The caudofemoralis (from the Latin ''cauda'', tail and ''femur'', thighbone) is a muscle found in the pelvic limb of mostly all animals possessing a tail. It is thus found in nearly all

tetrapod Tetrapods (; ) are four-limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant and extinct amphibians, sauropsids ( reptiles, including dinosaurs and therefore birds) and synapsids ( pelycosaurs, extinct t ...

Location

The caudofemoralis spans plesiomorphically between femur (thigh) and tail; in mammals it is reduced and found directly posterior/ caudal to the gluteus maximus and directly anterior/ cranial to the

biceps femoris The biceps femoris () is a muscle of the thigh located to the posterior, or back. As its name implies, it has two parts, one of which (the long head) forms part of the hamstrings muscle group. Structure It has two heads of origin: *the ''long h ...

Origin and insertion

The caudofemoralis originates from the transverse processes of the second, third and fourth caudal
vertebrae The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristi ...
. The caudodistal portion of the muscle in mammals lies deep to the proximocranial portion of the Biceps femoris; near the middle of the
thigh In human anatomy, the thigh is the area between the hip ( pelvis) and the knee. Anatomically, it is part of the lower limb. The single bone in the thigh is called the femur. This bone is very thick and strong (due to the high proportion of ...
, the caudofemoralis gives rise to a long, thin, and narrow
tendon A tendon or sinew is a tough, high-tensile-strength band of dense fibrous connective tissue that connects muscle to bone. It is able to transmit the mechanical forces of muscle contraction to the skeletal system without sacrificing its ability ...
that passes distally to the knee joint and inserts into the fascia lata that is anchored to the lateral border of the
patella The patella, also known as the kneecap, is a flat, rounded triangular bone which articulates with the femur (thigh bone) and covers and protects the anterior articular surface of the knee joint. The patella is found in many tetrapods, such as ...
.

Among archosaurians the caudofemoralis is divided in a ''pars pelvica/brevis'' (characterized by a pelvic origin) and a ''pars caudalis/longa'' (caudal origin), and the insertion on the femur is marked by the

fourth trochanter The fourth trochanter is a shared characteristic common to archosaurs. It is a knob-like feature on the posterior-medial side of the middle of the femur shaft that serves as a muscle attachment, mainly for the '' musculus caudofemoralis longus'' ...

(but this becomes reduced in

maniraptora Maniraptora is a clade of coelurosaurian dinosaurs which includes the birds and the non-avian dinosaurs that were more closely related to them than to ''Ornithomimus velox''. It contains the major subgroups Avialae, Deinonychosauria, Oviraptoros ...

ns and absent in birds).

Action

In mammals the caudofemoralis acts to flex the tail laterally to its corresponding side when the pelvic limb is bearing weight. When the pelvic limb is lifted off the ground, contraction of the caudofemoralis causes the limb to abduct and the shank to extend by extending the hip joint (acetabulofemoral or coxofemoral joint). In other tetrapods contraction of the caudofemoralis retracts the hindlimb.

Cited References

Vertebrate anatomy {{Muscle-stub