is formed by two tube like structures
the part near the lower part of body fuses and become -- vagina and uterine cavity
proper-----for bringing sperms in and developing the baby and delivering the baby
the part away becomes Fallopian tubes which connects with ovaries and bring ovum to uterus for fertilization.
saying all this----- sometime there is partial fusion of part of tubes forming uterus and
urteus can be- two small tubes, one cavity with septum within depending upon degree of fusion.
u can search internet with developmental anomalies of uterus
In your case there is fundal septum.
i. e. short septum in single cavity uterus in upper part- fairly mildest of variety
can be cause of infertility
but there are pt. who have given birth to babies and fundal septum is observed as incidental findings
further characterization of septum i.e. size, thickness, length. etc can be done by MRI