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Orbital and retro-orbital pain are relatively common clinical conditions that are associated with such disorders as trigeminal, lacrimal, and ciliary neuralgia, cluster headaches, paroxysmal hemicrania, inflammatory orbital pseudotumor, trochleitis, and herpetic neuralgia ophthalmicus, thus making the nerves supplying the orbit of great clinical importance. Surprisingly, how pain from this region reaches conscious levels is enigmatic. Classically, it has been assumed that pain reaches the ophthalmic division of the trigeminal nerve (V1 ) and travels to the descending spinal trigeminal nucleus. However, exactly where the receptors for orbital pain are located and how impulses reach V1 is speculative. In this project, we reviewed all of the reported connections between the orbital nerves and V1 in order to understand how pain from this region is transmitted to the brain. We found reported neural connections to exist between cranial nerve (CN) V1 and CNs III, IV, and VI within the orbit, as well as direct neural branches to extra-ocular muscles from the nasociliary, frontal, and supraorbital nerves. We also found reported neural connections to exist between the presumed carotid plexus and CN VI and CN V1 , CN VI and CN V1 and V2 , and between CN V1 and CN III, all within the cavernous sinus. Whether or not these connections are sympathetic or sensory or some combination of both connections remains unclear. An understanding of the variability and frequency of these neural connections could lead to safer surgical procedures of the orbit and effective treatments for patients with orbital pain.

The nervus terminalis (NT; terminal nerve) was clearly identified as an additional cranial nerve in humans more than a century ago yet remains mostly undescribed in modern anatomy textbooks. The nerve is referred to as the nervus terminalis because in species initially examined its fibers were seen entering the brain in the region of the lamina terminalis. It has also been referred to as cranial nerve 0, but because there is no Roman symbol for zero, an N for the Latin word nulla is a better numerical designation. This nerve is very distinct in human fetuses and infants but also has been repeatedly identified in adult human brains. The NT fibers are unmyelinated and emanate from ganglia. The fibers pass through the cribriform plate medial to those of the olfactory nerve fila. The fibers end in the nasal mucosa and probably arise from autonomic/neuromodulatory as well as sensory neurons. The NT has been demonstrated to release luteinizing-releasing luteinizing hormone and is therefore thought to play a role in reproductive behavior. Based on the available evidence, the NT appears to be functional in adult humans and should be taught in medical schools and incorporated into anatomy/neuroanatomy textbooks.

The anatomical understanding of the pain generators in osteoarthritis (OA) is incomplete and the teaching about these pain generators in medical school anatomy/histology courses is minimal. This review covers the nociceptive innervation of synovial joints for the purposes of teaching. Studies that discuss the presence of neuropeptides involved in pain, such as Substance P (SP) and calcitonin-gene-related peptide, are the focus of this review. Nociceptive free-nerve endings and SP staining nerves are found in the accessory ligaments, synovium, subchondral bone, menisci, and periosteum. The vasculature may also play a role in pain generation through vasospasm or ischemia, but this has yet to be proven. Joint denervation may relieve joint pain showing that it is indeed articular nerves that are carrying pain impulses but denervation does not identify the precise source of the pain. It remains unclear which of the anatomical loci of pain generation are primary in OA and if sources of pain vary in different patients and in different joints.

The sacroiliac joint (SIJ) is a putative source of low back pain. The objective of this article is to provide clinicians with a concise review of SIJ structure and function, diagnostic indicators of SIJ-mediated pain, and therapeutic considerations. The SIJ is a true diarthrodial joint with unique characteristics not typically found in other diarthrodial joints. The joint differs with others in that it has fibrocartilage in addition to hyaline cartilage, there is discontinuity of the posterior capsule, and articular surfaces have many ridges and depressions. The sacroiliac joint is well innervated. Histological analysis of the sacroiliac joint has verified the presence of nerve fibers within the joint capsule and adjoining ligaments. It has been variously described that the sacroiliac joint receives its innervation from the ventral rami of L4 and L5, the superior gluteal nerve, and the dorsal rami of L5, S1, and S2, or that it is almost exclusively derived from the sacral dorsal rami. Even though the sacroiliac joint is a known putative source of low back and lower extremity pain, there are few findings that are pathognomonic of sacroiliac joint pain. The controlled diagnostic blocks utilizing the International Association for the Study of Pain (IASP) criteria demonstrated the prevalence of pain of sacroiliac joint origin in 19% to 30% of the patients suspected to have sacroiliac joint pain. Conservative management includes manual medicine techniques, pelvic stabilization exercises to allow dynamic postural control, and muscle balancing of the trunk and lower extremities. Interventional treatments include sacroiliac joint, intra-articular joint injections, radiofrequency neurotomy, prolotherapy, cryotherapy, and surgical treatment. The evidence for intra-articular injections and radiofrequency neurotomy has been shown to be limited in managing sacroiliac joint pain.

OBJECTIVE: To delineate Sir Victor Horsley's influence on neurosurgeons who subsequently reported (through 1950) on the effects of motor cortex extirpation surgery. METHODS: We used the available literature to divide Horsley's influence into five categories, i.e., direct trainee, via a trainee or colleague, via personal contact and publications, via publications only, and no evidence of influence. RESULTS: Of 15 later neurosurgeons who reported results through 1950, the numbers corresponding to the five categories were 1, 6, 2, 3, and 3, respectively. CONCLUSION: Horsley's influence on neurosurgeons who performed motor cortex extirpation surgery was primarily indirect, with most influence occurring via trainees of his students or colleagues. Although indirectly associated with Horsiey, Paul Bucy was his truest disciple.

Many contemporary investigators are unaware of the important papers involving lesions of the primate primary motor cortex published prior to those revealed by a computer search of the literature (i.e., papers published prior to about 1966). In order to increase awareness of these reports, we present here an annotated bibliography of these papers beginning with that of Ferrier and Yeo (1884). We provide evidence that these papers can provide valuable information on the function of the primate motor cortex and on recovery of behavior after brain lesions, and are also useful for sharpening the questions posed by more refined modern studies.

From the late 1800s until approximately the middle of the 20th century, neurosurgeons made discrete motor cortex lesions in humans in attempts to reduce or eliminate a variety of involuntary movements, resulting mainly from epilepsy. In some cases, the neurosurgeons tested and recorded their patients' ability to perform various movements and to perceive various types of sensory stimuli after the operation. Although these studies have been largely forgotten, they have an immense advantage over primate lesion studies for understanding the function of the motor cortex because the patients were able to attempt to perform complex movements upon request, and to describe their perceptions of cutaneous stimuli, including integrated sensations (e.g., recognition of objects by palpation alone). We provide here a table containing the results of these studies pertaining to sensory deficits. The most consistent and persistent sensory deficits reported relate to object recognition and position sense. This finding is in keeping with recent electrophysiological studies in primates. Our analysis suggests that the “motor” cortex serves important sensory functions; hence, the term sensorimotor cortex, remains appropriate for the primate precentral (and postcentral) cortex.

The kinematics of stumbling and recovery induced by a rapidly reversing treadmill is described for eight healthy adults. Stability was achieved in approximately 400 ms following treadmill reversal (initiated at heel-strike) and the ensuing stumble. It appeared to be accomplished primarily by rapid flexion of the thigh and knee of the stance limb, which prevented damage to the knee joint and lowered the trunk, and by extension of the contralateral joints (swing limb), which contacted the ground presumably to deliver an impulsive thrust to counter the backward lean of the trunk. The movements of the ankle also contributed to the recovery from the stumble, but its movements were markedly more variable among the subjects than those of the thigh and knee. The observed kinematics to some extent resembled a crossed-extension reflex, which may have been triggered by muscle, joint, cutaneous or vestibular afferents. These data should provide a baseline by which to compare groups in which recovery from stumbling is known to be deficient (e.g., the elderly).

We used the Denny-Brown Research Collection to study in detail the reflex responses of monkeys after ablation of the anterior lobe, posterior lobe or the entire cerebellum. The Collection includes written, film and histological records, and photographs of the brain at autopsy. Large cerebellar ablations severely suppress proprioceptive responses, thereby significantly impairing the capacity to stand, walk, and hop. Cutaneous reflexes are also impaired, although more selectively, permitting expression of normally suppressed responses such as magnet reactions and tactile avoiding responses. Enhancement (release) of responses to truncal cutaneous stimulation, along with suppression of opposing proprioceptive responses, leads to postures of persistent flexion. Large cerebellar lesions also interfere with reflex responses mediated by visual and vestibular systems. More limited cerebellar ablations have similar, but less severe effects.

The nervous system has a variety of mechanisms whereby it can potentially initiate or accelerate joint disease. Whether these potential mechanisms are clinically significant factors in the etiology of osteoarthritis remains uncertain. However, 11 papers published in the past year provide further support for the view that these mechanisms are important in the pathogenesis of the disease.

In his extensive writings, Denny-Brown hypothesized that two competitive 'tropisms,' one positive (exploratory) and one negative (withdrawal) act to coordinate normal movements at all levels of the neuraxis. Lesions in particular areas of the central nervous system result in disequilibrium between these tropisms, leading to disorders of posture and movement, including involuntary movements. The tactile manifestations of unbalanced exploratory tropisms are grasping responses, whereas the complementary withdrawal tropisms are avoiding responses. In Denny-Brown's view, at the level of the cerebral cortex, grasping responses result from frontal lobe injury whereas avoiding responses result from parietal lobe lesions. In this report we review Denny-Brown's conceptions of positive and negative tropisms, their anatomical loci, and whether his hypothesis has merit in a contemporary approach to brain function. We find that Denny-Brown's view on the anatomical loci associated with these behaviors is incomplete, but that the idea of conflicting behavioral tendencies is valuable for understanding and managing some neurological and perhaps also psychiatric disorders. For example, his hypothesis offers an important perspective in understanding the paradoxical success of stereotaxic surgery to alleviate the symptoms of Parkinson's disease.

In this paper we review the literature on stepping in nonhuman and human primates with complete transection of the spinal cord and consider these data relative to the principle of “encephalization” of motor functions with ascension in phylogeny. We conclude that techniques useful for producing self-generated stepping behavior in nonprimates with complete spinal cord transection may not be successful in humans and other higher primates with complete transection.

Summary Objective and Design: transection of the anterior cruciate ligament 2 weeks after ipsilateral hindlimb deafferentation leads to osteoarthritis of the knee joint within 3 weeks. We analyzed the gait of six dogs that underwent this procedure in order to identify kinematic changes that could account for this rapid joint degeneration. All animals were video taped 1, 3, 6, 9 and 13 weeks after surgery while they trotted on a treadmill. Results: In each dog, extension of the hip, knee and ankle joints of the unstable limb was increased, and the yield phase of the unstable knee was delayed or attenuated. When killed, five of six dogs showed a large full-thickness cartilage ulcer on the distal and/or anterior surface of the medial femoral condyle of the unstable knee; in the sixth dog, a smaller ulcer was observed. However, the severity of pathology in each individual was not obviously related to differences among the dogs in postoperative joint kinematics. Conclusions: These data, and results of prior studies in humans and dogs, suggest that knee hyperextension resulting from limb deafferentation, and knee instability resulting from anterior cruciate ligament transection, operate in concert to create a mechanical environment (i.e., increased tibiofemoral separation and changes in the loading of articular surfaces) that results in rapid joint breakdown.

The Denny-Brown collection consists of films depicting the behavioral responses of approximately 450 monkeys after central nervous system lesions; operative, behavioral, and neuropathologic descriptions; and histologic slides. This collection is available for use by interested investigators. This report describes one case, DC60, to provide an example of the types of material that are available and how these materials might be used better to understand the nervous system. To demonstrate how precisely the actual lesions can be defined and compared with the planned ablations, this report also includes a detailed evaluation of the extent of the lesions made in this case, based on the histologic slides and on photographs of the brain taken before histologic processing.

In this brief study we provide evidence that earlier and more recent findings pertaining to the anatomy and physiology of the sacroiliac joint suggest that dysfunction in this joint could, similar to a herniated lumbar disc, produce pain along the sciatic nerve. These observations might explain some of the cases of sciatica in which no disc pathology can be found.

Transection of the anterior cruciate ligament in the dog leads to osteoarthritis. This study defines the kinematic changes in the unstable knee after transection of the cruciate ligament (six dogs) and after a sham operation (four dogs). In the dogs that were anterior cruciate ligament-deficient (ACL-D), the duration of stance 1 week postoperatively decreased 38% from the preoperative value, but only a 4% decrease was seen at 6 weeks. The duration of double hindlimb support increased from 6 to 19% of the entire cycle 1 week after surgery but returned to the baseline value by 18 weeks. As the unstable limb contacted the treadmill belt, the initial flexion (yield) and subsequent extension (propulsive) phases were not evident or were markedly attenuated in every ACL-D dog throughout the 26-week period of observation. The angular velocity patterns were characterized by a slight extension velocity at touchdown (compared with a zero value preoperatively) and a decrease in the peak velocities (both flexion and extension) during the remainder of the stance phase. None of these changes was observed in the animals that had a sham operation. These data indicate that, in the dog, the nervous system compensates for instability of the knee by altering angular, but not temporal, parameters. The extension velocity at touchdown and the reduction in peak flexion velocity during the yield component of the stance phase may reduce the ability of the limb to absorb impact forces and lead to the development of osteoarthritis of the knee. Alternatively, the reductions in flexion and extension of the knee during the stance phase and in the values for peak velocity presumably reflect protective muscular reflexes that may slow the rate of progression of joint breakdown.

The association between the laryngeal saccule and a laryngocele is an important clinical relationship. Here, we describe this and other clinical correlations of the saccule including infection and carcinoma and suggest that these should be discussed in medical gross anatomy courses. We also briefly present some descriptive information on the anatomy and function of the saccule in humans and other higher primates.

Shoulder, elbow and wrist joint angular displacement patterns were analyzed for five vervet monkeys across increasing speed. Within symmetrical gaits, the peak positions of the pattern for each joint tended to decrease with increasing speed as did the yield angle of the elbow (more "yielding"). Across the walk(run)-gallop transition there were no notable changes in the displacement patterns, but there was a consistent decrease in the range of elbow movements and an increase in the yield angle. Across symmetrical gaits, there was also a tendency for some of the peak positions to decrease. These results are compared with those available for cats and dogs, and are interpreted relative to functional and neurological aspects of forelimb movements in primates.

Hip, knee, and ankle joint displacement patterns are compared across both age and speed for five immature vervet monkeys sampled approximately every 6 months over a 3 year period. The analysis indicated that, as a group, the animals displayed no consistent changes in joint patterns as they grew. However, individual animals showed consistent patterns. There were also no consistent effects of size across animals at the walk-gallop transition. This is contrary to McMahon's prediction (J. Appl. Physiol. 39:619-627, 1975) based upon his elastic-similarity model of animal scaling. With increasing speed, when symmetrical gaits were used, all of the animals tended to show a decrease in the relative positions of the hip, knee, and ankle maximum values. Furthermore, across the walk-gallop transition, the animals tended to show a decrease in the range of ankle and knee movements.

The movement patterns of the joints of the right hind limbs and forelimbs of four vervet and one squirrel monkey were compared during right- and left-lead gallops. Although the overall displacement patterns were similar under both conditions, comparisons of the inflection points in the curves yielded consistent differences in the joints at various phases in the cycle. Some of these differences appear to reflect differing mechanical conditions, whereas others seem to represent variation in muscle activation patterns. Although some of the differences in the joints under the two conditions were consistent with those reported previously for other quadrupeds, others were not. This may reflect that different quadrupeds use slightly different biomechanical strategies during galloping.

Whereas Sir Victor Horsley is well known for his many contributions to neurosurgery, this is not the case for his treatments for both myxedema and cretinism. Horsley's research on thyroid physiology was concentrated in the years 1884-1890, while he was director of the Brown Institute for Animals. Based upon experimentation with dogs and monkeys as well as some human patients, Horsley demonstrated conclusively that removal of the thyroid gland produced tremors, rigidity, and paralysis, which he attributed to changes in lower motor centers. Furthermore, the development of imbecility suggested that thyroid excision produced deficits in higher cortical functioning. Horsley showed that it was possible to alleviate temporarily some of the psychological and physiological symptoms of both myxedema and cretinism using transplanted thyroid tissue. Several of Horsley's students, most notably George Murray, continued and extended his work by examining other ways in which myxedema and cretinism could be treated (e.g., by injecting an extract of thyroid tissue).

Sir Victor Horsley (1857-1916) is best known for the many pioneering neurosurgical procedures that he developed during the late 19th century. These advances enabled surgery to be performed on the brain with an acceptable mortality level.' Horsley's research was not limited to neurosurgery; it also extended into basic neurology (eg, motor cortex function) 2 and even general medicine, including many studies on the function of the thyroid gland.

During the last part of the 19th century and through the middle of the 20th century, surgeons sometimes extirpated parts of the human motor cortex to control abnormal involuntary movements. This procedure can be traced directly to Victor Horsley, who pioneered the first successful surgery of this type in 1886. Although many neurosurgeons followed Horsley's lead in performing this procedure, few used their results, as he did, to formulate concepts on the role of the motor cortex in movement control. Otfrid Foerster and Paul Bucy were the principal exceptions. We reviewed the surgical procedures these 3 notable neurosurgeons performed on the motor cortex and the hypotheses they subsequently developed on the functions of the motor cortex. We also evaluated these writings relative to contemporary views of motor cortex function.

Study design The posterior ligament of the human sacroiliac joint was examined for nerves and nerve endings using histologic and immunohistochemical techniques. Objective To identify nerve fibers and mechanoreceptors in the posterior ligament. Summary of background data According to the findings of previous studies, the human sacroiliac joint receives myelinated and unmyelinated axons that presumably conduct pain and proprioceptive impulses derived from mechanoreceptors and free nerve endings in the human sacroiliac joint. Methods Tissue obtained from six patients was stained with gold chloride and that obtained from six additional patients was stained using antibodies specific for substance P and protein gene product 9.5. Results The staining of joint tissue using the gold chloride technique showed myelinated and unmyelinated nerve fibers, two morphotypes of paciniform encapsulated mechanoreceptors, and a single nonpaciniform mechanoreceptor. Analysis using immunohistochemical staining for protein gene product 9.5 did not unequivocally show axons, nerve fascicles, or mechanoreceptors. Similarly, analysis based on immunohistochemical staining for substance P, one of several neurotransmitters known to signal pain from the periphery, showed reactive elements that may have been nerves, but because of background staining, could not be positively identified as such. Conclusions The presence of nerve fibers and mechanoreceptors in the sacroiliac ligament demonstrates that the central nervous system receives information, certainly proprioceptive, and possibly pain from the sacroiliac joint. Although it is not known how the central nervous system uses such information, it seems reasonable to speculate that the proprioceptive information is used to optimize upper body balance at this joint. In addition, because the staining techniques used generally to show nerves and nerve elements in periarticular connective tissue are nonspecific, the distinction between neural and nonneural should be made on the basis of both morphologic and staining characteristics.

Most contemporary investigators who study the behavioral effects of lesions of the primate motor cortex evaluate their findings in comparison to those of other recent investigators, but not in relation to the experimental neurologists who dominated this field around the mid-part of the 20th century. Utilizing selected recent reports, we demonstrate that these earlier papers, primarily those by D. Denny-Brown, provide valuable insights into the interpretation of some modern studies. Thus, we suggest that contemporary investigators of the primate motor cortex thoroughly review articles by the mid-20th century experimental neurologists. In addition, Denny-Brown and his contemporaries studied the effects of lesions in many other parts of the primate nervous system, and the associated reports are presumably also relevant to current investigations of these areas of the CNS.

Previous studies on cats walking backward have indicated that they adopt a presumably adaptive posture characterized by extreme dorsiflexion of the lumbar spine. Because humans do not show any marked postural changes during backward walking, we questioned whether the posture exhibited by cats during backward walking was in fact adaptive and whether it was typical of quadrupeds. We therefore compared forward and backward walking in three treadmill-trained dogs and found reduced temporal parameters during backward walking and a marked reduction in wrist palmar-flexion during the swing phase of a backward step, but no change in trunk posture. We suggest that the aberrant posture exhibited by cats during backward walking is more related to ethological factors than to biomechanical ones.