Back Muscles

What are extrensic muscles

Muscles that originate outside of the body part or region they control but insert into it

What are intrinsic muscles

Muscles that originate and insert within the same region or body part they control.

4 superficial extrensic muscles

Trapezius
Rhomboids
Lattismus Dorsi
Levator Scapulae

Deep extrensic muscles

Serratus post, sup, inf

What are the three layers of TLF enclosing the intrinsic muscles in the Lumbar spine

Post, Middle, Ant.

Where does the TLF run from medially

Tips of Sps supraspinous lig, median crest of sacrum.

Where doe the TLF run from laterally

Lsp TPs, angle of ribs.

TLF extends sup…

To the neck attaching medially to the nuchal line and laterally to the Csp TPs.

Superficial intrinsic muscles

Splenius capitis and cervicis

Intermediate (erector spinae) intrinsic muscles

Spinalis, Longissimus, Illiocostalis

Deep intrinsic muscles

Semispinalis, Multifidus, Rotatores, Segmental back muscles

What does the semi-spinalis divide into

Thoraci, Cervicus, Capitis

Semispinalis actions

Bilaterally: Thoracic and cervicus extend Tsp and Csp, capitis extends head
Unilaterally: Rotates Tsp and Csp and head to opposite side.

Multifidus Origin
Insertion
Action
Innervation

Sacrumm and common origin of ES.
SPs of all vertebrae from Lsp to Csp passes superomedially
Stabilises the vertebrae during local movements
Post rami of spinal nerves

Rotatores Origin
Insertion
Action

TPs
SPs
Roates and local extension

Interspinales & Intertransversari (Segmental back muscles)
Origin/Insertion
Action
Innervation

SPs and Tps of consecutive vertebrae
Spinalis - aids in extension and rotation
Intertransversari - aids in SB and stabilisation
Ant and Post rami of spinal nerves

Leveator costarum (segmental back muscles)
Origin
Insertion
Action
Innervation

Tip of TP
Inferolaterally to inf rib
Raises rib during inspiration
Post rami of Tsp

What are suboccipital muscles

Small group of deep muscles in the upper Csp. Located between the occiput, C1 and C2.

Inneveration of suboccipital muscles

All inneverated by post ramus of C1 - the suboccipital nerve

What are the 4 suboccipital muscles on each side.

Rectus capitis post major
Rectus capitis post minor
Obliques capitis sup
Obliques capitis inf

Rectus capitus post major
Origin
Insertion
Action

Post C2 SP
inf nuchal line
Extension of the head, rotation to same side

Rectus Capitis Post Minor
Origin
Insertion
Action

Post tubercule on post arch C1
Inf nuchal line, medially to major
Extension of head

Obliques Capitis Inferior
Origin
Insertion
Action

SP of C2
TP of C1
Rotation ipsilateal (Unilateral), extension (Unilteral)

Obliques Capitis Superior
Origin
Insertion
Action

TP of C1
Occiput between sup and inf nuchal lines
Extend head ( Bi) SB ipsilateral (unilateral)