I would definitely go the second way with `$\displaystyle`

: I find that it looks strange to have something centered after a bullet. To get the vertical alignment correct, just add `[t]`

after `\begin{aligned}`

, where "t" means "top". (See also the top of page 8 of the User's guide for the amsmath Package.)

Firstly here is a multiarrowed version:

```
\documentclass[a4paper,11pt]{article}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{amsfonts}
\usepackage{amsthm}
\usepackage{tikz}
\usetikzlibrary{calc}
\tikzset{arrowcases/.style={matrix anchor=west,%
nodes={anchor=base west,%
name=arrc-\the\pgfmatrixcurrentrow-\the\pgfmatrixcurrentcolumn},%
execute at begin cell=\node\bgroup\math\displaystyle,%
execute at end cell=\endmath\egroup;,%
ampersand replacement=\&}}
\def\beginarrowcases#1\endarrowcases{
\begin{tikzpicture}[baseline=(O)]
\matrix [arrowcases] {
#1
};
\coordinate (A) at (arrc-1-1.west);
\coordinate (B) at (arrc-\the\pgfmatrixcurrentrow-1.west);
\coordinate (start) at ($(A)!0.5!(B) - (1em,0)$);
\foreach \nn in {1,...,\pgfmatrixcurrentrow} {
\draw[->] (start) -- (arrc-\nn-1.west);
};
\coordinate (O) at ($(start)-(0,0.5ex)$);
\node at (-1em,0) {};
\end{tikzpicture}}
\begin{document}
\begin{align}
\mathbf{\nabla}\times \mathbf{E}&=0
\beginarrowcases
\mathbf{E}=-\mathbf{\nabla}\Phi \\
\hat{\eta}\times (\mathbf{E_2}-\mathbf{E_1})=0 \&
\text{(continuity)} \\
\mathbf{E}=-\mathbf{\nabla}\Phi \& \text{(again)}\\
\endarrowcases \\
1+1 &= 2
\end{align}
\end{document}
```

This is obtained by making a `matrix of math nodes`

like construction in `tikz`

to build a cases like setup and then drawing the arrows. The syntax requires `\&`

instead of `&`

and `\\`

at the end of each line, because of the way the `matrix`

construction is set-up in `tikz`

and becuase of interaction with the `amsmath`

package.

Secondly, here is how one replaces the `cases`

bracket with another delimiter directly in the `cases`

environment:

```
\documentclass[a4paper,11pt]{article}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{amsfonts}
\usepackage{amsthm}
\usepackage{tikz}
\makeatletter
\renewenvironment{cases}[1][\lbrace]{%
\matrix@check\cases\env@cases{#1}
}{%
\endarray\right.%
}
\def\env@cases#1{%
\let\@ifnextchar\new@ifnextchar
\left#1
\def\arraystretch{1.2}%
\array{@{}l@{\quad}l@{}}%
}
\makeatother
\begin{document}
\begin{align}
\mathbf{\nabla}\times \mathbf{E}&=0
\begin{cases}
\mathbf{E}=-\mathbf{\nabla}\Phi \\
\hat{\eta}\times (\mathbf{E_2}-\mathbf{E_1})=0
&\text{(continiuty)}
\end{cases}
\\
1+1&=2\\
\mathbf{\nabla}\times \mathbf{E}&=0
\begin{cases}[\langle]
\mathbf{E}=-\mathbf{\nabla}\Phi \\
\hat{\eta}\times (\mathbf{E_2}-\mathbf{E_1})=0
&\text{(continiuty)}
\end{cases}
\end{align}
\end{document}
```

This acheived by redefining the `cases`

environment to take an optional argument and putting that in the code at the place where `\lbrace`

was hard coded.

Using a `tikz`

picture for such a brace in this version is problematic. For a start one needs a construction that can be resized via `\left`

. Furthermore in your request, you have arrows pointing to each row and that is hard to control. Hence, the multiarrowed code above is probably more what you want.

## Best Answer

You can't break lines in

`\text`

, but you can use a`\parbox`

; adjust the width to suit.