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The brain case consists of eight bones. These include the paired parietal and temporal bones, plus the unpaired frontal, occipital, sphenoid, and ethmoid bones.

Parietal bone

The parietal bone    forms most of the upper lateral side of the skull (see [link] ). These are paired bones, with the right and left parietal bones joining together at the top of the skull. Each parietal bone is also bounded anteriorly by the frontal bone, inferiorly by the temporal bone, and posteriorly by the occipital bone.

Temporal bone

The temporal bone    forms the lower lateral side of the skull (see [link] ). Common wisdom has it that the temporal bone (temporal = “time”) is so named because this area of the head (the temple) is where hair typically first turns gray, indicating the passage of time.

The temporal bone is subdivided into several regions ( [link] ). The flattened, upper portion is the squamous portion of the temporal bone. Below this area and projecting anteriorly is the zygomatic process of the temporal bone, which forms the posterior portion of the zygomatic arch. Posteriorly is the mastoid portion of the temporal bone. Projecting inferiorly from this region is a large prominence, the mastoid process    , which serves as a muscle attachment site. The mastoid process can easily be felt on the side of the head just behind your earlobe. On the interior of the skull, the petrous portion of each temporal bone forms the prominent, diagonally oriented petrous ridge    in the floor of the cranial cavity. Located inside each petrous ridge are small cavities that house the structures of the middle and inner ears.

Temporal bone

This image shows the location of the temporal bone. A small image of the skull on the top left shows the temporal bone highlighted in pink and a magnified view of this region then highlights the important parts of the temporal bone.
A lateral view of the isolated temporal bone shows the squamous, mastoid, and zygomatic portions of the temporal bone.

Important landmarks of the temporal bone, as shown in [link] , include the following:

  • External acoustic meatus (ear canal)—This is the large opening on the lateral side of the skull that is associated with the ear.
  • Internal acoustic meatus —This opening is located inside the cranial cavity, on the medial side of the petrous ridge. It connects to the middle and inner ear cavities of the temporal bone.
  • Mandibular fossa —This is the deep, oval-shaped depression located on the external base of the skull, just in front of the external acoustic meatus. The mandible (lower jaw) joins with the skull at this site as part of the temporomandibular joint, which allows for movements of the mandible during opening and closing of the mouth.
  • Articular tubercle —The smooth ridge located immediately anterior to the mandibular fossa. Both the articular tubercle and mandibular fossa contribute to the temporomandibular joint, the joint that provides for movements between the temporal bone of the skull and the mandible.
  • Styloid process —Posterior to the mandibular fossa on the external base of the skull is an elongated, downward bony projection called the styloid process, so named because of its resemblance to a stylus (a pen or writing tool). This structure serves as an attachment site for several small muscles and for a ligament that supports the hyoid bone of the neck. (See also [link] .)
  • Stylomastoid foramen —This small opening is located between the styloid process and mastoid process. This is the point of exit for the cranial nerve that supplies the facial muscles.
  • Carotid canal —The carotid canal is a zig-zag shaped tunnel that provides passage through the base of the skull for one of the major arteries that supplies the brain. Its entrance is located on the outside base of the skull, anteromedial to the styloid process. The canal then runs anteromedially within the bony base of the skull, and then turns upward to its exit in the floor of the middle cranial cavity, above the foramen lacerum.

Questions & Answers

what usually cause blood pressurae
Abdullateef Reply
too much salt in the diet
Abuusu
older age
Abuusu
Even family history of high blood pressure
Abuusu
explain the cellular mechanism that produces tetanus and summation
Jenica Reply
epithelial cells polerity
jitendra Reply
tissues
Deepak
demonstrate the fluid replacement in the body
John Reply
the red blood cells is in the long bones or flat bones?
isbii
as age increases, the bone elongates .. will the joint vanish?
Sushruth Reply
what is anatomy?
Ivy Reply
structure
Allonda
discuss the organization of the body
Mwila Reply
explain the cellular mechanism that produces tetanus and summation
Chayanne Reply
explain why the muscle doesn't respond to low stimulus voltages
Chayanne
how would muscle contractions be affected if skeletal muscle fibers did have T - tubules?
Chayanne
tetanus is a disease caused by a bacteria causing rigidity and spasms of volutary muscles.. there is a prolonged construction of muscles caused by repeated stimuli
Marcus
muscles follow the "all or none law" when it comes to reponse to stimuli... muscle construction would have been affected because the T tubules are the conducting tracts that transport the or move the action potential in deporalizing the other parts of cell hence the muscle wont act as a single cell
Marcus
Skeletal muscle fibers do have t tubules that's how action potential propagates to spread throughout the muscle. Tetanus production is a phenomenon which is better explained in time rather then cellularly. Action potentials either separated in time or space are summated on the muscle and
Vikas
When the stimulus frequency hits more than 25 the individual twitches from the fibers summate and the muscle as a whole contracts. Cellulary, a good amount of calcium needs to be accumulated as is done by twitches adding together.
Vikas
what is the names of tarsus?
Fathia Reply
the region of the foot containing the seven tarsal bones.
Manja
the tarsal bones
Marcus
how the valves keep the blood moving in one direction?
Nonie Reply
They open and close during blood circulation,
Denis
Then valve open labb sound and valve close dabb sound
HARDIK
The valves for example the semilunar valves act to prevent back flow of blood from arteries to ventricles during ventricular diastole and help to maintain pressure on the major arteries .The aortic semilunar valve separate the left ventricle from opening of the aorta.
Denis
thank you
Nonie
😷
HARDIK
hi
Shakir
hello
Manja
Yes
kannan
what are estrogen and progesterone ? and their functions
Emmanuel
it's a body hormones and this is spread by women and it's can help to reproduction system...
HARDIK
yhe I also wana know
Lemasyanji
can we introduce ourselves and share contact?
Emmanuel
🤔
HARDIK
thanks
Emmanuel
i want ti study medicine.. what are the main course?
Emmanuel
Progesterone helps to maintain the endometrium wall which is later shed out of the body during the menstrual cycle
Smisha
Estrogen is another ovarian hormone which helps the primary follicle to develop into graafian follicle and cause ovulation
Smisha
what is decstro cardiac
priyanshi
Right sided heart in a guy
Vikas
Dextrocardia is a condition where the. heart lies in the right side of the thorax instead of the left and it occurs when the heart loops to the left instead of the right.
Idoko
hii
Vikas
can any talk me a scope of anatomy and physiology
Vikas
please
Vikas
It has valves that OPEN and close during circulation
xiao
What does the Thyroid gland means
Solomon Reply
It's a gland in your neck produces thyroid hormone maintains body metabolism
Vikas
how many joints are in the human foot?
Roghayeh Reply
I believe that is 33 joints
Ana
26 bones and 33 joints.
Amin
thank u.
Roghayeh
thanks
antouman
what is the nerve supply of orbicularis oculi?
Juliet Reply
buccal branch of the facial nerve (cranial nerve VII).
Jeremiah
thanks a lot
antouman
water is the compound formed when oxygen and hydrogen reacts together
Kabwe
what is chordinae tendinae
Aryan
Structures that keep the heart valves shut together n its "chordae"
Vikas
what is agglutination
Aryan
please can challenging questions be given out, and not what we already know, feel free to share hidden knowledge
barbie
people have usually have 2 kidneys.how are these located?
Roghayeh
what is the Function of Thyroid gland in our body
Fahim Reply
regulates body metabolic rate
Arif
describe blood cells
Sumanraj Reply
1.we have white blood 2.red blood. Blood I a platelate 3.plasma
UMAR
right
chimdinma

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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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