The Skeletal System: Axial Division Pearson Education, Inc.

Transcription

1 6 The Skeletal System: Axial Division

2 Figure 6.1a The Axial Skeleton SKELETAL SYSTEM 206 AXIAL SKELETON 80 Skull and associated bones 29 Skull Associated bones Cranium Face Auditory ossicles Hyoid APPENDICULAR SKELETON 126 (see Figure 7.1) Thoracic cage 25 Sternum Ribs 1 24 Vertebrae 24 Vertebral column 26 Sacrum 1 Coccyx 1 Anterior view of the skeleton highlighting components of the axial skeleton; the flowchart indicates relationships among the axial components.

3 Introduction The axial skeleton: Composed of bones along the central axis of the body Divided into three regions: Skull Vertebral column Thoracic cage

4 Introduction Functional anatomy of the axial skeleton: Framework that supports and protects organs in the dorsal and ventral body cavities Protects special sense organs for taste, smell, hearing, balance, and vision Attachment sites for muscles that: Adjust the posture of the head, neck, and trunk Move the thoracic cage for respiration Stabilize the appendicular skeleton

5 Figure 6.2 Cranial and Facial Subdivisions of the Skull (Part 1 of 2) SKULL FACE Maxillae Palatine bones Nasal bones Inferior nasal conchae Zygomatic bones Lacrimal bones Vomer Mandible 14 CRANIUM Occipital bone Parietal bones Frontal bone Temporal bones Sphenoid Ethmoid Auditory ossicles enclosed in temporal bones (detailed in Chapter 18) ASSOCIATED BONES 6 7 Hyoid bone 1

6 Figure 6.2 Cranial and Facial Subdivisions of the Skull (Part 2 of 2) Facial Bones Cranial Bones Nasal bone Zygomatic bone Maxilla Lacrimal bone Vomer Mandible Sphenoid Ethmoid Frontal bone Parietal bone Temporal bone Occipital bone

7 The Skull and Associated Bones Lambdoid suture Suture between the occipital bone and the two parietal bones (superior skull) Sagittal suture Suture between the two parietal bones

8 The Skull and Associated Bones Sagittal suture Between the two parietal bones Coronal suture Between the frontal bone and the two parietal bones

9 The Skull and Associated Bones Temporal bone Mastoid process External acoustic meatus Zygomatic arch Styloid process Sphenoid bone Squamous suture

10 Figure 6.3d The Adult Skull (Part 1 of 2) Parietal bone Supra-orbital foramen Sphenoid Temporal bone Ethmoid Palatine bone Lacrimal bone Frontal bone Coronal suture Optic canal Superior orbital fissure Inferior orbital fissure Zygomatic bone Nasal bone Maxilla Inferior nasal concha Vomer Mandible Infra-orbital foramen Middle nasal concha Perpendicular plate of ethmoid Mental foramen Anterior view of the bones of the adult skull

11 Figure 6.3e The Adult Skull (Part 1 of 2) Zygomatic bone Vomer Sphenoid Foramen ovale Palatine process of maxilla Maxilla Palantine bone Styloid process External acoustic meatus Foramen lacerum Carotid canal Temporal bone Mastoid process Jugular foramen Occipital condyle Occipital bone Foramen magnum Inferior view of the adult skull, mandible removed

12 Figure 6.4 Sectional Anatomy of the Skull, Part I (Part 1 of 2) Frontal bone Ethmoid Sphenoid Temporal bone Carotid canal Parietal bone Occipital bone Foramen magnum Crista galli Cribriform plate Sella turcica Foramen rotundum Foramen lacerum Foramen ovale Foramen spinosum Internal acoustic meatus Jugular foramen Hypoglossal canal Horizontal section

13 Figure 6.5 Sectional Anatomy of the Skull, Part I (Part 1 of 2) Sphenoid Sphenoidal sinus (right) Frontal sinus Crista galli Nasal bone Perpendicular plate of ethmoid Vomer Hypophyseal fossa of sella turcica Sagittal section

14 The Skull and Associated Bones The Occipital Bone Foramen magnum Opening for the spinal cord Occipital condyles Articulate with the first cervical vertebra Hypoglossal canals Opening for the hypoglossal nerve that innervates the tongue

15 The Skull and Associated Bones The Temporal Bone Relatively flat bone of the skull Mastoid process Styloid process Neck muscle attachment External acoustic meatus Entrance into the ear canal

16 The Skull and Associated Bones The Sphenoid Bone Sella turcica Hypophyseal fossa (fossa for the pituitary gland) Optic canals Openings for the optic nerves

17 The Skull and Associated Bones The Ethmoid Bone Perpendicular plate of the ethmoid Crista galli Cribriform plate Cribriform plate foramina (olfactory foramina) Openings for the olfactory nerves

18 The Skull and Associated Bones The Maxillae Make up the upper jaw Consists of a left and right maxilla Maxillary sinuses Infra-orbital foramen Openings for the maxillary nerve passing through the foramen rotundum

19 The Skull and Associated Bones The Mandible Makes up the lower jaw Mandibular condyle Articulates with the mandibular fossa of the temporal bone Mandibular notch Coronoid process Ramus Angle Body Mental foramina (openings for the passage of nerves) Mental protuberance (bony ridge on the anterior edge) = prominent chin

20 The Skull and Associated Bones The Hyoid Bone Slender, curved bone located inferior to the skull between the mandible and the larynx (voice box). Does not articulate with any other bone Serves as sites for attachment for tongue and larynx muscles and ligaments.

21 The Skull and Associated Bones Auditory ossicles Three tiny ear bones called auditory ossicles are housed within each temporal bone. the malleus the incus the stapes

22 Cavities of The Skull The largest cavity is the cranial cavity, which encloses, cushions, and supports the brain. The skull also has several smaller cavities, including the orbits (eye sockets), the oral cavity (mouth), the nasal cavity, and the paranasal sinuses.

23 Sinuses Have a mucous lining that helps to humidify and warm inhaled air. Cause these skull bones to be lighter. Provide resonance to the voice.

24 The Skull of Infants Major features of the infant skull 4 major fontanel areas Membranous areas where sutures will eventually form Anterior fontanel (baby s soft spot ) Posterior fontanel Sphenoidal fontanels Mastoid fontanels

25 The Skull of an Infant Functional anatomy of the fontanels Allow flexibility of the skull bones during the birthing process These membranous areas are actually the dura mater of the brain, which is a thick membranous material that helps to protect the brain. You can feel the infant s pulse in the area of the anterior fontanel. Blood vessels lie deep to the fontanel. They close by 15 months of age

26 The Vertebral Column The adult vertebral column is made up of 26 bones: 24 vertebrae 7 cervical vertebrae 12 thoracic vertebrae 5 lumbar vertebrae 1 sacrum (5 fused vertebrae) 1 coccyx (3 to 5 fused vertebrae)

27 The Vertebral Column Functional anatomy of the vertebral column Encloses and protects the spinal cord Supports the skull Supports the weight of the head, neck, and trunk Transfers weight to the lower limbs Helps maintain the upright position of the body

28 The Vertebral Column There are 4 major curves of the vertebral column Cervical curve Thoracic curve Lumbar curve Sacral curve These curves, along with muscle attachment to the various vertebral processes, help to maintain balance

29 The Vertebral Column Abnormal curvatures of the vertebral column Scoliosis Abnormal lateral curvature Kyphosis Exaggerated posterior curvature of the thoracic region Lordosis Exaggerated anterior curvature of the lumbar region Scoliosis Kyphosis Hunchback Lordosis Swayback

30 The Vertebral Column Special features of the vertebrae Cervical number 1 is the atlas nodding Cervical number 2 is the axis The axis has a structure called the dens The atlas pivots on the dens of the axis, allows rotation of the head shaking head

31 The Vertebral Column

32 The Vertebral Column Vertebral Processes (Cervical Vertebrae) Vertebral body Vertebral foramen Spinous process Transverse process Transverse foramen

33 The Vertebral Column Vertebral Processes (Thoracic Vertebrae) - The ribs articulate with the 12 thoracic vertebrae Vertebral body Vertebral foramen Spinous process Transverse process

34 The Vertebral Column Vertebral Processes (Lumbar Vertebrae)- support the weight of the torso Vertebral body Vertebral foramen Spinous process Transverse process

35 The Vertebral Column Cervical: smallest, lightest; transverse foramen; vertebral foramen triangular; short spinous process Thoracic: costal facets (for ribs); heart-shaped body; vertebral foramen is oval/round; long spinous process Lumbar; blocklike body; blunt spinous process

36 The Vertebral Column Sacrum and Coccyx Sacral foramina Median sacral crest Lateral sacral crest Sacral hiatus

37 The Thoracic Cage The thoracic cage has two functions: It protects the heart, lungs, thymus, and other structures within the cavity It serves as the attachment site for muscles involved in: Respiration Positioning the vertebral column Movements of the pectoral girdle and upper limb

38 The Thoracic Cage The Thoracic Cage Sternum Manubrium Body Xiphoid Jugular notch

39 The Thoracic Cage The Thoracic Cage Ribs True ribs: 1 7 False ribs: 8 12 *(floating ribs = 11 12)

40 The Thoracic Cage Rib Articulation Head Neck Tubercle of rib Body

41 Figure 6.27c The Thoracic Cage Tubercle of rib Transverse costal facet Angle Costal facet Neck Head (capitulum) Vertebral end A superior view of the articulation between a thoracic vertebra and the vertebral end of a left rib