diff --git a/docs/images/cable.tex b/docs/images/cable.tex
index ac45fe533b2ea23477e60af477ff1d47056b5bfd..f9008d0f50abca5a33df25a53f3f9947bbb24591 100644
--- a/docs/images/cable.tex
+++ b/docs/images/cable.tex
@@ -26,31 +26,54 @@
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 % axis
-\draw [pil,very thin] (-3.4,0) -- ( 3.5, 0);
-\draw [pil,very thin] (-3.2,-0.2) -- (-3.2, 0.5);
+%\draw [pil, very thin] (-3.4,0) -- ( 3.5, 0);
+%\draw [pil, very thin] (-3.2,-0.2) -- (-3.2, 0.5);
 
 % left volume
-\draw [white!60!black] (-3,-0.25) -- (-3, 0.25);
-\draw [white!60!black] (-3,-0.25) -- (-1,-0.25);
-\draw [white!60!black] (-3, 0.25) -- (-1, 0.25);
+\draw [white!60!black] (-6,-0.5) -- (-6, 0.5);
+\draw [white!60!black] (-6,-0.5) -- (-2,-0.5);
+\draw [white!60!black] (-6, 0.5) -- (-2, 0.5);
 
 % central volume
-\draw (-1,-0.25) -- (-1, 0.25);
-\draw (-1, 0.25) -- ( 1, 0.4);
-\draw (-1,-0.25) -- ( 1,-0.4);
-\draw ( 1,-0.4)  -- ( 1, 0.4);
+\draw [thick] (-2,-0.5) -- (-2, 0.5);
+\draw [thick] (-2, 0.5) -- ( 2, 0.8);
+\draw [thick] (-2,-0.5) -- ( 2,-0.8);
+\draw [thick] ( 2,-0.8) -- ( 2, 0.8);
 
 % right volume
-\draw [white!60!black] ( 1,-0.4) -- ( 3,-0.3);
-\draw [white!60!black] ( 1, 0.4) -- ( 3, 0.3);
-\draw [white!60!black] ( 3,-0.3) -- ( 3, 0.3);
+\draw [white!60!black] ( 2,-0.8) -- ( 6,-0.6);
+\draw [white!60!black] ( 2, 0.8) -- ( 6, 0.6);
+\draw [white!60!black] ( 6,-0.6) -- ( 6, 0.6);
+
+%\coordinate [label=above right:{\tiny$x_i$}] (B) at (0,0);
+\node [] (L) at (-4, 0) {};
+\node [] (C) at ( 0, 0) {};
+\node [] (R) at ( 4, 0) {};
+
+% nodes that define the centre of each face
+\node [] (Lface) at (-2, 0) {};
+\node [] (Rface) at ( 2, 0) {};
+\node [] (Tface) at ( 0, 0.65) {};
+\node [] (Bface) at ( 0,-0.65) {};
 
 % centroids
-\path (-2, 0) node [shape=circle, draw, fill=black, scale=0.5] {}
-      ( 0, 0) node [shape=circle, draw, fill=black] {}
-      ( 2, 0) node [shape=circle, draw, fill=black] {};
+\path (L) node [shape=circle, draw, fill=black, scale=0.2] {}
+      (C) node [shape=circle, draw, fill=black, scale=0.2] {}
+      (R) node [shape=circle, draw, fill=black, scale=0.2] {};
+
+\path (L) node [anchor=south west] {$x_{i-1}$}
+      (C) node [anchor=south west] {$x_{i}$}
+      (R) node [anchor=south west] {$x_{i+1}$};
 
-\draw ( 1,-0.4)  -- ( 1, 0.4);
+\draw [] (Lface) -- (-2.5, 1);
+\draw [] (Rface) -- ( 2.5, 1);
+\draw [] (Tface) -- (  -1, 1);
+\draw [] (Bface) -- (  -1, 1);
+\draw [] (1, -0.5) -- (1.5, -1);
+\node [] at (-2.5, 1.15) {$\Gamma_{{left}}$};
+\node [] at ( 2.5, 1.15) {$\Gamma_{{right}}$};
+\node [] at (  -1, 1.15) {$\Gamma_{{e}}$};
+\node [] at ( 1.7, -1.2) {$\Omega$};
 
 \end{tikzpicture}
 \end{document}