In human anatomy, the arm is the part of the upper limb between the shoulder and the elbow joints. In other animals, the term arm can also be used for analogous structures, such as one of the paired forelimbs of a four-legged animal or the arms of cephalopods. In anatomical usage, the term arm refers specifically to the segment between the shoulder and the elbow, while the segment between the elbow and wrist is the forearm. However, in common, literary, and historical usage, arm refers to the entire upper limb from shoulder to wrist. This article uses the former definition; see upper limb for the wider definition.

In primates the arm is adapted for precise positioning of the hand and thus assist in the hand's manipulative tasks. The ball and socket shoulder joint allows for movement of the arms in a wide circular plane, while the structure of the two forearm bones which can rotate around each other allows for additional range of motion at that level.

The humerus is the bone of the arm. It joins with the scapula above in the shoulder at the glenohumeral joint and with the ulna and radius below at the elbow. The elbow joint is the hinge joint between the distal end of the humerus and the proximal ends of the radius and ulna. The humerus cannot be broken easily. Its strength allows it to handle loading up to 300 pounds (140 kg).

Christina Judith Perri (born August 19, 1986) is an American singer-songwriter and musician from Philadelphia. Her song "Jar of Hearts" charted in the United States after it was featured on the Fox television show So You Think You Can Dance in 2010. Rolling Stone named her the "Band of the Week" on October 26, 2010. On May 10, 2011, Perri's "Jar of Hearts" was featured on Glee (Season 2, Episode 20 "Prom Queen"). Also, on June 27, 2011, Perri's "Jar of Hearts" was featured on Switched at Birth (Season 1, Episode 4 "Dance Amongst Daggers"). One of her songs, "A Thousand Years", has been in the Twilight saga movie Breaking Dawn.

Perri grew up in Bensalem, Pennsylvania (a suburb of Philadelphia) with her older brother, Nick Perri, who formerly played guitar with Shinedown, Silvertide, Perry Farrell and Matt Sorum. Her father is from Italy. She attended Archbishop Ryan High School as a member of the class of 2004. She taught herself how to play guitar as a 16-year-old by watching a videotape of Shannon Hoon from the group Blind Melon performing on VH1.

Michael "Mike" Robert Chang, Jr. is a fictional character from the Fox musical comedy-drama series Glee. The character is portrayed by actor and dancer Harry Shum, Jr., and has appeared on Glee since the fourth episode in the first season, "Preggers", first broadcast on September 23, 2009. Glee follows the trials of the New Directions glee club at the fictional William McKinley High School in the town of Lima, Ohio, of which Mike is a member. He is introduced as a football player who joins the club together with a few of his teammates, and quickly shows himself to be an excellent dancer.

Mike is played by Harry Shum, Jr. He has also been portrayed as a very young boy by Evan Kishiyama in the episode "The Substitute". When Shum was hired, he had been through the audition process, but as far as he knew "it was just like a regular acting gig where you go on for a day." In an interview with the New York Post, he elaborated, "I got hired as a day player and it turned into a week, and then a month and so on. I was just rolling with it—I mean, who would say no to that?"