Does our conventional body belong to the external sense bases? There are six internal sense bases named eye, ear, nose, tongue, body, and mind. There are six external sense bases named visible form, sound, odour, taste, and mental objects.
I have two parts in my question;

If we look at our own hand, leg, or any other conventional body part or if we touch and feel our own conventional body, do all these belong to the external sense bases?
If the answer is &quot;yes&quot; to the first part of the question, which form elements (rūpa) are included in internal?
OP: If we look at our own hand, leg, or any other conventional body part or if we touch and feel our own conventional body, do all
these belong to the external sense bases?

Yes, if we see, hear, smell, taste or feel parts of the body, then those are experienced, hence they are a part of the external sense bases. They are part of &quot;form&quot;.

OP: If the answer is &quot;yes&quot; to the first part of the question, which elements (rūpa) are included in internal?

No form elements are part of the internal sense bases, because the internal sense bases are part of &quot;name&quot;, not &quot;form&quot; - they are related to feeling and contact.
The internal sense bases are the mental interfaces to the physical senses, from my understanding.
From MN 137:

‘The six interior sense fields should be understood.’ That’s what I
said, but why did I say it? There are the sense fields of the eye,
ear, nose, tongue, body, and mind. ‘The six interior sense fields
should be understood.’ That’s what I said, and this is why I said it.
‘The six exterior sense fields should be understood.’ That’s what I
said, but why did I say it? There are the sense fields of sights,
sounds, smells, tastes, touches, and thoughts. ‘The six exterior sense
fields should be understood.’ That’s what I said, and this is why I
said it.

From SN 12.2:

And what is feeling? There are these six classes of feeling. Feeling
born of contact through the eye, ear, nose, tongue, body, and mind.
This is called feeling.
And what is contact? There are these six classes of contact. Contact
through the eye, ear, nose, tongue, body, and mind. This is called
contact.
And what are the six sense fields? The sense fields of the eye, ear,
nose, tongue, body, and mind. These are called the six sense fields.
And what are name and form? Feeling, perception, intention, contact,
and attention. This is called name. The four primary elements, and
form derived from the four primary elements. This is called form. Such
is name and such is form. These are called name and form.