How many joints are there in the human body?
360 joints.First: 147 joints in the vertebral column25 joints between the vertebrae.72 joints between the vertebrae and the ribs.Second: 24 joints in the thorax2 joints between the bones of the sternum and the thoracic cage.18 joints between the sternum and the ribs.2 joints between the clavicle and the scapulae (shoulder blade).2 joints between the scapulae and the thorax.Third: 86 joints in the upper extremity2 joints between the scapular bones.6 joints between the elbows.8 joints between the wrists.70 joints between the hand bones.Fourth: 92 joints in the lower extremity2 hip joints.6 joints between the knee bones.6 joints between the ankles.74 joints between the feet bones.Fifth: 11 joints in the Pelvis4 joints between the coccyx vertebrae.6 joints between the bones acetabulm.1 joint of the pubic sumphysis.Total number of joints: 360
Ball and socket joints and hinge joints are freely moveable joints. How they differ from one another?
They differ in the kind of movement they allow.Our ball and socket joints are the shoulder and the hip.The shoulder joint is composed mainly by the scapula and the humerus:(image taken from Kenhub)And the hip is composed by the os coxae and the femur:This type of joint allows all kind of movement: adduction, abduction, flexion, extension and circumduction.Hinge joints, on the other hand, allow movement in only one axis, mainly flexion and extension. They are unable to perform any other type of movement since they’re not made for that. This also means that attempting to do these movements or if there’s a force that causes a movement out of the normal axis, may result in injury or dislocation.For example, the elbow and the knee are hinge joints.The elbow joint is composed by the humerus and the ulna and they allow to flex and extend the elbow.The knee joint is composed by three bones, though: femur, tibia and patella. The patella works as a pulley to ease the quantity of force required by the quadriceps tendon and patellar tendon to extend the knee.
What is the difference between a hinge joint and a pivot joint?
Hinge joint:-Hinge joint allows on one way movement and is found in fingers, elbows, toes and knees. It is just like a hinge found on door which allows us to open and close.Pivot joint-Pivot joint allows upwards, downwards and sideways movement. It is mainly found in the first vertebrae of the vertebral column
Will doing a dumbbell bench press with 50 pounds give the same benefits in terms of gains as a barbell bench press with 100 pounds?
Thanks for the A2A! William Schaffer's answer is excellent and covers technical detail I could never hope to replicate. However, I’d like to expand on his answer a bit.In most gyms there will be a lot of people who can bench 225, and a few who can bench 315. There will be very few who can dumbbell press 100 in each hand and practically none who can do the same with 150 in each hand. That alone should give you an idea of the difference is strength needed to perform the various tasks. So, I would say that the benefits for a 50lbs dumbbell bench press would be greater than a barbell bench press with 100lbs.However, because of the strength and stability requirements, the dumbbell bench press becomes much more dangerous as the weights increase. Even with a barbell bench press, improper form often cause rotator cuff issues. With heavy (>100lbs) dumbbell bench presses, this danger is increased by at least an order of magnitude since spotting is much more difficult (unless you can get two spotters), and the two arms cannot work to support each other, and in fact, work against each other as any instability in one arm causes instability in the other which in turn feeds back to the originally unstable arm. This is the reason why only exceptionally strong people can dumbbell bench press with very heavy weights.Because of this difference, although the strength requirements of the dumbbell bench press are greater, because of the much higher potential for injury, it is more effective (in the heavy weight ranges) to increase your barbell bench press. If you are working with relatively light weights, however, the dumbbell bench press is probably more effective.
Is stretching good or bad?
The answer to your question is not simple, though it can be put manageably. Much of the conventional wisdom of stretching is based on lowest-common-denominator needs and bad theory. (There are a lot of myths in the fitness industry - it's sick!) If you're training for a sport, you'll need more pointed knowledge. To dance well, or play well, you need to be able to move through a certain range of motion (ROM). Duh. Stretching is training your body to be able to do that. Some more explanation will fill out what that means. What might help is to know what happens in a stretch. When a muscle gets extended, at a certain point the stretch reflex gets triggered. That's a natural reaction that aims to prevent overdoing it - your body says, "This far and no further." It's your body trying to protect itself. But the setting for the reflex is made by habit. That means two things: 1. The skeleton is what limits your range of motion - not the length of muscles, tendons, or ligaments. 2. You can train the muscles to go longer before firing the stretch reflex. This is what flexibility training is all about. It pays to know what *kind* of flexibility you want/need. "Flexibility", like "strength", is not a simple word; it depends on what kind of technique you do: 1. Static passive flexibility (can you do the splits?) 2. Static active (how high can you extend your leg - and hold it there?) 3. Dynamic (can you kick head-high?) What you choose determines the kinds of exercises you'll do. It also pays to know *where* you need to be flexible. If you're a cyclist, you won't get any benefit from high shoulder range of motion; on the other hand, wrestlers need that. It also pays to know *how much* flexibility you really need. Being able to go a little beyond your required ROM is enough; more won't help, it may even hurt your performance. With all that in mind, you can go about it in a decent way. (Thinking it out beforehand will save you time and effort.) For some guides to help through the details, see below. Good training!