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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

Chapter 20

The Axial Skeleton

Skeletal system includes both

Skeletal system includes both:

  • Axial skeleton

    • Skull

    • Vertebral column

    • Thoracic cage

  • Appendicular skeleton

    • Pectoral and pelvic girdles

    • Upper and lower limbs

The skull

The Skull

The cranium

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 skull1

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 skull2

The skull

The skull3

The skull

The skull4

The skull

Cranial bones

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 sectional anatomy of the skull1

The Sectional Anatomy of the Skull

The occipital and parietal bones

The Occipital and Parietal Bones

Occipital and parietal b ones

Occipital and Parietal Bones

  • Occipital bone

    • Foramen magnum

    • Occipital condyle

    • External occipital protuberance

  • Parietal bone

  • Frontal bone

    • Supraorbital foramen

    • Glabella

Frontal bone

Frontal bone

Temporal bone

Temporal bone

Temporal bone1

Temporal bone

  • Squamous suture

  • Zygomatic process

    • Zygomatic arch

  • Mandibularfossa

  • External auditory meatus

  • Styloid process

Temporal bone is divided in regions

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

The Sphenoid

Sphenoid bone

Sphenoid bone

  • Greater wings

  • Sellaturcica

    • For the pituitary gland

The ethmoid

The Ethmoid

Ethmoid bone

Ethmoid bone

  • Crista galli

    • Attachment of the dura mater

  • Cribiform plate

    • Passage of olfactory nerves

Ethmoid bone1

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

Facial bones

  • Maxillary bones

  • Mandible

  • Palatine bones

  • Nasal bones

  • Vomer

  • Inferior nasal conchae

  • Zygomatic bones

  • Lacrimal bones



  • Alveolar margim

  • Palatine process- anterior hard palate

  • Incisive fossa- passage for nerves and blood vessels

Maxillary bone

Maxillary bone

Vomer zygomatic and lacrimal bones

Vomer, Zygomatic and Lacrimal bones

  • Zygomaticbone

    • articulates with zygomatic process of temporal bone forming the zygomaticarch

Facial bones1

Facial bones



  • 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

The mandible and hyoid bones

The Mandible and Hyoid Bones

Cranial foramens to identify

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 identify1

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 identify2

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

The Vertebral Column

Vertebral column

Vertebral column

  • 7 cervical vertebrae

  • 12 thoracic vertebrae

  • 5 lumbar vertebrae

  • 5 sacrum fused vetebrae

  • 3-5 fused coccyx vertebrae

Vertebral column1

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

Spinal curvatures

Figure 7.16

Spinal curvatures1

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

Abnormal Curvatures of the Spine

Structure of a typical vertebra

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

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 vertebra1

Cervical vertebra

  • Axis or C2

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

Thoracic vertebrae

Thoracic vertebrae

  • Spinous process-long and downward

  • Rib facet – for articulation with 1 rib

Lumbar vertebrae

Lumbar vertebrae

  • Massive body

  • Short and thick and more horizontal spinous processes

  • No rib facets

  • No transverse foramem

  • Superior and inferior articular processes



  • 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

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

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

The ribs

  • Tubercle – is inferior

  • Costal groove –depression along the inferior side

  • Sternal end-articulates with sternum

Types of ribs

Types of ribs

  • True

    • Ribs 1-7

    • Attached to the sternum through their own cartilage

Types of ribs1

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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