Bones of the Axial Skeleton and Vertebral Column

Vocabulary practice flashcards covering the axial skeleton, skull divisions, hyoid bone, vertebral column regions, vertebral structures, rib articulations, sacrum, coccyx, and thoracic cage.

Axial Skeleton

The division of the human skeleton consisting of 80 total bones, which includes the skull, associated bones of the skull, vertebral column, and thoracic cage.

Cranial Bones

A group of 8 skull bones that enclose and protect the brain, consisting of the frontal bone (1), parietal bones (2), temporal bones (2), occipital bone (1), sphenoid bone (1), and ethmoid bone (1).

Facial Bones

A group of 14 skull bones forming the face, consisting of zygomatic bones (2), lacrimal bones (2), nasal bones (2), vomer (1), inferior nasal conchae (2), palatine bones (2), maxillae (2), and mandible (1).

Associated Bones of the Skull

A collection of 7 bones associated with the skull, comprising 6 auditory ossicles (malleus [2], incus [2], stapes [2]) and 1 hyoid bone.

Hyoid Bone

A unique axial bone located inferior to the mandible in the anterior neck, consisting of a central body, greater cornu, and lesser cornu.

Cervical Vertebrae

The 7 uppermost vertebrae ($C_1-C_7$) of the vertebral column, exhibiting an anterior curvature.

Thoracic Vertebrae

The 12 middle vertebrae ($T_1-T_{12}$) of the vertebral column that articulate with the 12 pairs of ribs and exhibit a posterior curvature.

Lumbar Vertebrae

The 5 lower vertebrae ($L_1-L_5$) of the vertebral column located in the lower back, exhibiting an anterior curvature.

Sacrum

A triangular bone of the vertebral column formed by the fusion of 5 sacral vertebrae ($S_1-S_5$), typically fusing completely by 26 years of age, and exhibiting a posterior curvature.

Coccyx

The terminal structure of the vertebral column composed of 4 fused coccygeal vertebrae ($Co_1-Co_4$).

Vertebral Arch

The posterior structure of a vertebra that bounds the vertebral foramen, formed by two pedicles and two laminae.

Vertebral Foramen

The central opening formed between the vertebral body and the vertebral arch through which the spinal cord passes.

Intervertebral Foramen

The lateral opening created between adjacent articulated vertebrae through which spinal nerves exit the spinal cord.

Atlas ($C_1$)

The first cervical vertebra, named after the Greek god Atlas, which lacks a body and spinous process and consists of anterior and posterior arches with prominent lateral masses.

Axis ($C_2$)

The second cervical vertebra, distinguished by a vertical peg-like process called the dens (odontoid process) and a bifid spinous process.

Atlantoaxial Joint

The pivot articulation formed between the atlas ($C_1$) and axis ($C_2$), held in place by the transverse ligament, providing the axis of rotation for head turning.

Transverse Costal Facet

An articular site located on the transverse process of thoracic vertebrae that articulates with the tubercle of a rib.

Demifacet

A partial articular surface found on the superior or inferior margins of a thoracic vertebral body where part of a rib head articulates.

Rib-Vertebra Articulation of $T_1$

The specific articulation pattern of the first thoracic vertebra ($T_1$), possessing one entire facet superiorly for the head of rib 1 and a demifacet inferiorly for rib 2.

Rib-Vertebra Articulation of $T_{11}$ and $T_{12}$

The specific articulation structure of thoracic vertebrae $T_{11}$ and $T_{12}$, each having one complete facet on the body and no facet on their transverse processes.

Sacral Promontory

The anteriorly projecting upper border of the body of the first sacral vertebra ($S_1$).

Median Sacral Crest

The prominent midline ridge along the posterior surface of the sacrum formed by the fusion of the sacral spinous processes.

True Ribs

Rib pairs 1 through 7, which connect directly to the sternum by their own separate costal cartilages.

False Ribs

Rib pairs 8 through 12, which do not attach directly to the sternum; pairs 8–10 attach indirectly via the costal cartilage of rib 7.

Floating Ribs

Rib pairs 11 and 12, which are a subset of false ribs that lack any anterior connection to the sternum or other costal cartilages.

Sternum

The single midline anterior thoracic bone consisting of three main structural parts: the manubrium, body, and xiphoid process.