Short answer
A tendon connects muscle to bone; a joint ligament connects bones to one another. Tendons carry the pull of contracting muscles, while ligaments hold bones together and constrain joint movement. Both can help stabilize a joint, so function alone does not separate them. 1 2
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At a glance
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| Question | Tendon | Ligament |
|---|---|---|
| What does it connect? | Muscle to bone | Bone to bone at a joint |
| Main role described here? | Transfers muscle tension to bone | Holds bones together and limits excessive motion |
| Can it support a joint? | Yes, with the muscle crossing it | Yes, through its bone attachments |
| Is location enough to identify it? | No; trace the muscle attachment | No; ligaments occupy several positions around the capsule |
These contrasts describe the structures in the supplied musculoskeletal account. 1 2
What each thing is
A tendon forms part of the connection between a muscle and the bone it pulls. Muscle connective-tissue layers join the tendon, which in turn joins the bone’s outer covering, the periosteum. A ligament is a fibrous band anchoring bones together at a joint, allowing normal movement while limiting its extent. 2 1
Key differences
The central difference is the attachment pathway: muscle–tendon–bone versus bone–ligament–bone. The first carries muscle-generated tension to move the skeleton; the second constrains how joint bones move relative to one another. These are different roles, not a movement-versus-no-movement divide. 2 1
Examples
- Shoulder: OpenStax describes relatively weak shoulder ligaments and important support from muscles and their tendons. The tendons belong to the muscle-to-bone pathway; the ligaments support the joint through bone anchoring. 1
- Hypothetical joint diagram: One band runs from a muscle to a bone, while another anchors two bones together. The first fits the tendon definition; the second fits the joint-ligament definition—even if both help keep the joint stable. 1
How to tell them apart
Trace the attachments rather than judging the structure by its proximity to a joint. A muscle-to-bone connection indicates a tendon; a band anchoring joint bones together indicates a ligament. The limit: an incomplete diagram or description may omit an attachment, so location or a generic label such as connective tissue is insufficient. 1
Where they overlap
Joint stabilization is shared work. Muscles crossing a joint can increase their contraction as forces on the joint increase, allowing the muscle–tendon unit to resist those forces. OpenStax describes this as a ligament-like supporting role, not a change in the tendon’s anatomical identity. 1
Edge cases
Not every muscle attachment is described as a discrete tendon: muscle connective tissue may join a broad, tendon-like sheet called an aponeurosis or join fascia. Conversely, a ligament need not sit outside the joint capsule; it may be incorporated into the capsule wall or located inside it. Neither shape nor capsule position alone settles the distinction. 2 1
Why the distinction exists
The terms distinguish two connections within a joint’s working system. Tendons link muscle contraction to a pull on bone; ligaments anchor the joint’s bones and constrain their relative motion. Naming the connections separately makes it possible to describe movement and support without treating all nearby connective tissue as interchangeable. 2 1
Common misconceptions
“Tendons move; ligaments stabilize” is useful shorthand but incomplete: tendons also participate in stabilization. “Ligaments stop movement” is likewise misleading; they allow normal joint movement while limiting excessive motion. The more reliable distinction is what each structure connects, not whether it has any supporting role. 1
Examples
Consider a hypothetical arm movement: when a skeletal muscle contracts, its tendon transmits force to the bone it attaches to. Now consider a joint whose bones are held together by a ligament; that band restrains excessive movement between bones even when nearby tendons also support the joint. The attachment points, not just the location near a joint, distinguish the structures. 1 2