scholarly journals Neural canal ridges: A novel osteological correlate of post-cranial neurology in dinosaurs

2019 ◽  
Author(s):  
Jessie Atterholt ◽  
Mathew J Wedel
Keyword(s):  
Spinal Cord ◽  
Nervous System ◽  
Peripheral Nervous System ◽  
Dura Mater ◽  
Vertebral Column ◽  
Ligamentum Flavum ◽  
Lateral Flexion ◽  
Caudal Vertebrae ◽  
Neural Canal ◽  
Dorsal Spinal

Bony ridges occur on the walls of the neural canal in caudal vertebrae of numerous sauropod dinosaurs. These neural canal ridges (NCRs) are anteroposteriorly elongated but do not extend to the ends of the canal. To date, we have observed NCRs in caudal vertebrae of Alamosaurus, Apatosaurus, Astrophocaudia,Brontomerus, Camarasaurus, and Diplodocus. Numerous similar structures occur in extant vertebrates: (1) Neurocentral joints are ventral to NCRs in sauropod caudal vertebrae, and NCRs occur in unfused juvenile arches. Hypothesis rejected. (2) Attachment scars from ligamentum flavum occur at the ends of the dorsal roof of the canal, not the midpoint of the lateral edges, and this mammalian ligament was probably absent in dinosaurs. Hypothesis rejected. (3) Smooth ridges separate the spinal cord from the dorsal spinal vein and paramedullary airways in some crocodilians and birds, respectively. However, these septa persist to the ends of the canal, giving it an 8-shape, unlike the discrete NCRs of dinosaurs. Hypothesis rejected. (4) Bony attachments for denticulate ligaments occur in some non-mammalian vertebrates. The dura mater around the spinal cord fuses to the periosteum of the neural canal in non-mammals, so the denticulate ligaments that support the spinal cord can leave ossified attachment scars. These spinal cord supports have been identified in teleosts, salamanders, and a juvenile lizard, and they are the best match for the morphology of the NCRs in sauropod vertebrae. Functions of NCRs remain obscure. Denticulate ligaments are largest in regions of the vertebral column that experience strong lateral flexion. The hypothesis that NCRs supported the spinal cord of sauropods during lateral tail-whipping is attractive, but inconsistent with our recent discovery of NCRs in a hadrosaur caudal. NCRs are a new osteological correlate of the peripheral nervous system in dinosaurs, and highlight the need for more study in this area.

scholarly journals Neural canal ridges: A novel osteological correlate of post-cranial neurology in dinosaurs

2019 ◽  
Author(s):  
Jessie Atterholt ◽  
Mathew J Wedel
Keyword(s):  
Spinal Cord ◽  
Nervous System ◽  
Peripheral Nervous System ◽  
Dura Mater ◽  
Vertebral Column ◽  
Ligamentum Flavum ◽  
Lateral Flexion ◽  
Caudal Vertebrae ◽  
Neural Canal ◽  
Dorsal Spinal

Bony ridges occur on the walls of the neural canal in caudal vertebrae of numerous sauropod dinosaurs. These neural canal ridges (NCRs) are anteroposteriorly elongated but do not extend to the ends of the canal. To date, we have observed NCRs in caudal vertebrae of Alamosaurus, Apatosaurus, Astrophocaudia,Brontomerus, Camarasaurus, and Diplodocus. Numerous similar structures occur in extant vertebrates: (1) Neurocentral joints are ventral to NCRs in sauropod caudal vertebrae, and NCRs occur in unfused juvenile arches. Hypothesis rejected. (2) Attachment scars from ligamentum flavum occur at the ends of the dorsal roof of the canal, not the midpoint of the lateral edges, and this mammalian ligament was probably absent in dinosaurs. Hypothesis rejected. (3) Smooth ridges separate the spinal cord from the dorsal spinal vein and paramedullary airways in some crocodilians and birds, respectively. However, these septa persist to the ends of the canal, giving it an 8-shape, unlike the discrete NCRs of dinosaurs. Hypothesis rejected. (4) Bony attachments for denticulate ligaments occur in some non-mammalian vertebrates. The dura mater around the spinal cord fuses to the periosteum of the neural canal in non-mammals, so the denticulate ligaments that support the spinal cord can leave ossified attachment scars. These spinal cord supports have been identified in teleosts, salamanders, and a juvenile lizard, and they are the best match for the morphology of the NCRs in sauropod vertebrae. Functions of NCRs remain obscure. Denticulate ligaments are largest in regions of the vertebral column that experience strong lateral flexion. The hypothesis that NCRs supported the spinal cord of sauropods during lateral tail-whipping is attractive, but inconsistent with our recent discovery of NCRs in a hadrosaur caudal. NCRs are a new osteological correlate of the peripheral nervous system in dinosaurs, and highlight the need for more study in this area.

Dorsal spinal cord herniation at the thoracolumbar junction presenting with scalloping of ossification of the ligamentum flavum: case report

2020 ◽  
Vol 32 (1) ◽  
pp. 56-60
Author(s):  
Takahiro Makino ◽  
Shota Takenaka ◽  
Gensuke Okamura ◽  
Yusuke Sakai ◽  
Hideki Yoshikawa ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Dura Mater ◽  
Ligamentum Flavum ◽  
Rare Condition ◽  
Thoracolumbar Junction ◽  
Gait Ataxia ◽  
Dorsal Spinal Cord ◽  
Epidural Catheter Placement ◽  
Spinal Cord Herniation ◽  
Dorsal Spinal

Dorsal spinal cord herniation is reportedly a rare condition. Here, the authors report an unusual case of dorsal spinal cord herniation at the thoracolumbar junction presenting with scalloping of ossification of the ligamentum flavum (OLF). A 75-year-old woman with a 2-year history of bilateral leg dysesthesia presented with progressive gait ataxia. Neurological examination showed bilateral patellar tendon hyperreflexia with loss of vibratory sensation and proprioception in her bilateral lower extremities. CT myelography revealed a posterior kink and dorsal herniation of the spinal cord at T11–12, with OLF between T10–11 and T12–L1. In addition, scalloping of the OLF was observed at T11–12 at the site of the herniated spinal cord. This scalloping was first noted 9 years previously and had been gradually progressing. The patient underwent surgical repair of the spinal cord herniation. Subsequently, her spinal cord herniation and vibratory sensation and proprioception in both legs partly improved, but gait ataxia remained unchanged. Dorsal spinal cord herniation reportedly occurs under conditions of vulnerability of the dorsal dura mater. In this case, acquired vulnerability of the dorsal dura mater owing to previous epidural catheter placement into the thoracolumbar space may have resulted in dorsal spinal cord herniation.

scholarly journals The neuropathology of “typical” Friedreich's ataxia in Quebec

1984 ◽  
Vol 11 (S4) ◽  
pp. 592-600 ◽  
Author(s):  
J.B. Lamarche ◽  
B. Lemieux ◽  
H.B. Lieu
Keyword(s):  
Spinal Cord ◽  
Central Nervous System ◽  
Nervous System ◽  
Peripheral Nervous System ◽  
Diagnostic Criteria ◽  
Clinical Findings ◽  
Spinal Ganglia ◽  
Cooperative Study ◽  
Segmental Demyelination ◽  
Dying Back

AbstractWe present the pathological data from the autopsies performed on 6 Friedreich's disease patients since the start of the Quebec Cooperative Study. All patients met the strict diagnostic criteria of the QCSFA. The anatomical lesions found in the peripheral and central nervous system were similar in all 6 cases and do not differ from those described in the literature. The clinical findings correlate closely with the histological lesions found in the peripheral nervous system and spinal cord. The evidence of segmental demyelination and remyelination in the spinal ganglia and posterior roots further supports the dying-back axonopathy hypothesis.

scholarly journals Sampling and Evaluating the Peripheral Nervous System

2019 ◽  
Vol 48 (1) ◽  
pp. 10-18 ◽  
Author(s):  
Mark T. Butt
Keyword(s):  
Spinal Cord ◽  
Nervous System ◽  
Sciatic Nerve ◽  
Peripheral Nervous System ◽  
Morphological Changes ◽  
Sampling Strategy ◽  
Mechanisms Of Toxicity ◽  
Test Article ◽  
Ganglion Neurons ◽  
The Brain

Many preclinical investigations limit the evaluation of the peripheral nervous system (PNS) to paraffin-embedded sections/hematoxylin and eosin–stained sections of the sciatic nerve. This limitation ignores several key mechanisms of toxicity and anatomic differences that may interfere with an accurate assessment of test article effects on the neurons/neurites peripheral to the brain and spinal cord. Ganglion neurons may be exposed to higher concentrations of the test article as compared to neurons in the brain or spinal cord due to differences in capillary permeability. Many peripheral neuropathies are length-dependent, meaning distal nerves may show morphological changes before they are evident in the mid-sciatic nerve. Paraffin-embedded nerves are not optimal to assess myelin changes, notably those leading to demyelination. Differentiating between axonal or myelin degeneration may not be possible from the examination of paraffin-embedded sections. A sampling strategy more consistent with known mechanisms of toxicity, atraumatic harvest of tissues, optimized fixation, and the use of resin and paraffin-embedded sections will greatly enhance the pathologist’s ability to observe and characterize effects in the PNS.

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