KUMC 09 Deep Back Muscles Student

8/2/2019 KUMC 09 Deep Back Muscles Student

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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 theback:

Innervated by dorsal (posterior) rami ofthoracic spinal nerves.

More laterally:

Innervated by lateral cutaneous branches of

the intercostal nerves.



Thoracolumbar Fascia

Triangular-shaped sheet of toughconnective tissue.

Partial site of origin of latissimus dorsi andabdominal oblique muscles.



Thoracolumbar Fascia Laminae

Posterior lamina to lumbar spinousprocesses.

Middle lamina to lumbar transverseprocesses.

Anterior lamina (deepest) to lumbartransverse 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 areinnervated 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 andspinous processes.




Run laterally upward to transverseprocesses and skull.

Run laterally and upward to insertion.

Two parts:

Splenius capitis.

Splenius cervicis.



Superficial Intrinsic Muscles

Splenius capitis:

O: spinous processes of C7 and T1-4.

I: superior nuchal line and mastoid.

Splenius cervicis:

O: spinous processes of T3-6.

I: C1-C4 transverse processes withlevator scapulae.




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.




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.




Longissimus:

Origin = transversus processes andsacrum.

Insertion = most of ribs.

Middle portion of erector spinae group.

Components:

Thoracis.

Cervicis.

Capitis.




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 transverseprocesses.

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 inferiornuchal lines.



Multifidus

Thick muscle mass.

Arises from sacrum and surroundingstructures and from transverse processesup to C4.

Including mammillary processes of lumbarvertebrae.

Traverses 3 segments.

Inserts on spinous processes C2-L5.



Rotatores

Pass from root of transverse process toroot of superior spinous process.

Long:

Span two segments.

Short:

Span one segment.



Intrinsic Segmental Muscles

Interspinales.

Intertransversarii.

KUMC 09 Deep Back Muscles Student

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