Ultrasound Blocks for the Anterior Abdominal Wall

28 | Ultrasound Blocks for the Anterior Abdominal Wall
tracking them for some distances whereas nerves do not
disappear.
Figure 2.3 – Ultrasound appearance of median nerve and of radial
nerve with the needle (in-plane approach).
Blood vessels appear as round hypo-echoic structures with a
well defined hyper-echoic border corresponding to the vessel
wall. The arteries are not compressible and are pulsating, veins
have a thinner border and are compressible (Figure 5.3, 13.3).
Muscles appear as heterogeneous or homogeneous
hypo-echoic structures with hyper-echoic septa and a
fibrous-lamellar texture (Figure 3.2). The periostium appears as
hyper-echoic as it reflects entirely the echoes. As a consequence,
the bone underlying the periostium appears as black (ultrasound
shadow) (Figure 4.1). The knowledge of normal anatomy is
essential for the identification of different tissues with
ultrasounds.