bfb3a285_SSA_Handbook___211__If_the_worker___
The spouse of a person entitled to disability or retirement insurance benefits, if he or she is: (A) Age 62 or over (may be divorced spouse in certain circumstances; see §311); or (B) Caring for a child who is under age 16; or a child under a disability which began before the child reached age 22 and entitled to benefits (see Chapter 3). [If the worker...] 
Is fully insured or insured for disability benefits, whichever is applicable as shown above.
SSA Handbook § 211
If the worker...