from Albinus: “The Fourth Order of Muscles”

Fig. 9.23 There are four ‘gullies’ around the spine: the erector spinae muscles in the back and the psoas in the front fill in these gullies and support the lumbar vertebrae.

Fig. 9.22 The psoas major is the major supporting guy-wire between the spine and the leg, joining upper to lower, breathing to walking, and acting with other local muscles in complex ways for steadying various movements.

from “Anatomy Trains” by Tom Myers

Fig. 9.26 The DFL attaches the inner femur to the core structures in front of the spine, including the diaphragm and mesentery (not pictured). In the center of the these connections lies the psoas major express, flanked by two sets of locals.

Fig. 9.24 The human psoas muscle makes a unique journey around the front of rht pelvis – forward and up from the trochanter to the iliopectineal ridge, then back and up to the lumbar spine. No other animal makes use of such a course for the psoas; in most quadrupeds, the psoas does not even touch the pelvis unless the femur is extended to its limit.

from “Anatomy Trains” by Tom Myers

Fig. 9.27 The inner line of hip-spine locals comprises the pectineus, linking via the lacunar ligament with the psoas minor

Fig. 9.28 The outer line of hip-spine locals comprises the iliacus, linking into the quadratus lumborum

from “Anatomy Trains” by Tom Myers