On the Fila Olfactoria and the Cribriform Region of the Crocodylia.

In mammals the fila olfactoria, fascicles of axons coursing from sensory neurons in the olfactory epithelium to the glomeruli of the olfactory bulb, not only have a topographic projection pattern but also serve as routes for cerebrospinal fluid (CSF) drainage from around the brain. Les is known about the fila olfactoria in nonmammalian taxa. This work explores the fila olfactoria of the American alligator (Alligator mississippiensis) using a combination of gross dissection, histology, Diffusible Iodine-based contrast-enhanced computed tomography, latex corrosion casting, and India ink tracers.

Forces Acting on the Foot of the American Alligator () During Pedal Anchoring.

This study was undertaken to explore the forces acting on the pes during pedal anchoring and to discern if pedal anchoring required the activation of the intrinsic pedal musculature. Replica feet equipped with strain gauges were moved over mud substrate, mimicking locomotion and pedal anchoring. Quantification of the substrate tracks demonstrated that they were similar to those made by freely moving , that the locomotor and pedal anchoring tracks were significantly different, and that the composition of the artificial feet significantly altered the tracks.

The Crocodylian proatlas functions to redistribute venous blood and cerebrospinal fluid.

The proatlas, a bone located between the skull and the neural spines of the cervical vertebrae, is best known from reptiles. Most previous studies of the proatlas have centered on its developmental, debating the relationship between the proatlas and the cervical neural arches. The present study was intended as a description of the proatlas in the American alligator (Alligator mississippiensis) and an experimental test of its hypothesized role in venous blood and cerebrospinal fluid (CSF) distribution.

On the spinal venous sinus of Alligator mississippiensis.

The epidural space of the American alligator (Alligator mississippiensis) is largely filled by a continuous venous sinus. This venous sinus extends throughout the trunk and tail of the alligator, and is continuous with the dural sinuses surrounding the brain. Segmental spinal veins (sl) link the spinal venous sinus (vs) to the somatic and visceral venous drainage.

The presence of a foramen of Luschka in the American alligator (Alligator mississippiensis) and the continuity of the intraventricular and subdural spaces.

In humans and most mammals, there is a notch-like portal, the foramen of Luschka (or lateral foramen), which connects the lumen of the fourth ventricle with the subdural space. Gross dissection, light and scanning electron microscopy, and μCT analysis revealed the presence of a foramen of Luschka in the American alligator (Alligator mississippiensis). In this species, the foramen of Luschka is a notch in the dorsolateral wall of the pons immediately caudal to the peduncular base of the cerebellum, near the rostral end of the telovelar membrane over the fourth ventricle.

Dynamic asymmetry in cerebrospinal fluid pressure: An indicator of regional differences in compliance.

Background: Dural compliance influences the shape and magnitude of the cerebrospinal fluid (CSF) pulsations. In humans, cranial compliance is approximately 2× greater than spinal compliance; the differential has been attributed to the associated vasculature. In alligators, the spinal cord is surrounded by a large venous sinus, which suggests that the spinal compartment may have higher compliance than is found in mammals.

The anatomical basis of amphibious hearing in the American alligator (Alligator mississippiensis).

The different velocities of sound (pressure waves) in air and water make auditory source localization a challenge for amphibious animals. The American alligator (Alligator mississippiensis) has an extracolumellar cartilage that abuts the deep surface of the tympanic membrane, and then expands in size beyond the caudal margin of the tympanum. This extracolumellar expansion is the insertion site for two antagonistic skeletal muscles, the tensor tympani, and the depressor tympani.

Histological Structure of the Medial and Lateral Patellofemoral Ligaments and Implications for Reconstructive Surgery and Anterior Knee Pain.

Biomechanically, the patellofemoral joint is one of the most complex human articulations and a common source of pain for active adults and adolescents, particularly females.1-4 Patellofemoral disorders account for 20%-40% of all knee problems seen in family practice, sports medicine, and orthopedic clinics.1, 3-5.

The Influence of Movement on the Cerebrospinal Fluid Pressure of the American Alligator ().

This study was undertaken to document how the cerebrospinal fluid (CSF) pressure varied during movements and physiological activities. Using surgically implanted pressure catheters; the CSF pressure was recorded from sub-adult American alligators () under anesthesia and post-recovery. Pressures were recorded during physiological activities (the cardiac cycle; passive and active ventilation); manual manipulation of the anesthetized animals (foot sweeps; tail oscillations; and body bends); as well as voluntary movements post-recovery (changes in body tone; defensive strikes; and locomotion).

The orbitalauricular chord of Alligator: The unusual functional linkage between the earflap and eyelid of Crocodylians.

One of the distinctive features of the Crocodylia is the presence of a superficial meatal chamber the aperture of which is regulated by two earflaps. The movements of the upper earflap have been detailed by multiple workers, however, the mechanics of the lower earflap remain unresolved. The present study was undertaken to document the mechanics of the lower earflap in the American alligator, Alligator mississippiensis, and to explore the functional bases of coordinated movements between the lower earflap and lower eyelid in this species.

Treadmill locomotion in the American alligator (Alligator mississippiensis) produces dynamic changes in intracranial cerebrospinal fluid pressure.

To examine the influence of movement on cerebrospinal fluid (CSF) dynamics, intracranial subdural pressure recordings were taken from sub-adult alligators (Alligator mississippiensis) locomoting on a treadmill. Pressure recordings documenting the cardiac, ventilatory, and barostatic influences on the CSF were in good agreement with previous studies. During locomotion the CSF exhibits sinusoidal patterns of pressure change that spanned a mean amplitude of 56 mm Hg, some 16 × the amplitude of the cardiac-linked pulsations.

Morphology of the distal tip of the spinal cord in Alligator mississippiensis.

Secondary neurulation is a common feature of vertebrate development, which in non-mammalian and non-anuran vertebrates, results in the formation of a caudal spinal cord. The present study was undertaken to describe the terminal end of the caudal spinal cord in a crocodylian, a group chosen for their unique status of a living-tailed archosaur. The caudal spinal cord of Alligator mississippiensis terminates near the intervertebral joint between the fourth and fifth terminal vertebrae.

Morphometrics of the Spinal Cord and Surrounding Structures in .

Understanding the fluid dynamics of the cerebrospinal fluid requires a quantitative description of the spaces in which it flows, including the spinal cord and surrounding meninges. The morphometrics of the spinal cord and surrounding tissues were studied in specimens of the American alligator () ranging from hatchlings through adults. Within any size class of alligators (i.

The morphology of the suboccipital region in snakes, and the anatomical and functional diversity of the myodural bridge.

The myodural bridge, that is, skeletal muscle fibers attaching to the cervical dura mater, has been described from a variety of mammals and other amniotes. To test an earlier assumption about the presence of the myodural bridge in snakes, a comparative study was designed using a group of Colubrine snakes. Serial histological sections revealed no evidence of the myodural bridge in any of the snakes examined.

Slithering CSF: Cerebrospinal Fluid Dynamics in the Stationary and Moving Viper Boa, .

In the viper boa (), the cerebrospinal fluid (CSF) shows two stable overlapping patterns of pulsations: low-frequency (0.08 Hz) pulses with a mean amplitude of 4.1 mmHg that correspond to the ventilatory cycle, and higher-frequency (0.

The functional morphology of the postpulmonary septum of the American alligator (Alligator mississippiensis).

The American alligator (Alligator mississippiensis) has a postpulmonary septum (PPS) that partitions the intracoelomic cavity. The PPS adheres to the capsule of the liver caudally and to the visceral pleura of the lung cranially; the ventrolateral portions of the PPS are invested with smooth muscle, the remainder is tendinous. Differential pressure transducers were used to record the intrathoracic (ITP) and intraperitoneal (IPP) pressures, and determine the transdiaphragmatic pressure (TDP).

The narial musculature of Alligator mississippiensis: Can a muscle be its own antagonist?

The crocodilian naris is regulated by smooth muscle. The morphology of this system was investigated using a combination of gross, light microscopic, and micro-CT analyses, while the mechanics of narial regulation were examined using a combination of Hall Effect sensors, narial manometry, and electromyography. Alligator mississippiensis, like other crocodilians, routinely switches among multiple ventilatory mechanics and does not occlude the nares during any portion of the ventilatory cycle.

Fibrocartilaginous metaplasia and neovascularization of the anterior cruciate ligament in patients with osteoarthritis.

Introduction: The anterior cruciate ligament (ACL) prevents the anterior translocation and medial rotation of the tibia against the femur. It is typically composed of dense regular connective tissue (DRCT), small amount of loose connective tissue, little vasculature, and few nerve endings. The objective of the current study was to evaluate the details of histological changes in ACLs of patients with clinically diagnosed osteoarthritis (OA).