Spinal Cord Morphology Flashcards
What are the spinal cord segments for the deep reflex motor dermatomes? Biceps brachii Brachialis Triceps brachii Muscles of hand Quadriceps femoris muscle Gastrocnemius muscle
C5-6 C6-7 C6-8 C8-T1 L2-4 L5-S2
What are the spinal cord segments for the superficial reflex motor dermatomes? Scapular Epigastric Abdominal Cremasteric Superficial anal
C5-T1 T7-9 T8-12 L1-2 S4-Co1
What singular artery is located deep in anteromedian sulcus and supplies most of the central gray matter and anteromedial portion of white matter of spinal cord?
Anterior spinal artery
Disruption of blood flow to what artery results in central cord syndrome, an ischemia of central region of spinal cord?
Anterior spinal artery
What course in the postero-lateral sulci of each side of the cord and supply about 75% of posterior columns? These along with radicular arteries supply peripheral margins of the cord
Posterior spinal arteries (2)
What artery usually arises from left inferior intercostal or superior lumbar arteries and contributes to anterior spinal artery? It is the major supply to inferior two-thirds of spinal cord
Anterior artery of Adamkiewicz
What artery may be compromised secondary to thoracolumbar fracture or surgical repair of abdominal aortic aneurysms (AAA)?
Anterior artery of Adamkiewicz
Where does ischemic necrosis of the spinal cord most frequently occur?
Adjacent to enlargements at C2-3, T1-4, L1
What is the net result of the gamma efferent pathway?
Alteration in muscle tone and reflexes and maintenance of accurate proprioceptive (position-sense) output from neuromuscular spindles
Describe the gamma efferent pathway
Supraspinal influences
Gamma efferent neuron (intrafusal fiber of NMS)
Ia efferent neuron
Interneuron alpha motor neuron
Motor end plate
Describe the location and function of the substatia gelatinosa (SG). Where does it send fibers to?
Location: posterolatearl tip of dorsal horn at all spinal levels
Function: pain/temperature pathway
Sends fibers to: Lateral spinothalamic tract (LSTT)
Describe location and function of nucleus proprius (NP). Where does it send fibers to?
Location: midportion of dorsal horn
Function: pain/temperature pathway
Sends fibers to: fasciculus proprius
Describe location and function of nucleus dorsalis (Clarke’s column). Where does it send fibers to?
Location: base of dorsal horn from C8-L2
Function: unconscious proprioceptive pathway
Sends fibers to: dorsal spinocerebellar tract
Describe location and function of visceral afferent nucleus. Where does it send fibers to?
Location: T1-L2 and S2-4
Function: visceral sensory integration relex center
Sends fibers t: intermediolateral gray, ventral horn, and hypothalamus via fasciculus proprius (RF)
Describe location and function of intermediate gray. Sends fibers to?
Location: between dorsal and ventral horns at all spinal levels
Function: sensorimotor integration center
Sends fibers to: ventral horn
Where is the phrenic nucleus located, and what does it innervate?
Location: C3-5, subdivision of medial motor cell column (MMCC)
Innervates respiratory diagphragm
Where is the intermediolateral nucleus located, and what does it innervate?
Lateral horn from T1-L3
Sends preganglionic sympathetic fibers to visceral structures
Where is the sacral autonomic nucleus located, and what does it innervate?
Lateral horn from S2-4
Sends preganglionic parasympathetic fibers to bowel and bladder
Summarize dorsal roots
Fibers in medial division enter posterior columns and convey proprioception, 2-pt tactile discrimination and vibratory information
Fibers in lateral division of dorsal root enter dorsolateral fasciculis of Lissaur and convey pain and temperature information
Summarize posterior columns
Descending (reflex fibers)
Short ascending fibers (component of VSTT)
Long ascending fibers (component of PC/ML; FG and FC)
Summarize fasciulus proprius
Spinoreticular fibers (slow/visceral pain fibers) Reticulospinal fibers (including MRST and LRST)
Summarize lateral spinothalamic tract
Pain and temperature info from opposite side of body
Unilateral lesion of LSTT results in contralateral loss of pain and temp two sensory dermatomal segments below lesion
Unilateral lesion of spinal lemniscus results in contralateral hemianalgesia and thermal hemianesthesia
Summarize dorsal spinocerebellar tract
Conveys unconscious precise proprioceptive information from inferior 1/2 of body and LE to cerebellum
Summarize ventral spinocerebellar tract
Conveys unconscious general proprioceptive information general nature from lumbosacral levels to cerebellum
Summarize ventral spinothalamic tract
Conveys light touch, pressure, and crude tactile information
Summarize spinoreticular fibers
Convey slow and visceral pain sensations to ascending reticular activating system (ARAS) as part of spino-reticulo-thalamic pathway
Summarize lateral corticospinal tract and rubrospinal tract
Lateral corticospinal tract: precise individual movements of digits, fractionation of movement
Rubrospinal tract: RST originates from red nucleus. In midbrain, it completely decussates and descends posterior to CST. In spinal cord, it courses anterior to LCST and terminates in intermediate gray at all levels. It is part of the cortico-rubro-spinal pathway, the major descending pathway to extrapyrmidal system
What are the spinal cord segments for the following sensory dermatomes? Shoulders Thumb Little finger, elbow Nipple Umbilicus Inguinal region Big toe Little toe Perianal region
C4 C6 T1 T4 T10 L1 L5 S1 S5
What does the lateral reticulospinal tract (LRST) do?
Originates in medullary reticular nuclei.
Fibers bilaterally descend adjacent in fasciculus proprius of anterolatearl funiculus and terminate in IG at all levels
Considered the principal descending pathway for autonomic reponses
What does the anterior corticospinal tract do?
Terminates in LMN pools in cervical segments
What does the medial vestibulospinal tract do?
Directly influences alpha motor neurons to extensor neck muscles
What does the medial reticulospinal tract do?
Originates in the medial pontine reticular nuclei and descends in ipsilateral anterior funiculus
Terminates in IG at all levels and influences gamma efferent loops
