BIOD151 Module 4 Study Guide Questions with
Solutions
Skull: General Anatomy & Function
The skull is formed by 22 bones: the cranium (8 bones) and facial bones (14 bones).
The cranium protects the brains and is composed of eight bones fitted tightly together in
adults. In newborns, certain bones are not completely formed and instead are joined by
membranous regions called fontanelles (see Figure 4.4), commonly called “soft spots.”
Fontanelles allow the bones of the skull to compress during childbirth and expand to
accommodate a rapidly growing infant brain. These regions begin to close around two months
but may last up to two years.
The large bones of the cranium have the same names as the lobes of the brain: frontal,
parietal, temporal, and occipital. See Figure 4.5 and Figure 4.6 for views of the cranium. On the
top of the cranium, the frontal bone (one bone) forms the forehead, the parietal bones (two,
paired bones) extend to the sides, and the occipital bone curves to form the base of the skull.
Below the much larger parietal bones, each temporal bone has an opening that leads to the
middle ear. The sphenoid bone not only completes the sides of the skull, it also contributes to
the floors and walls of the eye sockets. Likewise, the ethmoid bone, which lies in front of the
sphenoid, is a part of the orbital wall and, in addition, is a component of the nasal septum.
The sphenoid and ethmoid bones lie largely inside the skull (Figure 4.6).
The occipital bone contains a large opening, the foramen magnum, through which the spinal
cord passes to become the brain stem. Note the bone landmarks in Figure 4.7, below.
The bones of the cranium contain the sinuses, air spaces lined by mucous membrane
(see Figure 4.8). Sinuses reduce the weight of the skull and give a resonant sound to the
voice. Two sinuses called the mastoid sinuses drain into the middle ear. Mastoiditis, a
condition that can lead to deafness, is an inflammation of the mastoid sinuses. A sinus
infection (sinusitis) occurs when the soft tissues inside the sinuses become inflamed from a
virus, bacteria, or allergy.
The foramina of the skull allow for many functions, such as passage for blood vessels, nerves,
and the spinal cord (see Figure 4.9). The foramen magnum allows for passage of the spinal
cord into the skull. The carotid canal is an opening of the temporal bone for the internal carotid
artery. The external acoustic meatus (Figure 4.9, Figure 4.12) is for transmission of sound, also
,located within the temporal bone. Note the locations of the other highlighted
foramina in Figure 4.9 below.
There are fourteen facial bones. The mandible, lower jaw, is the only movable portion of the
skull (Figure 4.10). The mandible and vomer (Figure 4.11, Figure 4.12) are the only non-paired
bones of the facial skeleton; all other facial bones are paired. The maxillae, the upper jaw,
forms the anterior portion of the hard palate and contains the infraorbital foramen. Tooth
sockets are found in both the mandible and maxillae (Figure 4.10). The zygomatic bones give us
our cheekbone prominences, and the nasal bones form the bridge of the nose (Figure 4.10,
Figure 4.11).
The palatine bones make up the posterior portion of the hard palate and floor of the nasal
cavity (Figure 4.11). Each thin, scale-like lacrimal bone lies between an ethmoid bone and a
maxillary bone, and the thin, flat vomer joins with the perpendicular plate of the ethmoid to
form the nasal septum (Figure 4.12). The inferior nasal conchae are bones located inferiorly to
the middle conchae (Figure 4.11). The middle and superior nasal conchae are formed from
the grooves of the ethmoid bone. The nasal conchae act to swirl the air as it is breathed in
through the nasal passages, helping to warm and humidify the air before it enters the lower
respiratory system.
External Acoustic Meatus
is for transmission of sound, also located within the temporal bone. Note the locations of
the other highlighted foramina in Figure 4.9
(14) Facial Bones
Mandible (1)
Maxilla (2)
Zygomatic bone (2)
Nasal bones (2)
Lacrimal bones (2)
Palatine bones (2)
Inf. Nasal conchae (2)
Vomer (1)
The mandible, lower jaw, is the only movable portion of the skull (Figure 4.10). The mandible
and vomer (Figure 4.11, Figure 4.12) are the only non-paired bones of the facial skeleton; all
other facial bones are paired. The maxillae, the upper jaw, forms the anterior portion of the
hard palate and contains the infraorbital foramen. Tooth sockets are found in both the
, mandible and maxillae (Figure 4.10). The zygomatic bones give us our cheekbone
prominences, and the nasal bones form the bridge of the nose (Figure 4.10, Figure 4.11).
The palatine bones make up the posterior portion of the hard palate and floor of the nasal
cavity (Figure 4.11). Each thin, scale-like lacrimal bone lies between an ethmoid bone and a
maxillary bone, and the thin, flat vomer joins with the perpendicular plate of the ethmoid to
form the nasal septum (Figure 4.12). The inferior nasal conchae are bones located inferiorly to
the middle conchae (Figure 4.11). The middle and superior nasal conchae are formed from
the grooves of the ethmoid bone. The nasal conchae act to swirl the air as it is breathed in
through the nasal passages, helping to warm and humidify the air before it enters the lower
respiratory system.
Foramina
of the skull allow for many functions, such as passage for blood vessels, nerves, and the
spinal cord (see Figure 4.9).
Cartoid Canal
an opening of the temporal bone for the internal carotid artery
(4) Curvatures of the Vertebral Column
cervical (C1-7), thoracic (T1-12), lumbar (L1-5), sacral (and coccyx at the tail)
Spinous Processes
on all vertebrae for ligament and muscle attachment - located on the dorsal side of the
vertebrae and can be palpated (examined externally by touch) as bony projections along
the midline of the neck and back
Vertebral Body
located on the anterior portion and is the part of the vertebrae with the most surface area
Articular Facets
allow adjacent vertebrae to articulate with each other. Note how the spinal cord is protected in
the center of the vertebrae and the spinal nerves exit between the vertebrae
Cervical Vertebrae (C1-C7)
There are seven cervical vertebrae. A typical cervical vertebra has a long spinous process with
a bifid tip that splits into two parts posteriorly (except for C1). The cervical vertebral bodies are
small, and the vertebral foramen are large. The transverse processes have transverse foramina
for the passage of the vertebral arteries and vertebral veins. See Figure 4.15 below to view a
typical cervical vertebra.
