The Axial Skeleton
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Skeletal system includes both:
 Axial skeleton
Skull
Vertebral column
Thoracic cage
 Appendicular skeleton
Pectoral and pelvic girdles
Upper and lower limbs
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The Skull
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The cranium
 Cranial vault or calvaria
Superior, lateral, and posterior walls of the
skull
 Cranial floor or base
Anterior fossa
Middle fossa
Posterior fossa
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The skull
 Consists of the cranium and the bones of the
face
 Sutures
Lambdoid-between occipital and parietal
bones
Coronal-between parietal and frontal bones
Sagittal-between parietal bones
Squamous-between parietal and temporal
bones
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The skull
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The skull
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The skull
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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
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The Sectional Anatomy of the Skull
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The Sectional Anatomy of the Skull
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The Occipital and Parietal Bones
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Occipital and Parietal Bones
 Occipital bone
Foramen magnum
Occipital condyle
External occipital protuberance
 Parietal bone
 Frontal bone
Supraorbital foramen
Glabella
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Frontal bone
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Temporal bone
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Temporal bone
Squamous suture
Zygomatic process
Zygomatic arch
Mandibular fossa
External auditory meatus
Styloid process
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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
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The Sphenoid
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Sphenoid bone
 Greater wings
 Sella turcica
For the pituitary gland
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The Ethmoid
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Ethmoid bone
 Crista galli
Attachment of the dura mater
 Cribiform plate
Passage of olfactory nerves
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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
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Facial bones
 Maxillary bones
 Mandible
 Palatine bones
 Nasal bones
 Vomer
 Inferior nasal conchae
 Zygomatic bones
 Lacrimal bones
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Maxillae
 Alveolar margim
 Palatine process- anterior hard palate
 Incisive fossa- passage for nerves and blood
vessels
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Maxillary bone
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Vomer, Zygomatic and Lacrimal
bones
 Zygomatic bone
articulates with zygomatic process of temporal
bone forming the zygomatic arch
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Facial bones
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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
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The mandible
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The Mandible and Hyoid Bones
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Cranial Foramens to identify
 External view:
 Supraorbital foramen-for blood vessels and
nerves
 Infraorbital foramen-blood vessels and
nerves
 Mental foramen-blood vessels and nerves
 Stylomastoid foramen- nerve VII
 Carotid canal-for carotid artery
 External auditory meatus-leads to eardrum
 Incisive fossa-for blood vessels and nerves
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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
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Cranial Foramens to identify
 Foramen lacerum -internal carotid
 Jugular foramen -for jugular vein; IX, X,XI
cranial nerves
 Internal acustic meatus -for VII,VIII
 Hypoglossal canal -for XII
 Foramen magnum -for spinal cord
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The Fetal Skeleton
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Fontanels
 Anterior or frontal
Palpable for the first 1 ½ to 2 years of age
 Posterior of occipital
Closes by the end of the first year of age
 Mastoid
Closes by the end of the first year of age
 Sphenoid
Closes by the end of the first year of age
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Cranial bones
 Frontal
It is parted
 Temporal
It is incompletely ossified
 Presence of ossification centers
Conical protusions on the cranial bones
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The Vertebral Column
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Vertebral column
7 cervical vertebrae
12 thoracic vertebrae
5 lumbar vertebrae
5 sacrum fused vetebrae
3-5 fused coccyx vertebrae
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Vertebral column
 Intervertebral discs- pads of fibrocartilage
between the vertebrae
Nucleus pulposus- central soft region
Annulus fibrosus- outer ring. Collagen fibers
Herniated disc- protusion of the nucleus
pulposus
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Spinal curvatures
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Figure
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
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Abnormal Curvatures of the Spine
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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
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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)
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Cervical vertebra
 Axis or C2
Odontoid process or dens-allows rotation of
the head (when you nod no)
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Thoracic vertebrae
 Spinous process-long and downward
 Rib facet – for articulation with 1 rib
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Lumbar vertebrae
 Massive body
 Short and thick and more horizontal spinous
processes
 No rib facets
 No transverse foramem
 Superior and inferior articular processes
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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
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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
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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
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The ribs
 Tubercle – is inferior
 Costal groove –depression along the inferior
side
 Sternal end-articulates with sternum
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Types of ribs
 True
Ribs 1-7
Attached to the sternum through their own
cartilage
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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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