Superficial Back and Spinal Cord Flashcards
What is the function of the neural arch?
To protect the spinal cord on its posterior aspect
Which components of the vertebrae form the neural arch?
The pedicle and the lamina
How many vertebral regions are there in the vertebral column?
How many vertebrae are in each region?
Five- Cervical (7) Thoracic (12) Lumbar (5) Sacral (5) Coccygeal (4)
List the 4 curvatures of the vertebral column.
Which of these curvatures are primary and which are secondary?
What is the specific function of each secondary curvature?
Cervical 2* , Thoracic 1* , Lumbar 2, Sacrococcygeal 1
Cervical- allow infant to hold head up
Lumbar- allow child to throw weight back on lower limbs and walk
What are the 3 muscle groups of the back?
Which of these 3 groups contain muscles extrinsic to this region?
What is the function of the superficial group of extrinsic groups?
Superficial and Intermediate contain extrinsic muscles. Superficial functions in limb movement connect upper limb to trunk, intermediate in respiration
Deep
trapezius origin and attachment?
- The descending part originates from the occipital bone and the spinous processes of C1 to C7 and inserts onto the lateral third of the clavicle.
- The transverse part originates from the aponeuroses at the spinous processes of T1 to T4 and inserts onto the acromion.
- The ascending part originates from the spinous processes of T5 to T12 and inserts onto the scapular spine.
trapezius actions
- The descending part- draw the scapula obliquely upward, to rotate the glenoid cavity superiorly, to tilt the head to the same side, and to rotate the head to the opposite side.
- The transverse part- acts to draw the scapula medially (adducts it).
- The ascending part- acts to draw the scapula medially downward.
Together, all parts of the muscle act to steady the scapula on the thorax.
Latissimus Dorsi Attachments
- The vertebral part originates from the spinous processes of T7 to T12 and the thoracolumbar fascia and inserts onto the crest of the of the lesser tuberosity of the humerus.
- The scapular part originates from the inferior angle of the scapula and inserts onto the crest of the lesser tuberosity of the humerus.
- The costal part originates from ribs 9 to 12 and inserts onto the crest of the lesser tuberosity of the humerus.
- The iliac part originates from the posterior third of the iliac crest and inserts onto the crest of the of the lesser tuberosity of the humerus.
Latissimus Dorsi Actions
Together, all parts of the latissimus dorsi act to internally rotate, adduct, and extend the upper limb. It can also act as an accessory muscle of respiration – the “cough” muscle
Levator Scapulae Attachments
The levator scapulae originates from the transverse processes of C1 to C4 and inserts onto the superior angle of the scapula.
Levator Scapulae Actions
The levator scapulae acts to draw the scapula medially upward while moving the inferior angle of the scapula medially and to incline the neck to the same side.
Rhomboid Minor Attachments
The rhomboid minor originates from the spinous processes of C6 and C7 and inserts onto the medial border of the scapula above the scapular spine.
Rhomboid Major Attachments
The rhomboid major originates from the spinous processes of T1 to T4 and inserts onto the medial border of the scapula below the scapular spine.
Rhomboid Actions
Together, the rhomboid major and the rhomboid minor act to steady the scapula, retract the scapula, as well as to draw it medially upward.
How is the superficial group of extrinsic muscles arranged?
List the muscles in each layer, their function and innervation.
Superficial- trapezius (CN XI, C3c4), lattisimus dorsi (thoracodorsal n)
Deep- levator scapulae, rhomboid minor, rhomboid major (dorsal scapular and C3 C4 n)
List the enlargements of the spinal cord.
Why do these enlargements exist?
What is the specific function of each enlargement?
Cervical Enlargement innervates upper limb via brachial plexus
Lumbar Enlargement innervates lower limb via lumbosacral plexus
They contain increased neuron cell bodies responsible for movement and sensation of the limbs
Define conus medullaris
The terminal point of the spinal cord
Define filum terminale
An extension of pia mater off of the spinal cord that passes through the coccyx
Define cauda equina
All of the spinal nerves that exit the spinal canal below the spinal cord at L2
At which level does the spinal cord terminate?
L2
Where is a lumbar puncture performed and why?
Below L2, preferably around L4/L5. This location is below the termination of the spinal cord. The spinal nerves here are floating in cerebrospinal fluid so it is difficult for the needle to penetrate the nerve, it bounces off the cauda equina instead.
Why are there 8 cervical spinal nn. but only 7 cervical vertebrae?
From C1 to C7 the spinal neves exit above the corresponding vertebrae. T1 and lower the spinal nerves exit below the vertebrae. This leaves an open intervertebral foramen, above T1, for spinal nerve C8 to exit.
List the three meninges that wrap the spinal cord, in order from superficial to deep.
Dura mater
Arachnoid
Pia Mater
What fills the subarachnoid space?
What is the function of this space?
Cerebrospinal fluid. It causes a fluid buffer and shock absorber for the delicate parts of the spinal cord.
Where is the epi (extra) dural space and what is found within it?
Space between the dural sac and the inner bony boundaries. It contains epidural fat and an extensive venous plexus.
What is the denticulate ligament?
A toothlike extension of the pia mater taking to the dural sac. It laterally stabilizes the spinal cord.
How do ventral/dorsal roots differ from ventral/dorsal rootlets?
Rootlets arise from the cord - extending along the thickness of the cord segment. These rootlets merge to form a single dorsal and ventral root for each cord segment.
How do ventral/dorsal roots differ from ventral/dorsal rami?
The dorsal and ventral roots merge to form the true spinal nerve that exits the intervertebral foramen. It then branches into two parts, the ventral (innervate anterolateral body wall) and dorsal (innervate back) rami
Be familiar with the sulci of the cord as well as its vascular supply.
The posterior aspect has 2 arteries, one over each of the posterior intermediate sulci. The anterior aspect has a single artery applied to its surface.
What does the dorsal ramus innervate?
The muscles and blood vessels of the back
What does the ventral ramus innervate?
The muscles and blood vessels of the anterolateral aspects of the body wall.
Which specific branches off the dorsal/ventral rami are responsible for distributing the
cutaneous innervation?
The lateral and anterior cutaneous branches from the ventral ramus, coupled with the branches of the dorsal rami, innervate a band of skin/muscles and blood vessels of the body wall (a dermatome)
What vertebral levels exhibit “typical” (segmental) spinal nerve
T2-T11/12
How would you define a “typical spinal nerve”?
A spinal nerve whose ventral rami do not merge into a plexus. They remain separate and innervate a specific body dermatome. The dorsal rami always remain separate.
What is a dermatome?
A band of skin on the body wall innervated by the dorsal and ventral ramus of a specific spinal cord level.
For complete cutaneous sensory loss, how many spinal nerves would have to be lesioned and why?
3, because there is some overlap from each spinal nerve into the dermatome above and below it.
What types of fibers (modality) are found in the dorsal/ventral roots?
Dorsal root- sensory
ventral root- motor and preganglionic sympathetic
Where is the first point where a nerve becomes “mixed”?
At the union of the dorsal and ventral roots, the formation of the true spinal nerve.
How does the structural organization between the motor/sensory and ANS differ?
motor and sensory tracts utilize a single neuron to link the CNS with the effector organ in the PNS. The ANS utilizes 2 neurons to link these structures.
What does the PNS contain to facilitate this difference?
the PNS contains ANS ganglia as the site of synapse between two neurons involved in linking the CNS with the effector organ in the PNS: the pre- and post- ganglionic neurons.
Axial skeleton parts
Hyoid, skull, rib cage, vertebral column
Define intervertebral foramen
The place where superior and inferior vertebral notches come together, where spinal cord nerves exit
Demifacet
Site of articulation with ribs, also called articulate facets
