Docstoc

The Skeleton The Skull The Cranial Bones Cranial Bones The Frontal

Document Sample
The Skeleton The Skull The Cranial Bones Cranial Bones The Frontal Powered By Docstoc
					Lecture 5 - Bones Part 1 - Axial Skeleton




         The Skeleton                                            The Skull
                                                                   Formed by cranial and facial bones
           Consists of bones, cartilage,
           joints, and ligaments                                                                               Frontal bone
                                                                     Parietal bone                             Glabella
           Composed of 206 named
           bones grouped into two
           divisions:
                                                                     Nasal bone
                                                                     Sphenoid bone                             Superior orbital fissure
              Axial skeleton (80 bones)                              (greater wing)
                                                                     Temporal bone
              Appendicular skeleton                                  Ethmoid bone
                                                                                                               Inferior orbital fissure
                                                                     Lacrimal bone
              (126 bones)                                            Zygomatic bone
                                                                  Infraorbital foramen                         Middle nasal concha Ethmoid
           Axial skeleton:                                            Maxilla
                                                                                                               Perpendicular plate bone
                                                                                                               Inferior nasal concha
               consists of a skull,                                                                            Vomer bone
              vertebral column, and                                  Mandible

              bony thorax




              The Cranial Bones                                          Cranial Bones
                 The cranium serves to:                                         Formed from eight large bones
                    Enclose & protect the brain                                      Paired bones (2)
                                                                                         Temporal bones (x2)
                    Provide attachment sites for some head
                                                                                         Parietal bones (x2)
                    and neck muscles
                                                                                     Unpaired bones include (4)
                 Facial bones form anterior aspect                                       Frontal bone
                 Cranium is divided into two parts:                                      Occipital bone
                                                                                         Sphenoid bone
                    cranial vault and the base
                                                                                         Ethmoid bone

                                                             3                                                                            4




                                                                         Parietal Bones and Sutures
              The Frontal Bone
                                                                      Parietal bones (paired) form superior and
             Forms the forehead and roofs of the orbits               lateral parts of the skull
                                                                      There are four sutures of the cranium
             Forms superciliary arches
                                                                           Coronal suture – runs in the coronal plane
             Contains frontal sinuses                                           Located where parietal bones meet the frontal bone


             Contains supraorbital foramen                                 Squamous suture – occurs where each
                                                                           parietal bone meets a temporal bone inferiorly
             Unpaired

                                                             5




                                                                                                                                              1
Lecture 5 - Bones Part 1 - Axial Skeleton




             Parietal Bones and Sutures
                                                                      The Occipital Bone
               Sagittal suture – occurs where right and
               left parietal bones meet superiorly                       Forms the posterior portion of the
                                                                         cranium and cranial base
               Lambdoid suture – occurs where the
               parietal bones meet the occipital bone
                                                                         Articulates with the temporal bones and
               posteriorly                                               parietal bones

                                                                         Foramen magnum located at its base


                                                                                                                                8




                                                                                                    Sagittal suture


                                                                                                             Parietal bone


             The Occipital Bone
               Features and structures                            Lambdoid

                 Occipital condyles - Articulate with the first
                                                                  suture


                 vertebra of the vertebral column                 Occipital bone


                 External occipital protuberance (EOP) –
                 Site of muscle attachment
                                                                  External
                                                                  occipital                                           Mastoid
                                                                  protuberance                                        process



                                                                                            Occipital
                                                                                            condyle
                                                             9




                                                                  Temporal Bones
             Temporal Bones
             Lie inferior to parietal bones

             Form the inferolateral portion of the skull

             Specific regions of temporal bone
               Squamous, tympanic, petrous (rock),
               and mastoid regions

                                                            11




                                                                                                                                    2
Lecture 5 - Bones Part 1 - Axial Skeleton




        Coronal suture

                                                                                             The Sphenoid Bone
                                                                        Frontal bone
          Parietal bone                                                 Sphenoid bone
                                                                        (greater wing)
                                                                        Ethmoid bone
          Temporal bone

                                                                                                Spans the width of the cranial floor
                                                                        Lacrimal bone
         Lambdoid
         suture

        Squamous suture
         Occipital bone
                                                                        Nasal bone              Resembles a butterfly or bat
        Zygomatic process                                               Zygomatic bone
                                                                        Maxilla                 Consists of a body and three pairs of
                                                                                                processes
        External acoustic meatus
                 Mastoid process
                     Styloid process


                                                                                                Unpaired
                            Mandibular condyle
                                                                    Mandible


                                                 Mandibular angle


                                                                                                                                               14




             The Sphenoid Bone                                                            The Sphenoid Bone




                                                                                         Bones of the nasal cavity.
                     The Ethmoid Bone                                                                      Crista galli
                                                                                                   Ethmoid Cribriform       Frontal sinus
                                                                                                   bone    plate

                      It lies between the nasal & the                                        Sella turcica

                      sphenoid bones
                                                                                                                            Nasal bone

                                                                                            Sphenoid sinus                  Perpendicular plate
                                                                                                                            of ethmoid bone

                      Forms most of the medial bony region                                                                  Septal cartilage

                      between the nasal cavity and orbits                                        Palatine bone
                                                                                                                            Vomer




                                                                                17




                                                                                                                                                    3
Lecture 5 - Bones Part 1 - Axial Skeleton




                The Facial Bones                                                            Maxillary Bones
                    Unpaired bones (2)                                                         Articulate with all other facial bones
                         Mandible and Vomer                                                    except the mandible
                     a ed bo es
                    Paired bones (6)
                         Maxillae (x2)
                                                                                               Contain maxillary sinuses – largest
                         Zygomatic bones (x2)
                                                                                               paranasal sinuses
                         Nasal bones (x2)
                         Lacrimal bones (x2)
                         Palatine bones (x2)                                                   Contains the palatine process
                         Inferior nasal conchae (x2)
                                                                              19                                                                    20




         Maxillary Bone
                                                        Frontal sinus                       Other Bones of the Face
                                                        Superior        Ethmoid bone
                                                        nasal concha
                                                        Middle
                                                        nasal concha
                                                                                           Zygomatic bones
                                                                                               Form lateral wall of orbits
                                                        Inferior nasal concha
                                                        Nasal bone




                                                                                           Nasal bones
                                                        Maxillary bone                         Form bridge of nose
                                                        (palatine process)
                    Sphenoid sinus
         Sphenoid

                                                                                           Lacrimal bones
         bone       Pterygoid process

                                        Palatine bone
                                                                                               Located in the medial orbital walls
                                                                                                                                                    22




                                                                                       Mandible: Largest and strongest facial bone

                Other Bones of the Face
                Palatine bones
                    Complete the posterior part of the hard palate
                                                                                                                       Mandibular

                Vomer
                                                                                                                       fossa of
                                                                                            Temporomandibular joint
                                                                                                                       temporal bone

                    Forms the inferior part of the nasal septum
                                                                                                 Mandibular

                Inferior nasal conchae
                                                                                                 condyle


                    Thin, curved bones that project medially form the
                    lateral walls of the nasal cavity

                                                                                                          Mandibular
                                                                                                                                       Mental Foramen
                                                                                                          angle
                                                                              23




                                                                                                                                                         4
Lecture 5 - Bones Part 1 - Axial Skeleton




         The Skull
                                       Frontal bone
                                                                         Paranasal Sinuses
           Parietal bone

                                                                           Air-filled sinuses are located within
           Nasal bone                                                         Frontal bone
           Sphenoid bone
           (greater wing)                                                     Ethmoid bone
           Temporal bone
           Ethmoid bone
           Lacrimal bone
                                                                              Sphenoid bone
           Zygomatic bone
                                       Middle nasal concha Ethmoid
                                                                              Maxillary bones
            Maxilla
                                       Perpendicular plate
                                       Inferior nasal concha
                                                             bone
                                                                           Lined with mucous membrane
           Mandible
                                       Vomer bone
                                                                           Serve to lighten the skull

                                                                                                                   26




                                                                         The Hyoid Bone
                                                                     Lies inferior to the
                                                                     mandible
                                                                     The only bone with
                                                                     no direct articulation
                                                                     with any other bone
                                                                     Serves as attachment
                                                                     for tongue neck
                                                                     muscles

                                                                                                                   28




               The Vertebral Column
            Formed from 26 bones                                         Intervertebral Discs
            in the adult
                                                                           Cushion-like pads between vertebrae
            Transmits weight of
            trunk to the lower limbs
            Serves as attachment                                           Act as shock absorbers
            sites for muscles of the
            neck and back
                                                                           Compose about 25% of height of
            Surrounds and protects                                         vertebral column
            the spinal cord


                                                                                                                   30




                                                                                                                        5
Lecture 5 - Bones Part 1 - Axial Skeleton




           Vertebral Column
          About 28 inches long
                                                                                 Normal Curvatures
          Divided into five major regions
            Cervical vertebrae                                                   Four distinct curvatures give vertebral
               7 vertebrae of the neck region
                                                                                 column an S-shape
            Thoracic vertebrae
               12 vertebrae of the thoracic region                                 Cervical and lumbar curvature
            Lumbar vertebrae                                                          Are concave posteriorly (Lordosis)
               5 vertebrae of the lower back                                       Thoracic and sacral curvatures
            Sacrum                                                                    Are convex posteriorly (Kyphosis)
               Inferior to lumbar vertebrae (5 Segments that fuse)
            Coccyx
               Most inferior region of vertebral column (4 Segments that fuse)
                                                                                 Curvatures increase resilience of the spine

                                                                                                                                  32




         General Structure of a Vertebrae
                                                                                 Cervical Vertebrae
                                                                                 Seven cervical vertebrae (C1 – C7) – smallest
                                                                                 and lightest vertebrae

                                                                                             typical   i l     t b
                                                                                 C3 – C7 are t i l cervical vertebrae
                                                                                   Spinous processes are short and bifid (except C7)

                                                                                   Vertebral foramen are large and triangular

                                                                                   Transverse processes contain transverse foramina


                                                                                                                                  34




             Cervical Vertebrae                                                  Cervical Vertebrae




                                                                                                                                       6
Lecture 5 - Bones Part 1 - Axial Skeleton




                                                                    The Atlas
             The Atlas (C1)                                         C1              Posterior
                                                                    C2
                C1 is termed the atlas
                Lacks a body and spinous process
                Supports the skull                                                                            Transverse
                                                                                                              foramen
                  Superior articular facets receive the
                  occipital condyles
                Allows flexion and extension of neck                                                       Superior articular
                                                                                                           facet
                  Nodding the head “yes”                                             Anterior

                                                                         (a) Superior view of atlas (C1)

                                                             37




                                                                    The Axis
             The Axis (C2)
           Has a body and spinous process

                p j        p      y
           Dens 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 head from side to side
                The action of saying “No”
                                                             39




                                                                    Thoracic Vertebrae
             Thoracic Vertebrae (T1 – T12)
          All articulate with ribs
          Have heart-shaped bodies
          Each side of the body bears facets for
          articulation with ribs
          Transverse processes articulate with ribs
          Spinous processes are long and point
          inferiorly

                                                             41




                                                                                                                                7
Lecture 5 - Bones Part 1 - Axial Skeleton




                                                               Lumbar Vertebrae
             Lumbar Vertebrae (L1 – L5)
            Bodies are thick and robust

            Transverse processes are thin & tapered

            Spinous processes are thick, blunt, and
            point posteriorly

            Vertebral foramina are triangular


                                                          43




                                                               Sacrum
                                                                                               Sacral promontory

             Sacrum (S1 – S5)                                                                                Ala



             Formed from 5 fused vertebrae
             Superior surface articulates with L5
             Inferiorly articulates with coccyx
             Sacral promontory
               Where the first sacral vertebrae bulges into
                                                                                                     Sacral
               pelvic cavity                                             Apex
                                                                                                     foramina

                                                                                                    Coccyx


                                                          45                    (a) Anterior view




             Sacrum
                     Ala
                                                               Coccyx
                                                                Is the “tailbone”

                                                                Formed from 3 – 5 fused vertebrae
                 ed a
                Median
                Sacral crest


                      Sacral
                      foramina


                           Coccyx


                                 (b) Posterior view
                                                                                                                   48




                                                                                                                        8
Lecture 5 - Bones Part 1 - Axial Skeleton




                                                                           The Bony Thorax
             Bony Thorax
               Forms the framework of the chest
               Components of the bony thorax
                                      p         y
                 Thoracic vertebrae – posteriorly
                 Ribs – laterally
                 Sternum and costal cartilage – anteriorly
               Protects thoracic organs
               Supports shoulder girdle and upper limbs
               Provides attachment sites for muscles

                                                                    49




             Sternum                                                       Ribs
               Formed from three sections                                All ribs attach to vertebral column
                 Manubrium – superior section                            posteriorly
                    Articulates with medial end of clavicles & costal                                               (1 7)
                                                                           True ribs - superior seven pairs of ribs (1-7)
                    cartilage of 1st rib                                     Attach to sternum by costal cartilage
                 Body – bulk of sternum
                    Sides are notched at articulations for costal          False ribs – inferior five pairs of ribs (8-12)
                    cartilage of ribs 2–7
                 Xiphoid process – inferior end of sternum                 Ribs 11–12 are known as floating ribs


                                                                    51                                                           52




             Ribs
                                                                           Axial Skeleton Throughout Life
                                                                             Curvatures of the vertebral column
                                                                                Primary curvatures – thoracic and sacral
                                                                                curvatures
                                                                                   An infant's spine is C-shaped at birth
                                                                                Secondary curvatures – cervical and
                                                                                lumbar curvatures
                                                                                   Develops when a baby begins to walk
                                                                                   (“toddler” about 1 year old)
                                                                                   Redistributes weight of the upper body over
                                                                                   the lower limbs

                                                                                                                                 54




                                                                                                                                      9

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:13
posted:8/19/2011
language:English
pages:9