Koplas Monica C, Grooff Paul, Piraino David, Recht Michael
Imaging Institute, Cleveland Clinic Foundation, Hb6, 9500 Euclid Ave, Cleveland, OH 44195, USA.
Skeletal Radiol. 2009 Apr;38(4):349-54. doi: 10.1007/s00256-008-0606-5. Epub 2008 Nov 11.
The objectives of this study were to determine the frequency of a third head of the gastrocnemius and to describe the course, morphology, and insertion of the third head as seen on the basis of routine magnetic resonance (MR) imaging of the knee.
This study was a prospective study of 1,039 consecutive knee MR examinations which were performed for symptoms of pain not associated with claudication. The examinations were performed between September 2004 and January 2005 and were evaluated for the presence of an anomalous third head of the gastrocnemius and to determine its origin and course. Examinations were performed on a variety of magnets ranging from 0.2 to 1.5 T.
Of the 1,039 knees, 20 (1.9%) demonstrated an anomalous third head of the gastrocnemius which was seen arising near the midline of the posterior distal femur, between the mid and medial aspect, and joining the medial aspect of the lateral head of the gastrocnemius. The size of the third head varied from a thin threadlike muscle to a rather bulky muscle. In all of these patients, the third head coursed lateral to the popliteal vessels, and none coursed between the vessels. One additional case of a third head of the gastrocnemius was seen which joined the medial head of the gastrocnemius.
A third head of the gastrocnemius joining the lateral head is not an uncommon variant, seen in 1.9% of knee MR examinations. Most are not associated with vascular symptoms.
本研究的目的是确定腓肠肌第三头肌的出现频率，并根据膝关节常规磁共振成像描述第三头肌的走行、形态和附着点。
本研究是一项对1039例连续膝关节磁共振检查的前瞻性研究，这些检查是针对与跛行无关的疼痛症状进行的。检查在2004年9月至2005年1月期间进行，评估是否存在腓肠肌异常第三头肌，并确定其起源和走行。检查在0.2至1.5T的各种磁体上进行。
在1039例膝关节中，20例（1.9%）显示存在腓肠肌异常第三头肌，其起源于股骨远端后侧中线附近、中外侧之间，并与腓肠肌外侧头的内侧相连。第三头肌的大小从细如线状的肌肉到相当粗壮的肌肉不等。在所有这些患者中，第三头肌走行于腘血管外侧，无一例走行于血管之间。另外还发现1例第三头肌与腓肠肌内侧头相连。
腓肠肌第三头肌与外侧头相连并非罕见变异，在1.9%的膝关节磁共振检查中可见。大多数与血管症状无关。
