Often after an acute injury of the knee the quadriceps muscle will not contract, which is called âquad inhibition.â. Inability to straighten the leg. Athletes with acute patellar injuries may find that they cannot flex the knee joint fully or straighten the leg. This may be exacerbated by swelling of the knee.
The alkali metals are a group (column) in the periodic table consisting of the chemical elements lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr).
An example of a group in the periodic table is the alkali metal [alkali metals: The alkali metals are the elements in Group 1 of the periodic table. They have one electron in the outer shell.] group. This video clip shows some of the reactions that occur with this group.