A&P Chapter 12: The Axial Skeleton

Jennifer cannot reconstruct the entire cranium. She finds only one frontal bone, two temporal bones, one sphenoid bone, and one ethmoid bone. Which cranial bone is missing?

Answer: the ethmoid bone is missing. Cranium is formed by eight bones: frontal, two parietal, two temporal, the sphenoid, the ethmoid, and the occipital

While working an archeological dig, Jennifer unearths several bones that appeared to be the remains of a human skull. The skull is disarticulated. She carefully removes and cleans each bone. Her task is to identify the bones and determine if the bones are those of an adult skull or an infant skull. Among the bones she finds is an irregular shaped bone that resembles a bat. What is the name of this bone?

Answer: the shape of the sphenoid bone resembles a bat with its wings outstretched and legs extended down and back

After reconstructing the skull, Jennifer notes that the face forms about one eight of the entire skull. She also notes that there are significant gaps between the cranial bones. More than likely, this is the skull of an:

Answer: the skulls of both a fetus and a newborn infant have unique anatomical features not seen in an adult. The face at birth forms a relatively smaller proportion of the cranium (about 1/8 than in the adult. The fontanels (spaces between the skull bones) are unique features in the infant skull

The human skeleton system consists of two division. They are:

Axial and appendicular

Which of the following is not a bone in the skull?

Clavicle

Which two bones join to form the posterior part of the hard palate?

Ethmoid and sphenoid

Why are the last two ribs called floating ribs?

Floating ribs do not attach even indirectly to the sternum

Which structures are unique to the fetal skull and provide additional space for molding the head shape as the baby passes through the birth canal...

Fontanels

The bone that claims the distinction of being the only bone in the body that articulates with no other bones is the

Hyoid

A condition that is caused by an abnormally increased roundness in the thoracic curvature is

Kyphosis

The very small bone that lies just posterior and lateral to each nasal bone is the...

Lacrimal

The vertebral bones that support the small (lower section) of the back are the

Lumbar vertebrae

The bone that articulates with the temporal bone in the only movable joint of the skull is the:

Mandible

hyoid bone

Only the hyoid bone does not normally form a joint with any other bone

Forms the thorax

Ribs, vertebral column and sternum. Each rib articulates with both the body and the transverse process of the corresponding thoracic vertebra, and the tubercle of each rib articulates with the vertebrae's transverse process. Anteriorly, each rib of the first seven pairs joins a coastal cartilage that attaches to the sternum

Which bone serves as the keystone in the architecture of the cranium?

Sphenoid

Anteriorly, each rib of the first seven pairs attaches to the

Sternum

The medial part of the anterior chest wall is supported by a dagger shaped bone called the

Sternum

Three types of vertebrae are:

The cervical (with 7 in the vertebral column), thoracic (with 12), and lumbar (with 5)

The 14 bones of the face are:

Two maxillae, mandible, two nasal bones, two zygomatic bones, two lacrimal bones, two palatine bones, two inferior conchae, and a vomer. The two maxillae form part of the floor of the orbits, part of the roof of the mouth, and part of the floor and sidewalls of the nose; the mandible articulates with the temporal bone; the two nasal bones form the upper part of the bridge of the nose; the two zygomatic bones form the outer margin of the orbit, and they articulate with the maxillary, temporal, frontal, and sphenoid bones; the two lacrimal bones help form the sidewall of the nose and they join the maxilla, frontal bone, and ethmoid bone; the two palatine bones join each other in the midline forming the posterior part of the hard palate; the two inferior conchae form the upper and middle ledges of the nasal cavity; and the vomer completes the septum posteriorly.

Which of the following is a bone in the axial skeleton?

Vertebra

Which of the following is a facial bone?

Zygomatic bone

A floating rib

does not attach to the sternum

The eight bones of the cranium are:

the frontal, two parietal, the occipital, two temporal, the sphenoid, and the ethmoid. The frontal bone forms the forehead and part of the top of the cranium and joins two parietal bones in an immovable joint called a suture; the two temporal bones house the middle and inner ear structures and contain the mastoid sinuses; the occipital bone forms immovable joints with the parietal, temporal, and sphenoid bones; the sphenoid bone is in the central portion of the cranial floor, where it anchors the frontal, parietal, occipital, and ethmoid bones; the ethmoid bone is a complex irregular bone that helps make up the anterior portion of the cranial floor, medial wall of the orbits, upper parts of the nasal septum, and sidewalls and part of the nasal roof; lies anterior to the sphenoid and posterior to the nasal bones