TRUNK MYOLOGY Flashcards
Contralateral
Opposite side
Ipsilateral
Same side
Muscles of the posterior abdominal wall
4 muscles:
Quadratus lumborum
Psoas minor
Psoas major
Iliacus
Positioned deep to the erector spinae muscles
Quadratus lumborum
S: large flat quadrilateral
O: Iliolumbar ligament and adjacent part of iliac crest
I: middle 1/2 lower border 12th rib, lateral part T.P of L1– L5
D: upwards and medially
A: unilateral - side flexion to same side
Reverse origin insertion pelvis on standing leg
Fixation Diaphragm during deep inspiration
F:
NS: Subcoastal nerve T12-L4
Psoas Minor
Only 40% have it
S: weak muscle
O: T12-L1 VB + IVD
I: iliopubic eminence
D: anteriorly
A: weak flexor lumbar spine
F:
NS: Ramus L1
Psoas major
Hip
Shape: large and powerful
Origin: bodies and discs of vertebrae T12 – L5
Anterior aspect of all lumber transverse processes (TPs)
Insertion: lesser trochanter or Femur (with iliacus)
Direction: inferiorly
Actions: flexes hip and laterally flexes the lumbar spine working bi-laterally flexes is the lumbar spine
Function: sitting up from a lying position
Nerve supply: anterior rami L1,2,3,4
Iliacus
Hip
Shape: flat fan shaped
Origin: upper and posterior 2/3 iliac fossa of sacrum and anterior Sacroiliac ligament
Insertion: lesser trochanter of femur with psoas major
Direction: inferiorly anteriorly
Actions: flexes the hip
Function: sitting up from a lying position
Nerve supply: femoral nerve L2, 3
Thoracolumbar fascia
diamond shaped
3 layers fibrous connective tissue
Anterior,middle,posterior
Protective membrane between the 12th rib and pelvis protects posterior abdomen– kidney
Broad communal tendon muscle attachment e.g oblique internus
Compartmentalises muscle
Stabilisation and force transmission through lower back
Anterior abdominal wall
4 total
3 sheet muscle:
External oblique
Internal oblique
Transversus abdominis
1 Strap:
Rectus abdominis
Aponeurosus of these muscles reinforce and form abdominal wall
Aponeurosus
Sheet of fibrous tissue
Dense collagen content
Same action as tendon
Broad area of attachment between muscle and bone
Flat forms layers save space
Linea Alba
“White line”
Fibrous structure on front of body in midline “seem” between R and L
Joins the xiphoid process to the pubic symphysis
Point of attachment for abb muscles
Transmits force across the body from one side of the abdominal muscles to the other side
External oblique
S: most superficial anterolateral abb wall
O: Fleshy slips to the outer borders of ribs 5 to 12 and costal cartilages
I: •outer lip of anterior 2/3 iliac crest
•Via on a Aponeurosis to the linea Alba, pubic tubercle and ASIS (via inguinal ligament)
D:
A: •bilateral - Trunk and spine flexion
•Unilateral – ipsilateral flexion and contralateral rotation
•Reversed O/I – pelvis on the same side is raised in walking
F: pelvis raised same side walking
NS: Anterior Rami T7-12
Inferior boarder of external oblique
Forms inguinal ligament of pelvis between ASIS and the pubic tubercle
Internal oblique
S: Anterolateral abdominal wall deep to external oblique
O: lateral 2/3rds inguinal ligament
anterior 2/3rds illiacus crest
Thoracolumbar fascia
I: Inferior borders ribs 9–12
Via Aponeurosus to linear Alba
involvement rectus sheath
Via conjoint tendon to pubic crest and pectineal line of pubis
D: inferior
A: •bilateral - Trunk and spine flexion
•Unilateral – ipsilateral lateral flexion and rotation
•Reversed O/I – pelvis on the same side is raised in walking
F: pelvis raised same side walking
NS: Rami T7-12, Lumbar L1
Transversus abdominis
S: deepest sheet muscle
O: • costal cartilage lower 6 ribs
• Lateral 1/3 of inguinal ligament
• anterior 2/3rds inner lip illiacus crest
•thoracolumbar fascia
I:• Via Aponeurosus to linea Alba
• pubic tubercle
•pectinial line via conjoint tendon
D: horizontal fibres
A: forces diaphragm upwards
F: coughing sneezing
NS: Rami T7-12, lumbar L1
Rectus abdominus
S: x2 strap
O: Anterior pubic symphysis and pubic crest
I: Xiphoid process and costal cartilages of ribs 5–7
D: vertical
A: •Bilaterally flexes trunk and spine -posterior pelvic tilt
•unilaterally lateral flexion to same side
• reversed O/I posterior pelvic tilt
F: sit up
NS: Thorcoabdominal nerves T7-11
Subcostal nerve T12
Rectus sheath
Strong fibrous covering of rectus abdominis improves function prevent bowstringing of muscle during contraction
Formed by aponeurosis of abdominal muscles
• int oblique
• ext oblique
• abdominal fascia
Covers and invests rectus abdominis
Helps transmit force from one side of the abbs to other
Difference of arcuate sheath above and below arcuate line
Above:
Oblique externus passes in front
Oblique Internus passes in front and behind
Transversus passes behind
Below:
Oblique externus, oblique Internus and tansversus all pass in front
Actions abdominal muscles
See pictures
Functions abdominal muscles
Assists in trunk Stability and stabilise upper body and lower body
Transmits force between upper body and lower body
Contain and protect abdominal contents – organs
Raised intra-abdominal pressure particularly transversus due to horizontal arrangement of fibres
Forces diaphragm from upwards – cough/sneezing
If diaphragm is fixed this causes wrong result in expulsive arcs of the body e.g. vomiting/defecation
Abdominal pressure
Abdomen = container
Limits:
•Superior – diaphragm
- Inferior – pelvis, pelvic floor
- Anterolaterally – rectus sheath, sheet musculature
- Posterior – thoracal lumbar for sure, posterior abdominal wall, spinal column
Contraction of muscles increase force within a comfined space can result in herniation- diastasis rectus
What are the 3 muscles of erector spinae
Muscles that straighten out spine
- Spinalis
> Thoracics * most significant
> Cervicis
> Capitis - Longissumus
> Thoracics *
> Cervicis
> Capitis - Illiocostalis
> Lumborum *
> Thoracics
> Cervicis
Longissimus and Iliocostalis common origin
Muscles arise as cydrical belly and form common origin
flat U-shaped tendon attaches from numerous locations
Medially – spinous processes T11 – L5, Supraspinous ligament, medial sacral crest
Laterally – sacral crest Sarcotuberous Coxccygeal posterior illiac crest posterior Sarcoilliac ligaments
iliocostalis- Lumborum *
O: common errector spiny origin
I: via 6 slips into lower 6 ribs near angles
D: lateral, superior
iliocostalis- thoracis
O: lower 6 ribs
I: upper 6 ribs C7 TP
D: superior, medial
Iliocostalis- Cervicis
O: upper 6 ribs
I: Posterior tubercles of TP C4–7
D:
Longissumus- Thoracis
O: common errector spinae origin
TP L1-L5
I: 2 slips to the TP all 12 thoracic vertebrae adjacent 10 ribs
D: superior
Longissumus- cervicis
O: TP T1-6
I: posterior tubercle of TP C2-6
D:
Longissumus- capitis
O: TP T1–5 articular processes C4–7
I: Posterior aspect of mastoid process
D:
Spinalis- Thoracis
O: Spinous process T11 – L2
I: superior
D: T1–6
Spinalis- cervicis
Abscent or poorly developed
O: lower nuchal canal ligament spinal process T1-6
I: Spinous process C2
D:
Spinalis- capitis
Indistinct from semispinalis Capitis
3 muscles that interact with lumbar spine
Iliocostalis (lateral)
Longissumus (middle)
Spinalis (medial)
Erector spinae actions
Prevents pelvis from dropping on unsupported side when standing on one leg
BILATERAL:
Extension of relevant lumbar, thoracic or cervical spine
UNILATERAL
- Ipsilateral lateral flexion of relevant lumbar, thoracic or cervical spine
- Ipsilateral rotation of relevant thoracica cervical spine
- All movements depend upon the relevant muscle attachment and location
Erector spinae- nerve supply
Adjacent posterior primary Rami according to position
Erector spinae- combined action
Reaching to scratch the back of your knee with your legs straight
Combined extension ipsilateral lateral flexion and rotation
Poor full extent of the trunk:
•Returning trunk from a flex position particularly underload e.g. lifting a box from the floor
Semispinalis - Thoracis
O: TP T6-10
I: spinous processes C6-T2
Semispinalis- Cervicis
O: TP T1-6
I: spinous processes C2-6
Semispinalis- Capitis *
O: TP C4-T6
I: Between the superior and inferior nuchal lines of base of skull
Rotation head
Semispinalis
Action
Bilateral – extension of spine
Unilateral – contralateral rotation of spine
Multifidus
Deep to semi spinalis
O: posterior sacrum
Mammillary process lumbar vertebrae
TP thoracic vertebrae
Articular process C3-7
I: Spinouss processes L5-3
D: upwards medially
Multifidus- layered arrangement
Deep fibres – 1 spinal level above
Intermediate fibres- 2–3 spinal levels above
Superficial fibres- 3–4 spinal levels above
Rotatores
Best developed in thoracic region- most rotation
O: TP one vertebrae
I: Lamina of vertebrae above
Some fibers cross x2 spinal levels
Multifidus + Rotatores
Actions
Multifidus- Contralateral rotation of spine in addition to extension and lateral flexion
Rotatores- Contralateral thoracic spine rotation
*Both = stabilising muscle acting as extensile spinal ligaments to control movement
Multifidus + Rotatores
Nerve supply
Adjacent posterior rami
Inguinal ligament
Between ASIS and pubic tubercle
