The Lumbar Spine and Sacrum Flashcards
How many vertebrae are in the Lumbar spine?
- L1 - L5 and are the largest and strongest in the body
What type of curve dose the lumbar spine create?
A lordotic curve
Are the 5 vertebrae similar in size?
Yep
What is at the base of each transverse process?
A small prominence of bone called the accessory or mamillary process
What is the junction of the lamina to the pedicle called in the lumbar spine?
The pars interarticularis
Where does the spinal cord end?
Between L1 and L2
How many vertebra does the sacrum consist of ?
5 vertebrae and they are fused
What type curve does the sacrum have?
Kyphotic=
What shape is the sacrum?
It is wedge shaped and forms the posterior walls of the pelvis
What does the sacrum articulate with?
The L5 above, the coccyx below, and laterally with the articular surfaces of the iliac bones of the hip
What is the sacro-iliac joint?
The joint between the pelvis and the sacram.
What is distal to S5?
A triangular bone, the coccyx, consisting of 3-5 fused vertebrae.
What are sacral foramina or pelvic foramina?
Foramina that lie at the lateral ends of the lines across the sacrum that represent the fused vertebrae
What is the area lateral to the sacral foramina known as?
The pars lateralis
What is the pars lateralis at S1 more commonly known as?
Ala
What is the projecting edge of the first sacral vertebra called?
The sacral promontory
What is the sacral promontory used for?
A landmark for sacral screw insertion
What does the total pelvis or pelvic girdle consist of?
Two hop bones (ossa coxae), the sacrum and the coccyx.
What does the ossa coxae articulate with?
The sacrum and the coccyx
What forms the ossa coxae?
the fused ilium, ischium and pubis
What type of joint is the sacro-iliac joint?
A true synovial joint, with capsule and cartilage
What are the two main ligaments in the lumbar spine?
the anterior and posterior longitudinal ligaments
What role do the ALL and PLL play?
A key role in the maintenance of spinal balance and protecting the discs
Describe the ALL.
Stretches as a long dense band from the basi occiput to the sacrum
Runs along the anterior aspect of the vertebral bodies
Long fibers that run full length
Short fibers that attach to the vertebra
Describe the PLL.
Stretches from the basi occiput to the sacral canal.
Does not attach to the posterior edge of the vertebral bodies.
Describe the segmental ligaments.
They join the vertebral arches adn the ligamentum flavum which is its thickest in the lumbar spine
Joins each lamina
What joins the spinous processes?
The interspinous ligamnet.
What attaches to the tips of the spinous processes?
The supraspinous ligament
What runs between the transverse processes?
The intertransverse ligament
Describe the lumbo-sacral ligament
Very thick and extends from the anterior-inferior aspect of the L5 transverse process to the lateral aspect of the sacrum.
What is the Lumbo-sacral ligament also known as?
The sickle ligament.
Where does the Iliolumbar ligament attach?
Extends from the transverse process of L5 laterally and superiorly to the iliac crest
What is considered a near immovable part of the pelvis and why?
The sacro-iliac joint because it is so tightly bound and interlocked with ligaments.
What shape is the articular surface of the iliac bone?
cresent shaped, concave postero-superiorly
What are the ligaments attached to the sacro-iliac joint?
The ilio-lumbar ligaments
sacro-iliac ligaments
sacrospinous ligaments
sacro-tuberous ligaments
What is the superficial plane of the lumbar muscles made of?
The latissimus dorsi which arises from the lumbar aponeurosis
What is the intermediate plane of the lumber muscles made of?
The serratus posterior inferior
Name the deep muscles of the lumbar spine.
Transversospinalis - Runs from L1 inferiorly and laterally to the transverse processes of the underlying 4 vertebrae
Interspinalis - on either side of the midline connecting adjoining spinous processes
Spinalis - Lies on either side of the interspinalis and posterior to the transversospinalis
Longissimus - lies lateral to the spinalis in the posterior wall of the thorax and inserts into the lower 10 ribs
Iliocstalis - a thick mass forming part of the wall of the thorax
What is the lumbar muscles vital role?
Maintaining an upright posture
Maintains the lumbar lordosis
What are the two main anterior lateral muscles in the lumbar spine?
Quadratus lumborum - runs between the last rib, the iliac crest and the vertebral column
Psoas - originates from the transverse process and posterolateral aspect of the vertebral bodies from T12 to L5, its fibres run inferiorly and laterally to blend with the fibres of the iliacus muscle.
What is the inferior region of the spinal cord?
Conus medullaris and usually lies between the T12 and L1.
Where is the termination of the spinal cord proper?
The conus medullaris
At the point of the conus medullaris the spinal cord becomes a tapering band of tissues called?
Filum terminale
What is the name of the spinal nerve roots that emerge from around the filum terminale?
The cauda equina
How many pairs of lumbar spinal nerves are there?
5 pairs of sacral and 1 pair of coccygeal
What is each nerve a combination of?
Motor and sensory fibres
Where does the L4 nerve root exit?
L4/5 lateral foramen near the L4 pedicle.
What are nerve fibers collected together called?
Rami
What are groups of rami called?
Plexuses
What types of plexuses are there in the lumbar spine?
Lumbar plexus
Sacral plexus
What comprises the lumbar plexus?
The ventral rami of L1-L4 nerves
What comprises the sacral plexus?
Fibres from the ventral rami of the nerves at L4, L5 and S1-S3.
What comes off of the abdominal aorta?
Lumbar arteries which run beneath the psoas muscle adherent to the vertebral bodies.
What comes off of the lumbar arteries?
Posterior and abdominal brances
What comes off of the posterior artery?
The spinal artery
Which level does the abdominal aorta bifurcate?
L4
