Chapter 20
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Chapter 20. The Axial Skeleton. Skeletal system includes both:. Axial skeleton Skull Vertebral column Thoracic cage Appendicular skeleton Pectoral and pelvic girdles Upper and lower limbs. The Skull. The cranium. Cranial vault or calvaria

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Chapter 20

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Chapter 20

The Axial Skeleton


Skeletal system includes both:

  • Axial skeleton

    • Skull

    • Vertebral column

    • Thoracic cage

  • Appendicular skeleton

    • Pectoral and pelvic girdles

    • Upper and lower limbs


The Skull


The cranium

  • Cranial vault or calvaria

    • Superior, lateral, and posterior walls of the skull

  • Cranial floor or base

    • Anterior fossa

    • Middle fossa

    • Posterior fossa


The skull

  • Consists of the cranium and the bones ofthe face

  • Sutures

    • Lambdoid-between occipital and parietal bones

    • Coronal-between parietal and frontal bones

    • Sagittal-between parietal bones

    • Squamous-between parietal and temporal bones


The skull


The skull


The skull


Cranial Bones

  • one occipital bone

    • foramen magnum

  • two parietal bones

  • one frontal bone

    • frontal sinuses

    • glabella

  • two temporal bones

    • auditory ossicles

  • one sphenoid

  • one ethmoid


The Sectional Anatomy of the Skull


The Sectional Anatomy of the Skull


The Occipital and Parietal Bones


Occipital and Parietal Bones

  • Occipital bone

    • Foramen magnum

    • Occipital condyle

    • External occipital protuberance

  • Parietal bone

  • Frontal bone

    • Supraorbital foramen

    • Glabella


Frontal bone


Temporal bone


Temporal bone

  • Squamous suture

  • Zygomatic process

    • Zygomatic arch

  • Mandibularfossa

  • External auditory meatus

  • Styloid process


Temporal bone is divided in regions

  • Mastoid process

    • Mastoiditis

    • Meningitis

  • Stylomastoid foramen

    • Passage for cranial nerve VII

  • Internal acustic meatus

    • Passage for cranial nerves VII and VIII


The Sphenoid


Sphenoid bone

  • Greater wings

  • Sellaturcica

    • For the pituitary gland


The Ethmoid


Ethmoid bone

  • Crista galli

    • Attachment of the dura mater

  • Cribiform plate

    • Passage of olfactory nerves


Ethmoid bone

  • Perpendicular plate

    • Forms the superior part of the nasal septum

  • Superior and middle nasal conchae (turbinates)

    • Covered by mucosa

    • Warms and humidifies the air


Facial bones

  • Maxillary bones

  • Mandible

  • Palatine bones

  • Nasal bones

  • Vomer

  • Inferior nasal conchae

  • Zygomatic bones

  • Lacrimal bones


Maxillae

  • Alveolar margim

  • Palatine process- anterior hard palate

  • Incisive fossa- passage for nerves and blood vessels


Maxillary bone


Vomer, Zygomatic and Lacrimal bones

  • Zygomaticbone

    • articulates with zygomatic process of temporal bone forming the zygomaticarch


Facial bones


Mandible

  • Body- horizontal portion

  • Ramus-vertical portion

  • Mandibular condyle- articulates with temporal bone

  • Coronoid process

  • Angle

  • Alveolar margin- with sockets for the teeth

  • Mandibular foramen – site of Novocain injection


The mandible


The Mandible and Hyoid Bones


Cranial Foramens to identify

  • External view:

  • Supraorbitalforamen-for blood vessels and nerves

  • Infraorbital foramen-blood vessels and nerves

  • Mental foramen-blood vessels and nerves

  • Stylomastoidforamen- nerve VII

  • Carotid canal-for carotid artery

  • External auditorymeatus-leads to eardrum

  • Incisivefossa-for blood vessels and nerves


Cranial Foramens to identify

  • Internal view

  • Optic canal-for optic nerve

  • Superior and inferior orbital fissure

  • “ROS”

    • Rotundum- for a branch of V

    • Ovale-for a branch of V

    • Spinosum-for middle meningeal artery


Cranial Foramens to identify

  • Foramen lacerum-internal carotid

  • Jugularforamen-for jugular vein; IX, X,XI cranial nerves

  • Internal acusticmeatus-for VII,VIII

  • Hypoglossal canal-for XII

  • Foramen magnum-for spinal cord


The Vertebral Column


Vertebral column

  • 7 cervical vertebrae

  • 12 thoracic vertebrae

  • 5 lumbar vertebrae

  • 5 sacrum fused vetebrae

  • 3-5 fused coccyx vertebrae


Vertebral column

  • Intervertebral discs- pads of fibrocartilage between the vertebrae

    • Nucleus pulposus- central soft region

    • Annulus fibrosus- outer ring. Collagen fibers

    • Herniated disc- protusionof the nucleus pulposus


Spinal curvatures

Figure 7.16


Spinal curvatures

  • Four spinal curves- posterior view

    • Primary curvatures – present at birth

      • Thoracic - convex

      • Sacral- convex

    • Secondary curvatures – develops after birth

      • Cervical- concave

      • Lumbar- concave


Abnormal Curvatures of the Spine


Structure of a typical vertebra

  • Body- rounded portion. Anterior part

  • Vertebral Foramen-for the spinal cord

  • Transverse process

  • Spinous process-single and posterior

  • Intervertebral foramina-it is seen when 2 vertebras are put together. Passage of the spinal nerves


Cervical vertebra

  • Transverse foraminas- only present in cervical vertebrae

  • Atlas or C1

    • No body

    • Join with the head and provides for range of motion (when you nod yes)


Cervical vertebra

  • Axis or C2

    • Odontoid process or dens-allows rotation of the head (when you nod no)


Thoracic vertebrae

  • Spinous process-long and downward

  • Rib facet – for articulation with 1 rib


Lumbar vertebrae

  • Massive body

  • Short and thick and more horizontal spinous processes

  • No rib facets

  • No transverse foramem

  • Superior and inferior articular processes


Sacrum

  • Medial sacral crest-remnant of the spinous processes

  • Alae- formed by fusion of the transverse processes. It articulates with the hip bones

  • Sacral foramina- passage for blood vessels and nerves

  • Sacral canal- continuation of the verterbral canal


Sacrum and coccyx

  • Sacral hiatus-inferior opening of the sacral canal

  • Sacral promontory- rim on the anterior and superior part of the sacrum

  • Coccyx

    • Attached to the sacrum by ligaments


The bony thorax

  • Sternum

    • Manubrium-articulates with the clavicle

    • Body

    • Xiphoid process-inferior end. Made of hyaline cartilage in children and is ossified in adults

    • Jugular notch

    • Sternal angle-between the body and the manubrium


The ribs

  • Tubercle – is inferior

  • Costal groove –depression along the inferior side

  • Sternal end-articulates with sternum


Types of ribs

  • True

    • Ribs 1-7

    • Attached to the sternum through their own cartilage


Types of ribs

  • False

    • 8-12

    • 8-10 are vertebrochondral ribs

      • Attaches to the sternum indireclty through the cartilage of the C7

    • 11-12 are floating ribs

      • No attachment to the sternum


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