Medial compartment

A) This compartment is composed of the following:

1-Flexor tendons which are

-Flexor Hallosis longus.

-Flexor Digitorum longus.

-Tibialis posterior.

Mnemonic H D T(High Definition Television) from lateral to medial.

2-Medial collateral ligament:

-Look in the coronal view at the level of medial malleolus.
-You will see a typical striated appearance extending from medial malleolus to talus and calcaneus.
-In case of tear of this ligament, go to the T2 image, you will find fluid collection in the site of the ligament.

Normal medial collateral ligament(asterisk)

Injured medial collateral ligament(asterisk)

B)Injury of Tibialis posterior:

-One of the most common injured structures in the ankle.
-Can be teared by three ways:

*Type 1:Partial tear with hypertrophy of the tendon 4 to 5 times its normal size whether there is abnormal signal inside the tendon or not (normally tibialis posterior is equal to digitorum twice the size, in case of type 1 injury, tibialis posterior will be 4 to 5 times of digitorum size).

Type 1 tear of tibialis posterior.

*Type 2: Tibialis posterior tendon is divided into two parts.

*Type 3: Complete disappearance of the tendon of Tibialis posterior.

Teno-synovitis:

-Any tendon has a synovial sheath except tendon achilles.
-Any tendon can be affected with teno-synovitis which appears as a ball surrounded by fluid. 

Tenosynovitis around tendons of peroneus longus and brevis.