Page 415 - Fundamentals of anatomy physiology

402 Unit 2 Support and Movement

These muscles are best seen in posterior and lateral views often snap this tendon during a stumble or fall. Surgery may
(Figure 11–22a,b). The gastrocnemius muscle arises from two be necessary to reposition and reconnect the torn ends of the
heads located on the medial and lateral epicondyles of the femur tendon to promote healing.
just proximal to the knee. The fabella, a sesamoid bone, is occasion-
ally present within the lateral head of the gastrocnemius muscle. Deep to the gastrocnemius and soleus muscles are a pair
The gastrocnemius and soleus muscles share a common tendon, of fibularis muscles, or peroneus muscles (Figure 11–22a,b,d).
the calcaneal tendon, commonly known as the Achilles tendon. The fibularis muscles produce eversion and extension (plantar
flexion) at the ankle. Inversion is caused by the contraction of
11 &T i p s T r i c k s the tibialis (tib-e. -A-lis) muscles. The large tibialis anterior
The soleus is so named because it resembles the flat-bodied muscle flexes the ankle and opposes the gastrocnemius muscle
fish we call sole. (Figure 11–22b,c,d).

The term “Achilles tendon” comes from Greek mythology. Important digital muscles originate on the surface of the
Achilles was a warrior who was invincible but for one vulner- tibia, the fibula, or both (Figure 11–22a,b,c,d). Large synovial
able spot: the calcaneal tendon. Outside mythology, damage tendon sheaths surround the tendons of the tibialis anterior,
to the calcaneal tendon isn’t a fatal problem. Although it is extensor digitorum longus, and extensor hallucis longus
among the largest, strongest tendons in the body, its rupture muscles, where they cross the ankle joint. The positions of
is common. The applied forces increase markedly during rapid these sheaths are stabilized by superior and inferior extensor
acceleration or deceleration. Sprinters can rupture the calcaneal retinacula (Figure 11–22b,c,d).
tendon pushing off from the starting blocks, and the elderly
Intrinsic muscles of the foot originate on the tarsal and
metatarsal bones (Figure 11–23 and Table 11–19). Their con-
tractions move the toes and maintain the longitudinal arch of
the foot. p. 284

Table 11–19 Intrinsic Muscles of the Foot (Figure 11–23)

Muscle Origin Insertion Action Innervation
Flexion at metatarsophalangeal
Flexion/Extension Cuboid and lateral Proximal phalanx of joint of great toe Medial plantar
Flexor hallucis cuneiform bones great toe nerve (L4–L5)
brevis
Medial plantar
Flexor digitorum Calcaneus (tuberosity on Sides of middle Flexion at proximal interphalangeal nerve (L4–L5)
brevis inferior surface) phalanges, toes 2–5 joints of toes 2–5 Lateral plantar
Quadratus plantae Calcaneus (medial, inferior Tendon of flexor Flexion at joints of toes 2–5 nerve (L4–L5)
Lumbrical (4) surfaces) digitorum longus Medial plantar nerve (1),
Tendons of flexor Insertions of extensor Flexion at metatarsophalangeal joints; lateral plantar nerve (2–4)
Flexor digiti minimi digitorum longus digitorum longus extension at proximal interphalangeal
brevis joints of toes 2–5 Lateral plantar
Extensor digitorum Base of metatarsal bone V Lateral side of proximal Flexion at metatarsophalangeal joint of nerve (S1–S2)
brevis phalanx of toe 5 toe 5 Deep fibular
Extensor hallucis Calcaneus (superior and Dorsal surfaces of Extension at metatarsophalangeal nerve (L5–S1)
brevis lateral surfaces) toes 1–4 joints of toes 1–4 Deep fibular
Adduction/Abduction Superior surface of anterior Dorsal surface of Extension of great toe nerve (L5–S1)
Adductor hallucis calcaneus the base of proximal
Abductor hallucis phalanx of great toe Lateral plantar
Plantar interosseus (3) nerve (S1–S2)
Dorsal interosseus (4) Bases of metatarsal bones Proximal phalanx of Adduction at metatarsophalangeal Medial plantar
II–IV and plantar ligaments great toe joint of great toe nerve (L4–L5)
Abductor digiti minimi Calcaneus (tuberosity on Medial side of proximal Abduction at metatarsophalangeal Lateral plantar
inferior surface) phalanx of great toe joint of great toe nerve (S1–S2)
Bases and medial sides of Medial sides of toes 3–5 Adduction at metatarsophalangeal Lateral plantar
metatarsal bones joints of toes 3–5 nerve (S1–S2)
Sides of metatarsal bones Medial and lateral sides Abduction at metatarsophalangeal
of toe 2; lateral sides of joints of toes 3 and 4 Lateral plantar
As above toes 3 and 4 nerve (L4–L5)
Lateral side of proximal Abduction at metatarsophalangeal
phalanx, toe 5 joint of toe 5