Transcript DEEP BACK MUSCLES - University of Kansas Medical Center

DEEP BACK MUSCLES
Deep Back Muscles
Epaxial muscles.
 Hypaxial muscles.
 Pharyngeal arch muscles.

Cutaneous Nerves of the Back

Along either side of the midline of the
back:
Innervated by dorsal (posterior) rami of
thoracic spinal nerves.

More laterally:
Innervated by lateral cutaneous branches of
the intercostal nerves.
Thoracolumbar Fascia
Triangular-shaped sheet of tough
connective tissue.
 Partial site of origin of latissimus dorsi and
abdominal oblique muscles.

Thoracolumbar Fascia Laminae
Posterior lamina to lumbar spinous
processes.
 Middle lamina to lumbar transverse
processes.
 Anterior lamina (deepest) to lumbar
transverse processes.

Arrangement of Back Muscles

Three groups:
Superficial:
Extrinsic.
Intermediate:
Extrinsic.
Deep:
Intrinsic.
Superficial Extrinsic Muscles
Connect limb to axial skeleton.
 Innervated by ventral rami or CN XI.
 Include:

Trapezius.
Latissimus dorsi.
Levator scapulae.
Rhomboideus major.
Rhomboideus minor.
Intermediate Extrinsic Muscles
Respiratory muscles.
 Innervated by ventral (anterior) rami.
 Serratus posterior group:

Serratus posterior superior.
Serratus posterior inferior.

Refer to Syllabus: Table II, p. 71.
INTRINSIC (DEEP) BACK
MUSCLES
Intrinsic Back Muscles
True intrinsic muscles of the back are
innervated by dorsal (posterior) rami.
 Three groups:

Superficial
Intermediate
Deep

Refer to Table III, p 73 of Syllabus.
Spinotransversalis System
Consists of the Splenius group:
 Long muscles.
 Originate from ligamentum nuchae and
spinous processes.

Spinotransversalis System
Run laterally upward to transverse
processes and skull.
 Run laterally and upward to insertion.
 Two parts:

Splenius capitis.
Splenius cervicis.
Superficial Intrinsic Muscles

Splenius capitis:
O:
 I:


Splenius cervicis:
O:
 I:


spinous processes of C7 and T1-4.
superior nuchal line and mastoid.
spinous processes of T3-6.
C1-C4 transverse processes with
levator scapulae.
Spinotransversalis System
Intermediate Intrinsic

Sacrospinalis system:
Erector spinae.
Run longitudinally upward:
Transverse processes to rib.
Rib to rib.
Rib to cervical transverse processes.
Spinous processes to spinous processes.
Intermediate Layer of Intrinsic Deep Back Muscles

Components:
Iliocostalis.
Longissimus.
Spinalis.

Refer to Syllabus:
Table III.
P 73.
Intermediate Intrinsic

Iliocostalis:
Origin =
ilium and sacrum.
Insertion = most of the ribs.
Lateral part of the erector spinae group.
Extends back; keeps erect posture.
Components:
Lumborum.
Thoracis.
Cervicis.
Intermediate Intrinsic

Longissimus:
Origin =
transversus processes and
sacrum.
Insertion = most of ribs.
Middle portion of erector spinae group.
Components:
Thoracis.
Cervicis.
Capitis.
Intermediate Intrinsic

Spinalis:
Origin =
spinous processes of T11-L2.
Insertion = spinous processes of thoracic
and lower cervical vertebrae.
Components:
Thoracis.
Cervicis:
Usually absent.
Capitis:
Part of semispinalis capitis.
Deep Intrinsic Muscles

Transversospinalis system:
From transverse processes to transverse
processes.
Concealed by erector spinae.
Muscles arise laterally and insert medially.
Components:
Semispinalis.
Multifidus.
Rotatores.
Semispinalis
Traverse a couple of vertebral levels.
 Components:

Thoracis.
Cervicis.
Origin =
T1-4.
Insertion = C3-5.
Largely covered by semispinalis capitis.
Semispinalis

Components:
Capitis:
Origin =
T1-6 and C4-7.
Insertion =
between superior and inferior
nuchal lines.
Multifidus
Thick muscle mass.
 Arises from sacrum and surrounding
structures and from transverse processes
up to C4.

Including mammillary processes of lumbar
vertebrae.
Traverses 3 segments.
 Inserts on spinous processes C2-L5.

Rotatores
Pass from root of transverse process to
root of superior spinous process.
 Long:

Span two segments.

Short:
Span one segment.
Intrinsic Segmental Muscles
Interspinales.
 Intertransversarii.
