Sample Chapter 10 from the Textbook (35559.0K) - McGraw-Hill

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350 PART 2 Support and Movement Table 10.21 Muscles of the Thigh (see figures 10.30 and 10.32) Muscle Origin Insertion Nerve Action Anterior Compartment Quadriceps femoris (kwah′dri-seps fem′ŏ-ris) Sartorius (sar-tōr′ē-ū s) Medial Compartment Adductor brevis (a-dŭk′ter, a-dŭk′tōr brev′is) Adductor longus (a-dŭk′ter, a-dŭk′tōr lon′gŭs) Adductor magnus (a-dŭk′ter, a-dŭk′tōr mag′nŭs) Rectus femoris—anterior inferior iliac spine Vastus lateralis—greater trochanter and linea aspera of femur Vastus intermedius—body of femur Vastus medialis—linea aspera of femur Anterior superior iliac spine Pubis Patella and onto tibial tuberosity through patellar ligament Medial side of tibial tuberosity Pectineal line and linea aspera of femur Femoral Femoral Obturator Extends knee; rectus femoris also flexes hip Flexes hip and knee; rotates thigh laterally and leg medially Adducts and laterally rotates thigh; flexes hip Pubis Linea aspera of femur Obturator Adducts and laterally rotates thigh; flexes hip Adductor part: pubis and ischium Hamstring part: ischial tuberosity Adductor part: linea aspera of femur Hamstring part: adductor tubercle of femur Adductor part: obturator Hamstring part: tibial Adductor part: adducts thigh and flexes hip Hamstring part: extends hip and adducts thigh Gracilis (gras′i-lis) Pubis near symphysis Tibia Obturator Adducts thigh; flexes knee Pectineus (pek′ti-nē′ŭs) Pubic crest Pectineal line of femur Femoral and obturator Adducts thigh; flexes hip Posterior Compartment Biceps femoris (bī ′seps fem′ŏ-ris) Semimembranosus (sem′ē-mem-bră-nō′sŭs) Semitendinosus (sem′ē-ten-di-nō′sŭs) Long head—ischial tuberosity Head of fibula Long head—tibial Flexes knee; laterally rotates leg; extends hip Short head—femur Short head— common fibular Ischial tuberosity Medial condyle of tibia and collateral ligament Tibial Flexes knee; medially rotates leg; tenses capsule of knee joint; extends hip Ischial tuberosity Tibia Tibial Flexes knee; medially rotates leg; extends hip been identified based on their location in the thigh and are organized into compartments: The muscles of the anterior compartment flex the hip and/or extend the knee (see figure 10.28a); the muscles of the medial compartment adduct the thigh (figure 10.30); and the muscles of the posterior compartment extend the hip and flex the knee (figure 10.31). The anterior thigh muscles are the quadriceps femoris (fem′ŏ-ris) and the sartorius (sar-tōr′ē-ŭs; see table 10.20 and figure 10.28a). The quadriceps femoris is actually four muscles: the rectus femoris, the vastus lateralis, the vastus medialis, and the vastus intermedius. The quadriceps group extends the knee. The rectus femoris also flexes the hip because it crosses both the hip and knee joints. The quadriceps femoris makes up the large mass on the anterior thigh (see figure 10.28c). The vastus lateralis is sometimes used as an injection site, especially in infants who do not have well-developed deltoid or gluteal muscles. The muscles of the quadriceps femoris have a common insertion, the patellar tendon, on and around the patella. The patellar ligament is an extension of the patellar tendon onto the tibial tuberosity. The patellar ligament is the point that is tapped with a rubber hammer when testing the knee-jerk reflex in a physical examination. The sartorius is the longest muscle of the body, crossing from the lateral side of the hip to the medial side of the knee. As the muscle contracts, it flexes the hip and knee and laterally rotates the thigh. This is the action required for crossing the legs. The medial thigh muscles (see figure 10.30) are involved primarily in adduction of the thigh. Some of these muscles also laterally rotate the thigh and/or flex or extend the hip. The gracilis also flexes the knee.
cHAPTeR 10 Muscular System 351 Pectineus Gracilis Adductor brevis Adductor longus Adductor magnus Adductors Ischial tuberosity Adductor magnus Semitendinosus Hamstrings Biceps femoris Semimembranosus Fibula Tibia Insertion of gracilis on tibia Tibia Fibula Anterior view FiGuRe 10.30 Right Medial Thigh Muscles (Muscle names are in bold.) FiGuRe 10.31 Right Posterior Thigh Muscles Hip muscles are removed. (Muscle names are in bold.) Posterior view The posterior thigh muscles (figure 10.31), collectively called the hamstring muscles, consist of the biceps femoris, the semimembranosus (sem′ē-mem-bră-nō′sŭs), and the semitendinosus (sem′ē-ten-di-nō′sŭs; table 10.21). Their tendons are easily seen or felt on the medial and lateral posterior aspect of a slightly bent knee (figure 10.32). Ankle, Foot, and Toe Movements The muscles of the leg that move the ankle and the foot are listed in table 10.22 and illustrated in figures 10.33–10.35. These extrinsic foot muscles are divided into three groups, each located within a separate compartment of the leg: anterior, posterior, and lateral (figure 10.33). The anterior leg muscles (figure 10.34a) are extensor muscles involved in dorsiflexion and eversion or inversion of the foot and extension of the toes. The lateral muscles (figure 10.34b) are primarily everters of the foot, but they also aid plantar flexion. The fibularis brevis inserts onto the fifth metatarsal bone and everts and plantar flexes the foot. The fibularis longus crosses under the lateral four metatarsal bones to insert onto the first metatarsal bone and medial cuneiform. The fibular muscle was formerly referred to as peroneal, which means relating to the fibula; the term has now been simplified to fibular. The tendons of the fibularis muscles can be seen on the lateral side of the ankle (figure 10.34d). Shinsplints Clinical IMPaCT Shinsplints is a general term involving any one of the following conditions associated with pain in the anterior portion of the leg: 1. Excessive stress on the tibialis anterior, resulting in pain along the origin of the muscle 2. Tibial periostitis, an inflammation of the tibial periosteum 3. Anterior compartment syndrome. During hard exercise, the anterior compartment muscles may swell with blood. The overlying fascia is very tough and does not expand; thus, the nerves and vessels are compressed, causing pain. 4. Stress fracture of the tibia 2–5 cm distal to the knee Shinsplints can occur for several reasons: running with unsupportive shoes, running on a hard surface (such as concrete), or simply increasing your activity level too quickly. This injury can be treated by employing RICE and taking anti-inflammatory medicines. Runners might consider occasionally substituting a low-impact exercise, such as swimming or cycling.
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Sample Chapter 10 from the Textbook (35559.0K) - McGraw-Hill

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