Hi Sean,
It is a good topic,
I am just writing a webinar on medial gastrocnemius injuries at the distal end and another on rectus femurs injuries. Both of those muscles are fascinating. I am presenting the paper at the ASA meeiting and longer versions of the material will be recorded for the website soon. Keep an eye out for them.
The proximal tendon is less commonly examined and less commonly pathological. If it is injured an MRI is still the preferred modality for examination. You can see the origin sonographjically, however it can be tricky to overcome the anisotropy as it dives quickly and also the tendon is fairly short leading to an early MTJ.
I will email you a link to a resource that has some nice MRI examples of pathology so you will know what to look out for.
I rarely diagnose pathology here with ultrasound.
Personally ACL and PCL pathology should be left alone by ultrasound. There are published papers on assessment of both ligaments, however I think they belong ion the same basket as other structures like the TFCC, Slap lesions, hip labrum etc. I know people will disagree but that is my opinion.
I think ultrasound is a second rate test for these structures. I love ultrasound, but also accept there are better options sometimes and in these areas MRI is king.
Leave it to the magnet monkeys !
Steve