Intrinsic Muscles of the Back Flashcards
What muscles extend & hyperextend the head and are antagonistic to SCM?
Splenius capitis and cervicis, superficial muscles originating from the ligamentum nuchae and spinous processes of C7-T6.
Splenius capitis inserts in the mastoid process of temporal bone.
Splenius cervicis inserts in the transverse processes of C2-C4.
What is the ligamentum nuchae?
A strong elastic ligament from occiput along cervical spinous processes to bind vertebral together and prevent excessive head/neck flexion.
What are the erector spinae?
Illiocostalis, longissimus, and spinalis.
Prime back extensors, which resist bending forward and pull trunk to erect position.
In full flexion, erector spinae are relaxed.
O&I of Illiocostalis muscles, which extend and laterally flex vertebral column? (Most lateral erector spinae)
Lumborum; O- illiac crest, I- angles of ribs
Thoracis; O- inferior ribs T12-T6, I- angles of ribs
Cervicis; O- ribs from T6-T3, I- transverse processes of C6-C4
O&I of Longissimus muscles, which extend & laterally flex vertebral column (capitis extends and rotates head)?
Mainly passing b/w transverse processes:
Thoracis, Cervicis, and Capitis
O- transverse processes of lumbar through cervical vertebrae
I- transverse processes of thoracic or cervical vertebrae and to ribs superior to origin as indicated by name.
Capitis inserts into mastoid process of temporal bone.
O&I of Spinalis muscles, which extend the vertebral column? (Most medial erector spinae)
Thoracis and Cervicis
O- spinous processes of upper lumbar and lower thoracic vertebrae.
I- spinous processes of upper thoracic and cervical vertebrae.
What deep muscles extend the vertebral column and head and rotates them contralaterally? (Synergistic with contralateral SCM)
Semispinalis Thoracis, Cervicis, and Capitis regions
O- transverse processes of C7-T12
I- spinous processes of… Thoracis; T1-T4, Cervicis; C1-C7, Capitis; occipital bone.
What muscle laterally flexes the vertebral column, part of posterior abdominal wall, and assists with forced inspiration?
Quadratus lumborum, originating from the illiac creat and lumbar fascia inserting into the transverse processes of L1-L4 and lower margin of T12 rib.
What nerve innervates the erector spinae and semispinalis?
Spinal nerves of the dorsal rami
What nerve innervates the Splenii muscles?
Cervical spinal nerves of dorsal rami
What nerve innervates the quadratus lumborum?
T12 and upper lumbar spinal nerves of ventral rami
