ABSTRACT
The relationship between muscle strength and oestrogen is ambiguous and is still largely unresolved. The evidence for and against an effect of oestradiol on determinants of muscle function is equivocal and often contradictory. The bulk of the research in this area was performed during the eighties and nineties, using models of reproductive functioning such as; the menstrual cycle, the menopause and hormone replacement therapy, oral contraceptives and in vitro fertilisation treatment, to alter the female hormonal milieu. In the last decade, approximately 15 papers have demonstrated a relationship, both positive and negative, between the concentration of oestrogen and skeletal muscle strength. Conversely, around 20 articles have not shown any influence of oestrogen on a number of strength measures. The majority of these studies were performed using post-menopausal and eumenorrheic females. Most current studies use hormonal assays to confirm oestrogen status, however no recent studies have reported the bioavailable concentration of oestradiol. Similarly, no research in the last 10 years has used in vitro fertilisation treatment or pregnancy as acute and chronic models of supra-physiological changes in sex hormone concentration. Future work should focus on performing meta-analyses on each of the key components of muscle strength in an attempt to elucidate a causal relationship. In addition, models of reproductive functioning that cause the greatest magnitude of change to oestrogen concentration should be used, while controlling as many confounding factors as possible.
Subject(s)
Humans , Women , Estrogens , Muscle Strength , HormonesABSTRACT
Clinical and surgical importance of the levator scapulae muscle (LSM) requires a better knowledge of its anatomic variation mainly because of the possibility of new findings related to the embryologic development. This article reports a case of a left-sided LSM with atypical attachments in a 58-year-old preserved Caucasian female body. The muscle presented a bifurcation at its midpoint downward path. Its medial band attached to the anterior aspect of the left rhomboideus major muscle while its left band was fixed in the superior angle of the scapula after releasing a muscle expansion to the serratus anterior muscle. The morphometric analysis revealed LSM maximal width of 3.6 cm, bifurcation point located 6.6 cm apart from the C1 vertebral attachment; medial band legth of 5.7 cm and lateral band width of 2.1cm. Regarding anatomic variations of the LSM, they may remain unnoticed or perhaps contribute for pathologic conditions of the neck and the back...
Debido a la importancia clínica y quirúrgica del músculo elevador de la escápula, se hace necesario conocer mejor sus variaciones, principalmente la posibilidad de encontrar hallazgos relacionados con su desarrollo embriológico. Se presenta el caso de un músculo elevador de la escápula del lado izquierdo encontrado en un cadáver de sexo femenino de 58 años. El músculo elevador de la escáula presentaba una bifurcación en el punto medio en su trayectoria más baja. La banda medial se fijaba en la parte anterior del músculo romboides mayor izquierdo; mientras que su banda lateral se fijaba en el ángulo superior de la escápula después de enviar una expansión hasta el músculo serrato anterior. El análisis morfométrico reveló un ancho máximo de 3,6 cm, punto de bifurcación situado 6,6 cm bajo la inserción vertebral C1; longitudes de la banda medial 5,7 cm y lateral de 2,1cm. Las variaciones anatómicas del músculo elevador de la escápula pueden pasar inadvertidas, pero también pueden contribuir con algunas condiciones patológicas del cuello y espalda...