Glossary of Back Anatomy

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Vertebra Column
1) cervical = 7
2) thoracic = 12
3) lumbar = 5
4) sacral = 5 fused
5) coccygeal = 4 fused
primary curvatures
- present in fetus
- 1) thoracic
- 2) sacral
- concave anteriorly
secondary curvature
- appear when baby holds up head and sits upright
- 1) cervical
- 2) lumbar
- convex anteriorly
vertebrae basics
1) body
2) vertebral arch: pr of pedicles, pr of laminae
3)processes: 1 spinous, 4 articular (zygapophyseal or facet between vertebrae)
4) intervertebral and vertebral foarmen
intervertebral foramen
- spinal nerve and radicular blood vessels
- bound by pedicles of inferior and superior vertebrae
vertebral foramen
- vertebral arch and body of vertebae
- foramina and canal:
1) spinal cord
2) roots of spinal nerves
3)anterior and posterior spinal blood vessels
Cervical Vertebrae
- foramen transversarioum in transverse process: vertebral artery and vein through the c1-6
- bifid spines (not C7)
vertebra prominens
- C7
- palpable non-bifid spine
- C1
- no spine or body, but A & P arches and lateral masses
- posterior arch: groove for vertebral artery
- C2
- dens (odontoid process)
atlanto-occipital joint
- nodding (flexion - extension)
atlanto-axial joint
- rotation
"first yes then no"
Atlas first then Axis
- T2-T9 have 2 demifacets to articulate with the head of rib, and 1 costal facet for tubercle of the neck of the rib
- long pointed spinous processes, point inferiorlu and overlap
- largest bodies
- straight, heavy spinous processes
- mammillary process on tansverse process
- larger intervertebral discs
- articular processes large and oriented in saggital plane
- 5 fused sacral vertebrae
- A & P sacral foramina for passage of A&P primary rami of spinal nerves
- sacral promontory: upper end of the body of 1st sacral vertebra
- sacral hiatus: caudal opening of vertebral canal
- epdidural anesthesia done here
- 3-4 fused coccygeal vertebrae
intervertebral disc
- symphysis type of joint
- nucleus pulposus
- annulus fibrosus
nucleus pulposus
- gelatinous with 70-80% water
- remnant of notochord
- replaced with fibrous tissue with age
annulus fibrosus
- outer portion of intervertebral disc
- surrounds and supports pulposus
- supported by A&P longitudinal ligaments
Disc herniation
- nucleus pulposus herniates through ruptured annulus fibrosus
- posteriolateral aspect of disc (no A&P support there)
- L4-L5 disc, L5 impingement --> sciatica
- C3-C4 C4 is compressed
- C7-T1 8th cervical spinal nerve
Ligaments of vertebral column
1. Anterior Longitudinal Ligament - over anterior surface of vertebral bodies; from
axis to sacrum
- limits extension (hyperextension) of vertebral column and supports annulus
fibrosus (IV disc) anteriorly
- becomes atlanto-occipital ligament
2. Posterior Longitudinal Ligament - over posterior surface of vertebral bodies,
extending from axis to sacrum
- resists flexion of vertebral column
- supports IV disc properly
- becomes tectorial membrane
3. Supraspinous Ligament - attaches along tips of spinous processes and is
continuous with the ligamentum nuchae in the cervical region
4. Interspinous Ligament - between adjacent spinous processes and fuse with
supraspinous ligament
5. Ligamentum Flavum (yellow elastic tissue) - extends from lamina above to lamina
below. Helps to maintain upright posture. The posterior arches of C1 and C2
are also connected to the posterior border of the foramen magnum by posterior atlanto-axial and atlanto-occipital ligaments, the continuation of the ligamentum FLAVUM.
6. Intertransverse Ligaments - between adjacent transverse processes
7. Ligamentum Nuchae
- continuous with supraspinous ligament
- extends from CV7 to the skull
Joints of Vertebral Columnae
1. Atlantooccipital (flexion-extension or nodding and lateral bending of head)
2. Atlantoaxial (rotation of head)
3. Intervertebral discs (symphysis) between bodies - small amount of movement
between any two vertebrae
4. Joints between vertebral arches
- abnormal lateral curvature of the spine (lateral bending of vertebral column);
usually in the thoracic region
- can be associated with a congenital hemivertebra (absence of lateral half of
vertebra) -- referred to us secondary structural scoliosis
- can also be acquired from persistent severe sciatica (temporary bending due
to severe pain) --- called sciatic scoliosis
- compensatory scoliosis may be caused by a shortened lower limb
- abnormal exaggeration of the thoracic curvature
- senile kyphosis (round shoulders) can be due to degeneration of the
intervertebral disc
- an abnormal exaggerated lumbar curvature
- present in congenital double dislocation of the hip (support of pelvis
posterior to acetabulum)
- can be acquired from i ncreased weight of abnormal contents (obesity, pregnancy)
- it is usually a compensatory curve
Spina Bifida
- Failure of fusion of vertebral arch
1) Spina Bifida Occulta
- simply bony defect
- common in sacra and lumbar (may or may not be symptoms)
- L5 or S1, tuft of hair
2) Spina bifida cystica
- severe neural tube defect
- meningocele: herniation of meninges
- meningomyelocele: protrusion of meninges and spinal cord
O: external occipital protuberance, superior nuchal line,
ligamentum nuchae and spines of C1 - T12
I: acromion, scapular spine and lateral third of clavicle
INN: spinal accessory 11th cranial (motor) and C3, - C4 (sensory
BS: superficial branch of transverse cervical artery (br. of thyrocervical)
AC: elevates or shrugs (upper fibers), retracts (middle fibers), depresses
(lower fibers) and rotates the inferior angle of the scapula laterally.
Upper and Lower fibers - working with serratus rotate glenoid cavity
thus allowing abduction of the arm between 90 and 180 degrees.
Latissimus Dorsi
O: spinous processes of lower 6 thoracic vertebrae; those of all lumbar and
upper sacral vertebrae; iliac crest and lower 3 ribs.
I: floor of intertubercular (bicipital) groove of humerus
INN: thoracodorsal nerve (C6, C7, C8) from posterior cord of brachial plexus
BS: thoracodorsal artery (branch of subscapular)
AC: extends, adducts and medially rotates arm (e.g. chopping wood and doing the
crawl while swimming)
Rhomboid Major
O: spinous processes of T2 - T5
I: vertebral (medial) border of scapula
INN: dorsal scapular nerve ( C5)
BS: deep branch of transverse cervical
AC: adducts or retracts and medially rotates the inferior angle of the scapula
Rhomboid Minor
I: vertebral (medial) border of scapula
INN: dorsal scapular nerve ( C5)
BS: deep branch of transverse cervical
AC: adducts or retracts and medially rotates the inferior angle of the scapula
Levator Scapulae
O: transverse processes of upper four cervical vertebrae
I: upper medial border and superior angle of scapula
IN: C3, C4 and dorsal scapular nerve
BS: deep branch of transverse cervical
AC: elevates scapula
Triangle of Auscultation
1) trapezius
2) latissiumus dorsi
3) rhomboid major (medial scapula)
- enlarges within 6th intercostal space, when arms folded across chest and flexing chest with scapula drawn anteriorly
- respiratory sounds from inferior lobes of lungs
Lumbar Triangle
1) latissimus dorsi
2) external abdominal oblique
3) iliac crest

- site of lumbar hernia and infection
Serratus Posterior Superior
- deep to rhomboids
O: spinous processes of C7 to T3
I: 2nd to 5th ribs
IN: ventral rami of T1 - T4
AC: elevates ribs 2 to 5 (respiratory function).
Thereby increasing chest size
Serratus Posterior Inferior
- deep to latissimus dorsi
O: spinous processes of T11 to L3
I: 9th to 12 ribs
IN: ventral rami of T9 to T12
AC: depresses ribs 9 to 12 and draws them backwards (respiratory function)
- the bandage
- splenius capitis (inserts on skull)
- splenius cervicis (inserts on upper cervical transverse processes)
- innervated by dorsal rami of C4 to C8
- unilateral contraction rotates head so that the face is turned to the same side as the contracting muscle
- bilateral contraction extends neck and head
Erector Spinae
- divided into three columns from lateral to medial: iliocostalis,
longissimus and spinalis (I Love Sex)
- extends from sacrum and iliac crest to neck and skull
- Extends (acting bilaterally), laterally flexes to same side (acting
unilaterally) and rotates vertebral column
- primarily extensors of the vertebral column
Semispinalis Capitis
- powerful vertical muscle located deep to splenius and superficial to the
suboccipital triangle
O: transverse processes of C7 - T6
I: occipital bone (between nuchal lines)
IN: dorsal rami of cervical spinal nerves
AC: (bilateral contraction) extends head
- these are rotators and extensors of the vertebral column
- bilateral contraction extends vertebral column and unilateral
contraction rotates it to the opposite side (lateral flexion of spinal
- semispinalis capitis is a very powerful extensor of the head when
contracted bilaterally.
- semispinalis cervicis, extending from transverse processes to spines,
bilaterally extends and unilaterally turns body to opposite side.
Transversospinalis also regulate or prevent FLEXION of vertebral
Suboccipital Region
- a triangular area between the skull and upper end of vertebral
column. Contains 2 joints - atlanto - occipital and atlanto-axial
Sub-occipital muscles (4 in number) extend head and acting
unilaterally rotate Head to same side
Rectus Capitis. Post. Major - spine of 2nd cervical to lateral ½ of INF.
Rectus Capitis-Post-Minor - spine of 1st cervical to medial ½ of INF.
OBL. Capitis INFERIOR - Spine of C2 to transverse process of C1
OBL. Capitis SUPERIOR - transverse process of C1 to occipital bone just
INNERVATION - 1st cervical nerve (suboccipital)
Paravertebral Muscles
1. Rectus Capitis Anterior
2. Rectus Capitis Lateralis
3. Longus Colli
4. Longus Capitis
Spinal cord
- extends to L1/L2 (L3 in the newborn)
- ends at conus medullaris
- pia mater extends to filum terminale
- cervical and lumbar enlargements due to limb nerve supplies
- 31 segements --> nerves
Spinal nerves
- 31 pairs
Cervical: 8
Thoracic: 12
Lumbar: 5
Sacral: 5
Coccygeal: 1
- made up of dorsal and ventral rootlets from segment
- located in intervertebral foramen
- C1 nerve purely motor in
Dorsal Root
- sensory fibers with cell bodies in DRG
Ventral root
- motor fibers
- cell bodies in ventral and lateral horns of gray matter
dorsal primary ramus
- both skeletal motor and sensory fibers and autonomic fibers
- skin and deep muscles of back
ventral primary ramus
- both skeletal motor and sensory fibers and autonomic fibers
- cervical plexus (C1-C4)
brachial plexus (C5-T1)
lumbar plexus (T12-L4)
sacral plexus (L4-S4)
1st coccygeal
1st Cervical nerve
in 50% purely motor
where do cervical spinal nerves emerge?
- C1-C7 over its own vertebra
- only c8 comes below CV7
where do thoracic, lumbar, sacral and coccygeal nerves emerge from?
- below their respective vertebra
Anterior Spinal artery
branch of vertebral
posterior Spinal artery
- 2
- branches of vertebral or cerebellar arteries
radicular arteries
- reinforce spinal arteries
- from spinal branches of cervical, intercostal, lumbar and lateral sacral arteries
Dura Mater
- continuous with cranial dura, dural sac ends at S2
- forms filum of dura mater (coccygeal ligament) at S2
epidural space
- between dura and vertebral canal
- internal vertebral venous plexus (drained by spinal veins)
vertebral venous plexus
- veins are valveless (important for metastases of tumor cells or viruses)
- connections to caval and azygous systems, sinuses in cranial cavities
- subdural space between arachnoid and dural layer
- subarachnoid space over pia, ends at s2
- denticulate ligaments are lateral extensions in 21 prs that
- extends from conus medullaris to dural sac as filum terminale
Lumbar Puncture
- best down between L3 and L4 (iliac crest level at L4 spine serves as guide to
- needles is passed through interlaminar space in the midline, as the spinal
column is flexed
- layers transversed:
skin, superficial fascia, deep fascia, supraspinous ligament, interspinous
ligament, interlaminar space, epidural space, dura, arachnoid and
subarachnoid space (ligamentum flavum is not pierced because the needle
passes through the midline

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