Cord Flashcards
What is the average length of the spinal cord?
Ends where in the adult?
45 in males
42 cm in females
Between L1 and L2
What is the junction zone between two types of tissues (glial support and Schwann cells) at the point where the dorsal nerve enters the spinal cord?
Oberseteiner- Redlich space
How does the spinal cord segment correspond with the tip of the vertebral spine?
Cervical Minus 1
Upper Thoracic Minus 2
Lower thoracic and upper lumbar Minus 3 (Eg Spine 10 = L1 cord segment)
What spinal nerves are derived from the conus medullaris?
S4 S5 and 1 coccygeal nerve
Identify the dermatome
- Back of the head
- Shoulder
- Thumb
- Middle finger
- Small finger
- Inguinal region
- Umbilicus
- Nipple
- Big toe
- Small toe
- Genitalia
- Back of the head C2
- Shoulder C4
- Thumb C6
- Middle finger C7
- Small finger C8
- Inguinal region L1
- Umbilicus T10
- Nipple T4-5
- Big toe L5
- Small toe S1
- Genitalia S4-5
In the spinal cord where is
- CSF
- Bridging veins
- Blood vessels that supply and drain the cord
- Adipose tissue and venous plexus
- CSF: Subarachnoid space
- Bridging veins: Subdural space
- Blood vessels that supply and drain the cord: Epipia mater (VS intima pia closely adherent to cord)
- Adipose tissue and venous plexus: Epidural
Identify the myotome
- Deltoid
- Bicep
- Tricep
- Hypothenar muscles
- Quads
- Extensor hallucis
- Gastrocnemius
- Rectal sphincter
- Deltoid C5
- Bicep C6
- Tricep C7
- Hypothenar muscles T1
- Quads L4
- Extensor hallucis L5
- Gastrocnemius S1
- Rectal sphincter S3-4
What side of the cord is bigger in 75% of asymmetries?
What percentage of human have asymmetric cords?
Right
75% as well!
The cuneate tract is only present above what level?
T6
The intermediolateral cell column and nucleus dorsalis of clarke extends between?
C8 to L2
Which Rexed Laminae:
- For Exteroceptive sensation
- For Proprioreception
- Main motor area
- Intermediolateral horn
- For Exteroceptive sensation 1-4
- For Proprioreception 5-6
- Main motor area 9
- IML: 7
Remember that substantia gelatinos is laminae 2 while nucleus proprius is laminae 3-4
For segments S1 to S4 what what supplementary column is present?
Onuf (Onufrowicz) nucleus
What rexed laminae are renshaw cells seen in?
What NT do they release?
9
Glycine
Why are 15% of fibers in the posterior funiculus not primary afferents?
These fibers have synapsed in the Rexed 3-5: Nucleus proprius and neck of posterior horn– they are activated by both nociceptors and mechanoreceptors unlike the 85% that are activated by mechanoreceptors alone
T or F: Lesions in the posterior funiculus decrease the threshold to painful stimuli and augment all sensation conveyed by the anterior ST pathway.
T
Some with damage in the posterior column do not lose their conscious proprioreception. Why?
The spinocervical thalamic (Morin’s) tract compensates– located in the lateral funiculus
What part of the cord is only seen from C8 to L2– resulting in doral spinocerebellar fibers only being present above L2?
Nuucleus Dorsalis of Clark
What kind of sensation is conveyed by the dorsal and ventral spinocerebellar tracts?
Unconscious proprioreception
What are the three main types of dorsal column system functions?
- Passively impressed (vibration, 2 point discrimination, touch)
- Temporal or sequential (Directional line draw)
- Actively explored or manipulated (Shapes and patterns)
In cordotomy for pain where is the cord cut in relation to the denticulate ligament?
Anterior to the ligament. Posterior carries THERMAL SENSATION
What fibers flow through the anterior spinothalamic tract?
Light touch
What laminae to lateral spinothalamic fibers synapse on?
1-3
Posteriomarginal nucleus
Substantia gelatinosa
Nucleus proprius
What parts of the corticospinal tract are uncrossed?
Bundle of Turck (Anterior corticospinal tract) 8% initially but some of them cross on the way down leaving 2-5% uncrossed fibers the BUNDLE/tract OF BARNES
What motor neurons are innervated by the 1. rubrospinal tract from the midbrain 2. vestibulospinal tract from the pons 3. pontine reticulospinal tracts 4 medullary reticulospinal tracts
- rubrospinal tract: flexor
- vestibulospinal tract: extensor
- pontine reticulospinal tracts: extensor
4 medullary reticulospinal tracts: flexor
The descending sympathetic pathway goes down to what level?
T1
What is the NT of primary nociceptive and non nociceptive pain?
What is the primary NT in visceral afferentes?
What NT inhibits the nociceptive activity in the dorsal horn?
Substance P
Vasoactive intestinal peptide
Norepinephrine
What nerves supply the efferent innervation of the urinary bladder?
What innervates the
Internal urethral sphincter
Detrusor muscle
External sphincter
Sympathetic by the hypogastric n.
Parasympathetic by the pelvic n.
Somatic by the pudendal n. from the Onuf’s nucleus
Same 3 in the same order
What does the Barrington nucleus , M region do during micturition?
BN is also the pontine micturation center!
Inhibits the onuf’s nucleus and excites the sacral PS system resulting in micturition. If damaged there is URINARY RETENTION
What supratentorial areas are responsible for voiding?
- Hypothalamus
- Right inferior frontal region
- Right anterior cingulate gyrus
Identify which arteries supply
- C1 to T2
- T3 to L1
- L1 and below
- C1 to T2: Subclavian artery via veretbral, ascending cervical, inferior thyroid, deep cervical, superior intercostal
- T3 to L1: aorta via the Intercosta and lumbar a.
- L1 and below: internal iliac via the Iliolumbar and lateral sacral
What segment of the cord is most vulnerable?
T1 to T4 and L1
What sensations are disrupted in a lesions involving the anterior commissure only?
How about with involvement of the dorsal root only?
Pain and temperature only in the dermatomes involved on BOTH sides
Similar to above but only involves one side. Only the dermatome involved
In combined system degeneration what systems are involved?
Posterior column and lateral column tracts
Vit B12 deficiency
Friedreich’s ataxia spinocerebellar tracts are involved bilaterally
