Lumbar Vertebrae Learning Objectives

• General Features. • Classification: Typical and Atypical • Ossification • Applied anatomy

General Features • Lumbar vertebrae have Massive body. • Vertebral foramen is Triangular. • Spine is quadrangular. • Superior articular facet is concave. • Inferior articular facet is convex. • Posterioinferior part of root of transverse process has a rough elevation called accessory process. Classification

• Total number of Lumbar Vertebrae : 5 • Typical : First to Fourth • Atypical : Fifth Typical Lumbar Vertebrae

• Body • Vertebral foramen • Vertebral arch i. Pedicles ii. Laminae iii. Spine iv. Transverse processes v. Articular processes Body Body • Large • Transverse diameter > Anterio-posterior diameter • Upper and lower surfaces: Hyaline Cartilages • Anterior surface: Anterior longitudinal ligament(ALL) in midline. • Crura of diaphragm: Either side of ALL Right crus: Upper 3 Left crus: Upper 2 • Psoas major and tendinous arches: Upper and lower margins of sides of body. • Posterior surface: Posterior longitudinal ligament. Vertebral Foramen

• Triangular in cross section • Dura matar and Arachnoid matar : L1-L5 • Conus medullaris with pia matar: L1 • Cauda equina: L2-L5 Vertebral Arch

i. Pedicles: • Short and Strong • Inferior vertebral notches are deeper than superior. • Formation of intervertebral foramen. • Traversed by spinal nerves and radicular vessels. ii. Laminae: • Short and Thick. • Directed postero-medially. • Ligamentum flavum : Upper border and lower half of its anterior surface. • Posterior surface of lamina: Deep muscles of back iii. Spine: • Quadrilateral. • Posterior border: Supraspinatus ligament (Midline), Posterior lamella of thoracolumbar fascia. • Superior and Inferior borders: Interspinous ligaments (midline),Interspinalis muscles( each side) • Sides of spine: Deep muscles of back. iv. Transverse Process(TP): • Tapering and Thin. • Homologous with ribs.

• Medial and lateral arcuate ligaments: Tip of TP of L1. • Iliolumbar ligament: Tip of TP of L5 • Middle lamella of thoracolumbar fascia: L1-L5 • Anterior surface: Faint ridge: Anterior lamella of thoracolumbar fascia. Medial to ridge: Psoas major Lateral to ridge: Quadratus lumborum

• Upper and lower borders of TP : Intertransversarii muscles. • Accessory process: Medial intertransverse muscle. • Posterior surface of TP: Deep muscles of back. v. Articular process: • Superior articular facet: Concave, Medially • Inferior articular facet: Convex, Lateraly • Distance between the superior articular process is relatively more than inferior articular process in L1- L3 • Relation is reversed in L5 • Equal distant: L4 • Posterior border of superior articular process : Mamillary process : Medial intertransverse muscles and deep muscles of back. Atypical Vertebra

1. Thick and short transverse process: Connected to whole of pedicles and part of body. 2. The distance between inferior articular process is more than superior articular process. 3. The body is very much deeper anteriorly than posteriorly.

Fawcetts’s rule for identification of individual lumber vertebrae. • Trapezium : L1/L2

• Vertical rectangle : L3

• Square : L4

• Horizontal Rectangle : L5 Ossification Of Lumbar Vertebrae

Primary centers: 3 [1 Body, 1 for each half of vertebral arch] Appearance: 9-16 weeks IUL Fusion : Each half of vertebral arch with each other: 1 year : Vertebral arch with body: 3-6 years Secondary centers: 5 • 1 each :Annular epiphyseal ring(upper and lower surface of body). • 1 each: Tip of transverse process. •1: Tip of spine Appearance: Puberty Fusion: 25 years • 2 additional centers appear , 1 for each Mamillary process. Applied anatomy Anomalies of vertebral coloumn. Sacralization of 5th lumbar vertebra. Fusion of L5 with sacrum. Complete/Incomplete. Transverse process of L5 may articulate with ala of sacrum and compress the L5 spinal nerve. Spina bifida: It occurs due to non-fusion of two halves of the vertebral arch. Meninges and spinal cord are exposed and may herniate out in midline through the gap. Lumbar disc prolapse: Lumbar Spondylolysis: Degenerative conditions affecting the discs, vertebral bodies, and associated joints of the lumbar vertebrae. Cauda equina syndrome: Due to compression of cauda equina (L2-S1) Clinical presentation: 1. Flaccid paraplegia 2. Saddle – shaped anesthesia 3. Bladder and bowel involvement 4. Impotence 5. Absence of knee and ankle reflex