"largest muscle of the erector spinae group, and has a thoracic and lumbar component."
"origin: uppermost fascicles start from transverse processes of T1-4. Subsequent fascicles have bifid origins and arise from the transverse processes of T5-12 as well as the adjoining ribs of T5-12."
"insertion: caudal fibres of the thoracic fascicles form a wide aponeurosis with the uppermost fascicles inserting into the L1-5 spinous processes and their supraspinous ligaments. The pattern is as follows: 1st thoracic segment inserts into L1 2; 6th thoracic segment inserts into L5; 7th to 9th thoracic segments insert into the median sacral crest; 10th to 11th thoracic segments insert into posterior surface of the 3rd segment of the sacrum; 12th thoracic segment inserts into the sacrum and the dorsal iliac crest segment at a point inferior to the insertion of the intermuscular aponeurosis of the lumbar fibres of the longissimus thoracis."
"insertion: fascicles from the L1-L4 insertion converge on a single flat tendon. This convergence is known as the lumbar intramuscular aponeurosis and it covers the lateral surface of the muscle. The aponeurosis begins in the mid-lumbar region, tapering inferiorly before inserting on the medial surface of the ilium dorsal to the ala of the sacrum. The lumbar intramuscular aponeurosis is an extension of the erector spinae aponeurosis. L5 fascicles pass deep to the lumbar intramuscular aponeurosis, attaching at both the ventromedial aspect of the ilium and the upper fibres of the dorsal sacroiliac ligament."
"each fascicle has a ribbon-like tendon attaching to the point of origin, with the longest tendons at the higher level with progressive shortening towards the lower levels. This is accompanied by a uniformly long muscle belly and a caudal tendon."
"insertion: fascicles form an aponeurosis which inserts linearly to the medial end and dorsal segment of the iliac crest. Upper fascicles insert more medially and inferiorly, while lower fascicles inserting more laterally and superiorly."
"control of the descent of the thorax towards gravity when the abdominal muscles contract until abdominal muscles are fully flexed - at that point flexion is limited by passive tension from the components of the back."
"origin: tendons from the transverse processes of C2-C6"
"insertion: tendons to the transverse processes of T1-T4 or T5"
"insertion: fascicles from the L1-L4 insertion converge on a single flat tendon. This convergence is known as the lumbar intramuscular aponeurosis and it covers the lateral surface of the muscle. The aponeurosis begins in the mid-lumbar region, tapering inferiorly before inserting on the medial surface of the ilium dorsal to the ala of the sacrum. The lumbar intramuscular aponeurosis is an extension of the erector spinae aponeurosis. L5 fascicles pass deep to the lumbar intramuscular aponeurosis, attaching at both the ventromedial aspect of the ilium and the upper fibres of the dorsal sacroiliac ligament."
"origin: tips of the transverse processes and the posterior surface of the middle layer of the thoracolumbar fascia of L1-L4"
Expected headings
"Spinalis"
"Longissimus"
"Iliocostalis"
"Erector spinae aponeurosis"
"Relations"
"Action"
"origin: variable origin on the spinous processes of the axis, C3 and C4"
"lateral branches of dorsal rami of cervical, thoracic and lumbar spinal nerves"
"blends with the longissimus thoracis laterally; the erector spinae is considered in some texts to be a component of that muscle 1"
"insertion: caudal fibres of the thoracic fascicles form a wide aponeurosis with the uppermost fascicles inserting into the L1-5 spinous processes and their supraspinous ligaments. The pattern is as follows: 1st thoracic segment inserts into L1 2; 6th thoracic segment inserts into L5; 7th to 9th thoracic segments insert into the median sacral crest; 10th to 11th thoracic segments insert into posterior surface of the 3rd segment of the sacrum; 12th thoracic segment inserts into the sacrum and the dorsal iliac crest segment at a point inferior to the insertion of the intermuscular aponeurosis of the lumbar fibres of the longissimus thoracis."
"insertion: caudal fibres of the thoracic fascicles form a wide aponeurosis with the uppermost fascicles inserting into the L1-5 spinous processes and their supraspinous ligaments. The pattern is as follows: 1st thoracic segment inserts into L1 2; 6th thoracic segment inserts into L5; 7th to 9th thoracic segments insert into the median sacral crest; 10th to 11th thoracic segments insert into posterior surface of the 3rd segment of the sacrum; 12th thoracic segment inserts into the sacrum and the dorsal iliac crest segment at a point inferior to the insertion of the intermuscular aponeurosis of the lumbar fibres of the longissimus thoracis."
"insertion: caudal fibres of the thoracic fascicles form a wide aponeurosis with the uppermost fascicles inserting into the L1-5 spinous processes and their supraspinous ligaments. The pattern is as follows: 1st thoracic segment inserts into L1 2; 6th thoracic segment inserts into L5; 7th to 9th thoracic segments insert into the median sacral crest; 10th to 11th thoracic segments insert into posterior surface of the 3rd segment of the sacrum; 12th thoracic segment inserts into the sacrum and the dorsal iliac crest segment at a point inferior to the insertion of the intermuscular aponeurosis of the lumbar fibres of the longissimus thoracis."
"insertion: caudal fibres of the thoracic fascicles form a wide aponeurosis with the uppermost fascicles inserting into the L1-5 spinous processes and their supraspinous ligaments. The pattern is as follows: 1st thoracic segment inserts into L1 2; 6th thoracic segment inserts into L5; 7th to 9th thoracic segments insert into the median sacral crest; 10th to 11th thoracic segments insert into posterior surface of the 3rd segment of the sacrum; 12th thoracic segment inserts into the sacrum and the dorsal iliac crest segment at a point inferior to the insertion of the intermuscular aponeurosis of the lumbar fibres of the longissimus thoracis."