Back and Vertebral Flashcards
Vertebral arch
is firmly anchored to the posterior surface of the vertebral body by two pedicles, or lateral pillars of the arch. The roof of the arch is formed by the right and left laminae, which fuse at the midline. The vertebral arches are aligned to form lateral and posterior wall of the vertebral canal, extending from C1 to S5. This bony canal contains the spinal cord and its protective membranes, together with proximal portions of spinal nerves, vasculature, connective tissue, and fat. The vertebral arch has a number of characteristic projections which serve as: attachments for muscles and ligaments, levers for the actions of muscles, and sites of articulation with adjacent vertebrae.
Two types of spina bifida
Occulta,
more severe spina bifida involves complete failure of fusion of the posterior arch at he lumbosacral junction with a large out pouching of the meninges. This may contain CSF = meningocele; or a portion of the spinal cord = myelomeningocele. These abnormalities may result in a variety of neurological defects including problems ambulating (walking) and or bladder function
Occulta
(most common type (10% of population) where there is a defect in the arch of L5 or S1. Often asymptomatic although often a tuft of hair is observed over the spinous process.
lumbrosacral myelomeningocele
This is a T1-weighted MRI in the sagittal plane demonstrating a lumbrosacral myelomeningocele. There is an absence of the laminae and spinous processes in the lumbosacral region. You can also see the continuity of the spinal cord into the outgrowth and evidence of the meninges encompassing the cord.
Spinal nerves exit
the intervertebral foramen inferior to the vertebrae of the corresponding spinal level for which the nerve is named, EXCEPT: C1-C7 which exit the interverebral foramen superior to the vertebrae level
Vasculature of vertebral column
vertebrae are supplied by periosteal and equatorial branches of major cervical and segmented arteries and their spinal branches.
Spinal branches are of the:
vertebral and ascending cervical arteries in the neck
posterior intercostal arteries in the thoracic region
subcostal and lumbar arteries in the abdomen
Iliolumbar and lateral and medial sacral arteries in the pelvis
Spinal branches enter the IV foramen and divide into anterior and posterior vertebral canal branches
vertebrae are drained by anterior external vertebral plexus, anterior internal vertebral plexus, basivertebral veins that drain to the intervertebral vein to the posterior intercostal vein (in this example) and the accessory hemiazygos vein (in this example) Note that the extra dural venous plexus of veins also anastomoses here. Epidural plexus (both anterior and posterior) = Batson’s plexus. All these drain to the IVC ultimately in the lumbosacral regions.
Innervation of the vertebral column:
the zygapophysial joints are innervated by articular branches of the medial branches of the posterior rami
The vertebral column is innervated by the (recurrent) meningeal branches of the spinal nerves.
those inside supply the periosteum, ligamentum flava, annuli fibrosi posteriorly, posterior longitudinal ligament, spinal dura mater, and blood vessels within the vertebral canal.
Most meningeal branches run back through the IV foramen, some remain outside and supply the annuli fibrosi and anterior longitudinal ligament.
Vasculature of spinal cord:
3Longitudinally oriented vessels (anterior spinal a.) & feeder aa that enter the vertebral canal through the intervertebral foramina = segmental aa.
Anterior spinal artery arises from the vertebra a. – off the subclavian a. – and descends on the anterior surface of the spinal cord.
The anterior spinal artery also anastomoses with the segmental medullary arteries branching off the posterior intercostal aa.
Also have the anterior and posterior radicular aa from the posterior intercostal aa anastomosing with the posterior spinal a. which originate in the cranial cavity from the terminal branch of the each vertebral a = PICA
Venous drainage:
Veins from a number of longitudinal channels. 2 pairs on each side bracket the connections of the posterior and anterior roots to the cord. These drain into the extensive internal vertebral plexus within the extradural fat in the epidural space of the vertebral canal. These then drain into segmentally arranged vessels that connect with major systemic veins such as the azygos system in the thorax. The internal vertebral plexus also communicates with intracranial veins.
Back Musculature
- 3 groups
Superficial, intermediate, deep.
Superficial
anchor UL to axial skeleton
intermediate
Intermediate – assist in respiration
Deep
Deep – maintain posture; act on vertebral column (raise & lower spine)
Superficial Back Musculature
Trapezius m. Latissimus dorsi m. Rhomboid major m. Rhomboid minor m. Levator scapulae m.
The superficial muscles are immediately deep to the skin and superficial fascia. They attach the superior part of the appendicular skeleton (clavicle, scapula and humerus) to the axial skeleton (skull, ribs & vertebrae).
Because they function to move the appendicular skeleton (upper portion, UL) they may also be referred to as the appendicular group
Trapezius m
upper fibers elevate, middle fibers adduct and lower fibers depress scapula, and assists in rotating the scapula during abduction of the humerus above horizontal.
motor: CN XI proprioception: C3, C4
Accessory n. (CNXI):
runs deep to m., posteroinferiorly from jugular foramen
Ventral rami of C3-C4:
runs deep to m., posteriorly from intervertebral foramina
Transverse cervical a. & v.:
runs deep to m., posterolaterally from thyrocervical trunk
Proprioception = ability to sense position, location, orientation and movement of the body and/or parts of the body.
Nerves and vessels contributing to the subtrapezial plexus.
CN XI & C3-C4 ventral rami for subtrapezial plexus
CN XI: motor to trapezius & SCM
C3-C4 ventral rami: proprioception
Accessory nerve on deep surface of the trapezius m
Note: C3-C4 ventral rami (cut) at the medial edge that contribute to the plexus
Transverse cervical a. & v. = runs deep to the trapezius m., posterolaterally from the thyrocervical trunk
Transverse cervical a. gives rise to the superficial cervical a., deep to the trapezius m but superficial to the scapula
Splenius capitus & cervicis (spinotransversales mm.)
Cervical
Capitis: Bilaterally - draw head backward and extend neck; individually – rotate head/face ipsilaterally
Cervicis: Bilaterally - extend neck; individually – rotate head/face ipsilaterally
N: Posterior rami of the middle and lower cervical nn.
Greater Occipital N
C2 passes through the semispinalis capitis m. (easily found during superficial dissections, see Grant’s Dissector for more details)
If you can find the Greater Occipital n. (C2) superficially with the Occipital a. it will be easier to trace it deeper. However, you may not be able to see it well until you get the semispinalis capitis m.
Occipital a. & v
in sub-Q tissue
Just lat. to greater occipital n.
Vertebral artery
Passes through transverse foramen. Postganglionic Sympathetic nerves travel with this.
Sympathetic nerves
Travel with all blood vessels.
Ganglia in head
In superior/middle/inferior cervical.
