Lecture 8: The Axial Skeleton 🩻💀

Vocabulary flashcards covering major terms and structures discussed in Lecture 8 on the axial skeleton.

Axial Skeleton

80-bone division forming the body’s axis; skull, vertebral column, sternum, 12 pairs of ribs, and hyoid; supports/protects organs and provides muscle attachments.

Appendicular Skeleton

126-bone division; pectoral girdles & upper limbs plus pelvic girdle & lower limbs.

Suture

Immovable fibrous joint that unites skull bones (except the mandible).

Coronal Suture

Junction where frontal bone meets parietal bones anteriorly.

Lambdoid Suture

Junction where occipital bone meets parietal bones posteriorly.

Sagittal Suture

Midline joint where the two parietal bones meet; runs coronal to lambdoid sutures.

Squamous Suture

Joint where each temporal bone meets the parietal bone laterally.

Cranial Bones

Bones that encase and protect the brain (frontal, parietal, temporal, occipital, sphenoid, ethmoid).

Facial Bones

Bones forming facial structure; 13 fused plus the movable mandible.

Parietal Bones

Paired bones forming superior & lateral skull walls; joined by sagittal suture.

Frontal Bone

Single bone forming forehead, anterior cranial fossa, superior orbital walls; contains frontal sinus; meets parietals at coronal suture.

Temporal Bones

4 important structures, including the zygomatic process, external auditory meatus, styloid and mastoid processes, and meet the parietal bone at the squamous suture.

Occipital Bone

Posterior skull bone; contains foramen magnum & occipital condyles; meets parietals at lambdoid suture.

The Orbits

Cavities that encase eyes, attachment points for the eye muscles. Formed by 7 bones, including the Frontal, sphenoid, zygomatic, maxilla, palatine, lacrimal, ethmoid bones.

Sphenoid Bone

Bat-shaped keystone cranial bone articulating with all other cranial bones; has greater & lesser wings and pterygoid processes.

Zygomatic Bones

Paired cheek bones located below the orbits.

Maxillary Bones

Medially fused upper-jaw bones; keystone facial bones articulating with all others except mandible; house maxillary sinuses.

Lacrimal Bones

Small paired bones in medial orbit walls, lateral to each maxilla.

Ethmoid Bone

Deepest skull bone; forms superior nasal septum and medial orbit walls; cribriform plate with olfactory foramina and crista galli.

Vomer

Thin median bone forming inferior portion of nasal septumthat separates the left and right nasal cavities.

Palatine Bones

Paired bones forming posterior hard palate and part of nasal cavity; visible on skull’s inferior view.

Nasal Bones

Small paired bones forming the bridge of the nose.

Inferior Nasal Conchae

Paired shelves of bone forming the lower nasal cavity walls.

Paranasal Sinuses

Air-filled cavities within skull bones that lighten skull and connect to nasal cavity.

Frontal Sinus

Paranasal sinus located within the frontal bone.

Sphenoid Sinus

Paranasal cavity housed in sphenoid bone.

Ethmoid Sinus

Multiple small cavities within the ethmoid bone.

Maxillary Sinus

Largest paranasal sinus, located in each maxilla.

Mandible

Lower jaw; only movable skull bone.

Hyoid Bone

U-shaped neck bone that does not articulate with others; attachment for tongue and swallowing muscles.

Vertebral Column

Flexible protective column of 33 vertebrae connected by ligaments; articulates with skull, ribs, and pelvis.

Cervical Vertebrae

Seven smallest vertebrae (C1–C7); have transverse foramina; C1 atlas and C2 axis specialized for head movement.

Atlas (C1)

First cervical vertebra that articulates with occipital condyles; supports the head.

Axis (C2)

Second cervical vertebra featuring the dens, a pivot for head rotation.

Thoracic Vertebrae

Twelve vertebrae (T1–T12) that articulate with ribs.

Lumbar Vertebrae

Five massive vertebrae (L1–L5) bearing greatest body weight; have smaller vertebral foramina.

Sacrum

Single bone formed by fusion of five vertebrae; strengthens pelvis and protects pelvic organs.

Coccyx

Vestigial tailbone of 3–5 fused vertebrae.

Vertebral Body

Thick anterior weight-bearing portion of a vertebrathat provides support and stability to the spine.

Spinous Process

Posterior midline projection from vertebral arch

Transverse Process

Paired lateral projections from a vertebrathat extend outwards from the vertebral arch and serve as attachment points for muscles and ligaments.

Vertebral Foramen

Large central opening posterior to body; houses spinal cordand surrounding protective tissues.

Pedicle

Short bony pillar connecting vertebral body to transverse processthat helps to support the vertebra and protect the spinal cord.

Lamina

Flat plate connecting transverse and spinous processesof a vertebra that helps to form the vertebral arch and provides protection for the spinal cord.

Articular Processes

Superior & inferior projections bearing facets for vertebral articulationthat allow for movement and stability between adjacent vertebrae.

Articular Facet

Smooth surface on articular process that forms joints between vertebrae, allowing for flexibility and movement in the spine.

Thorax

Skeletal cage of thoracic vertebrae, ribs, and sternum that protects heart, lungs, and thymus.

Sternum

Flat bone in anterior thorax composed of manubrium, body, and xiphoid process.

Manubrium

Superior sternum part; articulates with clavicles and first rib cartilage.

Body of Sternum

Middle, longest part where costal cartilages of ribs 2–7 attach.

Xiphoid Process

Small inferior sternum part; attachment for diaphragm and rectus abdominismuscle. It is cartilaginous in youth and ossifies with age.

Ribs - 24 (12 pairs)

Twelve pairs of curved bones (costae) protecting thoracic organs and aiding respiration.

True Ribs

Vertebrosternal ribs 1–7 that attach directly to sternum via individual costal cartilages.

False Ribs

Vertebrochondral ribs 8–10; cartilage joins cartilage of rib 7 before reaching sternum. Ribs 11 and 12 are considered floating ribs as they do not attach to the sternum at all.

Floating Ribs

Pairs 11–12; do not connect to sternum, only to vertebrae.

Costal Cartilage

Hyaline cartilage bars that connect ribs to sternum and provide flexibilityto the rib cage during breathing.