Axial 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 ____

Meatus

• A type of depression

• passageway through a bone

• Ex: external auditory ____

Sinus

• A type of opening

• Hollow space within a bone

Fossa

• A type of depression

• site of muscle attachment

• Ex: supraspinous ____

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, external occipital protuberance

Sphenoid

• Lies in middle part of base of skull

• Articulates with all other cranial bones & holds them together

  • Lesser wing

  • Greater wing

Ethmoid

Small bone sits anterior to sphenoid bone

1. Crystal galli

2. Superior nasal conchae

3. Perpendicular plate

4. Middle nasal concha

Facial Bones

• 14 bones

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

  1. Nasal (2)

  2. Lacrimal (2)

  3. Maxilla (2)

  4. Mandible (1)

  5. Zygomatic (2)

  6. Vomer (1)

  7. Inferior nasal conchae(2)

  8. Palatine (2)

Maxilla

• Upper jawbone

• Articulate with every facial bone 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

  1. Horizontal plate

Inferior Nasal Conchae

Increase surface area of nasal cavity

Vomer

Forms inferior portion of nasal septum

Mandible

• Only movable bone of the skull

• Lower jawbone, largest & strongest facial bone

  1. Coronoid process

  2. Condylar process

  3. Mandibular notch

  4. Ramus of mandible

  5. Mental foramen

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

• Enable bones to flex during birth and allow more rapidly growing brain to expand

• May not fully closed until child is 18 months old

• 6 presents at birth

  1. Anterior ___ (1)

  2. Posterior ____ (1)

  3. sphenoidal (anterolateral) ___ (2)

  4. mastoid (posteriolateral) ___ (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 or bifid (split)

Trochanter

• A processes for connective tissue attachment

• Large, blunt projection found only on the femur

Crest

• A processes for connective tissue attachment

• A prominent border or ridge

Styloid

• A processes for connective tissue attachment

• A pointy projection

Vertebrae

• Supports the head & body, protects the spinal cord.

• 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

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

• Bifid spinous process

• Transverse foremen

Atlas

• C1

• No spinous process

• Articulates with occipital bone

Axis

• C2

• contains odontoid process (dens), has transverse foramen

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

Thoracic Vertebrae

• 12 vertebrae

• Round vertebral foramen, no transverse foramen

• 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

• Triangle vertebral foramen, no transverse foramen

  • Inferior articular process (longer)

  • Superior articular process (shorter)

  • Transverse process

Sacrum

• 5 vertebrae fused into one for adults

  1. Sacral promontory

  2. Posterior/Anterior sacral foramina

  3. Sacral canal

  4. Median sacral crest

  5. Lateral sacral crest

  6. Auricular surface

  7. Sacral hiatus

  8. Body

  9. Apex

  10. Traverse ridges

  11. Facet of superior articular process

Coccyx

• 4 vertebrae fused into one for adults

Sternum

• Jugular notch

• Clavicular notch

• Manubrium

• Sternal angle

• Body

• Xiphoid process

Ribs

• 12 vertebrae

• True ribs (T1-T7)

• False ribs (T8 -T12)

• Floating ribs (T11-T12)

  1. Clavicular notch

  2. Clavicle

  3. Scapula

  4. Costal cartilages (connect sternum to the ribs)

  5. Intercostal space (space between adjacent ribs)

Temporal bone

1. External acoustic meatus

2. Zygomatic process

3. Styloid process

4. Mastoid process

Processes that Form Joints

• Condyle

• Head

• Facet

Processes for Connective Tissue Attachment

• Tuberosity

• Spinous

• Trochanter

• Crest

• Styloid

Function Cranial Bones

• Enclose & protect the brain

• Stabilize position of brain, blood & lymphatic vessels & nerves