Final answer:
The tough connective tissue surrounding the shaft of long bones is the periosteum, which covers the diaphysis. The interosseous membrane of the leg connects the tibia and fibula bones, while a tendon sheath surrounds tendons at joints to prevent friction.
Step-by-step explanation:
The tough connective tissue surrounding the shaft of long bones is known as the periosteum. The periosteum is a dense layer of vascular connective tissue enveloping the bones except at the surfaces of the joints. Additionally, the diaphysis is the tubular shaft that runs between the proximal and distal ends of a long bone, which is covered by the periosteum.
The interosseous membrane of the leg is another example of dense connective tissue which unites the shafts of the tibia and fibula bones, providing additional stability to the leg. This membrane, alongside ligaments at the distal tibiofibular joint, forms the tibiofibular syndesmosis, which is crucial for ankle stability. Furthermore, the tendon sheath is a type of connective tissue that surrounds a tendon, especially where it crosses a joint to ensure smooth movement by preventing friction with the lubricating fluid it contains.