L-2 Thoracic and Lumbar spine

Muscles of the Back

• Key muscles include Trapezius, Levator scapulae, Teres major, Rhomboid major, Serratus anterior, Transversospinales, Latissimus dorsi, Teres minor, Rhomboid minor, Serratus posterior, Erector spinae, Quadratus lumborum.
• Pain from these muscles can be referred anywhere from the origin to the insertion.

Principle of Somatic Dysfunction

• Hypertonic muscles can pull joints out of place.
• This can lead to segmental vertebral somatic dysfunctions.
• Rotated joints can pull and elongate muscles, causing them to strain.

Erector Spinae

• Consists of spinalis, longissimus, and iliocostalis muscles.
• Runs from medial to lateral.
• Extends and ipsilaterally sidebends the spine.

Intrinsics

• Composed of interspinalis and intertransversarii muscles.

Transversospinales

• Consists of the multifidus, rotatores, and semispinalis muscles.

Muscle Mechanics: Short Restrictors

• Short restrictors cross one vertebral segment.
• Muscles that are short restrictors include: rotatores, levatores costarum, interspinalis, and intertransversarii.
• Short restrictors typically create Fryette type II somatic dysfunctions.

Muscle Mechanics: Long Restrictors

• Long restrictors cross more than two segments.
• Muscles that are long restrictors include: multifidus, semispinalis thoracis, spinalis, longissimus, and iliocostalis.
• Long restrictors tend to create Fryette's type I somatic dysfunctions.

Quadratus Lumborum

• Originates from the inferior border of the 12th rib.
• Inserts on the apices of the transverse processes of L1-4, the iliolumbar ligament, and the posterior third of the iliac crest.
• Functions to fix the 12th rib during respiration, laterally flex the trunk, and hike the hip.
• Innervated by the anterior primary rami (T12-L3).

Hypertonic Quadratus Lumborum

• May lead to somatic dysfunction of rib 12 (inhalation dysfunction) and L1-L4.
• May lead to a superior shear of the innominate and iliolumbar ligament tightness/tenderness.

Iliopsoas

• Originates from T12 to L4/5 vertebral bodies and transverse processes and the intervertebral discs.
• Inserts onto the lesser trochanter of the femur.
• Acts as a strong hip flexor.
• Tightness can cause hip flexion or, in reverse action, trunk flexion.

PSOAS Spasm

• Causes the lumbar spine to flex initially.
• Rotation and sidebending of the upper lumbar vertebrae (L1 or L2) occurs towards the side of the shorter psoas muscle, may lead to Fryette Type II flexion dysfunction (L1 FR₁S₁/FRRSR)
• Results in posterior rotation of the innominate.
• Causes lower back, groin/hip pain, and a flexed forward standing posture.

Diaphragm

• Major structures that pierce the diaphragm are: Aorta, Inferior Esophagus & Inferior vena cava.
• Separates the thoracic cavity from the abdominal cavity.
• Functions in breathing, posture, phonation, digestion, and venous return.

Diaphragm Structure

• Originates from the crura of the bodies of L1, 2 (left) and L1-3 (right).
• Originates from the medial and lateral arcuate ligaments and the inner aspect of the lower six ribs
• Has two slips from the posterior aspect of the xiphoid.
• The insertion is at the central tendon.
• Assists inspiration and raises intra-abdominal pressure.
• Innervated by the phrenic nerve (C3, 4, 5) for motor function.
• Sensory innervation: phrenic, intercostals (6-12), and upper two lumbar nerve roots.

Diaphragmatic Tightness

• Can cause somatic dysfunctions in L1,2,3, the lower 6 ribs, and the lower 6 thoracic vertebrae.
• Treating the diaphragm can improve fluid dynamics, venous return, and digestion

Obliques

• Rotating trunk to the right involves contracting the right internal oblique and the left external oblique simultaneously.
• Internal obliques act as ipsilateral trunk rotators.
• External obliques act as contralateral trunk rotators.

Thoracolumbar Fascia (TLF)

• Functions as a retinaculum for paraspinal musculature in the lumbar region.
• Acts as an insertion site for the majority of the abdominal/trunk and extremity musculature.
• TLF provides stability at extremes of motion of the lumbar spine, due to muscle's ability to exert forces on it.
• The three layers of the TLF fuse into a thoracolumbar composite.
• Thoracolumbar composite is connected to the PSIS and sacrotuberous ligaments.
• TLF assists in maintaining the integrity of the lower lumbar spine and the sacroiliac joint.
• Recent studies indicate the TLF has mechanoreceptors and nociceptors.

Vertebrae

• There are 12 thoracic and five lumbar vertebrae.

Vertebral Anatomical Landmarks

• The spine of Scapula aligns with T3.
• Inferior Angle of Scapula aligns with T7.
• The Iliac Crest aligns with the L4-L5 interspace.
• The 12th Rib wraps supero-medially to T12 vertebra.

Vertebrae Structure

• Each vertebrae consists of: body, posterior arch, 2 pedicles , 2 superior & 2 inferior zygapophyseal facets, 2 laminae, 2 transverse processes and a single spinous process.
• A vertebral segment is a single vertebra.
• A vertebral unit consists of 2 adjacent vertebrae with associated arthrodial, ligamentous, muscular, vascular, neural & lymphatic elements.

Vertebral Motion

• Movements are described in relation to the anterior and superior surfaces of the vertebrae.
• Motion refers to the movement of the superior vertebra on the inferior one.
• Vertebral units demonstrate coupled motions.
• Human spine can move in 3 planes due to the superior facet orientation of vertebrae.
• Motion depends on the spinal region (cervical, thoracic, and lumbar).
• Movements occur in the sagittal plane (flex/ext.), transverse plane (rotation), and coronal plane (sidebend).
• Movements are around the R/L axis, sup/inf axis & ant/post axis

Facet Joints

• Synovial joints that guide and limit gross, segmental, and coupled movements of the spine.
• Vertebral motion differs slightly based on the orientation of the superior facets.
• The orientation of the superior facets of a vertebra determines the preferred spinal motion.

Superior Facet Orientation

• Cervical: backward, upward, medial (BUM).
• Thoracic: backward, upward, lateral (BUL).
• Lumbar: backward, medial (BM).

Lumbar Motion

• The primary motion of the Lumbar Spine is FLEXION/EXTENSION.
• The facets face backward and medial (BM).
• Motion takes place around a right-left axis in the sagittal plane.

Thoracic Motion

• The primary motion of the Thoracic Spine is ROTATION.
• The facets face backward, upward, and lateral (BUL).
• Motion takes place the superior-inferior axis in the transverse plane.
• Sidebending is restricted by the ribs.