Triplication of the lesser occipital nerve.

Triplication of the lesser occipital nerve (LON) was observed bilaterally in an adult male cadaver during routine prosection of the posterior triangle. The three LONs were studied to determine the clinical importance of this variation. The origin of one LON was from a nerve to the trapezius that had a common origin with the trunk of the supraclavicular nerve (C3,4) from the cervical plexus. Such a common origin of a LON may explain the pain referred to the shoulder and arm that is experienced by some patients with cervicogenic headache. Another LON ran across the roof of the posterior triangle, passed through the trapezius and was closely related to the point of exit of the greater occipital nerve (GON) from the trapezius. This LON supplied the nape of the neck, back of the scalp and the auricle. The anomalous course taken by this LON through the trapezius may be an explanation for cervicogenic headache precipitated by neck movement. The close relationship of this variant LON to the exit of the GON from the trapezius seems to be relevant to the management of cervicogenic headache. The authors suggest that the reason for the complete pain relief experienced by some patients with cervicogenic headache by anesthetic blockade of the GON may be because both the GON and LON are blocked simultaneously due to their proximity in these patients.

Anomalous flexor digiti minimi brevis in Guyon's canal.

In an adult male cadaver, the flexor digiti minimi brevis, a muscle of the hypothenar eminence, was found to arise from the superficial transverse septum (between the superficially placed flexor carpi ulnaris, palmaris longus, and flexor carpi radialis muscles, and the deeply placed flexor digitorum superficialis muscle) in the distal fourth of the flexor aspect of the left forearm. The muscle exhibited two strata of muscle fibers at its origin. The superficial stratum was a thin layer of transversely running fibers confined to the forearm, which has not been previously reported. The deep stratum, a thick layer of longitudinally running fibers, formed the bulk of the muscle. It traversed Guyon's canal superficial to the ulnar nerve and vessels to reach the hypothenar eminence. Its course through Guyon's canal could be a cause for ulnar tunnel syndrome. The ulnar nerve trunk innervated not only the anomalous flexor digiti minimi brevis muscle, but also abductor digiti minimi and palmaris brevis. This may be due to the common phylogeny of these three muscles from the same muscle mass.

Dual sensory innervation of the dorsum of the thumb.

The value of the thumb has been described as being almost equal to the rest of the fingers combined (Decker and du Plessis, eds. 1986, Lee McGregor's synopsis of surgical anatomy. 12th ed. p 496). Normal hand function is dependent upon the integrity of both the sensory and motor innervation of the thumb. A thorough knowledge of normal and anomalous sensory innervation of the digits has clinical application because of the increased use of local anesthesia and developments in plastic surgery involving the skin of the digits. Herein is reported an unusual variation in the sensory innervation of the thumb in an adult cadaver. The normal innervation of the dorsum of the thumb is reviewed, and the clinical importance of this variation is discussed.

Experience of anatomy demonstrators in Tamil Nadu, India.

Questionnaires were sent to 118 previous holders of demonstrator posts in anatomy at the Christian Medical College, Vellore, India, in order to determine the role of these posts in the medical profession. Sixty-three (94%) of the respondents had postgraduate medical qualifications. Forty-four (66%) of the respondents were surgeons, and 23 (34%) were in non-surgical fields. Thirty-eight (57%) had jobs that involved teaching. Almost all the respondents found the teaching experience useful in their careers and especially those respondents who had qualified in surgical specialties rated their experience reviewing anatomy very highly. The usefulness of this posting is discussed.

Significance of the role of self-study and group discussion.

The study of anatomy is experiencing a reduction in course duration and content, lecture and dissection hours, and number of lectures and examinations. This necessitates that medical students develop skills for self-study. Toward that end, a self-study module in basic anatomy was tested. Fifty-seven new entrants were given a pretest (Pretest A) containing a questionnaire on basic anatomy. Then, in three groups each of 11 and two groups each of 12, they learned basic anatomy from recommended books in the library by self-study for 2 hours. They discussed what they had learned among their group members during a practical exercise, followed by a posttest (Posttest A). A control group of 57 new entrants during another year was given the same pretest (Pretest B) and a lecture on basic anatomy. Then, without opportunity for self-study, they were given a posttest (Posttest B). The answers were scored out of 40. The students' mean mark in Pretest A was poor. All the groups performed well in the practical exercise. In Posttest A, the mean mark increased significantly (P < 0.001), by 9.4. It shows that self-study and group discussions significantly helped the students in construction of core anatomical knowledge as well as the acquisition, assimilation, and application of anatomical concepts and content. The mean mark in Pretest B was also poor. In Posttest B, the mean mark increased significantly (P < 0.001), by 14.2. This indicates that the traditional teaching session is also useful and serves to advance student knowledge. Thus our innovative study module can create a positive learning environment and can become an alternative to traditional instruction in teaching anatomical terminology and basic anatomy.

Introduction to histology through the use of familiar objects: innovative teaching module.

To introduce first-year medical students to fundamental concepts in histology and facilitate interpretation of two-dimensional images in the context of the three-dimensional nature of the object, a simple teaching module consisting of active exercises plus group discussions, using familiar objects from everyday use, was planned. In the process of mentally reconstructing sections through familiar objects, and representing in diagrams the appearance of these sections, students learned the use of common histology terms; the value of studying sections in series and at different planes; and spatial relationships of a) a nucleus within a cell, and b) tissue components within solid and hollow organs. Their understanding of these concepts was found to be good when evaluated by a multiple-choice-questions test, suggesting that this is an effective method for introducing beginners to fundamentals of histology.

Bony markers at the distal end of the radius for estimating handedness and radial length.

Measurements of the size of the bony markers at the distal end of the radius as well as the length of the radius in 61 left and 64 right dry radii were statistically analyzed. Since 90-95% of the general population is right-handed, as based on differences in the size of the right sided markers relative to the left, it is proposed that the greater distance between the dorsal tubercle and styloid process and the greater dorso-palmar diameter of the carpal articular surface opposite the dorsal tubercle are indicative of right-handedness. The length of the radius correlated with: the radio-ulnar transverse diameter at the distal end; the distance between the dorsal tubercle and the styloid process; the dorso-palmar diameter of the distal end opposite the dorsal tubercle; the dorso-palmar diameter of the carpal articular surface opposite to the dorsal tubercle; the dorso-palmar diameter of the distal end opposite the medial margin of the groove for the extensor pollicis longus; the dorso-palmar diameter of the distal end opposite the floor of the groove for the extensor pollicis longus and, finally, the height of the dorsal tubercle in relation to the posterior margin of the carpal articular surface (P < 0.001). Regression equations of the length of the radius for these markers have been derived.