A&P1.18 Flashcards
Muscles of the Back
Paraspinal Muscles
- Exist in a staggered pattern from the occipital bone to the sacrum
- Arranged in 3 layers that are all covered by more superficial layers of back & neck ms. (Ex: Trapzeius, rhomboids, latissimus dorsi)
- Act collectively to hold bipeds (two feet) upright against gravity
- Are always in a state of partial, sustained contraction to maintain an upright posture => under constant stress**
Aka “paravertebral ms.”
Para = next to
Paraspinal = next to the spine (either side)
Paraspinal Muscles
List the layers of this group and the muscles each contains
- Deep layer
** Intertransversarii
** Interspinalis
** Rotatores - Intermediate layer
** Multifidus
**Semispinalis - Superficial layer
** Iliocostalis
** Longissimus
** Spinalis
NOT MADE ON MANIKEN
Muscles of the Back
Deepest layer of the paraspinal muscles
Made up of very small muscles which span 1 joint (NOT MADE)
NOT MADE ON MANIKEN
Muscles of the Back
Intermediate layer of paraspinal muscles
Made up of slightly larger muscles than deepest layer spanning 2-6 joints.
Still deep = pink clay
Muscles of the Back
Erector Spinae Group
- Superficial layer of paraspinal muscles
- Made up of longer muscles which span 8-10 joints
- This layer has 3 divisions:
**Spinalis
**Longissimus
**Iliocostalis - Collectively referred to as the Erector Spinae group
- All emerge from the thoracolumbar aponeurosis
Muscles of the Back: Deep Layer of Paraspinal Ms - L, O, I, A
Intertransversarii
L: Posterior back deep
O: Tranverse process of inferior vertebrae
I: Transverse process of superior vertebrae
A: Lateral flexion of torso
NOT MADE ON MANIKEN
Super deep => unable to palpate
Muscles of the Back: Deep Layer of Paraspinal Ms - L, O, I, A
Interspinales
L: Posterior back deep
O: Spinous process of inferior vertebrae
I: Spinous process of superior vertebrae
A: Extension of torso
NOT MADE ON MANIKEN
Muscles of the Back: Deep Layer of Paraspinal Ms - L, O, I, A
Rotatores
L: Posterior back deep
O: Tranverse processes of L5-C3
I: Spinous process of next vertebrae superiorly
A: Extension & rotation of torso to opposite side
NOT MADE ON MANIKEN
Run at an angle to help with rotation
Muscles of the Back: Intermediate Layer of Paraspinal Ms - L, O, I, A
Multifidus
L: Posterior back deep
O:
* Sacrum
* Transverse processes of L5-T1
I: Spinous processes of all vertebrae
A:
* Maintain posture
* Slight rotation & extension of torso
The only muscle that attaches to the sacrum
Muscles of the Back: Intermediate Layer of Paraspinal Ms - L, O, I, A
Semispinalis
L: Posterior back deep
O: Transverse processes of thoracic & cervical vertebrae
I:
- Spinous processes of T4-C2
- Occipital bone between superior & inferior nuchal line
A:
- Extension of head & torso
- Rotation of head & torso to opposite side
Parallel fibers
Has 3 regions:
- Semispinalis capitis = “head”
- Semispinalis cervicis = “neck”
- Semispinalis thoracis = “thorax”
Attachments of the Back Muscles
Thoracolumbar Aponeurosis
- Dense, thick layer of CT in lumbar region
- Anchoring point for muscles
Muscles of the Back: Superficial Layer of Paraspinal Ms - L, O, I, A
Iliocostalis
Erector Spinae Group
L: Posterior back deep
O: Emerges from thoracolumbar aponeurosis to bodies of ribs 12-3
I:
* All ribs
* Transverse processes of C7-C4
A:
- Bilateral: Extension of head & torso
- Unilateral: Lateral flexion of head & torso to same side
Parallel fibers
- Lateral to lamina groove => most lateral of all erector spinae muscles
- Maintains upright posture
Muscles of the Back: Superficial Layer of Paraspinal Ms - L, O, I, A
Longissimus
Erector Spinae Group
L: Posterior back deep
O: Transverse processes of L5-C4
I:
* Transverse processes of T12-C2
* Ribs
* Mastoid process
A:
- Bilateral: Extension of head & torso
- Unilateral: Lateral flexion of head & torso to same side
*Maintains upright posture
*Runs right along lamina groove
Muscles of the Back: Superficial Layer of Paraspinal Ms - L, O, I, A
Spinalis
Erector Spinae Group
L: Posterior back deep
O:
* Transverse processes of upper lumbar & lower thoracic
* Spinous process of C7
I: Spinous processes of upper thoracic & cervical vertebrae
A:
- Bilateral: Extension of head & torso
- Unilateral: Lateral flexion of head & torso to same side
4 “rainbows”
Muscles of Neck
Anterior scalenes
L: Lateral neck superficial
O: Transverse processes of C3-C6
I: 1st rib
A:
- Bilateral: Elevation of ribs in forced inhalation
- Unilateral: Lateral flexion of head at neck to same side
