CHAPTER 7
Answers to “What Did You Learn?”
1.
The skull is composed of both cranial and facial bones.
2.
The three skull sutues that can be seen from a superior view of the skull are the
coronal, sagittal, and lambdoid sutures. The frontal and parietal bones articulate
at the coronal suture, the two parietal bones articulate,at the sagittal suture, and
the parietals and occipital bones articulate at the lamboid suture.
3.
The three parts of the temporal bone are the squamous part, the tympanic part, and
the petrous part (where the mastoid process is located).
4.
The occipital bone contains the superior and inferior nuchal lines. They are
attachment sites for both muscles and ligaments that balance the weight of the
head over the vertebrae of the neck and stabilize its articulation at the occipital
condyles.
Male skulls tend to have more pronounced nuchal lines than female
skulls.
5.
The sella turcica or hypophyseal fossa is a depression in the middle cranial fossa.
This depression houses the pituitary gland and is part of the sphenoid bone.
6.
Most of the hard palate is formed by horizontal medial extensions of the maxilla
called palatine processes. The posterior portion of the hard palate is formed by
the articulation of the palatine process of the maxilla with the horizontal plate of
the palatine bone.
7.
The ethmoid, frontal, maxillae, and sphenoid bones of the skull contain the
paranasal sinuses.
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8.
The lateral wall of the orbit is formed from the orbital surface of the zygomatic,
the greater wing of the sphenoid, and the zygomatic process of the frontal bone.
9.
The three tiny bones of the auditory ossicles are the malleus, incus, and stapes.
10.
The male skull is generally more robust than the female skull and has prominent
muscle markings. The external surface of the occipital bone in a female is
relatively smooth, with no major bony projections, while the male skull has welldemarcated nuchal lines and a prominent bump for the external occipital
protuberances. The mastoid process in a female is smaller than that of a male.
The forehead in a female is usually more vertically oriented and rounded than
males. The female’s subraorbital margin exhibits a thin, sharp border, in contrast
with the male’s thick, rounded border. The females have less prominent and
bulky superciliary arches than males. The mandibles are smaller and lighter in a
female skull than in a male. Both the sinuses and teeth in a female skull are
smaller than those in a male skull.
11.
The two main fontanelles are the posterior fontanelle (which disappears/closes by
9 months of age) and the anterior fontanelle (which disappears/closes by 15
months).
12.
The five vertebral regions, proceeding from superior to inferior ends are:
cervical, thoracic, lumbar, sacral, and coccygeal.
13.
The dens is located on the second cervical vertebra, called the axis. A fracture to
the dens would fracture the axis.
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14.
Transverse foramina are located in the transverse foramen in the cervical vertebra.
These foramina allow the passage of the vertebral arteries and veins. The
intervertebral foramina are lateral openings between adjacent vertebrae. These
openings allow the passage of spinal nerves. The vertebral foramen are located
between the vertebral bodies and the vertebral arches. The spinal cord passes
through the vertebral foramen.
15.
The three components of the sternum are the manubrium, the body (gladiolus),
and the xiphoid process. Ribs 1-7 articulate directly with the sternum.
16.
The tubercle of a rib articulates with the costal facet of the transverse process of a
thoracic vertebra.
Answers to “Content Review”
1.
Facial bones form the bones of the face and they protect the entrances to the
digestive and respiratory systems. Cranial bones form the rounded cranium that
completely surrounds and encloses the brain.
2.
Sutures are immovable fibrous joints that form boundaries between cranial bones.
They allow brain growth and typically fuse in our adult years after skull growth is
complete. They allow the skull of mimic the brain shape unless they fuse early,
then they will alter growth of the cranium to reflect those sutures that remain
open.
3.
The parietal bones, the temporal bones, the sphenoid bone, and the first cervical
vertebra [the atlas] articulate with the occipital.
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4.
The middle cranial fossa lies between the posterior edge of the lesser wings of
sphenoid (anteriorly) to the anterior part of the petrous portion of the temporal
bone (posteriorly).
5.
The nasal conchae are thin, scroll-like bones that project into the nasal cavity.
The superior nasal conchae are the most superior and the inferior nasal concha are
the most inferior. The middle lies between the superior and the inferior nasal
conchae. The superior and middle nasal conchae are part of the ethmoid bone,
whereas the inferior nasal conchae are not part of another bone.
6.
The seven bones that form the orbit include: the frontal and sphenoid that
form the roof of the orbit; the maxilla and palatine bones that form the floor of the
orbit; the lacrimal and ethmoid bones form the medial wall of the orbit; and the
zygomatic, sphenoid, and frontal form the lateral wall of the orbit. The sphenoid
forms the posterior wall of the orbit.
7.
The paranasal sinuses are cavities in the frontal, ethmoid, sphenoid and maxillary
bones. They have a mucus lining that helps to humidify and warm inhaled air.
Foreign particulate matter is trapped in this mucus and then eventually swallowed.
This helps to condition the inhaled air to protect the delicate gas exchange
surfaces in the lungs. Additionally, the inclusion of these cavities helps to lighten
the skull and assists in resonance during sound production.
8.
The first cervical vertebra, the atlas, lacks a spinous process and a vertebral body.
It has depressed, oval superior articular facets that articulate with the occipital
condyles of the occipital bone (the atlanto-occipital joint) and permit the
movement of the head called ‘nodding’ [a ‘yes’ movement]. The second cervical
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vertebra, the axis, has a prominent odontoid process [the fused body of the atlas.
It rests in the articular facet of the atlas and is held in place by a transverse
ligament. The movement at this joint (the atlantoaxial joint) permits the shaking
of the head ‘no’.
9.
The lumbar region is most at risk for disc herniation because of the relatively
great mobility here and because of the increased weight on the discs in this
region.
10.
Ribs are elongated, curved, flattened bones that originate on or between thoracic
vertebrae and usually end in the wall of the thoracic cavity. The first 7 pairs of
ribs, the true ribs, connect individually to the sternum by costal cartilage. Rib
pairs 8 – 12 are called false ribs because they do not connect directly to the
sternum. The pairs of ribs 8 – 10 have costal cartilages that connect to the costal
cartilage of rib pair 7. The last two pairs of false ribs, rib pairs 11 and 12 are
called floating ribs because they have no connection to the sternum.
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