Axial and Appendicular Skeleton

Axial Skeleton

• 80 Bones

• Provides framework that supports & protects the organs

  • Skull

  • Vertebral column

  • Thoracic cage

Appendicular Skeleton

• Upper & lower extremities, associated pectoral & pelvic girdles

• 126 bones

Projection

The point where muscles, tendons & ligaments attach

Depression/Groove/Opening

• Blood vessels & nerves travel

  1. Foramen

  2. Meatus

  3. Sinus

  4. Fossa

Smooth Region

Place where bones articulate (meet and move together)

Foramen

• A type of opening

• Opening in bone through which nerves & vessels pass

• Ex: vertebral foramen

Meatus

• A type of opening

• passageway through a bone

• Ex: external auditory meatus

Sinus

• A type of opening

• Hollow space within a bone

Fossa

• A type of opening

• site of muscle attachment

• Ex: supraspinous fossa

Cranial Bones

• 8 bones 

• Protect brain & form cranial cavity

  • Frontal bone (1)

  • Parietal bones (2)

  • Temporal bones (2)

  • Occipital bone (1)

  • Sphenoid bone (1)

  • Ethmoid bone (1)

Parietal

Form sides & roof of cranial cavity

Temporal

Form inferiolateral portion of cranium

Frontal

• 2 separate bones at birth that fused soon after

• Forms forehead & anterior part of cranial floor

Occipital

• Forms posterior & base of cranium

• Contains foramen magnum where spinal cord merges with brainstem

Sphenoid

• Lies in middle part of base of skull

• Articulates with all other cranial bones & holds them together

Ethmoid

Small bone sits anterior to sphenoid bone

Facial Bones

• 14 bones

• Forms framework of the face, and attachment points for facial muscles

  • Mandible (1)

  • Maxilla (2)

  • Zygomatic bone (2)

  • Nasal bone (2)

  • Lacrimal bones (2)

  • Palatine bones (2)

  • Inferior nasal conchae (2)

  • Vomer (1)

Maxilla

• Upper jawbone

• Articulate with every bone of the face except the mandible

Zygomatic

Cheekbones

Lacrimal

• Smallest bones of the face

• Form medial wall of each orbit

Nasal

Forms bridge of the nose

Palatine

L-shaped bones that form posterior aspect of hard palate

Inferior Nasal Conchae

Increase surface area of nasal cavity

Vomer

Forms inferior portion of nasal septum

Mandible

Lower jawbone, largest & strongest facial bone

Sutures

• Immovable joint where bones fused together

  1. Sagittal

  2. Coronal

  3. Lambdoid

  4. Squamous

Sagittal Suture

Between 2 parietal bones

Coronal Suture

Unites frontal bone with both parietal bones

Lambdoid Suture

Unites 2 parietal bones with occipital bone

Squamous Suture

Unites parietal and temporal bones

Fontanels of Fetal Skull

• Soft spots consists of membranous gaps between incompletely formed bones

• May not fully closed until child is 18 months old

• 6 presents at birth

  1. Anterior fontanel (1)

  2. Posterior fontanel (1)

  3. sphenoidal (anterolateral) fontanels (2)

  4. mastoid (posteriolateral) fontanels (2)

Hyoid Bone

• Does not articulate with any other bones, supports the tongue

• Inferior to skull between mandible & pharynx

Condyle

• A processes that form joints

• A large round projection that forms joints

Head

• A processes that form joints

• Rounded projection found on the end of a bone, supported by a neck

Facet

• A processes that form joints

• A small, smooth, flat articular surface

Tuberosity

• A processes for connective tissue attachment

• Large rounded projection usually with rough surface

Spinous Process

• A processes for connective tissue attachment

• Sharp, slender projection

Trochanter

• A processes for connective tissue attachment

• Large, blunt projection

Crest

• A processes for connective tissue attachment

• A prominent border or ridge

Styloid

• A processes for connective tissue attachment

• A pointy projection

Vertebrae

• 33 bones or 26 fused

• 4 curvatures

  1. Cervical (7)

  2. Thoracic (12) (Primary)

  3. Lumbar (5)

  4. Sacrum fused (5)

  5. Coccyx fused (4)  (Primary)

Body (Centrum)

Thick weight-bearing portion

Transverse Process

Two lateral projections

Vertebral Arch

Comprises of lamina & pedicle

Pedicle

Connect the vertebral body to the lamina

Lamina

Connect the spinous process to the pedicle

Spinous Process

Single posterior projection

Vertebral Foramen

• Opening in vertebral arch

• Spinal cord passes through

Cervical Vertebrae

• 7 bones 

• C1 is the Atlas

• C2 is the Axis

• C3-C6 are typical cervical vertebrae

• C7 is vertebra prominens

Typical Cervical Vertebrae

C3 to C6

Atlas

• C1

• Articulates with occipital bone

Axis

• C2

• Found beneath atlas, contains odontoid process (dens)

Vertebra Prominens

• C7

• Long spinous process compared to typical cervical vertebrae and not bifid (splits into two)

Transverse Foramen

A hole in each transverse process

Spinous Process

Bony projection that are bifid (split) or single point

Thoracic Vertebrae

• 12 vertebrae

• Support rib cage, protect thoracic organs

  • Superior costal fascet

  • Superior articular fascet

  • Traverse costal fascet

  • Transverse process

  • Spinous process

  • Lamina

  • Pedicle

  • Vertebral foramen

  • Body

Lumbar Vertebrae

• 5 vertebrae

  • Inferior articular process

  • Superior articular process

Sacrum

• 5 vertebrae fused into one for adults

  • Sacral promontory

  • Posterior/Anterior sacral foramina

  • Sacral canal

  • Median sacral crest

  • Lateral sacral crest

  • Auricular surface

  • Sacral hiatus

  • Body

  • Apex

  • Traverse ridges

  • Facet of superior articular process

Coccyx

• 4 vertebrae fused into one for adults

Sternum

• Jugular notch

• Clavicular notch

• Manubrium

• Sternal angle

• Body

• Xiphoid process