Skeletal System: Bones, Joints, Cartilage, Ligaments, Bursae
Our system is formed of muscles, tendons, ligaments, bones, cartilage, joints and bursae. Our muscles work with the systemanervosum to contract once stirred up with impulses (messages through the receptor arc) from motor nerves. The muscles are connected to the bones with ligaments. Our systemaskeletale is formed principally of bones and gristle. Bones attach to bones with gristle or ligaments. Bursae are tiny fluid-filled sacs at friction points close to joints to shield ligaments and tendons from rubbing against blank bones.
Our skeleton forms a robust, solid internal framework of bones for our body, nonetheless our bones solely conjure regarding 14 July of our total weight. Bones get their snap from powerful elastic ropelikefibers of scleroprotein. The core of some tiny bones is named marrow, it’s soft and gelatinlike.
The laborious outside of bones is strengthened by robust rods known as osteons. Bones have special cells known as osteoblasts that create new bone and osteoclasts that divide the previous bone. Bones grow by obtaining longer on the ends known as the long bone plate or growth plate. Bones are created rigid by laborious deposits of minerals like phosphate and metal.
The bones of the skeleton support our skin, provide our body form, defend and support our organs and create it potential for North American country to maneuver by acting as single and double levers. Bones don’t progress their own; muscles move our bones by propulsion on them. Muscles cannot push against the bone, thus muscles are available in pairs, one muscle pulls the bone a way and therefore the paired muscle pulls the bone back the opposite way.
We have a complete of 233 bones. Some bones are available in pairs that square measure virtually identical in size and form the bones within the left arm are constant because the bones within the right arm. There also are single bones within the median plane of our body the vertebrae in our back and neck. However, since our bones are perpetually being remodeled as we have a tendency to age, each their structure and type will modification. Our bones may be stiffly connected to every alternative or joined by rubbery gristle, or flexibly connected by muscular or ligamentous joints. An Adult skeleton has 206 bones, though some peoples have further bones in their spine (backbone).
A baby’s skeleton has three hundred bones or additional. because the baby grows, a number of the bones fuse like the bones within the os and therefore the pelvis. most women and girls have smaller skeletons than boys and men of constant age. There are 2 main components of the skeleton the skeletal structure and therefore the skeletal structure.
The skeletal structure
There are 126 bones within the arms, shoulders, hips, and legs. The skeletal structure is formed of our limbs or appendagestwo arms and 2 legsour pelvis and right and left shoulders. Our arms suspend from our shoulders
The skeletal structure (trunk) is formed of the eighty bones in our higher body. Bones of the skeletal structure include:
- Skull (facial and os bones)
- Vertebrae within the spine (backbones)
- Sternum (breastbone)
- Our arms and shoulders suspend from the skeletal structure.
- and legs connected to our hips.
- Bones of the higher Appendage (Arm)
- Shoulder girdle—scapula (shoulder blade), bone (collar bone)
- Humerus—long bone of the higher arm
- Radius—long bone of the forearm; connects with the arm bone to make the elbow
- Ulna—long bone of the forearm; connects with the arm bone to make the elbow
- Carpals—8 tiny bones of the carpus
- Metacarpals—small bones of the hand
- Phalanges—14 bones of the fingers (3 in every finger) and thumb (2 within the thumb)
- Bones of the Lower Appendage (Leg)
- Pelvic Girdle—made of the proper and left hip bones that square measure joined within the back with the bone and within the front at the symphysis bone
- Hipbone—made of the ilium, bone and ischial bone
- Femur—long bone of the thigh and longest bone within the body; connects with pelvis to make and ball-and-socket joint and therefore the leg bone and leg bone to make the genu
- Tibia—long bone of the lower leg (shin bone); connects with the femoris to make the knee
- Fibula—thinner, oslongum of the lower leg
- Patella—kneecap (Learn additional regarding knee anatomy)
- Tarsals—small bones of the hand
- Phalanges—bones of the toes (3 in every toe and a pair of within the huge toe)
Jointsalso known as articulationsare shaped wherever the surfaces of 2 or additional bones meet and articulate with one another. There square measure regarding four hundred joints within the physical body. Joints permit each movement and suppleness. Joints are classified by what quantity movement they allow function or what they’re created ofstructure. Joints are typically classified structurally by the tissue that connects them.
The tissue may well be gristle, animal tissue, synovia, or some combination of the 3. Functionally, joints may be classified by the degree of movement potential, the amount of bones concerned, and therefore the complexness of the joint. Most body joints permit North American country to maneuver, and a few solely permit movement in sure ways in which. fastened or immoveable joints permit no movement. A separated joint happens once the bones of the joint are forced out-of-place, typically whereas taking part in sports however may also happen with accidents. There are three major useful joints and three major styles of structural joints.
Types of Synovial Joints
immovable (synarthrosis) joints—the bones are command along by animal tissue in order that they don’t move at all; example is that the os bones
slightly movable (amphiarthrosis) joints—the bones are command along by gristle that enables solely a bit movement; examples square measure the joints within the spine
freely movable (diarthrosis) joints—also known as secretion joints, permit the foremost movement; examples are hip and knee joints
Types of Structural Joints
fibrous: the articulary surfaces (point on the bone’s surface wherever the 2 bones meet) are command along by fibrous animal tissue. little movement is feasible. samples of fibrous joints are sutures, syndesmoses, and gomphoses.
cartilaginous (amphiarthroses): the bones in gristly joints are command along by gristle that permits slight movement.
synchondroses-these are temporary joints wherever the gristle converts to bone by the time we have a tendency to square measure adults. the expansion plates of long bones are samples of this sort of joint.
symphyses-these joints have a pad of cartilage separating the bones; AN example is that the symphysis bone
synovial-the bony surfaces on the ends of the bones are coated with articulary gristle and separated by a slippery, lubricating fluid known as synovial fluid. They bones are command along within the joint by ligaments lined with secretion membranes that turn out the synovia. These freely moving joints square measure principally found in our arms and legs. secretion joints also include
a joint cavity or joint area: space between the articulating surfaces; articulating surfaces are the bone surfaces that move against one another once the joint moves. The articulating surfaces are coated with a layer of gristle that cushions and protects the bones. The synovium defines the boundaries of the joint area—everything outside of the synovium is outside the joint space. The synovium is wrapped by layers of animal tissue that type the joint capsule.
Anarticulary capsule: a sac-like structure that surrounds the joint ANd has AN outer layer lined with a synovium (synovium) that produces the synovia. synovia acts as a material, forms a fluid seal and helps distribute the force placed on the joint.
reinforcing ligaments: powerful, fibrous connective tissues that connect the bones and reinforce the joint capsule. On the surface of the joint capsule square measure thick strap-like bands, known as collateral ligaments. These ligaments direct the force that travels through the joint and keep the joint heading in the right direction. Outside of those structures are the muscles that travel across the joint.
Types of secretion Joints
Based on the kind of movement the joint permits and its structure, secretion joints may be place into many classes.
Gliding (plane) joint: have flat or slightly incurved articulary surfaces and permit glide movements. The manner they’re certain along by the ligaments might not permit movement all told directions. samples of a articulatiosynovialis are the intertarsal and intercarpal joints of the hands and feet.
hinge joint: have a hogged (curved outward) a bone that matches into the concave (curved inward) part of another bone. The action of the hinge joint is like that of a door hinge and motion is proscribed to bending and straightening. Our elbows and knees square measure samples of hinge joints.
pivot (swivel) joint: have a bone with a rounded finish fitting into a groove in another bone. Pivot joints permit one bone to pivot on the opposite bone. an example is head of the radius rotates at intervals the groove of the elbow bone.
condylar (ellipsoidal) joint: these joints have a bony surface that’s oval-shaped fitting into a concave surface of another bone. These joints permit bending, straightening, abduction, motility and movement. An example of condular joints are within the hands.
saddle joint: these joints square measure simialr to outgrowth joints however permit additional movement. the sole saddle joints are within the thumb.
ball-and-socket joint: these bones match along sort of a ball during a socket: the spherical finish of 1 bone fits into the concave socket of the opposite bone. the sole ball-and-socket joints are the shoulders and hips.
Joints of the higher Appendage (Arm)
Shoulder—links the arm to the trunk. it’s placed faraway from the trunk therefore the arm will move freely. The arm hangs vertically beside the trunk.
Elbow—the elbow will bend from fifteen – a hundred and eighty °. Once the elbow is bent, the shoulder and skeletal structure are within the same plane.
Joints of the Lower Appendage (Leg)
Hip—links the leg to the trunk. The leg hangs vertically below the trunk. The ball-and-socket joint is wherever the os joins the femoris. The ball-and-socket joint will bend from zero-125 ° and straightened from one hundred fifteen to 0 °.
Knee—the knee will bend from zero – one hundred thirty ° and extend from one hundred twenty – zero °. The knee is created by the leg bone, fibular, femoris and patella.
Metatarsal—joints within the foot
Phalangeal—joints within the toes