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9: The Appendicular Muscles

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    12529
      • Muscles of the rotator cuff

        Information

        The rotator cuff is the name given to the group of four muscles that are largely responsible for the ability to rotate the arm. Three of the four rotator cuff muscles are deep to the deltoid and trapezius muscles and cannot be seen unless those muscles are first removed and one is on the anterior side of the scapula bone and cannot be seen from the surface.

        On the anterior side of scapula bone is a single muscle, the subscapularis. It is triangular in shape and covers the entire bone. Its origin is along the fossa that makes up most of the “wing” of the scapula and it inserts on the lesser tubercle of the humerus bone. The subscapularis muscle is shown in Figure 9.1.

        image

        Figure 9.1. The subscapularis muscle of the rotator cuff, in red, anterior view.

        On the posterior side of the scapula bone are the other three muscles of the rotator cuff. All three insert on the greater tubercle of the humerus, allowing them, in combination with the subscapularis, to control rotation of the arm. The supraspinatus muscle is above the spine of the scapula. The infraspinatus muscle is below the spine of the scapula. The relatively

        thin teres minor muscle is the most inferior of the rotator cuff muscles. The three posteriorly- positioned muscles of the rotator cuff are shown in Figure 9.2.

        image

        Figure 9.2. The muscles of the rotator cuff and arm, posterior view.

        The teres major muscle has its origin on the scapula, like the rotator cuff muscles, but is not involved in rotating the arm. It inserts lower on the humerus than the rotator cuff muscles and is involved in adducting the arm (bringing it closer to the midline of the body.)

        LAB 9 EXERCISES 9-1

        1. Using the full-scale arm model, locate and identify all four muscles of the rotator cuff, as well as the deltoid muscle and the teres major muscle.

        2. The following are muscles of arm rotation and adduction. For each, give its origin(s) and insertion(s) and whether or not it is part of the rotator cuff.

        Muscle

        Origin(s)

        Insertion(s)

        Part of rotator cuff?

        Subscapularis

        Supraspinatus

        Infraspinatus

        Teres major

        Teres minor

        Deltoid

        LICENSES AND ATTRIBUTIONS

        CC LICENSED CONTENT, ORIGINAL

      • A&P Labs. Authored by: Ross Whitwam. Provided by: Mississippi University for Women. Located at: http://www.muw.edu. License: CC BY-SA: Attribution-ShareAlike

        CC LICENSED CONTENT, SPECIFIC ATTRIBUTION

      • Figure 9.1. The subscapularis muscle of the rotator cuff, in red, anterior view.. Authored by: Was a bee. Provided by: Images in Figure 9.1 were made out of, or made from, content published in a BodyParts3D/Anatomography web site. The content of their website is published under the Creative Commons Attribution 2.1 Japan license. The author and licenser of the contents is http://lifesciencedb.jp/bp3d/?lng=en.. Located

        at: https://commons.wikimedia.org/wiki/F...le_frontal.png. License: CC BY-SA: Attribution-ShareAlike

      • Figure 9.2. The muscles of the rotator cuff and arm, posterior view.. Authored by: OpenStax College. Located

        at: http://cnx.org/resources/e5ba9b5bb7343a347f55336ebd7a61f3b35b0cdc/1119_Muscles_that_Move_the_Humerus.jpg. Lice nse: CC BY-SA: Attribution-ShareAlike

        image

        158

        Muscles of the upper arm

        Information

        Anatomists refer to the upper arm as just the arm or the brachium. (The lower arm is the forearm or antebrachium.) There are three muscles on the upper arm that are parallel to the long axis of the humerus, the biceps brachii, the brachialis, and the triceps brachii.

        The biceps brachii is on the anterior side of the humerus and is the prime mover (agonist) responsible for flexing the forearm. It has two origins (hence the “biceps” part of its name), both of which attach to the scapula bone. It inserts on the radius bone. The biceps brachii has two synergist muscles that assist it in flexing the forearm. Both are found on the anterior side of the arm and forearm. One of these is the brachioradialis muscle which is largely on the forearm (see the next section) and the other is the brachialis, which is largely on the upper arm. The brachialis muscle is deep to the biceps brachii and both its origin and its insertion are more distal to the shoulder than its equivalents on the biceps brachii. Like the biceps brachii the origin of the brachialis is on the humerus. Parts on the brachialis can be seen peeking out from under the biceps brachii, especially lower on the arm. The locations of these three muscles are shown in Figure 9.3.

        image

        Figure 9.3. The muscles of the arm.

        On the posterior side of the arm is the triceps brachii muscle. It the antagonist to the biceps brachii. When the triceps brachii contracts it extends the forearm, undoing any flexing brought about by contractions of the biceps brachii. As a result, when the triceps brachii is contracted, the biceps brachii and its synergists must be relaxed, and vice versa. The triceps brachii has three origins, called the long head, the lateral head, and the medial head. Figure 9.4 shows the three origins of the triceps brachii in different colors. It is easiest to view the triceps brachii from the posterior, but the medial head and its origin are deep to the lateral head and the long head, and so is the medial head of the triceps brachii is partially obscured from the posterior.

        image

        Figure 9.4. The three heads of the triceps brachii color-coded to distinguish them. Keep in mind, despite the

        different colors all three are parts of the same one muscle.

        LAB 9 EXERCISES 9-2

        1. Using the full-scale arm model, locate and identify the biceps brachii, brachialis, and triceps brachii muscles.

        2. The following are muscles of arm rotation and adduction. For each, give its origin(s) and insertion(s).

        Muscle

        Origin(s)

        Insertion(s)

        Biceps brachii

        Brachialis

        Triceps brachii

        CC LICENSED CONTENT, ORIGINAL

      • A&P Labs. Authored by: Ross Whitwam. Provided by: Mississippi University for Women. Located at: http://www.muw.edu. License: CC BY-SA: Attribution-ShareAlike

        CC LICENSED CONTENT, SPECIFIC ATTRIBUTION

      • Figure 9.3. The muscles of the arm.. Authored by: OpenStax College. Located

        at: http://cnx.org/resources/6669b272a691b9377071de429a1336fec0469a5c/1120_Muscles_that_Move_the_Forearm.jpg. Lice nse: CC BY-SA: Attribution-ShareAlike

      • Figure 9.4. The three heads of the triceps brachii color-coded to distinguish them. Keep in mind, despite the different colors all three are parts of the same one muscle.. Authored by: Was a bee. Provided by: Images in Figure 9.4 were made out of, or made from, content published in a BodyParts3D/Anatomography web site. The content of their website is published under the Creative Commons Attribution 2.1 Japan license. The author and licenser of the contents is http://lifesciencedb.jp/bp3d/?lng=en. Located

        at: https://commons.wikimedia.org/wiki/F...nimation02.gif. License: CC BY-SA: Attribution- ShareAlike

        Muscles of the lower arm and hand

        Information

        Anatomists refer to the lower arm as the forearm or antebrachium. The musculature of the forearm is complicated. Figure 9.5 shows the muscles of the forearm.

        image

        Figure 9.5. Muscles of the forearm.

        Figure 9.6 shows the muscles of the hands.

        image

        Figure 9.6. The muscles of the hands.

        LAB 9 EXERCISES 9-3

        1. Using the full-scale arm model, locate and identify the muscles of the forearm selected by your instructor.

        2. Write down the muscles of the forearm selected by your instructor and, for each, give the location of that muscle and what effect contracting that muscle has.

        Muscle

        Location & description

        Action(s)

        LICENSES AND ATTRIBUTIONS

        CC LICENSED CONTENT, ORIGINAL

      • A&P Labs. Authored by: Ross Whitwam. Provided by: Mississippi University for Women. Located at: http://www.muw.edu. License: CC BY-SA: Attribution-ShareAlike

        CC LICENSED CONTENT, SPECIFIC ATTRIBUTION

      • Figure 9.5. Muscles of the forearm.. Authored by: OpenStax College. Located

        at: https://cnx.org/resources/6669b272a6...he_Forearm.jpg. Lic ense: CC BY-SA: Attribution-ShareAlike

      • Figure 9.6. The muscles of the hands.. Authored by: OpenStax College. Located

        at: https://cnx.org/resources/49b609261e...f_the_Hand.jpg. Licen se: Public Domain: No Known Copyright

        Muscles of the hips and thighs

        Information

        There are three layers of gluteal muscles on the posterior hips, just like there are three layers of muscles in the abdominal trunk. The largest of them is the most superficial muscle,

        the gluteus maximus. Its origin is on the ilium of the coxal bone, and it inserts part-way down the shaft of the femur. It helps maintain erect posture, abducts the thigh, and rotates the thigh outward.

        Below the gluteus maximus is the smaller gluteus medius. The gluteus medius muscle helps abducts the thigh along with the gluteus maximus, but can rotate the thigh inward where the gluteus maximus rotates the thigh outward.

        The below the gluteus medius are several muscles, one of which is the gluteus minimus, the smallest of the gluteal muscles. It is a synergist for the gluteus medius.

        image

        Figure 9.7. The three layers of gluteal muscles, gluteus maximus, gluteus medius, gluteus minimus.

        Like the forearm, the upper leg, or thigh, has a dense arrangement of many muscles. On the anterior side, the most prominent of the muscles are the sartorius muscle and the four muscles that make up quadriceps muscle group (the “quads”.)

        The quadriceps sounds like it should be just one muscle, akin to the triceps brachii, but it is a group of four muscles, three visible on the surface, and the fourth obscured. The three surface muscles of the quadriceps are the rectus femoris in the center, the vastus medialis on the medial side, and the vastus lateralis on the lateral side. These three muscles are visible in Figure 9.9. Below the rectus femoris and largely hidden by it is the vastus intermedius. This

        muscle’s position can be seen in Figure 9.9. The four muscle of the quadriceps all extend the lower leg, and the rectus femoris additionally can flex the thigh at the hip.

        image

        Figure 9.9. The superficial muscles of the thigh.

        image

        Figure 9.9. The quadriceps group of four muscles. The view on the left has the rectus femoris cut away to show

        the vastus intermedius which is below it.

        The sartorius muscle is a distinctively long and thin muscle that crosses the thigh diagonally. It is visible in Figure 9.9. Sartorius comes from the Latin for tailor, and this is sometimes called the tailor’s muscle, although the reasons for the nickname are obscure. It may be because the shape of the muscle is thin and long, like a tailor’s measuring tape; it may be because it is close to the inseam a tailor measures when tailoring pants, or it may be because it helps bring about the cross-legged position that tailors often adopt when working.

        In the posterior thigh the bulk of the musculature is made up of three long muscles that are collectively called the hamstrings. The origin of this nickname is obscure, but it may have to do with the practice of butchers of hanging the thighs of butchered animals such as pig (the “hams”) by the tendons of these three muscles. Move from the medial edge to the lateral edge of the posterior thigh, the hamstring muscles are the semimembranous muscle,

        the semitendinosus muscle, and the biceps femorismuscle. Notice the upper leg has a “biceps” muscle just like the upper arm does. This is why you have to indicate which biceps you are taking about when discussing one or other of these muscles. On the medial edge of the posterior thigh is the gracilis muscle. It is also visible on the medial edge of the thigh from the anterior.

        image

        Figure 9.10. The muscles of the posterior thigh.

        image

        Figure 9.11. The hamstring group of muscles of the posterior thigh.

        LAB 9 EXERCISES 9-4

        1. Using the full-scale leg model, locate and identify the muscles of the thigh listed in the table below.

        2. Write down the muscles of the thigh in the table below and, for each, give the location of that muscle and what effect contracting that muscle has.

        Muscle

        Location & description

        Action(s)

        Rectus femoris

        Vastus intermedius

        Vastus medialis

        Vastus lateralis

        Sartorius

        Gracilis

        Semimembranosus

        Semitendinosus

        Biceps femoris

        LICENSES AND ATTRIBUTIONS

        CC LICENSED CONTENT, ORIGINAL

      • A&P Labs. Authored by: Ross Whitwam. Provided by: Mississippi University for Women. Located at: http://www.muw.edu. License: CC BY-SA: Attribution-ShareAlike

        CC LICENSED CONTENT, SPECIFIC ATTRIBUTION

      • Figure 9.7. The three layers of gluteal muscles, gluteus maximus, gluteus medius, gluteus minimus.. Authored by: Beth ohara~commonswiki. Located at: https://commons.wikimedia.org/wiki/F..._Muscles_3.PNG. License: CC BY- SA: Attribution-ShareAlike

      • Figure 9.7. The three layers of gluteal muscles, gluteus maximus, gluteus medius, gluteus minimus.. Authored by: Beth ohara~commonswiki . Located at: https://commons.wikimedia.org/wiki/F..._Muscles_1.PNG. License: CC BY- SA: Attribution-ShareAlike

      • Figure 9.9. The superficial muscles of the thigh.. Authored by: OpenStax College. Located

        at: https://cnx.org/resources/49a26b0c63...e_the_Femur.jp

        1. License: CC BY-SA: Attribution-ShareAlike

      • Figure 9.9. The quadriceps group of four muscles. The view on the left has the rectus femoris cut away to show the vastus intermedius which is below it.. Authored by: CFCF. Provided by: Images in Figure 9.4 were made out of, or made from, content published in a BodyParts3D/Anatomography web site. The content of their website is published under the Creative Commons Attribution 2.1 Japan license. The author and licenser of the contents is http://lifesciencedb.jp/bp3d/?lng=en. Located

        at: https://en.wikipedia.org/wiki/Quadri...driceps_3D.gif. License: CC BY-SA: Attribution-ShareAlike

      • Figure 9.9. The quadriceps group of four muscles. The view on the left has the rectus femoris cut away to show the vastus intermedius which is below it.. Authored by: Athikhun.suw. Located

        at: https://commons.wikimedia.org/wiki/F...ius_muscle.jpg. License: CC BY-SA: Attribution- ShareAlike

      • Figure 9.10. The muscles of the posterior thigh.. Authored by: OpenStax College. Located

        at: http://cnx.org/resources/49a26b0c6351a2052a16c4fcd339bc092505e492/1122_Gluteal_Muscles_that_Move_the_Femur.jp

        1. License: CC BY-SA: Attribution-ShareAlike

      • Figure 9.11. The hamstring group of muscles of the posterior thigh.. Authored by: BruceBlaus. Located

        at: https://commons.wikimedia.org/wiki/F..._Hamstring.png. License: CC BY-SA: Attribution-ShareAlike

        PUBLIC DOMAIN CONTENT

      • Figure 9.7. The three layers of gluteal muscles, gluteus maximus, gluteus medius, gluteus minimus.. Authored by: Dr. Johannes Sobotta. Provided by: Sobotta's Human Anatomy 1909. Located at: https://commons.wikimedia.org/wiki/F...Sobo_1909_575- 576.png. License: Public Domain: No Known Copyright

        Muscles of the lower leg and foot

        Information

        The muscles of the lower leg, called simply the leg by anatomists, largely move the foot and toes. The major muscles of the lower leg, other than the gastrocnemius which is cut away, are shown in Figure 9.12. The gastrocnemius muscle has two large bellies, called the medial head and the lateral head, and inserts into the calcaneus bone of the foot via its calcaneal tendon (also known as the Achilles tendon.) The soleus muscle is deep to the gastrocnemius, and the two muscles serve together as the calf of the leg. The gastrocnemius muscle is shown in Figure 9.13.

        image

        image

        Figure 9.13. The gastrocnemius muscle

        Figure 9.14 shows the muscles of the feet.

        image

        LAB 9 EXERCISES 9-5

        1. Using the full-scale leg model, locate and identify the muscles of the lower leg listed in the table below.

        2. For each of the muscles of the leg, give the location of that muscle and what effect contracting that muscle has.

          Muscle

          Location & description

          Action

          Gastrocnemius

          Soleus

          Tibialis anterior

          Fibularis longus

          LICENSES AND ATTRIBUTIONS

          CC LICENSED CONTENT, ORIGINAL

      • A&P Labs. Authored by: Ross Whitwam. Provided by: Mississippi University for Women. Located at: http://www.muw.edu. License: CC BY-SA: Attribution-ShareAlike

        CC LICENSED CONTENT, SPECIFIC ATTRIBUTION

      • Figure 9.12. The muscles of the lower leg.. Authored by: OpenStax College. Located

        at: http://cnx.org/resources/adeb0a7399f...Move_the_Foot_ and_Toes.jpg. License: CC BY-SA: Attribution-ShareAlike

      • Figure 9.13. The gastrocnemius muscle. Authored by: Nikai . Located

        at: https://commons.wikimedia.org/wiki/F...trocnemius.png. License: CC BY-SA: Attribution-ShareAlike

      • Figure 9.14. The muscles of the feet.. Authored by: OpenStax College. Located

    at: https://cnx.org/resources/747c45c729...f_the_Foot.jpg. Licens e: CC BY-SA: Attribution-ShareAlike

    8

    9

    10

    5

    7

    11

    6

    image

    image

    image

    IDENTIFY THE MUSCLES OF THE ARM

    1

    2

    3

    4

    LAB 9 EXERCISES 9-7

    IDENTIFY THE DEEP MUSCLES OF THE ARM &

    SHOULDER

    1

    5

    2

    3

    6

    4

    7

    LAB 9 EXERCISES 9-9

    image

    IDENTIFY MUSCLES OF THE ABDOMEN & LEG

    1

    2

    3

    4

    5

    6

    7

    8

    LAB 9 EXERCISES 9-9

    image

    image

    11

    *connective tissue

    10

    3

    6

    7

    9

    IDENTIFY THE MUSCLES OF THE THIGH & LEG

    1

    4

    5

    2

    12

    1

    LAB 9 EXERCISES 9-10

    IDENTIFY THE MUSCLES OF THE THIGH

    4

    5

    6

    3

    image

    image

    image

    2

    LAB 9 EXERCISES 9-11

    MUSCLES OF THE LEG

    1

    3

    5

    2

    4

    MODELS: Arm and Leg

    Name

    Action

    Origin

    Insertion

    Forearm movers

    Biceps brachii

    Flexes arm at elbow

    Scapula

    Radius

    Brachialis

    Flexes arm at elbow

    Humerus

    Ulna

    Triceps brachii

    Extends arm at elbow

    Humerus & Scapula

    Ulna

    Pronator teres

    Pronates forearm

    Humerus & Ulna

    Radius

    Supinator

    Supinates forearm

    Humerus & Ulna

    Radius

    Brachioradialis

    Flexes arm at elbow (beer raising)

    Humerus

    Radius

    Hand & finger movers

    Flexor carpi radialis

    Flexes & abducts hand at wrist

    Humerus

    Carpal Bones

    Palmaris longus

    Flexes hand at wrist

    Humerus

    Carpal Bones

    Flexor carpi ulnaris

    Flexes & adducts hand at wrist

    Humerus

    Carpal Bones

    Extensor carpi radialis

    Extends & abducts hand at wrist

    Humerus

    Carpal Bones

    Extensor digitorum

    Extends fingers

    Humerus

    Digits

    Extensor carpi ulnaris

    Extends & adducts hand at wrist

    Humerus

    Carpal Bones

    Muscles of the thigh & leg

    Flexor digitorum longus

    Flexes toes

    Tibia

    Digits

    Flexor hallucis longus

    Flexes hallux

    Fibula

    big toe

    Tibialis anterior

    Dorsiflex foot at ankle, inverts foot

    Tibia

    1st metatarsal

    Extensor digitorum longus

    Extends toes

    Tibia & fibula

    digits

    Fibularis (peroneus) longus

    plantarflexes

    Tibia & fibula

    1st metatarsal

    Gastrocnemius

    plantarflexes

    Femur

    calcaneous

    Soleus

    Plantarflexes

    Femur & tibia

    calcaneous

    Name

    Action

    Origin

    Insertion

    Muscles of the leg & thigh

    Psoas major

    Flexes thigh at hip (also flexes vertebral column)

    Thoracic and Lumbar Vertebrae

    Femur

    Iliacus

    Flexes thigh at hip

    Ilium

    Femur

    Adductor longus

    Adducts thigh at hip

    Pubis

    Femur

    Adductor magnus

    Adducts thigh at hip

    Pubis and Ischium

    Femur

    Gracilis

    Adducts thigh at hip

    Pubis

    Tibia

    Gluteus maximus

    Extends thigh at hip, rotates thigh laterally

    Ilium, Sacrum and Coccyx

    Femur, ITB

    Gluteus medius

    Abducts thigh at hip, rotates thigh medially

    Ilium

    Femur

    Sartorius

    Flexes leg at knee (also flexes + rotates thigh at hip)

    Ilium

    Tibia

    Tensor fascia latae

    tenses the ITB, supports knee

    Ilium

    ITB

    Iliotibial band (IT band/tract)

    Not a muscle

    n/a

    n/a

    Quadriceps femoris

    Rectus femoris

    Extends leg at knee (also flexes thigh at hip)

    Ilium

    Tibia

    Vastus lateralis

    Extends leg at knee

    Femur

    Tibia

    Vastus medialis

    Extends leg at knee

    Femur

    Tibia

    Vastus intermedius

    Extends leg at knee

    Femur

    Tibia

    Hamstrings

    Biceps femoris

    Flexes leg at knee (also extends thigh at hip)

    Ischium & Femur

    Tibia & Fibula

    Semitendinosus

    Flexes leg at knee (also extends thigh at hip)

    Ischium

    Tibia

    Semimembranosus

    Flexes leg at knee (also extends thigh at hip)

    Ischium

    Tibia