The iliohypogastric (IH) nerve emerges at the lateral margin of the psoas major – typically together with the ilioinguinal (II) nerve
The IH descends across the anterior surface of the quadratus lumborum and it pierces the posterior aponeurotic extension of the transverse abdominis; it runs along and on top of the iliac crest sandwiched between the transversus abdominis and internal oblique. It innervates the inferior portions of these two muscles
The lateral cutaneous branch innervates the iliac crest and the skin of the hip between the iliac crest and the greater trochanter
The IH/II nerve block does not anaesthetize the lateral cutaneous branch of the IH nerve
The anterior cutaneous branch pierces the anterior aponeurotic extension of the external oblique muscle and innervates the skin above the medial part of the inguinal ligament
Iliohypogastric (IH) nerve (magenta), lateral and anterior cutaneous branches (red and green arrows), IH nerve trajectory between the transversus abdominis and internal oblique (cyan arrow), quadratus lumborum (yellow asterix), transversus abdominis (magenta asterix), psoas major (cyan asterix), iliacus (green asterix)
The ilioinguinal nerve (IIN) typically emerges together with the iliohypogastric (IH) nerve from the lateral margin of the psoas major, descends laterally across the anterior side of the quadratus lumborum, pierces the posterior aponeurotic extension of the transversus abdominis, and runs medially together with the IH nerve sandwiched between the transversus abdominis and the internal oblique – first on top of the iliac crest, and then on top of the inguinal ligament
The IIN exits via the external inguinal ring and terminates as the anterior scrotal/labial branches
Together with the IH nerve the IIN innervates the inferior portions of the transversus abdominis and the internal oblique
The anterior scrotal branches innervate the skin proximal to the symphysis and the lateral parts of the male scrotum and the female labia majora
Ilioinguinal nerve (IIN, magenta), anterior scrotal branches (red arrow), IIN runs between the transversus abdominis and internal oblique on top of both the iliac crest and the inguinal ligament (blue and green arrows). Quadratus lumborum, transversus abdominis, psoas major, and iliacus (yellow, magenta, cyan & green asterixs).
The brachial plexus runs across the first rib in close relationship to the subclavian artery
On top of the first rib the branches of the brachial plexus are located postero-superior to the artery
The subclavian artery (green arrow) ends at the lateral margin of the first rib (blue arrow) where it becomes the axillary artery which dives under the clavicle (magenta arrow)
The lowermost branches of the brachial plexus – originating from the C8 and T1 spinal nerve roots – run across the first rib in the corner between the rib and the subclavian artery
This is called the corner pocket
The lowermost branches of the brachial plexus run across the first rib in the corner pocket
It is important to locate the probe on top of the first rib
With in-plane needle approach the needle tip will impinge on the rib instead of producing a pneumothorax, if the needle is inserted too deep
The movie shows the typical sonographic image when the probe is placed on top of the first rib P = pleura, c1 = first rib, SA = subclavian artery, asterixs = nerve divisions of the brachial plexus. Post = posterior, ant = anterior
Local anesthetic has to be injected in the angle between the subclavian artery, the first rib and the bundle of nerve divisions
SA = subclavian artery
nd = bundle of nerve divisions
p = pleura
c1 = first rib
The video shows how the needle (asterixes) is inserted with in-plane technique and advanced underneath the bundle of nerve divisions (nd) of the brachial plexus in order to inject local anesthetic in the corner pocket. SA = subclavian artery, c1 = first costa, p = pleura.
It is mandatory to insert the needle with in-plane technique for the supraclavicular brachial plexus block in order to minimize the risk of pneumothorax
The needle is inserted with in-plane technique. The fascicular profiles (black profiles) are meticulously avoided by the needle tip. The needle is advanced under the neural epineurium. SA = subclavian artery, asterixs = divisions of the brachial plexus, LA = local anesthetic.
