313

Fig. 333. Isometric contraction. Anterior portion of the deltoid muscle.
Solid arrow - direction of isometric contraction
Dashed arrow - direction of counterpressure

For the middle portion of deltoid muscle, the patient has to abduct the arm from the position which is shown in Fig. 334 while the practitioner resists this movement.

Fig. 334. Isometric contraction. Middle portion of the deltoid muscle.
Solid arrow - direction of isometric contraction
Dashed arrow - direction of counterpressure