Chapter 7: The Skeleton

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Chapter 7 The Skeleton
Part A
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The Axial Skeleton

• Consists of 80 bones
• Three major regions
• Skull
• Vertebral column
• Thoracic cage

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The Axial Skeleton
Cranium
Skull
Facial bones
Clavicle
Thoracic cage (ribs and sternum)
Scapula
Sternum
Rib
Humerus
Vertebra
Vertebral column
Radius
Ulna
Sacrum
Carpals
Phalanges
Metacarpals
Femur
Patella
Tibia
Fibula
Tarsals
Metatarsals
(a) Anterior view
Phalanges
Figure 7.1a
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The Skull

• Two sets of bones
• Cranial bones
• Enclose the brain in the cranial cavity
• Gives attachment sites for head and neck muscles
• Facial bones
• Framework of face
• Contains cavities for the special sense organs of
  sight, taste, and smell
• Provides openings for the passage of air and food
• Secures the teeth
• Anchors the facial muscles of expression, which
  we use to show emotion

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Bones of cranium (cranial vault)
Coronal suture
Squamous suture
Facial bones
Lambdoid suture
(a) Cranial and facial divisions of the skull
Figure 7.2a
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Cranial Bones

• Occipital bone
• Parietal bones (2)
• Frontal bone
• Temporal bones (2)
• Ethmoid bone
• Sphenoid bone
• Remember
• Old P-People From T-Texas Eat Spiders

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Frontal bone
Parietal bone
Nasal bone
Sphenoid bone (greater wing)
Temporal bone
Ethmoid bone
Lacrimal bone
Ethmoid bone
Zygomatic bone
Maxilla
Mandible
Vomer
(a) Anterior view
Mandibular symphysis
Figure 7.4a
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Parietal Bones and Major Associated Sutures

• Superior and lateral aspects of cranial vault
• Four sutures mark the articulations of parietal
  bones with frontal, occipital, and temporal
  bones
• Coronal suturebetween parietal bones and frontal
  bone
• Sagittal suturebetween right and left parietal
  bones
• Lambdoid suturebetween parietal bones and
  occipital bone
• Squamous (squamosal) suturesbetween parietal and
  temporal bones on each side of skull

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Frontal bone
Coronal suture
Sphenoid bone (greater wing)
Parietal bone
Ethmoid bone
Temporal bone
Lacrimal bone
Lambdoid suture
Squamous suture
Nasal bone
Occipital bone
Zygomatic bone
Zygomatic process
Maxilla
Occipitomastoid suture
Mandible
(a) External anatomy of the right side of the
skull
Figure 7.5a
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Occipital Bone

• Most of skulls posterior wall and posterior
  cranial fossa
• Contains the foramen magnum large hole through
  which the brain connects with the spinal cord
• Articulates at the occipital condyles with 1st
  vertebra
• Sites of attachment for the many neck and back
  muscles

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Sagittal suture
Parietal bone
Sutural bone
Lambdoid suture
Occipital bone
Occipitomastoid suture
(b) Posterior view
Figure 7.4b
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Maxilla
Intermaxillary suture
Palatine bone
Median palatine suture
Maxilla
Zygomatic bone
Sphenoid bone (greater wing)
Temporal bone (zygomatic process)
Vomer
Temporal bone
Parietal bone
Foramen magnum
(a) Inferior view of the skull (mandible removed)
Figure 7.6a
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Temporal Bones

• Inferolateral aspects of skull and parts of
  cranial floor
• Contains the zygomatic process, external acoustic
  meatus, the styloid process, and the mastoid
  process
• Articulates with the mandible
• at the TMJ

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Sphenoid Bone

• Complex, butterfly-shaped bone
• Keystone bone
• Articulates with all other cranial bones
• Three pairs of processes
• Contains the sella turcica and the hypophyseal
  fossa that surround the pituitary gland

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Ethmoid Bone

• Deepest skull bone
• Superior part of nasal septum, roof of nasal
  cavities
• Contributes to medial wall of orbits
• Contains the superior and middle nasal conchae
• Contains the crista galli (roosters comb)
• The attachment site for the outermost covering of
  the brain

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Figure 7.10
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Sutural Bones

• Tiny irregularly shaped bones that appear within
  sutures
• http//www.sciencekids.co.nz/videos/humanbody/skul
  lbones.html

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Sagittal suture
Parietal bone
Sutural bone
Lambdoid suture
Occipital bone
Occipitomastoid suture
(b) Posterior view
Figure 7.4b
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Facial Bones (14 Total)

• Unpaired Bones
• Mandible
• Vomer

• Paired Bones
• Maxillary bones (2)
• Zygomatic bones (2)
• Nasal bones (2)
• Lacrimal bones (2)
• Palatine bones (2)
• Inferior nasal Conchae (2)

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Mandible

• Lower jaw
• Largest, strongest bone of face
• Articulates at the temporomandibular joint (TMJ)
  only freely movable joint in skull

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Temporomandibular joint
Ramus of mandible
Mandibular angle
Body of mandible
(a) Mandible, right lateral view
Figure 7.11a
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Maxillary Bones

• Medially fused to form upper jaw and central
  portion of facial skeleton
• Keystone bone of the facial bones all facial
  bones except the mandible articulate with it

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Zygomatic Bones

• Cheekbones
• Inferolateral margins of orbits
• Articulates with 3 separate zygomatic processes
• Frontal zygomatic process
• Maxillary zygomatic process
• Temporal zygomatic process

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Nasal Bones and Lacrimal Bones

• Nasal bones
• Form bridge of nose
• Attach to the cartilage that forms most of the
  skeleton of the nose
• Lacrimal bones
• In medial walls of orbits
• Forms part of the canal that drains tears into
  the nasal cavity
• Lacrimation crying/tear production

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Frontal bone
Parietal bone
Nasal bone
Sphenoid bone (greater wing)
Temporal bone
Ethmoid bone
Lacrimal bone
Ethmoid bone
Zygomatic bone
Maxilla
Mandible
Vomer
(a) Anterior view
Mandibular symphysis
Figure 7.4a
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Palatine Bones and Vomer

• Palatine bones
• Posterior one-third of hard palate
• Posterolateral walls of the nasal cavity
• Small part of the orbits

• Vomer
• Plow shaped
• Lower part of nasal septum

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Maxilla
Intermaxillary suture
Palatine bone
Median palatine suture
Maxilla
Zygomatic bone
Sphenoid bone (greater wing)
Temporal bone (zygomatic process)
Vomer
Temporal bone
Parietal bone
Foramen magnum
(a) Inferior view of the skull (mandible removed)
Figure 7.6a
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Orbits

• Encase eyes and lacrimal glands
• Sites of attachment for eye muscles
• Formed by parts of seven bones
• Frontal bones
• Zygomatic
• Sphenoid bones
• Palatine
• Ethmoid
• Lacrimal
• Maxilla

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Roof of orbit
Lesser wing ofsphenoid bone
Orbital plate offrontal bone
Medial wall
Sphenoid body
Lateral wall of orbit
Orbital plateof ethmoid bone
Zygomatic processof frontal bone
Greater wing ofsphenoid bone
Lacrimal bone
Orbital surface ofzygomatic bone
Nasal bone
Floor of orbit
Zygomatic bone
Orbital surface ofmaxillary bone
Zygomatic bone
(b) Contribution of each of the seven bones
forming the right orbit
Figure 7.13a
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Nasal Cavity

• Roof, lateral walls, and floor formed by parts of
  four bones
• Ethmoid
• Palatine bones
• Maxillary bones
• Inferior nasal conchae
• Nasal septum of bone and hyaline cartilage
• Ethmoid
• Vomer
• Anterior septal cartilage

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Frontal sinus
Ethmoid bone
Nasal bone
Maxillary bone (palatine process)
Sphenoid bone
Palatine bone (perpendicular plate)
Palatine bone (horizontal plate)
(a) Bones forming the left lateral wall of the
nasal cavity (nasal septum removed)
Figure 7.14a
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Paranasal Sinuses

• Mucosa-lined, air-filled spaces
• Lighten the skull
• Enhance resonance of voice
• Found in frontal, sphenoid, ethmoid, and
  maxillary bones

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Frontal sinus
Frontal sinus
Ethmoidal air cells (sinus)
Ethmoidal air cells
Sphenoid sinus
Sphenoid sinus
Maxillary sinus
Maxillary sinus
(b) Medial aspect
(a) Anterior aspect
Figure 7.15
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Hyoid Bone

• Not a bone of the skull
• Does not articulate directly with another bone
• Site of attachment for muscles of swallowing and
  speech

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Developmental Aspects of the Skull

• At birth, the newborns skull not fully
  developed and sutures
• have not yet fused
• Allows for head compression during birth
• Allows for brain growth in the infant
• Unossified regions are covered with fibrous
  membranes called
• fontanelles little fountains
• Anterior fontanelle is present until 1-1/2 2
  years of age

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Homeostatic Imbalance of the Skull
The Cleft Lip and Palate Caused by right and
left halves of the palate failing to fuse
medially Leads to difficulties
feeding/nursing Risk for aspiration (inhalation)
pneumonia
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Review Slides
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