What Are Bones Made Of
If youve ever seen a real skeleton or fossil in a museum, you might think that all bones are dead. Although bones in museums are dry, hard, or crumbly, the bones in your body are different. The bones that make up your skeleton are all very much alive, growing and changing all the time like other parts of your body.
Almost every bone in your body is made of the same materials:
- The outer surface of bone is called the periosteum . Its a thin, dense membrane that contains nerves and blood vessels that nourish the bone.
- The next layer is made up of compact bone. This part is smooth and very hard. Its the part you see when you look at a skeleton.
- Within the compact bone are many layers of cancellous bone, which looks a bit like a sponge. Cancellous bone is not quite as hard as compact bone, but it is still very strong.
- In many bones, the cancellous bone protects the innermost part of the bone, the bone marrow . Bone marrow is sort of like a thick jelly, and its job is to make blood cells.
Anatomy And Physiology I
- List and identify the bones of the brain case and face
- Locate the major suture lines of the skull and name the bones associated with each
- Locate and define the boundaries of the anterior, middle, and posterior cranial fossae, the temporal fossa, and infratemporal fossa
- Define the paranasal sinuses and identify the location of each
- Name the bones that make up the walls of the orbit and identify the openings associated with the orbit
- Identify the bones and structures that form the nasal septum and nasal conchae, and locate the hyoid bone
- Identify the bony openings of the skull
The;cranium; is the skeletal structure of the head that supports the face and protects the brain. It is subdivided into the facial bones;and the;brain case, or cranial vault . The facial bones underlie the facial structures, form the nasal cavity, enclose the eyeballs, and support the teeth of the upper and lower jaws. The rounded brain case surrounds and protects the brain and houses the middle and inner ear structures.
In the adult, the skull consists of 22 individual bones, 21 of which are immobile and united into a single unit. The 22nd bone is the;mandible;, which is the only moveable bone of the skull.
Figure;1.;Parts of the Skull. The skull consists of the rounded brain case that houses the brain and the facial bones that form the upper and lower jaws, nose, orbits, and other facial structures.
What Bones Protect The Spinal Cord
The human spinal cord is protected by the spinal column, which is made up of bones called vertebrae. Each vertebra consists of the spinous process, transverse process and body. The spinal cord passes through the vertebral foramen, the middle opening in the vertebrae.
The spinal cord is a bundle of nerve fibers that transmits information between the brain and the peripheral nervous system. It is a conduit for motor information that travels down the spinal cord, a conduit for sensory information that travels up the spinal cord and a center to coordinate reflexes. The spinal cord consists of 31 segments that span approximately 43 centimeters in length in women and 45 centimeters in men. Two spinal nerves branch from each segment of the spinal cord.
Different spinal nerves perform different functions. Cranial spinal nerves transmit signals to the back of the head, neck, shoulders, arms, hands and diaphragm. The thoracic spinal nerves control the signals to the chest muscles and parts of the back and abdomen. Lumbar spinal nerves transmit signals to the lower parts of the abdomen, back and buttocks and parts of the leg. Finally, the sacral spinal nerves control the signals to the lower legs, thighs and feet.
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Symptoms Of A Cranial Bone Condition
With all the structures in your head and neck, its sometimes hard to pinpoint when symptoms are coming from an issue with the cranial bones.
Symptoms that suggest some type of cranial bone fracture include:
- bruising around the eyes or behind your ears
- clear fluid or blood draining from your ears or nose
- a feeling of weakness in your face
Symptoms of a structural issue with the cranial bones include:
- a dull, aching pain
- numbness or tingling in your face
- hearing or vision problems
What Happens When You Break A Bone
Your healthcare provider will classify a fracture based on the way the bone breaks. Types of fractures include:
- Stable : The ends of the broken bones line up.
- Stress fracture: Overuse causes a crack in the bone.
- Open : The broken bone breaks the skin.
If you break a bone, youll need an imaging test called an X-ray so your doctor can identify the type of fracture. Depending on the severity of the break, youll need to immobilize it in a cast or brace for three to eight weeks. Broken bones can take several months to heal completely.
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Why Is The Skeleton Important
When considering the four major functions of the skeleton it is easy to see why it is so important.; Without it we would simply be a pile of ‘jelly’ lying on the floor, unable to move and with no blood or immunity.; So maintaining a healthy functioning skeleton is part and parcel of being able to do all our daily activities and participate in all physical activities effectively.
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.
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What Are Bones And What Do They Do
Bones provide support for our bodies and help form our shape. Although they’re very light, bones are strong enough to support our entire weight.
Bones also protect the body’s organs. The skull protects the brain and forms the shape of the face. The spinal cord, a pathway for messages between the brain and the body, is protected by the backbone, or spinal column. The ribs form a cage that shelters the heart and lungs, and the pelvis helps protect the bladder, part of the intestines, and in women, the reproductive organs.
Bones are made up of a framework of a protein called collagen, with a mineral called calcium phosphate that makes the framework hard and strong. Bones store calcium and release some into the bloodstream when it’s needed by other parts of the body. The amounts of some vitamins and minerals that you eat, especially vitamin D and calcium, directly affect how much calcium is stored in the bones.
Bones are made up of two types of bone tissues:
What Are Joints And What Do They Do
Joints are where two bones meet. They make the skeleton flexible without them, movement would be impossible.
Joints allow our bodies to move in many ways. Some joints open and close like a hinge , whereas others allow for more complicated movement a shoulder or hip joint, for example, allows for backward, forward, sideways, and rotating movement.
Joints are classified by their range of movement:
- Immovable, or fibrous, joints don’t move. The dome of the skull, for example, is made of bony plates, which move slightly during birth and then fuse together as the skull finishes growing. Between the edges of these plates are links, or joints, of fibrous tissue. Fibrous joints also hold the teeth in the jawbone.
- Partially movable, or cartilaginous;, joints move a little. They are linked by cartilage, as in the spine. Each of the vertebrae in the spine moves in relation to the one above and below it, and together these movements give the spine its flexibility.
- Freely movable, or synovial , joints move in many directions. The main joints of the body such as those found at the hip, shoulders, elbows, knees, wrists, and ankles are freely movable. They are filled with synovial fluid, which acts as a lubricant to help the joints move easily.
Three kinds of freely movable joints play a big part in voluntary movement:
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What Protects The Brain And Spinal Cord
What protects the brain and spinal cord? The cerebrospinal fluid is a clear, watery liquid that surrounds, cushions and protects the brain and spinal cord. The CSF also carries nutrients in the blood to the brain. It circulates through chambers called ventricles and over the surface of the brain and spinal cord.
What 3 things protect the brain and spinal cord?;The brain and spinal cord are covered by three layers of meninges, or protective coverings: the dura mater, the arachnoid mater, and the pia mater.
What system protects the brain and spinal cord?;The skeletal system also protects internal organs and produces blood cells. Bones provide calcium that is essential for the proper functioning of the nervous system. The skull protects the brain from injury. The vertebrae protect the spinal cord from injury.
What protects the spinal cord?;The spinal cord is protected by bones, discs, ligaments, and muscles. The spine is made of 33 bones called vertebrae. The spinal cord passes through a hole in the center of each vertebra. Between the vertebrae there are discs that act as cushions, or shock absorbers for the spine.
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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Structure Of The Paranasal Sinuses
Skull Sinuses: This image shows the position of the sinuses in the human skull.
Paranasal sinuses are a group of four, paired, air-filled spaces that surround the nasal cavity , above the eyes , between the eyes , and behind the eyes . The sinuses are named for the facial bones that they are located behind.
- The maxillary sinuses are located under the orbits in the maxillary bones.
- The frontal sinuses are superior to the orbits and are in the frontal bone.
- The ethmoid sinuses are formed from several discrete air cells within the ethmoid bone between the nose and the orbits.
- The sphenoid sinuses are in the sphenoid bone at the center of the skull base under the pituitary gland.
- The paranasal sinuses are lined with respiratory epithelium.
The paranasal sinuses form developmentally through excavation of bone by air-filled sacs from the nasal cavity. This process begins prenatally and continues through the course of an individuals lifetime.
What Does The Skeletal System Do
The skeletal system has many functions. Besides giving us our human shape and features, it:
- Allows movement: Your skeleton supports your body weight to help you stand and move. Joints, connective tissue and muscles work together to make your body parts mobile.
- Produces blood cells: Bones contain bone marrow. Red and white blood cells are produced in the bone marrow.
- Protects and supports organs: Your skull shields your brain, your ribs protect your heart and lungs, and your backbone protects your spine.
- Stores minerals: Bones hold your bodys supply of minerals like calcium and vitamin D.
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How Do Muscles Work
The movements that muscles make are coordinated and controlled by the brain and nervous system. The involuntary muscles are controlled by structures deep within the brain and the upper part of the spinal cord called the brain stem. The voluntary muscles are regulated by the parts of the brain known as the cerebral motor cortex and the cerebellum .
When you decide to move, the motor cortex sends an electrical signal through the spinal cord and peripheral nerves to the muscles, making them contract. The motor cortex on the right side of the brain controls the muscles on the left side of the body and vice versa.
The cerebellum coordinates the muscle movements ordered by the motor cortex. Sensors in the muscles and joints send messages back through peripheral nerves to tell the cerebellum and other parts of the brain where and how the arm or leg is moving and what position it’s in. This feedback results in smooth, coordinated motion. If you want to lift your arm, your brain sends a message to the muscles in your arm and you move it. When you run, the messages to the brain are more involved, because many muscles have to work in rhythm.
The Nasal Septum And Nasal Conchae
The;nasal septum;consists of both bone and cartilage components . 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;, 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.
Figure;15.;Nasal Septum. The nasal septum is formed by the perpendicular plate of the ethmoid bone and the vomer bone. The septal cartilage fills the gap between these bones and extends into the nose.
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How Can I Keep My Skeletal System Healthy
To keep your skeletal system strong and healthy, you should:
- Get plenty of vitamin D and calcium in your diet to keep bones strong.
- Drink plenty of water to help keep tissues healthy.
- Exercise regularly to strengthen bones and joints.
- Stay at a healthy weight to avoid putting extra pressure on your bones and cartilage.
- Wear protective gear during contact sports such as football and hockey.
- Be cautious on stairs to avoid falls.
What Does The Skeleton Do
The skeleton provides four major functions, which are;
1. Support:; It provides a framework to support the organs and tissues of the body.;;
2. Protection:; It protects our internal organs.; The skull protects the brain; the thorax protects the heart, lungs and other viscera .
3. Movement:; It provides a framework for muscles to attach.; Then when the muscles contract they pull on the bones of the skeleton, which act like levers to create movement.;
4. Supply & Storage:; The bones that make up the skeleton are a source of both red blood cells and white blood cells , which are formed within the bone marrow.
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Flat Bones Of The Skull
The bones of your skull surround and protect your brain and also provide support to your face. Many of the bones of your skull are flat bones. These include:
- Frontal bone. This bone forms your forehead and the upper portion of your eye sockets.
- Parietal bones. You have two parietal bones on either side of your head. They form the top and sides of your skull.
- Occipital bone. This bone forms the back of your skull. It has an opening near the bottom that allows your spinal cord to meet your brain.
- Nasal bones. You have two nasal bones that form the bridge of your nose. They form the bridge of your nose.
- Lacrimal bones. You also have two small lacrimal bones that form part of your eye socket.
- Vomer bone. This bone forms your nasal septum, the space between your nostrils.