Presentation on theme: "Muscles of the Posterior Trunk"— Presentation transcript:
1 Muscles of the Posterior Trunk MyologyMuscles of the Posterior Trunk
2 Latissimus DorsiFibers of the latissimus dorsi twist in such a way that the superior fibers attach distally on the humerus and the inferior fibers attach proximally.Sometimes the latissimus blends with the teres majorThe spinal and pelvic attachments are all via thoracolumbar fascia.Since it has an attachment onto the inferior angle of the scapula, it can move the scapula. When trunk is fixed, it can depress, retract and downwardly rotate the scapula.If the arm is fixed, the lat can elevate the trunk at the shoulder joint toward the humerus (as in a “pull up”).The latissimus dorsi and pectoralis major are both large powerful muscles which attach trunk to the arm. The both adduct and medially rotate the humerus.
3 Latissimus Dorsi latissimus = wide dorsi = back O: Thoracolumbar aponeurosis, posterior sacrum, posterior iliac crest, lower 3 or 4 ribs, and inferior angle of the scapulaI: Medial lip of the Bicipital Groove of the humerusA: Extends, medially rotates, adducts the arm (handcuff position)** Reversed muscle action bilaterally causes anterior tilt of the pelvis. Unilateral contraction causes elevation of the pelvis, contralateral rotation of the trunk, and lateral deviation of the trunk.N: Thoracodorsal nervePalpation: Page 207
4 Rhomboids They are deep to the trapezius Rhomboid minor is superior to rhomboid major.Rhomboid minor attaches to the scapula, inferior to the levator scapulae.Deep to the rhomboids are the splenius capitis, splenius cervicis, serratus posterior superior and erector spinaeThey also cause downward rotation of the scapula.Are sometimes called Christmas Tree muscles due to their shape.Rounded Shoulders is a common condition in which scapulae are protracted (abducted) and depressed and the humeri are medially rotated. When rhomboids are weak, the can contribute to this condition. This is especially true if the protractors (pecs) are tight.
5 Rhomboid Major and Minor O: Rhomboid Major: Sp’s T2-T5Rhomboid Minor: Sp’s C7-T1I: Medial border of the scapula from the rootof the spine of the scapula to the inferiorangle of the scapulaA: Retracts, elevates, and downwardlyrotates the scapula.**Reversed muscle action: Unilaterallycauses contralateral rotation of the trunkN: Dorsal scapular nervePalpation: Page 212
6 Serratus AnteriorMajority of this muscle lies deep to the scapula and lats posteriorly and pecs anteriorly.Lowest 4-5 slips of costal attachments interdigitate with external oblique.Lies next to (anterior to) the subscapularis.Serrated appearance comes from attaching onto separate ribs, which creates the notched look of a serrated knife.Prime mover of protraction, upward rotation, & medial tilt of scapula.Required during forceful protraction of scapula i.e. reaching, pushing, punching, throwing.
7 Serratus Anterior O: Outer borders of the 1st through 9th ribs I: Anterior surface of the entiremedial border of the scapulaA: (PUSS) Protracts, upwardlyrotates, and stabilizes thescapulaN. Long thoracic nerve (of Bell)Palpation: Page 215
8 Serratus Posterior Superior Thin, quadrilateral shaped muscleImportant for respiration specifically inspiration since it elevates ribs 2-5 increasing the size of the thoracic cage (Boyle’s Law).Lies deep to the rhomboids
9 Serratus Posterior Superior O: SP’s of C7-T3I: Superior borders of Ribs 2-5 (deep to the rhomboids)A: Elevation of ribs 2-5N: intercostal nervesPalpation: Page 219
10 Serratus Posterior Inferior O: SP’s of T11-L2I: Inferior borders of Ribs 9-12A: Depression of ribs 9-12N: subcostal & intercostal nervesPalpation: Page 221
11 The Erector Spinae Group Name tells us that these muscles make the spine erect.Lie deep in the back and neckIn lumbar region, this group is deep to the lat and serratus posterior inferior.In thoracic region, deep to trap, lats, rhomboids, serratus posterior superior, splenius capitis & splenius cervicis.In cervical region, deep to trap, splenius cap/cerv, and SCMIn trunk, erector spinae are superficial to transversospinalis group, QL, and ribcage.In neck erector spinae group is superficial to suboccipitals.Spinalis, longissimus, and iliocostalis make up erector spinae group.From medial to lateral the acronym SLI name the muscle of the group
12 Erector Spinae Group (Overview of entire group) O: PelvisI: Spine, ribcage, headA: Bilateral Contraction: causesExtension of the trunk, neck, andhead; anterior pelvic tilting.Unilateral contraction: causeslateral flexion and Ipsilateralrotation of the trunk, head, andneck; elevation of the pelvisN: Dorsal rami of the spinal nerves
13 Individual Erector Group Muscles IliocostalisSubdivided into lumborum, thoracis, and cervicisMost lateral of the threeLongissimusSubdivided into thoracis, cervicis, and capitisLongest & largest of the three with most superior attachments.SpinalisMost medial of the three
14 Iliocostalis O: Iliocostalis Lumborum: Medial iliac crest and sacrum Iliocostalis Thoracis: angles of ribs 7 – 12Iliocostalis Cervicis: angles of ribs 3-6I: Iliocostalis Lumborum: angles of ribs 7 – 12Iliocostalis Thoracis: angles of ribs 1-7 and C7 TPIliocostalis Cervicis: TP’s of C4 – C6A: Bilateral contraction: Extends the trunk and neck and anteriorly tilts the pelvis.Unilateral contraction: Lateral flexion and ipsilateral rotation of the trunk and neck; elevation of the pelvis at the lumbosacral joint.N: Dorsal rami of the cervical, thoracic, and lumbar spinal nervesPalpation: Page 227
15 LongissimusO: Longissimus Thoracis: Medial iliac crest, posterior sacrum, and TP’s of L1 – L5Longissimus Cervicis: TP’s of T1 – T5Longissimus Capitis: TP’s of T1 – T5 and the AP’s of C5 - CtI: Longissimus Thoracis: TP’s of all thoracicvertebrae and the 9 lower ribsLongissimus Cervicis: TP’s of C2 – C6Longissimus Capitis: Mastoid processA: Bilateral contraction: Extends the trunk and neck and anteriorly tilts the pelvis.Unilateral contraction: Lateral flexion and ipsilateral rotation of the trunk, neck, and head; elevation of the pelvis at the lumbosacral joint.N: Dorsal rami of the cervical, thoracic, and lumbar spinal nervesPalpation: Page 230
16 Spinalis O: Spinalis Thoracis: SP’s of T11 – T12 Spinalis Cervicis: Inferior nuchal ligament and SP ofC7Spinalis Capitis: Usually considered to be part ofthe semispinalis capitisI: Spinalis Thoracis: SP’s of T4 – T8Spinalis Cervicis: SP of C2Spinalis Capitis: Usually considered to be part of the semispinalis capitisA: Bilateral contraction: Extends the trunk and neck.Unilateral contraction: Lateral flexion and ipsilateral rotation of the trunk, neck, and headN: Dorsal rami of the cervical, thoracic, and lumbar spinal nervesPalpation: Page 233
18 Transversospinalis Group (Overview of entire group) O: PelvisI: Spine & headA: Bilateral contraction: Extension of the head, neck, and trunk and Anterior tilting of the pelvisUnilateral contraction: Lateral flexion of the head, neck, and trunk; Contralateral rotation of the neck and trunkN: Dorsal rami of the cervical, thoracic, and lumbar spinal nerves
19 Transversospinalis Group Very deep in the back and lie in the laminar groove (over the laminae between the SPs/TPs)In trunk, directly deep to the erector spinae groupIn neck, deep to trap, SCM, & splenius capitis.Name tells us that this group attaches from TP (transverso) to SP (spinalis). The transverse process attachment is inferior with the spinous process attachment superior.Subdivided, superficial to deep into: semispinalis, multifidus, and rotatores.Semispinalis attaches superiorly to vertebrae 5 or more levels aboveMultifidus attaches superiorly 2-4 levelsRotatores attach superiorly 1-2 levels.Only multifidus attaches onto pelvis.Only semispinalis attaches onto head.The term paraspinal musculature is used to describe erector spinae and transversospinalis groups.
20 Semispinalis O: Semispinalis Thoracis: TP’s T6-T10 Semispinalis Cervicis: TP’s T1 – T5Semispinalis Capitis: TP’s of C7 – T6and the AP’s of C4 – C6I: Semispinalis Thoracis: SP’s of C6 – T4Semispinalis Cervicis: SP’s of C2 – C5Semispinalis Capitis: OcciputA: Bilateral contraction: Extension of the head, neck, and trunkUnilateral contraction: Lateral flexion of the head, neck, and trunk; Contralateral rotation of the neck and trunkN: Dorsal rami of the cervical, thoracic, and lumbar spinal nervesPalpation: page 240
21 Multifidus O: Posterior sacrum, PSIS, L5-C4 I: SP’s 2-4 levels superior to inferior attachmentA: Bilateral contraction: Extension of the neck and trunk ; Anteriorly tilts the pelvis.Unilateral contraction: Lateral flexion of the neck, and trunk; Contralateral rotation of the neck and trunk; Elevates the pelvis.N: Dorsal rami of the cervical, thoracic, and lumbar spinal nervesPalpation: page 243
22 Rotatores O: TP’s of the lumbar, thoracic, and cervical vertebrae I: Lamina of the vertebrae one to two levels aboveA: Bilateral contraction: Extension of the neckand trunk;Unilateral contraction: Contralateral rotation of the neck and trunkN: Dorsal rami of the cervical, thoracic, and lumbar spinal nervesNot palpable
23 Quadratus Lumborum Refer to as QL Very deep and forms part of posterior abdominal wallMajority deep to erector spinaeMust be accessed with palpation from lateral to medial (i.e. come in from the side).Can elevate the pelvis. Often the term “hiking the hip” is used to describe the action.
24 Quadratus Lumborum O: Rib 12, L1-4 TPs I: Posterior Iliac Crest. A: Bilateral contraction: Extension of trunk; anterior tilting of the pelvisUnilateral contraction: Lateral trunk flexion; “hiking” up of the hip; depression of the 12th ribN: Lumbar plexusPalpation: page 248
25 InterspinalsPaired muscles that are located on either side of the interspinous ligaments between the apices of the SPs of adjacent vertebrae.Located deep to supraspinous ligament (nuchal ligament in cervical region).Not located throughout entire spine. Primarily found in cervical & lumbar regions.May be important at fixating the spine.
26 Interspinals O: From a SP I: SP directly superior (not well developed or absent in the thoracic spine)A: Extension of neck and trunkN: Dorsal rami of the cervical, thoracic, and lumbar spinal nervesPalpation: page 251
27 Intertransversarii Located between TPs and very deep. Attach onto anterior tubercles and posterior tubercles of TPs in cervical spine.Do not exist in thoracic region since levator costarum and intercostals take their place.Important as fixators of spine (stabilize)
28 Intertransversarii O: From a TP of a vertebrae I: TP directly superior (in the thoracic region these muscles are found between T10 and L1)A: Lateral flexion of neck and trunkN: Dorsal rami of the cervical, thoracic, and lumbar spinal nervesNot palpable
29 Levator Costarum O: TP’s of C7-T11 I: Rib 1-12 (inferiorly) A: Elevation of ribs (primary action). In addition contributes to extension of the trunk when contracting bilaterally and lateral flexion of the trunk when contracting unilaterallyN: Dorsal rami of the thoracic spinal nervesNot palpable
30 Which muscle of the deep spinal group performs rotation? interspinalisintertansversarirotatoresdeep spinal
31 Levator Costarum Name tells us that the elevate the ribs Attach from vertebrae TP and run inferolaterally on to rib directly inferior.Controversy as whether they are respiratory muscles that move ribs or move/fixate spinal joints
32 Subcostales Usually well developed in lower thoracic region. Lie deep to the ribcage and superficial to the plural membrane.Thought to be respiratory muscles which depress the ribs for forced expiration.