Axial Skeleton Flashcards
Typically, how many bones are in the adult human body?
206
How many bones are in the axial skeleton?
80
What does the axial skeleton consist of, and how many bones are in each?
- skull (22), bones associated with skull (7)
- vertebral column (26)
- thoracic cage (25)
The skull is composed of what two types of bones?
- cranial bones
- facial bones
Name and describe the cranial bones.
- 8 bones that form the cranium and have direct contact with the brain
- parietal bone x2
- occipital bone
- temporal bone x2
- frontal bone
- sphenoid bone
- ethmoid bone
Name and describe the facial bones.
- 14 bones that form the face and have no brain contact
- zygomatic bone x2
- vomer
- mandible
- nasal bone x2
- lacrimal bone x2
- maxilla x2
- inferior nasal conchae x2
- palatine bone x2
What are sutures? Name the 4 major sutures.
- immovable joints between skull bones
- coronal suture
- lambdoid suture
- sagittal suture
- squamous suture
Describe the coronal suture.
junction between frontal and parietal bones
Describe the lambdoid suture.
junction between occipital and parietal bones
Describe the sagittal suture.
junction between parietal bones
Describe the squamous suture.
junction between temporal and parietal bones
Name 5 functions of cranial bones.
- attachment of meniges
- attachment of muscles
- chambers
- housing glands
- articulation sites
Name 3 parts on the frontal bone.
- coronal suture
- supraorbital margin
- supraorbital foremen (notch)
Name 5 parts on the parietal bone.
- coronal suture
- lambdoid suture
- sagittal suture
- squamous suture
- parietal foremen
Name 5 parts on the temporal bone.
- zygomatic process
- mastoid process
- styloid process
- external acoustic meatus
- mandibular fossa
Name 4 parts on the occipital bone.
- occipital condyle
- foramen magnum
- hypoglossal canal
- jugular notch
Name 9 parts on the sphenoid bone.
- greater wing
- lesser wing
- foramen ovale
- optic canal
- sella turcica
- body
- pterygoid process
- superior orbital fissure
- pterygoid canal
Why is the sphenoid bone called the “keystone bone”?
it articulates with almost every other bone in the skull
The ethmoid articulates with…
more than half of the bones in the skull
Name 5 parts on the ethmoid bone.
- ethmoidal sinuses
- crista galli
- superior nasal concha
- middle nasal concha
- perpendicular plate
What are 4 functions of bones of the face?
- gives shape to the face
- forms part of the orbital and nasal cavities
- support the teeth
- serve as muscle attachment sites
Name 4 parts of the zygomatic bone.
- frontal process
- orbital surface
- temporal process
- maxillary process
Name 2 parts of the vomer bone.
- ala
- vertical plate
Name 3 parts of the palatine bone.
- orbital process
- perpendicular plate
- horizontal plate
Name 5 parts of the mandible.
- mandibular notch
- coronoid process
- condylar process
- alveolar process
- mental foramen
What does the nasal complex consist of?
bones and cartilages forming the nasal cavities and sinuses around them
What is the paranasal sinuses, and what is its functions?
- air-filled spaces in skull bones around nasal cavity
- mucous lining humidifies and warms inhaled air
- lightens skull
- resonant chambers for sound production while speaking
Describe the orbits.
- bony cavities in the skull that hold and protect the eyes
- consist of multiple bones
- also contain muscles that move the eyes
Name all of the bones of the orbital complex.
Roof: - frontal bone - sphenoid bone Floor: - maxilla Walls: - medially: maxilla, lacrimal, and ethmoid bones - laterally: zygomatic, sphenoid, and frontal bones - posteriorly: sphenoid
What are the auditory ossicles? Name all of them.
- 3 tiny bones in each temporal for hearing
- malleus x2
- incus x2
- stapes x2
Describe the hyoid bone.
- located between the mandible and the larynx
- does not articulate with another bone
- attachment site for tongue and muscles of larynx used in swallowing
How many bones are in the vertebral column?
26
How are the bones in the vertebral column divided?
24 individual vertebrae:
- 7 cervical vertebrae (neck)
- 12 thoracic vertebrae (superior back)
- 5 lumbar vertebrae (inferior concave back)
2 inferior bones are fusions of several vertebrae:
- Sacrum (5 fused vertebrae)
- Coccyx (4 fused vertebrae)
What are the 4 adult spinal curvatures?
- cervical curvature (slightly concave)
- thoracic curvature (convex)
- lumbar curvature (concave)
- sacral curvature (slightly convex)
Name 3 abnormal spinal curvatures.
- kyphosis (hunchback)
- lordosis (swayback)
- scoliosis
Describe the atlas (C1).
- has deep superior articular facets that articulate with the occipital condyles of the occipital bone
- holds head, allows “yes” movement
- no body, fused to the next vertebrae
Describe the axis (C2).
- has a dens (body of C1 that is fused to C2)
- acts as a pivot for the rotation of the atlas and the skull
- bifid (2) spinous process
What is the relative size for the cervical, thoracic, and lumbar vertebrae?
- cervical: small
- thoracic: medium
- lumbar: large
What is the body shape for the cervical, thoracic, and lumbar vertebrae?
- cervical: kidney-shaped bean
- thoracic: heart-shaped
- lumbar: large, round or oval
What does the thoracic vertebrae have that none of the other types have?
costal facets for ribs are present on body and transverse processes
What does the cervical vertebrae have that none of the other types have?
transverse foramen
Describe the transverse processes for each type of vertebrae.
- cervical: small, C3-C6 often bifid (contain transverse foramen)
- thoracic: medium-sized
- lumbar: large, thick and blunt
Describe the angle of articular facets for each type of vertebrae.
- cervical: anteroinferior, posterosuperior
- thoracic: anteromedial, posterolateral
- lumbar: lateral, medial
Describe the spinous process for each type of vertebrae.
- cervical: slender, C2-C6 are often bifid (C1 has no spinous process)
- thoracic: long, most project inferiorly
- lumbar: short (thick and blunt), project posteriorly
Describe the sacrum.
originally 5 vertebrae, usually fuse in the third decade of life
Name and describe the 2 major structures of the sacrum.
- alae: anterolateral “wing-like” projections
- promontory: anteriosuperior edge of 1st vertebrae
What is the thoracic cage, and what does it consist of?
- bony frame around chest
- thoracic vertebrae posteriorly
- ribs laterally
- sternum anteriorly
What is the function of the thoracic cage?
protects heart, lungs, trachea, esophagus, and other thoracic organs
What is the sternum, and what are the 3 parts of it?
- the “breastbone” in anterior midline
- manubrium
- body, sometimes with foramen (4-10%)
- xiphoid process
How many pairs of ribs are there, and where do they articulate?
- 12 pairs
- articulate posteriorly with thoracic vertebrae
What are the true ribs?
- ribs 1-7
- articulate anteriorly with the sternum via costal cartilages
What are the false ribs?
- ribs 8-12
- their costal cartilages do not attach directly to the sternum
What are the floating ribs?
- ribs 11-12
- false ribs that do not articulate with the sternum
How are infant skulls different?
- infant cranial bones are connected by flexible areas of dense regular connective tissue called fontanelles
What are the 2 major fontanelles?
- anterior: ossifies at 15 months
- posterior: ossifies at 9 months
