Axial Skeleton and Bone Markings

Comprehensive practice flashcards covering the axial skeleton, bone surface markings, skull anatomy, vertebral column regions and pathologies, hyoid bone, and thoracic cage structure.

How many bones are found in the adult human body?

$206$ bones.

In an anatomical view of the human skeleton, what division is highlighted along the central axis of the body?

Axial skeleton

What are the five primary functions of bone described in the skeletal system overview?

Organ protection, mineral storage, body movement, blood cell production, and body support.

What major structures and bone counts make up the axial skeleton?

The skull ($8$ cranial bones and $14$ facial bones), the hyoid bone, the vertebral column ($26$ bones), and the thoracic cage ($12$ pairs of ribs, associated cartilage, and sternum).

In skeletal terminology, what is the definition of a process?

A prominent projection.

How is a tubercle distinguished from a tuberosity?

A tubercle is a small rounded bump, whereas a tuberosity (or tuber) is a knob.

What is a trochanter?

A tuberosity on the proximal femur.

What are the skeletal definitions of a lingula and a hamulus?

A lingula is a flat, tongue-shaped process, while a hamulus is a hook-shaped process.

What is the difference between a condyle and a facet?

A condyle is a smooth rounded articular surface, while a facet is a small flattened articular surface.

In skeletal terminology regarding depressions, how are a fossa, a notch, and a fovea defined?

A fossa is a general term for a depression, a notch is a depression in a bone margin, and a fovea is a little pit.

What are the definitions of a crest, a spine, and a line?

A crest (or crista) is a prominent ridge, a spine is a very high ridge, and a line (or linea) is a low ridge.

How do skeletal openings differ between a foramen, a canal (meatus), and a fissure?

A foramen is a hole, a canal or meatus is a tunnel, and a fissure is a cleft.

Which suture shown on the superior skull extends transversely across the top in the position where a person wears a crown?

Coronal suture

What is the anatomical function of the sagittal suture?

It separates the parietal bones into right and left halves.

Which suture connects the parietal bones to the occipital bone?

Lambdoid suture

What structure attaches to the external occipital protuberance and pulls on it to create bony ridges on the posterior neck?

The nuchal ligament.

What are the two processes that meet to form the zygomatic arch?

The zygomatic process of the temporal bone and the temporal process of the zygomatic bone.

Which two bones articulate at the mandibular fossa?

The temporal bone and the mandible (specifically the mandibular condyle of the mandible).

Which two bones form the bony nasal septum?

The perpendicular plate of the ethmoid bone and the vomer bone.

What are the three distinct cranial fossae that subdivide the floor of the cranial cavity?

Anterior cranial fossa, middle cranial fossa, and posterior cranial fossa.

What structure of the ethmoid bone extends upward into the cranial cavity, flanked by the cribriform plate?

Crista galli

What prominent saddle-shaped depression in the sphenoid bone houses the pituitary gland?

Sella turcica

Which three cranial foramina are located on the greater wing of the sphenoid bone?

Foramen rotundum, foramen ovale, and foramen spinosum.

Which two bony plates unite to form the hard palate?

The palatine process of the maxillary bone (forming the anterior two-thirds) and the horizontal plate of the palatine bone.

Which four sets of cavities make up the paranasal sinuses?

Frontal sinuses, ethmoidal labyrinth (sinuses), sphenoidal sinuses, and maxillary sinuses.

What unique anatomical feature distinguishes the hyoid bone from every other bone in the human body?

It is the only bone in the body that does not articulate with another bone; it is suspended and attached to the skull solely by muscles and ligaments.

What are the three main anatomical landmarks of the hyoid bone?

The body, the greater horn, and the lesser horn.

How many vertebrae are present in each regional division of the adult vertebral column?

$7$ cervical vertebrae, $12$ thoracic vertebrae, $5$ lumbar vertebrae, $1$ sacrum (fused), and $1$ coccyx (fused), totaling $26$ bones.

Which regions of the vertebral column exhibit a lordotic curve (curved anteriorly)?

The cervical region and the lumbar region.

What clinical condition is characterized by an excessive concave curvature of the thoracic spine?

Kyphosis (hyperkyphosis).

What is lordosis?

An excessive convex curvature of the lumbar spine.

What are the two structural components of an intervertebral disk?

The annulus fibrosus (outer fibrous cartilage ring) and the nucleus pulposus (inner gelatinous center).

What happens anatomically during a disk herniation?

The nucleus pulposus protrudes through the annulus fibrosus, compressing a spinal nerve root in the intervertebral foramen.

What are the distinctive anatomical characteristics of the atlas ($\text{C1}$)?

It is a ring of bone with no vertebral body and no spinous process; its superior articular facets articulate with the occipital condyles to support the skull.

What upward projection on the axis ($\text{C2}$) acts as a pivot allowing the atlas to rotate?

The dens (odontoid process).

What unique opening is found in the transverse processes of all cervical vertebrae, and what structure does it transmit?

The transverse foramen, which transmits the vertebral artery.

What specialized articular markings identify a thoracic vertebra?

Costal facets (demifacets) on the vertebral body for articulation with the head of a rib, and costal facets on the transverse processes for articulation with the tubercle of a rib.

What are the three named anatomical parts of the sternum from superior to inferior?

Manubrium, body, and xiphoid process.

What are vertebrosternal ribs, and which rib pairs fall into this category?

True ribs (rib pairs $1$ through $7$); they connect directly to the sternum via their own individual costal cartilages.

What are vertebrochondral ribs, and how do they attach anteriorly?

Rib pairs $8$ through $10$ (part of the false ribs, pairs $8-12$); they do not attach directly to the sternum, but instead join the costal cartilage of rib $7$.

What are vertebral ribs, and which pairs are they?

Floating ribs (rib pairs $11$ and $12$); they attach only to the thoracic vertebrae posteriorly and have no anterior attachment.

What anatomical landmarks on a single rib articulate with the vertebrae?

The head articulates with the body of the vertebra, and the tubercle articulates with the transverse process of the vertebra.