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External and internal views of base of skull

This image shows the superior and inferior view of the skull base. In the top panel, the inferior view is shown. A small image of the skull shows the viewing direction on the left. In the inferior view, the maxilla and the associated bones are shown. In the bottom panel, the superior view shows the ethmoid and sphenoid bones and their subparts.
(a) The hard palate is formed anteriorly by the palatine processes of the maxilla bones and posteriorly by the horizontal plate of the palatine bones. (b) The complex floor of the cranial cavity is formed by the frontal, ethmoid, sphenoid, temporal, and occipital bones. The lesser wing of the sphenoid bone separates the anterior and middle cranial fossae. The petrous ridge (petrous portion of temporal bone) separates the middle and posterior cranial fossae.

Frontal bone

The frontal bone    is the single bone that forms the forehead. At its anterior midline, between the eyebrows, there is a slight depression called the glabella    (see [link] ). The frontal bone also forms the supraorbital margin of the orbit. Near the middle of this margin, is the supraorbital foramen, the opening that provides passage for a sensory nerve to the forehead. The frontal bone is thickened just above each supraorbital margin, forming rounded brow ridges. These are located just behind your eyebrows and vary in size among individuals, although they are generally larger in males. Inside the cranial cavity, the frontal bone extends posteriorly. This flattened region forms both the roof of the orbit below and the floor of the anterior cranial cavity above (see [link] b ).

Occipital bone

The occipital bone    is the single bone that forms the posterior skull and posterior base of the cranial cavity ( [link] ; see also [link] ). On its outside surface, at the posterior midline, is a small protrusion called the external occipital protuberance    , which serves as an attachment site for a ligament of the posterior neck. Lateral to either side of this bump is a superior nuchal line    (nuchal = “nape” or “posterior neck”). The nuchal lines represent the most superior point at which muscles of the neck attach to the skull, with only the scalp covering the skull above these lines. On the base of the skull, the occipital bone contains the large opening of the foramen magnum    , which allows for passage of the spinal cord as it exits the skull. On either side of the foramen magnum is an oval-shaped occipital condyle    . These condyles form joints with the first cervical vertebra and thus support the skull on top of the vertebral column.

Posterior view of skull

This figure shows the posterior view of the skull and the major parts are labeled.
This view of the posterior skull shows attachment sites for muscles and joints that support the skull.

Sphenoid bone

The sphenoid bone    is a single, complex bone of the central skull ( [link] ). It serves as a “keystone” bone, because it joins with almost every other bone of the skull. The sphenoid forms much of the base of the central skull (see [link] ) and also extends laterally to contribute to the sides of the skull (see [link] ). Inside the cranial cavity, the right and left lesser wings of the sphenoid bone    , which resemble the wings of a flying bird, form the lip of a prominent ridge that marks the boundary between the anterior and middle cranial fossae. The sella turcica    (“Turkish saddle”) is located at the midline of the middle cranial fossa. This bony region of the sphenoid bone is named for its resemblance to the horse saddles used by the Ottoman Turks, with a high back and a tall front. The rounded depression in the floor of the sella turcica is the hypophyseal (pituitary) fossa    , which houses the pea-sized pituitary (hypophyseal) gland. The greater wings of the sphenoid bone extend laterally to either side away from the sella turcica, where they form the anterior floor of the middle cranial fossa. The greater wing is best seen on the outside of the lateral skull, where it forms a rectangular area immediately anterior to the squamous portion of the temporal bone.

Questions & Answers

what is anatomy
philemon Reply
what is anatomy in terms of medicine
philemon
it is the study of human and animal form by observing and examined them and sometimes dissecting them and view the tiny thing by the use of microscope
Kwasi
Describe early studies into the working of human body.
Tonny Reply
please guys help me to answer this question; Define the two divisions of the skeleton ?
Jonathan Reply
two example of appendicular skeleton
Jonathan
upper limb ;eg humerus n lower limb;eg tibia
BRIAN
write notes on the level of organizations of the body .citing examples for each level
Kaddijatou Reply
Jonathan Nyakpaab
Jonathan
what is pathology
Ericka Reply
1 What is Nasogastric Tube 2 what is the difference between Nasogastric Aspiration and Nasogastric Feeling
ONOJA Reply
You measure a patient’s blood pressure at 130/85. Calculate the patient’s pulse pressure and mean arterial pressure. Determine whether each pressure is low, normal, or high.
ONOJA
normal blood pressure 120/80
Mohd
what are nocciceptors
Soul
hfjfjcjjjghkbv
Mohd
1 Its a flexible tube of plastic that pass through the nose, down to the eausophagus, and into the stomach, used to add or remove substances in the stomach.
Andile
2 Nasogastric aspiration is process of draining stomach contents via a tube and Nasogastric feeding is a process of giving food liquid through nasogastric tube
Andile
andile sir what is meant by clonoscopy
Soul
colonoscpopy is an exam use to detect abnormalities in the small intestine or the colon
Kwasi
What is the skin
Astony Reply
What is physiology?
Njaleny Reply
it is the study of the structure of the human body and its reationship
Hannah
Physiology is the function of a living organism.
Tammy
It is the study of human body and how it works.
Excellent
if physiology is the function of a living organism.What method is keep for living organism.
Ayoore
what are Nocciceptors
Soul
Nocciceptors are pain receptor
Kwasi
Or is a sensory neutron that responds to damage
Kwasi
It is d entrance to the uterus
Umunna Reply
It is a small sensitive part of female sex organ which is found above d entrance to the vagina
Umunna
A small hole in d skin which contains d root of a hair
Umunna
A thin membrane which covers d entrance to the vagina in young girls
Umunna
Is a gland that produces milk in women and other female mammals
Umunna
A repeated process in which a woman's uterus gets ready for pregnancy which ends in a period if she does not get pregnant
Umunna
hello
Tamba
hi sir
Mir
Hi
Umunna
hi
Shafiq
why should one consider studying neuroanatomy to physiology?
Ramadhan
hy
kaabe
hi
HANIFA
hmm
Hussain
hi
Muhammad
Hi
miya
hello
Adnan
hello
Ayoore
so in summary describe the level of structural complexity within the body
Freda Reply
how can we describe briefly the levels of organization
Frimpong
what is blood clotting
Yahya Reply
Tiny bits in your blood called platelets get "turned on" by triggers released when a blood vessel is damaged. They stick to the walls in the area and each other, changing shape to form a plug that fills in the broken part to stop blood from leaking out. When activated, platelets also release chemic
Nilesh
what is a cell membrane?
lameck Reply
the cell membrane also called the plasma membrane regulates the transport materials entering and existing the cell.
Frimpong
what's gonna happen if your body doesn't produce enough white blood cells?
Jovanna
how is speech controlled by the nervous system?
Joseph Reply
The broca's area
Udebuana
what does the HCG
Njaleny
chemical level cellular level tissue level organ level organ system level organism
Chidera Reply
Yes Yes because they can perform more than one activity in the body
Chidera
the functional and structural unit of the body
Chidera
A group of 2 or more tissue that come together to perform a specific function
Chidera
A group of organs that work together to perform a specific function or meet the physiological needs of the body
Chidera
It's the highest level of organization
Chidera
2 or more cells coming together to perform a specific function
Chidera
Skeletal muscles can be tetanized but not cardiac muscle.Discuss
Okeke Reply

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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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