APK 2 full

• Functions of the lumbar spine

  • Attachment point for muscles
  • Consist of 5 vertebrae in lower back to provide support for weight of body
  • Surrounds and protects the spinal cord
  • Allows for a wide range of body motions
• Movements available at the lumbar spine

  • Flexion-extension
  • Lateral inflexions
  • Rotations
• Structures that limit the movements of the lumbar spine

  • Iliolumbar ligament – stability of lumbosacral junction – restricts side flexion and rotational movement at L5-S1 joint
  • Orientation of facet joints limits rotation
• Characteristics of a typical lumbar vertebra (L1-L4)

  • Large vertebral body
  • Vertebral arch
  • Seven processes
  • Spinous process is short and thick and projects perpendicular from the body
  • Articular facets vertical, superior facets directed posteromedially and medially. Also have a curved articular surface
  • Mammillary process on posterior aspect of the superior articular process
• Characteristics of the atypical lumbar vertebra (L5)


  • Has the largest body and transverse processes of all vertebrae
  • Anterior aspect of the body has a greater height compared to the posterior. Creates the lumbosacral angle between the lumbar region of the vertebrae and the sacrum
• The shape of the individual vertebrae contributes to the normal curve of the lumbar spine
• Lumbar spine curved inwards forming a lordotic (backward C) shape
• Anterior superior iliac spine


  Bony protuberance located at the junction of the superior margin (iliac crest) and the anterior margin of the ilium
• Posterior superior iliac spine

  Bony prominence that indicates the posterior end of the iliac crest. Located where the superior border (iliac crest) meets the posterior border of the ilium
• Iliac crest

  Curved part at the top of the hip. Forms the wing-like part of the pelvis which people rest their hands on
• Joints to be studied

  • Intervertebral joints
  • Facet/apophyseal joints
• Information to include for each joint

  • Classification
  • Bones that articulate to form the joint
  • Joint surfaces
  • Stability of the joint
  • Associated ligaments
  • Physiological movements
• Intervertebral joints

  • Classification: fused, fibrocartilaginous symphysis
  • Connect directly adjacent vertebrae of the vertebral column
  • Ligaments: longitudinal (anterior and posterior), ligamenta flava, interspinous, supraspinous, intertransverse, nuchal (C-spine only)
  • Joint capsule: not enclosed in joint capsule, stability provided by anterior and posterior longitudinal ligaments
  • Physiological movements: flexion, extension, lateral flexion and axial rotation of the vertebral column
• Characteristics of facet/apophyseal joints in different regions of the spine

  • Cervical: Articular surfaces are flat and ovoid in shape. Superior ones face superoposteriorly while the inferior ones project anteriorly
  • Thoracic: Articular surfaces are thin and almost flat. Superior ones are directed posteriorly and superolaterally, while the inferior project anteriorly and superomedially
  • Lumbar: Superior articular surfaces are vertical and concave, oriented posteromedially. Inferior ones are vertically convex and face anterolaterally
• Facet/apophyseal joints

  • Surrounded by a thin and loose fibrous joint capsule which is lines by a synovial membrane that secretes viscous synovial fluid, which acts as lubricant
  • Ligaments: Ligamenta flava, interspinous, supraspinous, intertransverse
  • Physiological movements: Allows nonaxial movements in one plane, facilitates multiplanar and multidirectional movement of the spine
• Components of the intervertebral disc


  • Annulus fibrosus (Outer ring)
  • Nucleus pulposus
  • Vertebral end plates
• The form of the lumbar disc changes with movement
• When the spine bends forward, the height in front of the disc decreases while the posterior height increases. The opposite occurs while bending backwards
• Contents of the intervertebral foramen

  • Spinal nerve root, dorsal root ganglion, recurrent meningeal (sinuvertebral) nerve, segmental spinal arteries, intervertebral veins, transforaminal ligaments, fat
• Functions of the pelvis

  • Transfer of weight from the upper axial skeleton to the lower appendicular components of the skeleton, especially during movement
  • Provides attachment for a number of muscles and ligaments used in locomotion
  • Contains and protects the abdominopelvic and pelvic viscera
• Pubic symphysis

  • Between the pubis bodies of the two hip bones
  • Secondary cartilaginous joint
  • Composed of fibrocartilage interpubic disc
  • Ligaments to strengthen interpubic joint = superior pubic ligament and inferior (arcuate) pubic ligament
  • Limited movement but important for cushioning the stress related to walking and running
  • During pregnancy, hormones cause structural changes to increase its width and mobility to prepare pelvis for childbirth
• Sacroiliac joint

  • Between the ilium and the hip bones, and the sacrum
  • Synovial joint
  • Bears weight of the axial skeleton and transfer it to hip bones
  • Weight is then distributed to the two femurs in standing or ischial bones in sitting
• Movements in the pelvic region

  • Anterior pelvic tilt (sitting up, arched back, bum out)
  • Posterior pelvic tilt (slouching, lumbar lordosis, core muscles in)
  • Lateral pelvic tilting (bum shuffling, one hip at a time)
• Muscles to study

  • Internal abdominal oblique
  • External abdominal oblique
  • Rectus abdominis
  • Transversus abdominis
  • Multifidus
• Internal abdominal oblique

  • Muscle of the abdomen, broad and flat
  • Originates from the thoracolumbar fascia, anterior 2/3 of the iliac crest, lateral 2/3 of the inguinal ligament
  • Inserts into inferior margins and costal ends of the 10th-12th ribs and their adjacent cartilages; linea alba via its broad aponeurosis; pecten pubis via its inguinal falx
  • Action: flexes, laterally flexes, and rotates trunk, compresses and provides structural support to adjacent abdominal structures
  • Innervation: anterior rami of 7th-12th thoracic nerves, iliohypogastric and ilioinguinal nerves
  • Arterial supply: lower posterior intercostal, subcostal, deep circumflex iliac, and superior and inferior epigastric arteries
• External abdominal oblique

  • Muscle of the abdomen, broad and flat
  • Originates from the external surfaces and inferior borders of the anterior halves of the 5th-12th ribs
  • Inserts via broad aponeurosis at; the anterior superior iliac spine, and anterior half of iliac crest; pubic crest and pubic tubercle; linea alba
  • Flexes, laterally flexes, and rotates trunk; compresses and provides structural support to adjacent abdominal structures
  • Innervation: anterior rami of 7th-12th thoracic nerves
• Rectus abdominis

  • Muscle of the abdomen, long and strap-like
  • Originates from the pubic crest via its lateral fibres; pubis symphysis via its medial fibres
  • Inserts onto the xiphoid process; anterior aspects of the 5th-7th costal cartilages
  • Action: flexes trunk, compresses and provides structural support to adjacent abdominal structures
  • Innervation: anterior rami of 6th-12th thoracic nerves
  • Arterial supply: superior and inferior epigastric arteries
• Transversus abdominis

  • Broad, flat skeletal muscle in the abdomen
  • Originates from the internal aspects of the 7th-12th costal cartilages; thoracolumbar fascia; anterior 2/3 of iliac crest; lateral 1/3 of inguinal ligament
  • Inserts onto the linea alba via its broad aponeurosis; pubic crest; pecten pubis via its inguinal falx
  • Action: compresses and provides structural support to adjacent abdominal structures
  • Innervation: anterior rami of 7th-12th thoracic nerves, iliohypogastric and ilioinguinal nerves
  • Arterial supply: lower posterior intercostal, subcostal, superficial and deep circumflex iliac, and superior and inferior epigastric arteries
• Multifidus


  • Most central of the 3 transversospinal muscles, intrinsic muscle of the back – found along the entire length of back and posterior neck region, long and thick
  • Originates from the posterior superior iliac spine, dorsal surface of sacrum, mammillary process of lumbar vertebrae, transverse processes of thoracic vertebrae, articular processes of 4th-7th cervical vertebrae
  • Inserts into spinous processes of lumbar vertebrae; spinous processes of thoracic vertebrae; spinous processes of axis-7th cervical vertebrae
  • Action: extends neck and trunk, stabilises vertebral column
  • Innervation: medial branches of posterior rami of cervical, thoracic, and lumbar nerves
  • Arterial supply: occipital, deep cervical, and vertebral arteries, dorsal branches of posterior intercostal arteries
• Lumbar region function

  • Surrounds and protects spinal cord from injury
  • Accepts and distributes load
  • Produces and accumulates movements of force
  • Serves as an attachment point for muscles
• Neural control unit

  Evaluating stability and coordinating and response
• Spinal muscles

  An active subsystem that provides dynamic stability
• Spinal column

  A passive subsystem that provides intrinsic stability
• Differences between lumbar and thoracic vertebrae

  • Shape and size of neural canal
  • Shape and size of vertebral body
  • Presence/absence of rib 'demifacets'
  • Shape, length, and angle of spinous process
  • Orientation of facet joint surfaces
• Spinal nerves

  31 pairs: 5 in lumbar region, 5 in sacral region, 1 in coccygeal region
• The lumbar (and cervical) regions are enlarged to accommodate nerve plexi
• Nerve roots exit via intervertebral foramina
• Cauda equina

  The spinal cord is shorter than the spinal column, ending level with the L1/L2 vertebrae. Nerve roots below L1/L2 are elongated to accommodate this. Compression of the cauda equina can be a medical emergency.
• Pelvis structure

  • Innominate bone: ilium, ischium, pubis
  • Sacrum: sacral foramina
  • Sacroiliac joints: interaction between innominate and sacrum
• Pelvis function

  • Supports and protects the viscera
  • Support bodyweight transmitted through vertebrae
  • Is a significant attachment point for lumbar musculature and ligaments