01 / Location & anatomical relationships
From the shoulder toward the hand on either side of the body.
02 / Structure & organization
In everyday speech, arm may mean the entire upper limb; anatomically, the brachium is the shoulder-to-elbow region. The upper limb includes arm, forearm and hand, each with separate bones and muscle compartments.
03 / Function
Its muscles and bones work together to lift and carry things.
04 / Mechanism
Different joints place your hand where it needs to go. The shoulder aims the arm, the elbow changes its reach, and forearm movement turns the palm. Nerves coordinate muscles so these actions happen smoothly.
Working together: muscular system
When you bend your elbow, some muscles contract while others relax. Their coordinated pull moves the bones at the joint.
Meet this body system →FOR DEEPER STUDY
Connect structure with function
Use precise regional names when tracing a nerve or describing movement. Structures crossing several joints can influence more than one region.
Check your understanding
Locate the arm in relation to its neighbors. Explain how the structural features described above support its function, then distinguish it from a nearby structure with a different role.
Keep learning
Continue with OpenStax Anatomy and Physiology for system-level study. This atlas is educational and has not undergone independent medical peer review.