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Pivot joint

At a pivot joint    , a rounded portion of a bone is enclosed within a ring formed partially by the articulation with another bone and partially by a ligament (see [link] a ). The bone rotates within this ring. Since the rotation is around a single axis, pivot joints are functionally classified as a uniaxial diarthrosis type of joint. An example of a pivot joint is the atlantoaxial joint, found between the C1 (atlas) and C2 (axis) vertebrae. Here, the upward projecting dens of the axis articulates with the inner aspect of the atlas, where it is held in place by a ligament. Rotation at this joint allows you to turn your head from side to side. A second pivot joint is found at the proximal radioulnar joint    . Here, the head of the radius is largely encircled by a ligament that holds it in place as it articulates with the radial notch of the ulna. Rotation of the radius allows for forearm movements.

Hinge joint

In a hinge joint    , the convex end of one bone articulates with the concave end of the adjoining bone (see [link] b ). This type of joint allows only for bending and straightening motions along a single axis, and thus hinge joints are functionally classified as uniaxial joints. A good example is the elbow joint, with the articulation between the trochlea of the humerus and the trochlear notch of the ulna. Other hinge joints of the body include the knee, ankle, and interphalangeal joints between the phalanx bones of the fingers and toes.

Condyloid joint

At a condyloid joint    (ellipsoid joint), the shallow depression at the end of one bone articulates with a rounded structure from an adjacent bone or bones (see [link] e ). The knuckle (metacarpophalangeal) joints of the hand between the distal end of a metacarpal bone and the proximal phalanx bone are condyloid joints. Another example is the radiocarpal joint of the wrist, between the shallow depression at the distal end of the radius bone and the rounded scaphoid, lunate, and triquetrum carpal bones. In this case, the articulation area has a more oval (elliptical) shape. Functionally, condyloid joints are biaxial joints that allow for two planes of movement. One movement involves the bending and straightening of the fingers or the anterior-posterior movements of the hand. The second movement is a side-to-side movement, which allows you to spread your fingers apart and bring them together, or to move your hand in a medial-going or lateral-going direction.

Saddle joint

At a saddle joint    , both of the articulating surfaces for the bones have a saddle shape, which is concave in one direction and convex in the other (see [link] c ). This allows the two bones to fit together like a rider sitting on a saddle. Saddle joints are functionally classified as biaxial joints. The primary example is the first carpometacarpal joint, between the trapezium (a carpal bone) and the first metacarpal bone at the base of the thumb. This joint provides the thumb the ability to move away from the palm of the hand along two planes. Thus, the thumb can move within the same plane as the palm of the hand, or it can jut out anteriorly, perpendicular to the palm. This movement of the first carpometacarpal joint is what gives humans their distinctive “opposable” thumbs. The sternoclavicular joint is also classified as a saddle joint.

Questions & Answers

Types of living things
Evah Reply
search up "taxonomy"
there are many kingdoms: animal, plants, fungi, and more
a better question would be "What are the various classifications of living organisms?"
learn to ask questions that aren't too vague
what is the largest bone of human?
Aicon Reply
thats a google question
search "largest bone in skeletal system"
The skull
femur in thighs
the diagram of cell membrane
Teboh Reply
***bit.ly/3kfrdfV Link to cell membrane diagram and more info... Remember, you can search the A&P book.
describe diffusion as used in body fluid movement
brenda Reply
how was the movement?
classify joint function with example
James Reply
cytoskeleton diagram
Miriam Reply
two types of cells biological name
eukaryotic and prokaryotic
Difference between extracellular and intracellular
Eli Reply
extra (exit) outside the cell, intra inside the cell
extracellular is 1/3 of total body water...intracellular 2/3 of total body water
what is culture?
is the way of life of people
He meant in the context of biology...as in "tissue culture".
what does depolarization mean...in terms of the cardiovascular system?
depolarization means contraction
Depolarization, in the context of nerve and muscle tissue, is the decrease in membrane potential (the separation of charge between the extracellular and intracellular compartments). Basically, the charge in the cell becomes more positive when depolarization occurs.
In fact, the word 'polarize' used to mean dividing into extremes or opposite sides. The opposite is true for 'depolarize'
intracellular fluid is the fluid compartment of the body consisting of all water present within the cell...while extracellular fluid is water present out of the cell
Why apoptosis is important?
Duchess Reply
name the body organ which helps in the oxygenation of body.
Eli Reply
respiratory system (lungs) brings in oxygen...cardiovascular system (blood) circulate it
the heart
Mpho explain
cells... tissues...organs
Angel Reply
...organ system...organism...species...population...
connection between respiratory and circulatory system
Philip Reply
what's respiratory system
what is the site of CHON synthesis?
send them boi
dont send via email...use google drive
Which major organ lies deep to the right hypochondriac region?
Biswajit Reply
deep as in most posterior kidney, or deep as in inferior small intestine?
what is the weakest muscle in the body?
zharla Reply
Connective tissues composed with the blood
blood cell
Why is left bronchi narrow?
what is the most widely distributed connective tissue in the body?
Aila Reply

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