeleton
introduction4
Axial skeleton

Forms the long axis of the body

80 bones in three major regions

Skull

Vertebral column

Bony thorax

Ribs

Sternum

Appendicular

Bones of upper & lower extremities and girdles

126 bones in three major regions

Girdles

Shoulder girdle

Pelvic girdle

Upper extremity

Lower extremity

Introduction
the skull

THE SKULL

SECTION I

the skull8
The Skull
  • The skull is the body’s most complex bony structure
  • It is formed by two sets of bones, the 8 cranial bones and the 14 facial bones
  • These 22 bones combine to form the cranial cavity and the facial features
  • In addition, there are 3 bones in each inner ear to assist in sound transmission
the skull introduction
The Skull: Introduction
  • The bones of the skull provide . . .
    • A case to house the brain, the cranium
    • A framework for the face
    • Cavities to house the organs of sight, taste, and smell
    • Passages for air and food
    • Attachment sites for the teeth
    • Attachment sites for muscle
the skull introduction10
The Skull: Introduction
  • Most bones of the skull are flat bones
  • Except for the mandible, all bones are firmly united by interlocking sutures
  • The major sutures of the skull are . . .
    • Coronal (Between Frontal & Parietal)
    • Sagittal (Between Parietal bones)
    • Squamosal (Between Parietal & Temporal)
    • Lambdoidal (Between Parietal & Occipital)
  • Other skull sutures connect facial bones and are named after these structures
slide11

________

________

________

Sagittal

slide12

Coronal

Lambdoid

Squamous

overview of skull geography
Overview of Skull Geography
  • Facial bones form the anterior aspect
  • The cranial bones enclose the brain
vault
Vault
  • The cranial vault or calvaria forms the superior, lateral, and posterior aspects of skull
  • The cranial base forming the inferior aspect of skull
cranial base
Cranial Base
  • Cranial base forms the skull’s inferior aspect
  • Three prominent ridges divide the base into fossae
  • The brain rests on these cranial fossae completely enclosed by the cranial vault
  • The brain occupies the cranial cavity
cavities of the skull
Cavities of the Skull
  • In addition to the large cranial cavity there are many smaller cavities
    • Middle and inner ear cavities
    • Nasal cavity
    • Orbits of the eyes
    • Several bones contain air filled sinuses
      • Sinuses surrounding the nasal cavity are referred to as the paranasal sinuses
    • The skull has about 85 named openings (foramina, canals and fissures)
cranium
Cranium
  • The 8 cranial bones include; 2 parietal, 2 temporal frontal, occipital, sphenoid, ethmoid
  • The cranium is self-bracing allowing the bones to be thin, yet strong
frontal bone
Frontal bone
  • Forms the anterior portion of the cranium, the forehead, roofs of the orbits, and most of the anterior cranial fossa
frontal bone landmarks
Frontal bone - landmarks
  • Frontal squama
  • Supraorbital margins
  • Supraorbital foramen
  • Orbits
  • Anterior cranial fossa
  • Glabella
  • Frontal sinuses
parietal bones
Parietal bones

Parietal

  • Forms most of the superior & lateral aspects of the skull
  • Articulates with other cranial bones to form four major sutures
parietal bones landmarks
Parietal bones - landmarks
  • The four largest sutures cranial sutures, Coronal, Sagittal, Lambdodial, Squamosal
occipital bone
Occipital bone
  • Articulates with parietal & temporal
occipital bone24
Occipital bone
  • Joins w/ sphenoid in the cranial floor
  • Forms internal walls of posterior cranial fossa
occipital bone ext landmarks
Occipital bone - Ext. landmarks
  • Foramen magnum, Occipital condyles, External occipital protuberance, Nuchal lines, External occipital crest
occipital bone int landmarks
Occipital bone - Int. landmarks
  • Hypoglossal canal, Posterior cranial fossa
temporal bone
Temporal Bone
  • Forms the infero-lateral aspects of the skull
  • Parts of the cranial floor
  • Divided into four regions; squamous tympanic, mastoid, and petrous-(int)
temporal bone28
Temporal Bone
  • The internal petrous region contributes to the cranial base
  • The petrous region and the sphenoid bone form the middle cranial fossa
temporal bone landmarks
Temporal Bone - landmarks
  • Zygomatic process
    • Meets the zygomatic bone
    • Forms the cheek
  • Mandibular fossa
    • Receives condyle of mandible
temporal bone landmarks30
Temporal Bone - landmarks
  • External Auditory Meatus
    • Middle and inner ear
  • Styloid process
    • Muscle of tongue
  • Mastoid process
    • Muscles of neck
temporal bones landmarks
Temporal bones - landmarks
  • Jugular foramen
    • Entry point for the Jugular artery
  • Internal acoustic meatus
    • Entry point for the auditory nerve

Jugular Foramen

temporal bones landmarks32
Temporal bones - landmarks
  • Stylomastoid foramen
    • exit for facial nerve
  • Carotid canal
    • entrance for the carotid artery which supplies blood to cerebral hemispheres
sphenoid bone
Sphenoid bone
  • Bone spanning the width of middle cranial fossa
  • Articulates as central wedge of all cranial bones
  • Consists of central body and three processes; greater and lesser wings and pterygoid process (pos. view)
sphenoid landmarks
Sphenoid - landmarks
  • Sella turcica (enclosure for pituitary gland)
  • Optic foramina (passage of optic nerves)
  • Superior orbital fissure (Nerves III, IV, V enter orbit)
  • Foramen rotundum & ovale (Cranial Nerve V to face)
  • Foramen spinosum (Middle meningeal artery)
ethmoid bone
Ethmoid bone
  • Forms most of the area between the nasal cavity & orbits of eyes
  • Lies between nasal bones & sphenoid
  • Complex shape gives rise to nasal septum, sinuses and cribiform plate
ethmoid bone landmarks
Ethmoid bone - landmarks
  • Cribiform plates
    • Forms roof of nasal cavity
  • Olfactory formina
    • Olfactory nerves enter brain
  • Crista galli
    • Attachment of the dura mater which secures brain in cavity
ethmoid bone landmarks37
Ethmoid bone - landmarks
  • Perpendicular plate
    • Forms superior part of nasal septum
  • Lateral mass
    • House ethmoid sinuses
  • Nasal concha
    • Project into nasal cavity
  • Orbital plates
    • Medial walls of orbits
facial bones
Facial bones
  • Consists of 14 bones w/ only mandible and vomer unpaired
  • Others include maxillae, lacrimals, nasals, zygomatics, inferior nasal conchae, and palatines (not pictured)
mandible
Mandible
  • Forms the lower jaw
  • Largest, strongest bone of the face
  • It has a body and two upwardly projecting sections called rami
  • Houses lower dentition
mandible landmarks
Mandible - landmarks
  • Mandibular angle
  • Mandibular notch
  • Coronoid process
  • Mandibular condyle
  • Alveolar margin
  • Mandible formina
  • Mental formina
  • Ramus of mandible
maxillary bone
Maxillary bone
  • Forms upper jaw and central portion of facial skeleton
  • Fused medially
  • Articulates with all facial bones except mandible
  • Upper dentition
  • Forms 2/3 of hard palate of the mouth

Zygomatic

process

Maxillary

bone

maxillary bones landmarks
Maxillary bones - landmarks
  • Alveolar margin
    • Upper dentition
  • Frontal process
    • Forms lateral aspects of nose
  • Zygomatic process
    • Articulates with zygomatic bone
  • Maxillary sinuses
    • (Fig. 7.11)
maxillary bones landmarks43
Maxillary bones - landmarks

Palatine Process

  • Palatine processes
    • Forms roof of mouth
  • Incisive fossa
    • Passage of nerves and blood vessels
  • Infraorbital foramen
    • Infraorbital nerve and blood vessel to face
maxillary bones landmarks44
Maxillary bones - landmarks
  • Inferior orbital fissure
    • Located deep within the orbit
    • Permits passage of the zygomatic nerve, maxillary nerve, and blood vessels to reach face
zygomatic bones
Zygomatic bones
  • Commonly called the cheekbones
  • Form prominences of cheeks and inferolateral margins of orbits
  • Articulate with the Zygomatic process of temporal bone and Zygomatic process of maxallae

Zygomatic

Process of

Temporal

Zygomatic

bone

nasal bones
Nasal bones
  • Forms bridge of the nose
  • Thin, rectangular shape
  • Fused medially
  • Articulate with the frontal bone and maxillary bones laterally
  • Nasal cartilages
lacrimal bones
Lacrimal Bones
  • Forms part of the medial border of each orbit
  • Articulates with frontal, ethmoid & maxillae
  • Forms part of Lacrimal fossa
    • Permits tears to drain from orbit to nasal cavity
lacrimal bones48
Lacrimal Bones
  • Lacrimal fossa
    • Permits tears to drain from orbit to nasal cavity
palatine bones
Palatine bones
  • The horizontal plates forms the posterior portion of hard palate
  • Vertical plate forms part of the posterolateral wall of nasal cavity and a small portion of orbit
palatine bones landmarks
Palatine bones - landmarks
  • Horizontal plate
    • Posterior section of hard palate
  • Vertical plate
    • Part of the posteriolateral walls of nasal cavity
  • Orbital surface
    • Part of inferior medial aspect of orbit
vomer
Vomer
  • Forms part of the nasal septum
  • Discussed with the nasal cavity
vomer landmarks
Vomer - landmarks
  • Plow shape
    • Divides nasal septum into right and left parts
inferior nasal conchae
Inferior Nasal Conchae
  • Form lateral walls of nasal cavity
  • Project medially from the lateral walls of nasal cavity
  • Largest of nasal conchae
inferior nasal conchae landmark
Inferior Nasal Conchae - Landmark
  • The Inferior nasal conchae is just one of three in the nasal cavity
  • Superior and middle concha are on the Ethmoid bone
nasal cavity
Nasal cavity
  • The nasal cavity is constructed of bone and hyaline cartilage
  • The cavity is divided into right and left parts by the nasal septum
  • Superior, middle and inferior nasal concha project into the cavity
  • The nasal septum and conchae are lined with mucus-secreting mucosa
nasal cavity60
Nasal cavity
  • Roof of the cavity is the cribriform plates of ethmoid
  • Lateral walls are the superior, middle, and inferior conchae, and vertical plates of palatines
nasal cavity61
Nasal cavity
  • Floor of cavity is formed by palatine processes of the maxillae and the palatine bones
  • Septum is formed by vomer and the perpendicular plate of ethmoid

Palatine

the orbits
The Orbits
  • The orbits are bony cavities within which the eyes are encased and cushioned by fatty tissue
  • The muscles that move the eyes and the tear producing lacrimal glands are housed within the orbit
  • Formed by frontal, sphenoid, maxilla, zygomatic, lacrimal, palatine & ethmoid
  • Contain superior & inferior orbital fissures
  • Optic foramina
paranasal sinuses
Paranasal sinuses
  • Five skull bones; frontal, sphenoid, ethmoid, and the paired maxillary contain mucus-lined, air-filled sinuses
  • Cluster around nasal cavity
  • Connected to nasal cavity to allow air to enter and mucus to drain
  • Lighten skull, warm and humidify air, enhance voice resonance
paranasal sinuses65
Paranasal sinuses
  • Note positioning around nasal cavity
paranasal sinuses66
Paranasal sinuses
  • Sphenoid sinus
  • Frontal sinus
  • Ethmoidal air cells
  • Maxillary sinuses
hyoid bone
Hyoid bone
  • Not really a part of the skull, it is unique in that it is the only bone that does not articulate with any other bone
  • Positioned just inferior to the mandible
  • Anchored by stylohyoid ligaments to the styloid processes of temporal bone
  • Acts as a movable base for the tongue
hyoid bone68
Hyoid bone
  • Body
    • Neck muscle attachment
  • Greater horn
    • Neck muscle attachment
  • Lesser horn
vertebral column general characteristics
Vertebral Column:General Characteristics
  • Formed from 26 irregular bones in adult
  • It contains four distinct curvatures
  • It provide axial support for the trunk
  • Transmits weight of trunk to lower limbs
  • Protects spinal cord
  • Attachment site for ribs and muscles
  • Separated by intervertebral discs
  • There are 24 vertebrae, a sacrum (5 fused) and a coccyx (4 fused)
general characteristics
General Characteristics
  • Alignment
    • Anterior/ posterior
    • Lateral
  • Curvatures
    • Compensatory curves
  • Features
    • Weight bearing
    • Muscle attachment
    • Protection
regional characteristics
RegionalCharacteristics
  • Cervical C1-C7
    • Neck / movable
  • Thorasic T1-T12
    • Rib cage / limited movement
  • Lumbar L1-L5
    • Low back / movable
  • Sacral 5 fused
    • Joins the pelvis
  • Coccyx 4 fused
    • Terminus
characteristics ligaments
Characteristics - Ligaments
  • Ligaments hold the vertebral column in an upright position
    • The broad Anterior Longitudinal Ligament prevents hyperextension and is quite strong
    • The cord like Posterior Longitudinal Ligament prevents hyperflexion and is relatively weak
characteristics ligaments74
Characteristics - Ligaments
  • Ligaments also connect specific vertebra and support disc position
    • Supraspinos ligament
    • Ligamentum flavum
    • Interspinous ligament
characteristics ligaments75
Characteristics - Ligaments
  • The ligamentum flavum connects the lamina of adjacent vertebrae
  • The ligamentum flavum contains significant amount of elastic fibers and is especially strong
  • The ligament stretches forward, then recoils as we straighten to an erect position
intervertebral discs
Intervertebral Discs
  • Intervertebral discs are cushion like pads interposed between vertebra
  • The discs provide compressibility of the spine and resist tension on the spine
  • Compression flattens discs
  • Discs are thickest in the cervical and lumbar regions to which improves flexibility
intervertebral discs77
Intervertebral Discs
  • Discs are pads positioned between vertebral bodies
  • Two components
    • Anulus fibrosus
    • Nucleus pulposus
intervertebral discs78
Intervertebral Discs
  • Nucleus pulposus is the gelatinous mass that enables the spine to absorb compressive stress
  • The Anulus fibrosus has an outer ring consisting of ligamentous tissue and an inner ring consisting of fibrocartilage
    • Functions to contain the nucleus pulposus during compression
    • Collagen fibers are organized similar to fibers in osteons forming X’s that resist twisting
characteristics discs
Characteristics - discs
  • Anulus fibrosus surrounds the outer margin
  • Nucleus pulposus can shift under pressure
  • Herniated or prolapsed disc typically occurs posteriolaterally compressing nerve roots

Herniation

of disk

characteristics discs80
Characteristics - discs
  • MRI of lumbar region showing normal and herniated discs
  • Note the posterior displacement
normal curvatures
Normal Curvatures
  • Cervical and lumbar are concave
  • Thoracic and are sacral are convex
  • Curves increase spinal resiliency
  • Primary curvatures
    • Thoracic and sacral
  • Secondary curvatures
    • Cervical and lumbar
slide82

Curves develop in response to:

Upright posture

Weight bearing

Musculature

general structure of vertebrae
General structure of vertebrae
  • Common pattern
    • Body or centrum
    • Vertebral arch
      • lamina
      • pedicle
    • Vertebral foramen
      • Passage for spinal cord
general structure of vertebrae84
General structure of vertebrae
  • Seven different processes project from each arch
    • Spinous process
    • Transverse process
    • Superior and inferior articular processes
    • Facets
general structure of vertebrae85
General structure of vertebrae

Superior Articular

Process

  • Interlocking pattern
    • Superior and inferior processes interlock
    • The inferior from above and the superior from the vertebrae below form a movable joint
    • The movement contributes to spinal rotation
general structure
General structure
  • Pedicles have notches on their superior and inferior borders
  • Lateral openings are called intervertebral foramen
    • Spinal nerves from spinal cord exit through these foramina
regional characteristic cervical
Regional Characteristic: Cervical
  • Body is oval, but wide side to side C3 - C7
  • Spinous process is short and bifid (split) except in C7
  • Vertebral foramen is triangular
  • Transverse processes contain foramina for blood vessels leading to brain
cervical vertebrae c1 and c2
Cervical Vertebrae C1 and C2
  • The first two cervical vertebrae are named the atlas and axis respectively
  • There is no intervertebral disc between them
  • They are highly modified for carrying the skull on top of the vertebral column
  • The atlas (C1) functions as a cradle to support the head
  • The axis (C2) functions as a pivot point for the rotation of the atlas
cervical vertebrae c1
Cervical Vertebrae C1
  • Lateral masses articulates with the occipital condyles of the skull
cervical vertebrae c190
Cervical Vertebrae C1

Body of the

Vertebrae is

missing

  • Inferior articular surface articulates with C2 below
cervical vertebrae c2
Cervical Vertebrae C2
  • The axis has the odontoid process or dens is its unique feature
  • The dens is the missing body of the atlas which fuses with the atlas during embryonic development
regional characteristic cervical92
Regional Characteristic: Cervical
  • Spinous processes project directly posteriorly
  • Superior facets directed superoposteriorly
  • Inferior facets directed inferoanteriorly
  • Flexion/extension, lateral flexion and rotation
regional characteristic thoracic
Regional Characteristic: Thoracic
  • Body is larger than cervical; heart shaped
  • Spinous process is long and sharp
  • Vertebral foramen is circular
  • Transverse processes project posteriorly and bear facets for ribs
regional characteristic thoracic94
Regional Characteristic: Thoracic
  • Body bears two costal demifacets
  • Spinous processes projects inferiorly
  • Superior facets directed posteriorly
  • Inferior facets directed anteriorly
  • Rotation, limited lateral flexion, flexion/extension prevented
regional characteristic lumbar
Regional Characteristic: Lumbar
  • Body is massive and kidney shaped
  • Spinous processes are short and blunt
  • Vertebral foramen is triangular
  • Transverse processes are perpendicular to spinous process but has no special features
regional characteristic lumbar96
Regional Characteristic: Lumbar
  • Spinous process projects posteriorly
  • Superior facets directed medially
  • Inferior facets directed laterally
  • Flexion/extension, some lateral flexion, rotation prevented
sacrum
Sacrum
  • The triangular shaped structure formed by five fused vertebrae
  • Forms the posterior wall of the pelvis
  • Articulates with L5 of the vertebral column
  • Articulates with the iliac bone of the pelvic girdle
  • Transfers the weight of the upper torso and limbs to the lower extremities
sacral
Sacral
  • Ala are fused remnants of transverse processes that articulate with hip bones to form the sacro iliac joints of the pelvis
  • Sacral promontory
    • Center of gravity is 1 cm posterior of this point
  • Transverse line are sites of vertebral fusion
  • Sacral foramina transmit blood vessels and nerves
sacral99
Sacral
  • On the posterior aspect median sacral crest are fused spinous processes
  • The vertebral canal continues inside the sacrum as the sacral canal
  • Sacral hiatus is at the inferior end of the sacral canal
  • Superior articular surface form a joint with the spinal column
coccyx
Coccyx
  • Coccyx articulates with sacrum
the bony thorax
The Bony Thorax
  • The thorax is the chest which includes
    • Thoracic vertebrae posteriorly
    • The ribs laterally
    • The sternum and costal cartilages anteriorly
  • It is cone shaped with its broad opening inferiorly
  • The thorax forms a bony cage around the heart, lungs and major blood vessels
functions of the bony thorax
Functions of The Bony Thorax
  • Protection
  • Attachment point for muscles of the back, chest, and shoulders
  • The intercostal muscles attach to the thorax to lift and depress the thorax during respiration
the sternum
The Sternum
  • The sternum lies in the anterior midline of the thorax
  • It is three fused bones
    • Manubrium
      • Jugular notch
      • Clavicular notch
    • Sternal body
      • Sternal angle
    • Xiphoid process
      • Xiphisternal joint
bony thorax
Bony Thorax
  • Thorax is the chest and its bony underpinnings is called the thoracic cage
  • Elements consist of the thoracic vertebrae, ribs, sternum, and costal cartilages which secure ribs to the sternum
  • A cone opening inferiorly, the thorax provides a protective cage around the vital organs of the thoracic cavity (heart, lungs, great blood vessels)
bony thorax continued
Bony Thorax - continued
  • Provides support for the shoulder girdles
  • Bony attachment points for muscles of the back, chest and shoulders
  • Intercostal spaces between ribs are occupied by the intercostal muscles which lift and depress the thorax during breathing
sternum
Sternum
  • Located on the anterior midline of the thorax
  • Consists of three fused bones; manubrium, body, and xiphoid process
  • Manibrium articulates with clavicle & 2 ribs
  • Body with ribs 2 - 7
  • Xiphoid attachment site for abdominal muscle
slide110
Ribs
  • Twelve pairs forming thoracic cage
  • All attach posteriorly to thoracic vertebrae
  • Curve inferiorly toward anterior body surface
  • Ribs 1-7 attach directly to sternum by separate costal cartilages and are referred to as true ribs
  • Ribs 8-10 attach indirectly to sternum by attaching to costal cartilages immediately above
  • Ribs 11-12 have no anterior attachments and are referred to as floating ribs
slide111
Ribs
  • Ribs are bowed flat bones
  • Long shaft
  • Tear drop shaped with a costal groove on inner surface
  • Head of rib has 2 facets to articulate with its vertebrae as well as the one above
slide112
Ribs
  • Neck is just beyond the head
  • Angle of rib
  • Costal cartilages attach rib to sternum
  • Attachments are secure but flexible
slide113
Ribs
  • Tubercle of rib articulates with transverse process
  • Ligaments secure rib to transverse process
  • Note how the transverse processes of thoracic vertebrae are angled posteriorly
abnormal curvatures
Abnormal Curvatures
  • Scoliosis
    • An abnormal lateral curvature of the spinal column
    • Curvature can occur in an “S” or “C” deviation
abnormal curvatures116
Abnormal Curvatures
  • Kyphosis
    • An exaggerated dorsal curvature in the dorsal region
    • Common is aged individuals because of osteoporosis
abnormal curvatures117
Abnormal Curvatures
  • Lordosis
    • Accentuated lumbar curvature
    • Being overweight or pregnant causes an excessive load up front
the axial skeleton throughout life
The Axial Skeleton Throughout Life
  • Fontanels
  • Cleft palate
  • Adult Skeletal Changes
the axial skeleton throughout life122
The Axial Skeleton Throughout Life
  • Discs become thinner and more prone to herniation
  • Loss of a few centimeters of height
  • Osteoporosis
  • Rigid thorax (costal cartilage ossification) restricts breathing
  • Loss of bone mass in facial bones
ad