Part 44

Action.—Adducts the thigh.

=Adductor Magnus= (Fig. 24, No. 18). Location.—Posterior femoral region.

Origin.—From the fine constituting the lower boundary of the ischiatic fossa on the outer lateral part of the pelvis.

Insertion.—The fibers pass downward and are inserted to the superior curve of the internal femoral condyle. The internal head of the gastrocnemius blends with this muscle just above its attachment.

Shape.—Long, narrow.

Relations.—Posteriorly to the adductor magnus and anteriorly to the semimembranosus.

Action.—Strongly adducts the thigh.

THE TIBIAL GROUP

Gastrocnemius Peroneus longus Extensor longus digitorum Tibialis posticus Flexor longus hallucis Flexor perforatus annularis primus pedis Flexor perforatus medius secundus pedis Flexor perforans digitorum profundus Soleus Tibialis anticus Extensor hallucis brevis Flexor perforatus indicis secundus pedis Flexor perforatus medius primus pedis Flexor perforatus indicis primus pedis Extensor brevis digitorum Flexor hallucis brevis Extensor annularis brevis

=Gastrocnemius= (Fig. 23, No. 11). Location.—Posterior tibial region.

Origin.—There are three heads: the internal, the external, and the tibial. The external head extends by a short, flattened, strong tendon from the postero-external part of the external condyle of the femur; the internal head extends from the outer surface of the inner condyle of the femur; and the tibial head extends from the entire inner rim of the tibial summit and from the free edge of the adjacent crest.

Insertion.—At the lower fourth of the tibial shaft, terminates in a broad, flat tendon which passes over the shallow, longitudinal groove of the tibial cartilage, and, crossing the tibio-tarsal joint, is inserted to the posterior surface of the hypotarsus of the metatarsal bone, and finally, below this point, merges into the podothecal sheath confining the flexor tendons.

Shape.—Large, fleshy, somewhat cone-shaped with the base upward.

Relations.—The posterior fleshy muscle of the post-tibial region located anterior to the soleus.

Action.—Extends the metatarsus on the tibia.

=Soleus= (Fig. 25, No. G, 1). Location.—The posterior tibial region.

Origin.—From the posterior part of the head of the tibia.

Insertion.—By a long slender tendon to the proximal end and toward the inner angle of the tibial cartilage, some of the fibers passing to the tendon of the gastrocnemius.

Shape.—Small, flattened.

Relations.—Anteriorly, with the flexor perforans digitorum profundus and posteriorly, with the gastrocnemius.

Action.—Similar to that of the gastrocnemius.

=Peroneus Longus= (Fig. 23, No. 12). Location.—Antero-lateral tibial region.

Origin.—From the raised crest in front of the head of the tibia, and from the fascia that covers the outer side of the knee-joint.

Insertion.—The fibers, passing downward, then downward and outward, terminate in a small tendon at the lower third of the tibia. This tendon bifurcates just above the tibial condyles at the outer part of the limb, the shorter and stronger attaches to the fibrous fascia covering the tibial cartilage, the other merging with the tendon of the flexor perforatus medius primus pedis about 1 centimeter below the hypotarsus of the tarso-metatarsus.

Relations.—Covers over all the muscles of the anterior tibial region.

Shape.—A broad muscular sheet.

Action.—Assists the flexor perforatus medius primus pedis.

=Tibialis Anticus= (Fig. 24, No. 22). Location.—In the anterior tibial region.