Blood Supply And Lymphatics
Most of the blood supply to the skull and its associated structures comes from the common carotid arteries and vertebral arteries . The common carotid artery splits into the internal and external carotid arteries. The external carotid is the main blood supply to the skull bones and meninges. It travels up the side of the neck with eight main branches feeding the superficial structures of the skull and face. Of these branches, the maxillary artery is the most prominent and clinically relevant. The middle meningeal artery is a branch of the maxillary artery, and injury secondary to blunt force trauma to the lateral skull at the pterion can lead to epidural hematoma. The internal carotid has no branches in the neck and enters the base of the skull, supplying intracranial structures. The internal carotid and vertebral arteries combine to form a large anastomosis called the circle of Willis. The anterior communicating artery, two anterior cerebral arteries, two middle cerebral arteries, two posterior communicating arteries, two posterior cerebral arteries, and basilar artery all contribute to this anastomosis. The dural venous sinuses and superficial and deep veins of the head drain into the internal and external jugular veins bilaterally and ultimately to the superior vena cava and right atrium of the heart.
The Nasal Septum And Nasal Conchae
The nasal septum consists of both bone and cartilage components see also ). The upper portion of the septum is formed by the perpendicular plate of the ethmoid bone. The lower and posterior parts of the septum are formed by the triangular-shaped vomer bone. In an anterior view of the skull, the perpendicular plate of the ethmoid bone is easily seen inside the nasal opening as the upper nasal septum, but only a small portion of the vomer is seen as the inferior septum. A better view of the vomer bone is seen when looking into the posterior nasal cavity with an inferior view of the skull, where the vomer forms the full height of the nasal septum. The anterior nasal septum is formed by the septal cartilage, a flexible plate that fills in the gap between the perpendicular plate of the ethmoid and vomer bones. This cartilage also extends outward into the nose where it separates the right and left nostrils. The septal cartilage is not found in the dry skull.
The Bone That Protects Your Brain
Humans are capable of living without some of our organs. We can have a perfectly normal life with only one kidney, without reproductive organs, without a spleen and even, if a cancer situation requires it, without a stomach.
What is physically impossible is living without a brain, so it is not surprising that evolution has led us to protect this structure in the safest way that anatomy allows.
In this post we are going to talk about the bones that protect our brains, how they are constituted, we will detail its parts and highlight the importance of this protective bone for the human being.
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The Two Temporal Bones
These two bones are located on the sides, one on each side of the head. These two bones protect the temporal lobes, thus ensuring that auditory language and speech understanding are not susceptible to trauma.
They also protect the brainstem, which is the major communication pathway for the brain, spinal cord, and peripheral nerves. The temporal bones are therefore responsible for ensuring that the area responsible for controlling respiration and heart rate is not affected.
These two bones have a hole that serves to support the ear, thus allowing sounds to reach the eardrum on each side of the head. Otherwise, we could not perceive any sound.
Facial Bones Of The Skull
The facial bones of the skull form the upper and lower jaws, the nose, nasal cavity and nasal septum, and the orbit. The facial bones include 14 bones, with six paired bones and two unpaired bones. The paired bones are the maxilla, palatine, zygomatic, nasal, lacrimal, and inferior nasal conchae bones. The unpaired bones are the vomer and mandible bones. Although classified with the brain-case bones, the ethmoid bone also contributes to the nasal septum and the walls of the nasal cavity and orbit.
The maxillary bone, often referred to simply as the maxilla , is one of a pair that together form the upper jaw, much of the hard palate, the medial floor of the orbit, and the lateral base of the nose ). The curved, inferior margin of the maxillary bone that forms the upper jaw and contains the upper teeth is the alveolar process of the maxilla ). Each tooth is anchored into a deep socket called an alveolus. On the anterior maxilla, just below the orbit, is the infraorbital foramen. This is the point of exit for a sensory nerve that supplies the nose, upper lip, and anterior cheek. On the inferior skull, the palatine process from each maxillary bone can be seen joining together at the midline to form the anterior three-quarters of the hard palate a). The hard palate is the bony plate that forms the roof of the mouth and floor of the nasal cavity, separating the oral and nasal cavities.
Inferior Nasal Conchae
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Is Head The Same As Skull
Traditionally we tend to refer to the head and the skull as simple synonyms. However, technically they are not, as the skull is a portion of the head. The term skull refers to the bony structures that cover and protect the brain, forming part of a whole that is the head.
This, therefore, includes both these skull bones and the rest of the elements that make up the facial skeleton: mouth, eyes, jaw, nose, etc.
In this context, the classification of the bones of the head is carried out according to this differentiation. On the one hand, we have a group of neurocranial bones: flattened bony elements that surround the brain, protecting it.
On the other hand, we have the group of the viscerocranium: bones of much more variable shapes that accompany and make possible much broader biological functions .
Therefore, in this article we will differentiate between the bones of the neurocranium and the viscerocranium, reviewing the bones that make up each of these groups.
The Bones Of The Skull Protect The Brain
- Slides: 56
The bones of the skull protect the brain and guard the entrances to the digestive and respiratory systems. steven lee M. S. Pathology FTCC
steven lee M. S. Pathology FTCC
Frontal bone Zygomatic bone maxilla vomer steven lee M. S. Pathology FTCC mandible
Frontal bone Zygomatic Process Supraorbital Foramen Glabella Supraorbital Margin Infraorbital foramen Middle nasal concha Perpendicular plate maxilla Alveoli processes vomer steven lee M. S. Pathology FTCC Inferior nasal concha mandible Alveoli processes
Frontal eminence Superciliary arch steven lee M. S. Pathology FTCC
steven lee M. S. Pathology FTCC
Middle na ncha Inferior nasal co steven lee M. S. Pathology FTCC Perpendicular plate Infraorbital foramen vomer
steven lee M. S. Pathology FTCC
Optic foramen or canal e sur fis tal rbi ) r o ne rio id bo pe Su heno b or bo r y rio llar e f i In ax (m
When the supraorbital foramen is not completely enclosed by bone, there is a supraorbital notch, rather than a foramen, on the orbital rim, as is the case for this specimen. steven lee M. S. Pathology FTCC
Optic canals permit passage of the optic nerves from the eyes to the brain. steven lee M. S. Pathology FTCC
The inferior orbital fissure permits passage of cranial nerves and blood vessels. steven lee M. S. Pathology FTCC
The superior orbital fissure permits passage of cranial nerves and blood vessels to the orbit steven lee M. S. Pathology FTCC
steven lee M. S. Pathology FTCC
steven lee M. S. Pathology FTCC
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Skull Bone Anatomy & Clinical Significances
Skull: The skull is a skeletal framework of the head of vertebrates, that supports the face and makes a protective cavity concerning the brain. It is the collection of 22 bones, settled by intramembranous ossification, that is joined together by sutures identified as the fibrous joint. These joints combine together in adulthood, therefore permitting brain growth throughout the adolescence.The skull is supported by the uppermost vertebra, known as the atlas, allowing nodding motion. The atlas shifts on the subsequent-lower vertebra, the axis, to permit for side-to-side motion.
The skull bones can be classified into two groups: Cranium and facial bones.
The Skeletal System Consists Of More Than Bones
When you look at the human skeleton the 206 bones and 32 teeth stand out. But look closer and youll see even more structures. The human skeleton also includes ligaments and cartilage. Ligaments are bands of dense and fibrous connective tissue that are key to the function of joints. Cartilage is more flexible than bone but stiffer than muscle. Cartilage helps give structure to the larynx and nose. It is also found between the vertebrae and at the ends of bones like the femur.
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Anatomy Of The Bones In The Cranium
The cranium is somewhat spherical, mostly resembling a baseball cap. Anatomically, the cranium is divided into two parts: cranial roof and cranial base.
Also known as calvarium, this part of the cranium is formed by the frontal, occipital, and two parietal bones.
It is composed of the frontal, sphenoid, ethmoid, occipital, parietal, and temporal bones.
Now, let us discuss these individual bones in a bit detail:
1. Frontal Bone: It is an unpaired flat bone that makes up the forehead and upper part of the eye sockets.
2. Parietal Bones: This is a pair of flat bones located on either side of the head, just behind the frontal bone. It protects the brain lying underneath.
3. Temporal Bones: Another paired bone, located under each of the parietal bones. However, unlike the previous, these are irregular bones. These bones protect auditory nerves and a few ear structures that control hearing and balance.
4. Occipital Bone: It is an unpaired flat bone found at the back of the skull. It has an opening through which the spinal cord passes and connects to the brain.
5. Sphenoid Bone: An unpaired irregular bone located just below the frontal bone. It forms a large part of the skull base, as it spans the width of the skull.
6. Ethmoid Bone: Another unpaired irregular bone located in front of the sphenoid bone that forms a part of the nasal cavity.
Cranial Bones Mnemonic
Here are some sentences that will help you to remember the names of these cranial bones:
Neurocranial Bones: Brain Protection
A total of eight bones flattened and naturally welded together form the structure that protects the brain from blows and injuries, thus ensuring that the nervous system does not suffer damage throughout the life of the person.
We have heard it said many times that babies cannot hit their heads because they dont have bones yet. This, despite the fact that you always have to watch out for the little ones, is not entirely true.
At the moment we are born we already have these skull bones the problem is that, due to the disproportionate size of the brain in relation to the other organs at birth, these bones are not well welded together. As childhood progresses, these holes disappear, thus forming a compact structure.
Next we will see one by one these bones of the neurocranium: two temporal bones, two parietal bones and one frontal, occipital, ethmoid and sphenoid.
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The Adult Human Skeleton Is Made Up Of 206 Bones
These bones provide structure and protection and facilitate motion. Bones articulate to form structures. The skull protects the brain and gives shape to the face. The thoracic cage surrounds the heart and lungs. The vertebral column, commonly called the spine, is formed by over 30 small bones. Then there are the limbs and the girdles that attach the four limbs to the vertebral column.
The Two Parietal Bones
The two parietal bones occupy the area that makes up the crown and its surroundings. They are two symmetrical bones and welded together.
Its function is to protect the part of the cerebral cortex underneath, which is where perception, imagination, judgment, thought, etc. occur. In the same way, it ensures the integrity of the parietal lobes and the subcortical organs underneath. These parietal lobes are responsible for regulating moods and processing sensory stimuli.
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Clinical Relevance: Cranial Fractures
Fractures of the cranium typically arise from blunt force or penetrating trauma. When considering cranial fractures, one area of clinical importance is the pterion a H-shaped junction between the temporal, parietal, frontal, and sphenoid bones.
The pterion overlies the middle meningeal artery, and fractures in this area may injury the vessel. Blood can accumulate between the skull and the dura mater, forming an extradural haematoma.
Fig 2 Lateral view of the skull, showing the path of the meningeal arteries. Note the pterion, a weak point of the skull, where the anterior middle meningeal artery is at risk of damage.
Some Joints Don’t Move Or Move Very Little
One way to classify joints is by range of motion. Immovable joints include the sutures of the skull, the articulations between teeth and the mandible, and the joint located between the first pair of ribs and the sternum. Some joints have slight movement an example is the distal joint between the tibia and fibula. Joints that allow a lot of motion are located in the upper and lower limbs.
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Infants Have More Bones Than Adults
An infant skeleton has almost a hundred more bones than the skeleton of an adult. Bone formation begins at about three months gestation and continues after birth into adulthood. An example of several bones that fuse over time into one bone is the sacrum. At birth the sacrum is five vertebrae with discs in between them. The sacrum is fully fused into one bone usually by the fourth decade of life.
Lateral View Of Skull
A view of the lateral skull is dominated by the large, rounded brain case above and the upper and lower jaws with their teeth below . Separating these areas is the bridge of bone called the zygomatic arch. The zygomatic arch is the bony arch on the side of skull that spans from the area of the cheek to just above the ear canal. It is formed by the junction of two bony processes: a short anterior component, the temporal process of the zygomatic bone and a longer posterior portion, the zygomatic process of the temporal bone, extending forward from the temporal bone. Thus the temporal process and the zygomatic process join together, like the two ends of a drawbridge, to form the zygomatic arch. One of the major muscles that pulls the mandible upward during biting and chewing arises from the zygomatic arch.
On the lateral side of the brain case, above the level of the zygomatic arch, is a shallow space called the temporal fossa. Below the level of the zygomatic arch and deep to the vertical portion of the mandible is another space called the infratemporal fossa. Both the temporal fossa and infratemporal fossa contain muscles that act on the mandible during chewing.
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What Is The Bone That Protects Your Brain
The skull is the bone that protects your brain.
Bones are rigid organs that, in addition to making movement possible and allowing the body to be properly supported, have the mission of protecting sensitive organs. That is why our brain is surrounded by a series of bones with different morphology and functionality that fulfill the purpose of protecting the store of all our information, our perception and our cognition.
Anyway, the role of the human head is not limited only to the protection of the brain, but it is also the place where most of our senses reside and the one that gives us individual personality. That is why a total of 22 bones fulfill these and many other functions, guaranteeing correct morphology and physiology.
In this article we will see what are the bones that make up our head, paying special attention to the functions they perform and their biological purpose.
Introduction To The Skeletal System
Humans are vertebrates, animals having a vertabral column or backbone. They rely on a sturdy internal frame that is centered on a prominent spine. The human skeletal system consists of bones, cartilage, ligaments and tendons and accounts for about 20 percent of the body weight.
The living bones in our bodies use oxygen and give off waste products in metabolism. They contain active tissues that consume nutrients, require a blood supply and change shape or remodel in response to variations in mechanical stress.
Bones provide a rigid framework, known as the skeleton, that support and protect the soft organs of the body.
The skeleton supports the body against the pull of gravity. The large bones of the lower limbs support the trunk when standing.
The skeleton also protects the soft body parts. The fused bones of the cranium surround the brain to make it less vulnerable to injury. Vertebrae surround and protect the spinal cord and bones of the rib cage help protect the heart and lungs of the thorax.
Bones work together with muscles as simple mechanical lever systems to produce body movement.
Hematopoiesis, the formation of blood cells, mostly takes place in the red of the bones.
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