Structures · Vertebrae
L4 vertebra
Vertebra 4 of the lumbar (lower back) spine. This page uses the vertebral level system; the cord segments that lie opposite it have different names.
At a glance
- Level system
- L4 vertebra (vertebral level)
- Cord segments opposite its body
- None: below the end of the cord in this model; the canal holds the cauda equina hereModel mapping. Frostell et al. 2016; De Leener et al. 2018; Cadotte et al. 2014
- Canal, front to back × side to side
- 17.7 × 34.1 mmMeasured on one model: the Visible Human male, imaged as a supine cadaver. Not a normal range
What the sources say
“The lower back contains the L1–L5 lumbar vertebrae.” Betts et al. 2022, §7.3
“Lumbar Vertebrae Lumbar vertebrae carry the greatest amount of body weight and are thus characterized by the large size and thickness of the vertebral body ( Figure 7.28 ).” Betts et al. 2022, §7.3
Connections to the rest of the body
Muscle attachments
Segmental muscles join neighbouring vertebrae
The smallest back muscles span a single joint, from one vertebra to the next.
Muscle attachments
The diaphragm anchors to the lumbar spine
Behind, the breathing muscle takes origin from the lumbar vertebrae and the 12th ribs; in front, from the sternum and lower ribs.
Arterial supply
Lumbar arteries supply the lower back and the cord
Four pairs of lumbar arteries leave the abdominal aorta beside the lumbar vertebrae; they are the lower counterparts of the intercostal arteries.
Read more
- The intervertebral disc
The fibrocartilage pad between two vertebral bodies: a tough outer ring around a gel-like core. How it bears weight and lets the spine bend, how it changes with age, and what a herniated disc is.
- The L4–L5 motion segment
Two lumbar vertebrae, the disc between them, the joints and ligaments that tie them, and the nerves that pass by. One of the two most common places for a disc to herniate, and a good place to see how bone, disc and nerve fit together.
- The vertebral column
The flexible stack of bones that carries the head and trunk, protects the spinal cord and lets the back move. Its five regions, its four curves and the parts every vertebra shares.
For learning only. Levels and sizes vary between people; nothing here describes a particular person or gives medical advice. Sources: Betts et al. 2022, §7.3; Frostell et al. 2016; De Leener et al. 2018; Cadotte et al. 2014; Betts et al. 2022, §13.4; Betts et al. 2022, §11.3; Betts et al. 2022, §11.4; Betts et al. 2022, §20.5.