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The present study describes transitions in myosin heavy chain expression in the extraocular muscles of rats between the ages of E17 and adult. The unique phenotype of the extraocular muscle is reflected in its fibre type composition, which is comprised by six distinct profiles, each defined by location (orbital versus global layer) and innervation pattern (single versus multiple terminals). During extraocular muscle myogenesis, developmental myosin heavy chains were expressed in both primary and secondary fibres from embryonic day E17 through the first postnatal week. At this time, the downregulation of developmental myosin heavy chain isoforms began in the global layer in a fibre type-specific manner, reaching completion only after the first postnatal month. By contrast, developmental isoforms were retained in the overwhelming majority of orbital layer fibres into adulthood and expressed differentially along the length of these fibres. Fast myosin heavy chain was detected pre- and postnatally in developing secondary fibres and in all of the singly innervated fibre types and one of the multiply innervated fibre types in the adult. As many as four fast isoforms were detected in maturing extraocular muscle, including the extraocular muscle-specific myosin heavy chain. Slow myosin heavy chain was expressed in primary fibres throughout development and in one of the multiply innervated fibre types in the adult. In contrast, the pure fast-twitch retractor bulbi initially expressed slow myosin heavy chain in fibres destined to switch to the fast myosin heavy chain developmental programme. Based upon spatial and temporal patterns of myosin heavy chain isoform transitions, we suggest that epigenetic influences, rather than purely myogenic stage-specific factors, are critical in determining the unique extraocular muscle phenotype.

This study examined the impact of implementing a rotating dissection schedule on the attitudes and performance of first-year dental students in the gross anatomy laboratory at the University of Kentucky. In 2002-2003, half of the students assigned to each cadaver dissected the assigned objectives during the first 90 min of the laboratory session. During the last 30 min, the non-dissecting group members came into the laboratory and had the day's dissection demonstrated and explained to them via peer instruction. Dissection responsibilities rotated with each laboratory session. Eighty-eight percent of student participants were satisfied with the rotating dissection approach according to a mid-term survey, and this satisfaction level remained unchanged at the end of the semester for most students. Students' perceptions of the quality of peer laboratory presentations varied, with only 44% rating them as good or better. Eighty percent of students perceived that rotating dissection did not impede their performance, and this was confirmed by analysis of grade data. Student satisfaction and the ability to devote additional weekly curriculum time to studying anatomy in a very compressed curriculum were the main student-described benefits.

Traditionally, the nerve to the mylohyoid has been considered a motor nerve. However, dissection and clinical studies have challenged this dogma implicating the nerve to the mylohyoid as a nerve of accessory sensory innervation to mandibular teeth. Within the infratemporal fossa, the nerve to the mylohyoid branches from the inferior alveolar nerve and may be anesthetized with an inferior alveolar nerve block. However, because of the variability in location of branching and the potential barriers formed by both the pterygomandibular fascia and the sphenomandibular ligament, the nerve to the mylohyoid may escape anesthesia in an inferior alveolar nerve block. This may prevent profound local anesthesia of the mandibular teeth and may account, at least in part, for the high failure rate of the inferior alveolar nerve block. Alternative local anesthesia procedures may be employed to ensure adequate anesthesia of the nerve to the mylohyoid is achieved. This review provides a background of anatomical and clinical research of the nerve to the mylohyoid and outlines techniques suggested for providing a neural blockade of the nerve to the mylohyoid.

This article describes the emerging role of educational multiuser virtual environments, specifically Second Life™, in anatomical sciences education. Virtual worlds promote inquiry-based learning and conceptual understanding, potentially making them applicable for teaching and learning gross anatomy. A short introduction to Second Life as an anatomical educational tool is provided, along with description of existing anatomy applications and future directions for this innovative teaching modality.