China
Africa
Explore chapters and articles related to this topic
Tissue coverage for exposed vascular reconstructions (grafts)
Published in Sachinder Singh Hans, Mark F. Conrad, Vascular and Endovascular Complications, 2021
Kaitlyn Rountree, Vikram Reddy, Sachinder Singh Hans
The two heads of the sternocleidomastoid muscle (SCM) originate from the manubrium of the sternum and the medial clavicle; as they ascend superiorly, the fibers of the two heads blend together to insert on the mastoid process of the temporal bone. The major function of the SCM is rotation of the head and flexion of the neck. Motor innervation is supplied from the accessory nerve which perforates the muscle at the level of the carotid bifurcation.11 The blood supply to the SCM is segmental and variable with the exception of the superior segment. Cadaveric dissections and latex injection studies have consistently reported a reliable blood supply to the superior aspect of the muscle from the occipital artery derived from the external carotid artery (ECA). The middle portion of the muscle belly is variably supplied by branches from the superior thyroid artery (STA) or, in 20–27% of cases, directly by branches of the ECA. The lower portion of the sternocleidomastoid muscle belly is variably supplied by either the transverse cervical artery, the Thyrocervical trunk and or the superficial cervical artery.12
Neurologic Diagnosis
Published in Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw, Hankey's Clinical Neurology, 2020
Fibrillation potentials may also take the form of trains of positive sharp waves (see Figure 1.49c, Figure 1.51) that are of longer duration and slightly greater amplitude and are often induced by needle movement. They are always pathologic and represent the spontaneous contraction of a single muscle fiber that has lost its nerve supply. If a motor neuron is lost or when its axon is interrupted, the distal part of the axon degenerates over several days. Within 10–14 days, the muscle fibers of the involved motor unit begin to generate fibrillation potentials. These denervation potentials may also be recorded in some primary necrotizing muscle diseases with muscle fiber splitting, inflammation, or vacuolation (e.g. Duchenne's muscular dystrophy, polymyositis, inclusion body myositis, and muscle trauma including surgery), because the terminal innervation of some muscle fibers is damaged by the disease process. Fibrillation potentials continue until the muscle fiber is reinnervated by regeneration of the interrupted motor axon if the motor neuron remains intact, by the outgrowth of new axons from remaining healthy nerve fibers (collateral sprouting), or until the atrophied muscle fibers degenerate and are replaced over years by connective tissue.
Comparative Anatomy and Physiology of the Mammalian Eye
Published in David W. Hobson, Dermal and Ocular Toxicology, 2020
The musculature of the eyelids includes the muscles which close the eye, the orbicularis oculi, and those that open the eye, the levator palpebrae being the major muscle. A smooth muscle (Muller’s muscle) is found deep, extending along the course of the levator. It is under adrenergic innervation and results in a widened palpebral margin when stimulated. The orbicularis muscle fibers are arranged in bundles parallel to the free lid margin. The muscle is restricted in its circular sphincter action by restrictions in the nasal and temporal extremities. A firm attachment is accomplished by the medial palpebral ligament in all animals except the primate, which has a common tendon of the superficial heads of the pretarsal orbicularis oculi that inserts in the medial orbital wall. On the temporal side, the common tendon of the temporal pretarsal orbital axis assumes the function of the lateral ligament in primates, while in the other animals it is the retractor anguli muscle which serves this function. These structures allow the lid to close from laterally to medially, propelling tears to the medial aspect where the lacrimal puncta are found. The innervation to the eyelids includes sensory, motor, and autonomic portions. The sensory to the upper lid is the frontal branch of the ophthalmic division of the fifth cranial nerve, while the lower is the maxillary division of the fifth cranial nerve. Motor innervation is provided by the third (levator) and seventh (orbicularis) cranial nerves. The autonomic innervation is sympathetic to Muller’s and the smooth muscle of the third eyelid.
Neurotrophic keratopathy: current challenges and future prospects
Published in Annals of Medicine, 2022
Erin NaPier, Matthew Camacho, Timothy F. McDevitt, Adam R. Sweeney
The cornea is an avascular, prolate-shaped connective tissue that provides refractive power, structural integrity, and antimicrobial functions in the anterior portion of the eye [3]. It is mainly innervated by the nasociliary nerve of the ophthalmic branch (V1) of the trigeminal nerve and occasionally by sensory nerves of the maxillary branch (V2) innervate the inferior cornea [3,4]. Additionally, there is autonomic innervation from the superior cervical ganglion (sympathetic) and ciliary ganglion (parasympathetic), however, the role and density of these nerves remain unclear [4]. It is estimated that the subbasal plexus of the cornea has ∼19,000–44,000 axons [4]. Corneal innervation is critical in providing trophic factors (e.g. substance P, calcitonin gene-related peptide, acetylcholine, serotonin, neuropeptide Y) which help to maintain a healthy corneal epithelium. The mutual relationship between corneal nerves and epithelium is essential for corneal homeostasis as epithelial cells secrete neurotrophic factors (e.g. nerve growth factor and ciliary neurotrophic growth factor) with parallel effects on corneal nerves. Loss of innervation results in decreased metabolism and mitosis of epithelial cells, consequently leading to epithelial breakdown and hindered corneal healing [1,5,6]. This may result in persistent epithelial defects, ulceration, stromal melting, and perforation [7].
Comparison of reliability and efficiency of two modified two-point discrimination tests and two-point estimation tactile acuity test
Published in Physiotherapy Theory and Practice, 2022
Kory Zimney, Gina Dendinger, Macey Engel, Jordan Mitzel
Two-point discrimination (TPD) testing is a cutaneous sensory assessment that measures the tactile acuity of an individual to distinguish between two light touch stimuli applied simultaneously to the body (Nolan, 1982). TPD has been used to objectively evaluate sensory deficits and recovery of touch following peripheral nerve injury or surgery (Lundborg and Rosén, 2004; Moberg, 1990). A tactile acuity measurement, like TPD, was originally thought to be based solely on changes in peripheral nerve innervation density in the area being tested following peripheral nerve injury (Johansson and Vallbo, 1979; Lundborg and Rosén, 2004). Subsequent research and understanding of tactile acuity has been expanded to include not only the function of peripheral nerve innervation fields, but also the somatotopic organization through the spinal cord pathways and into the sensory cortices of the brain (Lotze and Moseley, 2007; Yang et al, 1994). This helps explain why some individuals can have changes in their tactile acuity without any history of peripheral nerve damage.
Habitual use of psychological coping strategies is associated with physiological stress responding during negative memory recollection in humans
Published in Stress, 2022
The hypothesis that the average SCL trajectory would follow an upside-down u-shaped curve was not supported. The average trajectory of SCL showed the opposite pattern, indicating that the SNS did not, on average, innervate the eccrine sweat glands in preparation for fight-or-flight responding. Mean decreases in SCL are observed during some tasks, such as a mirror-tracing task (El-Sheikh et al., 2010); the increases in SCL following the 3-min mark observed in this study may indicate recovery. Rather than fight-or-flight responses, decreases in SCL may represent engagement responses (Porges, 2007). Lower SNS innervation of various target organs promotes calm and allows physiological resources to be devoted to attending to social cues, adjusting behavior to meet social expectations, and negotiating complex relationships with others. The decreases in SCL at the beginning of the interview may therefore permit recall and sharing of a negative autobiographical memory with the experimenter. Measurement of autonomic innervation of other target organs is needed to further investigate this possibility.