Innervation of Propatagial Musculature in a Flying Squirrel, <i>Glaucomys volans </i>(Rodentia, Sciuridae)

Abstract

The propatagium of gliding and flying mammals is of both functional and phylogenetic interest. The innervation of the propatagial muscle, platysma II, was studied with the axonal tracer wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) in a flying squirrel, Glaucomys volans. Injections of WGA-HRP into the proximal third of platysma II labeled motoneurons in the lateral part of the medial subdivision of the ipsilateral facial nucleus and in the ipsilateral ventral horn of the brachial enlargement. Injections into distal regions of platysma II labeled motoneurons in the ipsilateral ventral horn of spinal segments C5-C8 but not in the facial nucleus. Injections along the whole length of the muscle labeled afferent axons in the ipsilateral dorsal horn of spinal segments C4-T1. These results demonstrate a mixed facial and spinal motor innervation of propatagial musculature in the flying squirrel and indicate that this pattern of mixed innervation is more widespread among flying and gliding mammals than previously reported. Mixed facial and cervical propatagial innervation, independently derived in different flying and gliding mammals, may represent a common solution in the design of the propatagium. These findings complicate the use of propatagial muscle innervation patterns for the establishment of phylogenetic relationships among flying and gliding mammals.

Natural History of Progressive Supranuclear Palsy: A Clinicopathologic Study from a Population of Brain Donors

“…Gait disorders, instability and falls have been reported to be the most common symptoms of PSP, both at the onset and during the course of the disease (table 2). Falls together with supranuclear opthalmoplegia are considered as mandatory for the diagnosis of PSP in the NINDS-SPSP criteria [17]. In our cohort, gait disorder and instability were present in all patients, whereas only 3 patients did not report multiple falls (although instability was reported in all 3 patients).…”

“…Litvan et al [28] reported moderate to severe upward gaze palsy to be more frequent than downward abnormalities and suggested that upward gaze palsy in association with early gait instability and falls may be a better predictor of the disease. Other visual/ocular symptoms in PSP include diplopia, blurring of vision, light sensitivity, burning eyes, blepharospasm and eyelid apraxia [17, 24, 48]. …”

“…Diagnoses were reconfirmed after death by a movement disorders specialist (S.P. ), who applied standard criteria for PSP [17] (vertical supranuclear gaze palsy, prominent postural instability, falls in the first year of onset, disease onset <40 years of age and no evidence of other disorders to explain the neurologic findings). Diagnoses of dementia and psychiatric disorders were made by the patients’ treating physicians and were clearly documented in the medical files.…”

Midbrain Atrophy in Vascular Parkinsonism

“…The clinical diagnoses of IPD and probable PSP were based on the UK Parkinson’s Disease Society Brain Bank clinical diagnostic criteria for PD [13] and the clinical criteria of the National Institute of Neurological Disorders and Stroke and Society for Progressive Supranuclear Palsy (NINDS-SPSP) [14]. Some PSP patients had only vertical gaze slowing at the time of initial examination, but eventually showed vertical gaze palsy at follow-up.…”

The relationship between 3-D kinematics and gliding performance in the southern flying squirrel,Glaucomys volans

“…There are at least two mechanisms that may help keep flow attached to the wing at higher angles of attack in flying squirrels. First is the presence of a propatagium, an extension of the wing membrane between the wrist and neck rostral to the forelimb (Chickering and Sokoloff, 1996). The propatagium can be oriented downward with respect to the rest of the wing membrane giving the wing a greater overall curvature, which can help to guide the flow more smoothly over the wing.…”