OIANs of Trunk, Abdominals, Suboccipitals

Splenius CAPITIS — origin?

SP of C7-T4, and the ligamentum nuchae.

Splenius CERVICIS — origin?

SP of T3-6.

Splenius CAPITIS — insertion?

Lateral part of the superior nuchal line, and the mastoid process.

Splenius CERVICIS — insertion?

TP of C2-5.

Splenius — action, bilateral vs. unilateral?

Bilateral: extension of the cervical region. Unilateral: lateral flexion and rotation to the SAME side.

Splenius CAPITIS — innervation?

Dorsal rami of C3-5.

Splenius CERVICIS — innervation?

Dorsal rami of C4-8.

Iliocostalis — origin (all subdivisions)?

Common broad tendon from the posterior iliac crest, sacrum, sacroiliac ligaments, and spinous processes of the sacral and inferior lumbar vertebrae.

Iliocostalis LUMBORUM — insertion?

Inferior border of the angle of ribs 12-6.

Iliocostalis THORACIS — insertion?

All of the ribs.

Iliocostalis CERVICIS — insertion?

Superior 6 ribs, and posterior tubercles of C4-C6.

Iliocostalis — action, unilateral vs. bilateral?

Unilateral: laterally flexes head/vertebral column to the same side. Bilateral: extends head and trunk.

Iliocostalis — innervation?

Dorsal rami of cervical, thoracic, and lumbar spinal nerves.

Longissimus THORACIS — origin?

Common origin (shared across the muscle).

Longissimus CERVICIS and CAPITIS — origin?

Common origin, PLUS transverse processes at lower levels.

Longissimus THORACIS — insertion?

Tips of TP T1-T12, and tubercles of the inferior border of ribs 9, 10.

Longissimus CERVICIS — insertion?

Superior thoracic TP to cervical TP.

Longissimus CAPITIS — insertion?

Arises with cervicis; attaches to the mastoid process.

Longissimus (general, all subdivisions) — action, unilateral vs. bilateral?

Unilateral: laterally flexes head/vertebral column to the same side. Bilateral: extends head and trunk.

Longissimus CAPITIS — what ADDITIONAL action does it have?

It also rotates the head to the same side.

Longissimus — innervation (all subdivisions)?

Dorsal rami of cervical, thoracic, and lumbar spinal nerves.

Spinalis — origin (all subdivisions)?

Common origin, from the spinous processes.

Spinalis THORACIS — insertion?

Tips of the SP of thoracic vertebrae.

Spinalis CERVICIS — insertion?

From the ligamentum nuchae to the axis.

Spinalis — action?

Extensor of the vertebral column, also the head.

Spinalis — innervation (all subdivisions)?

Dorsal rami of cervical, thoracic, and lumbar spinal nerves.

Semispinalis THORACIS — origin?

TP superomedially, T6-T10.

Semispinalis CERVICIS — origin?

TP superomedially, T1-T6.

Semispinalis CAPITIS — origin?

TP T1-T6 (and the C7 articular process).

Semispinalis THORACIS — insertion?

SP T1-T4, C6-7.

Semispinalis CERVICIS — insertion?

SP C2-5.

Semispinalis CAPITIS — insertion?

Inferior to the superior nuchal line.

Semispinalis THORACIS and CERVICIS — bilateral action?

Extensors of the vertebral column.

Semispinalis CAPITIS — bilateral action?

Extensor of the head (when active bilaterally).

Semispinalis (all subdivisions) — unilateral action?

Rotates the trunk/head to the OPPOSITE side.

Semispinalis — innervation (all subdivisions)?

Dorsal rami of cervical, thoracic, and lumbar spinal nerves.

Multifidus — origin?

Laminae (mammillary process) of S4-C2, including the zygapophysial capsule; may be absent in the thoracic region.

Multifidus — insertion?

Superomedially, spanning 2-4 vertebrae, to the spinous process.

Multifidus — action, unilateral vs. bilateral?

Unilateral: lateral flexion of the vertebral column, and rotation to the OPPOSITE side. Bilateral: extends the trunk and stabilizes the vertebral column.

Multifidus — innervation?

Dorsal rami of cervical, thoracic, and lumbar spinal nerves.

Rotatores — origin (both brevis and longus)?

Transverse processes of the entire vertebral column.

Rotatores BREVIS — insertion?

Superomedially, to the SP of the NEXT vertebra.

Rotatores LONGUS — insertion?

Superomedially, to the 2nd SP up.

Rotatores — action (both brevis and longus)?

Rotates the superior vertebra to the opposite side; bilaterally stabilizes the superior vertebra.

Rotatores — innervation (both brevis and longus)?

Dorsal rami of cervical, thoracic, and lumbar spinal nerves.

Levator Costarum — origin?

Tip of the thoracic transverse process.

Levator Costarum — insertion?

Inferolaterally, to the angle of the adjacent inferior rib.

Levator Costarum — action?

Elevates ribs during inspiration; proposed to also be involved in lateral flexion.

Levator Costarum — innervation?

Dorsal rami of thoracic spinal nerves.

Obliquus capitis superior — origin?

TP of C1.

Obliquus capitis superior — insertion?

Occipital bone — deep to splenius capitis/cervicis, superficial to rectus capitis posterior major/minor.

Obliquus capitis superior — action?

Extension at the AO joint, plus a bit of lateral flexion (stabilizer of the occiput on C1).

Obliquus capitis inferior — origin?

SP of C2, lateral to rectus capitis posterior major.

Obliquus capitis inferior — insertion?

TP of C1.

Obliquus capitis inferior — action?

Ipsilateral rotation at the AA joint.

Rectus capitis posterior major — origin?

SP of C2.

Rectus capitis posterior major — insertion?

Occipital bone, lateral to midline at the inferior nuchal line.

Rectus capitis posterior major — action?

Extension at the AO joint, AND ipsilateral rotation at the AA joint.

Rectus capitis posterior minor — origin?

Posterior tubercle of C1.

Rectus capitis posterior minor — insertion?

Occipital bone, medial to rectus capitis posterior major.

Rectus capitis posterior minor — action?

Extension at the AO joint only.

What innervates ALL FOUR suboccipital muscles?

Dorsal rami of C1 (the suboccipital nerve).

Rectus Abdominis — origin?

Pubic crest and symphysis.

Rectus Abdominis — insertion?

Costal cartilages 5-7, and the xiphoid process.

Rectus Abdominis — action?

Flexes the trunk.

Rectus Abdominis — innervation?

Ventral rami of spinal nerves T5-12.

External Abdominal Oblique — origin?

External surface of ribs 5-8 (anterior fibers) and ribs 9-12 (lateral fibers).

External Abdominal Oblique — insertion?

Outer lip of the iliac crest, and the linea alba (via aponeurosis).

External Abdominal Oblique — action, bilateral vs. unilateral?

Bilateral: flexes the trunk (lateral fibers tilt the pelvis posteriorly). Unilateral: rotates the trunk to the OPPOSITE side; also compresses the abdomen.

External Abdominal Oblique — innervation?

Ventral rami of spinal nerves T5-12.

Internal Abdominal Oblique — origin?

Lateral 2/3 of the inguinal ligament, iliac crest, thoracolumbar fascia.

Internal Abdominal Oblique — insertion?

Crest of pubis, pectineal line, linea alba.

Internal Abdominal Oblique — action?

Upper anterior fibers flex the trunk. Unilaterally, works WITH the external oblique of the OPPOSITE side to rotate the trunk.

Internal Abdominal Oblique — innervation?

Ventral rami of spinal nerves T7-12, plus the iliohypogastric and ilioinguinal nerves.

Transverse Abdominis — origin?

Lower 6 ribs, thoracolumbar fascia (attached to TP of lumbar vertebrae), iliac crest, inguinal ligament.

Transverse Abdominis — insertion?

Linea alba, pubic crest.

Transverse Abdominis — action?

Stabilizes the trunk via fixation of the linea alba; compresses the abdomen.

Transverse Abdominis — innervation?

Ventral rami of spinal nerves T7-12, plus the iliohypogastric and ilioinguinal nerves.

Quadratus Lumborum — origin?

Iliolumbar ligament, and the internal lip of the iliac crest.

Quadratus Lumborum — insertion?

Tips of the lumbar transverse processes, and the inferior border of rib 12.

Quadratus Lumborum — action?

Extends and laterally flexes the vertebral column; fixes rib 12 during inspiration.

Quadratus Lumborum — innervation?

Branches of the ventral rami of T12, L1-3(4).

Psoas Major — origin?

Transverse processes of lumbar vertebrae, sides of the vertebral bodies (T12, L1-5), and the intervertebral discs.

Psoas Major — insertion?

Lesser trochanter of the femur.

Psoas Major — action?

Increases lumbar lordosis, assists in lateral flexion; flexes the hip, and flexes the pelvis on the trunk.

Psoas Major — innervation?

The lumbar plexus, via branches of the primary ventral rami L1-L3(4).

Trapezius Origin

medial 1/3 of superior nuchal line; external occipital protuberance, nuchal ligament, SP of C7-T12

Trapezius Insertion

lateral 1/3 of clavicle, Acromion and spine of scapula

Trapezius Innervation

Spinal Accessory nerve (CN XI) (C3-C4 via cervical plexus)

Trapezius Action

Superior Fibers- Scapular elevation and upward rotation

Middle Fibers- Scapular retraction

Inferior Fibers- Scapular depression

Latissimus Dorsi Origin

SP of T7-T12; Thoracolumbar fascia; post. 1/3 of iliac crest; ribs 9-12

Latissimus Dorsi Insertion

Floor of intertubercular sulcus of humerus

Latissimus Dorsi Innervation

Thoracodorsal nerve, (C6-C8)

Latissimus Dorsi Action

GH Joint (shoulder) extension, ADduction, and Internal Rotation; scapular retraction

Serratus Anterior Origin

External and lateral surface of Ribs 1-8

Serratus Anterior Insertion

Anteromedial border of scapula

Serratus Anterior Action

Scapular protraction; anchors scapula to thoracic wall

Serratus Anterior Innervation

Long Thoracic Nerve (C5-C7)

Serratus Posterior Superior Origin

SP C7-T12

Serratus Posterior Superior Insertion

posterior aspect of ribs 2-5