Test your knowledge: various anatomy.
Which of the sentences below are correct, and which are false?
A The proximal tibiofibular joint surfaces are normally flat formed.
B The talo-calcaneo joint, part of the subtalar joint, has 2 different articular surfaces.
C The palmaris longus muscle is always present in healthy subjects
D The flexor carpi ulnaris muscle is only attached at the os pisiforme
E The semimembranosis, sartorius and gracilis muscle are forming the pes anserinus
F An absent anterior superior labrum is called ‘Buford-complex’.
The answers can be found underneath the image below.
A False. Only in 10-33% of the joint, the surfaces are flatformed. The most common type of surface is the trochoid type.
B True. The talo-calcaneo joint has in 37% of investigated subjects 3 distinct facets on the calcaneus. A missing anterior facet revealed in 10% and 53% of subjects shows fusion of the anterior and middle facets on the calcaneus. So, in most of the observed cases there are 2 different articular surfaces ( Shahabpour et al., 2011).
C. False. It is not. There is an absence of the Palmaris longus muscle in 3%-15% of the investigated population (n=519). There are differences in ethnicity. African American and Asian have significant fewer absence of the Palmaris longus muscle than other ethnical groups (Thompson et al., 2001).
D. False. The attachment of the flexor carpi ulnaris is more complex. Its insertion is into the pisiform bone and then via ligaments into the hamate bone and the 5th metacarpal bone, acting to flex and adduct the wrist joint.
E. False. Instead of the semimembranosis muscle, the semitendinosis muscle is part of the pes anserinus.
F. True. It is a normal variantion of the labrum. There is an absence of the anterior superior labrum and a presence of a cordlike middle glenohumeral ligament. This normal variation may be mistaken for a detached labrum/avulsed labrum (Tirman et al., 1996). Read more about the labrum here.