13 gross anatomy

Skeletal muscles enable movement. Smiling, frowning, speaking, singing, breathing, dancing, running, and playing a musical instrument are just a few examples. Most often, purposeful movements require the coordinated action

of several skeletal muscles.

Materials

• ▶▶  Human torso model or large anatomical chart showing human musculature

• ▶▶  Human cadaver for demonstration (if available)

• ▶▶  Disposable gloves

• ▶▶  Human Musculature video (from Cadaver Dissection Video Series for Human Anatomy & Physiology, Pearson,
  ISBN: 0-321-85920-0)

• ▶▶  Tubes of body (or face) paint

• ▶▶  1” wide artist’s brushes

  For instructions on animal dissections,

  see the dissection exercises (starting on p. 695) in the cat and fetal pig editions of this manual.

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194 Exercise 13
Classification of Skeletal Muscles

Types of Muscles

Muscles that are most responsible for producing a particular movement are called prime movers, or agonists. Muscles that oppose or reverse a movement are called antagonists. When a prime mover is active, the fibers of the antagonist are stretched and in the relaxed state. Antagonists can be prime movers in their own right. For example, the biceps muscle of the arm (a prime mover of flexion at the elbow) is antagonized by the triceps (a prime mover of extension at the elbow).

Synergists aid the action of agonists either by assisting with the same movement or by reducing undesirable or unnecessary movement. Contraction of a muscle crossing two or more joints would cause movement at all joints spanned if the synergists were not there to stabilize them. For example, the muscles that flex the fingers cross both the wrist and finger joints, but you can make a fist without bending at the wrist because synergist muscles stabilize the wrist joint.

Fixators, or fixation muscles, are specialized synergists. They immobilize the origin of a prime mover so that all the tension is exerted at the insertion. Muscles that help maintain posture are fixators; so too are muscles of the back that stabi- lize or “fix” the scapula during arm movements.

Naming Skeletal Muscles

Remembering the names of the skeletal muscles is a monumen- tal task, but certain clues help. Muscles are named on the basis of the following criteria:

• Direction of muscle fibers: Some muscles are named for the direction in which their muscle fibers run with reference to some imaginary line, usually the midline of the body. A muscle with fibers running parallel to that imaginary line will have the term rectus (straight) in its name. For example, the rectus abdominis is the straight muscle of the abdomen. Likewise, the terms transverse and oblique indi- cate that the muscle fibers run at right angles and obliquely (respectively) to the imaginary line. Muscle structure is determined by fascicle arrangement. The most common patterns of fascicle arrangement are circular, convergent, parallel, and pennate (Figure 13.1).

• Muscle size: Terms such as maximus (largest), minimus (smallest), longus (long), and brevis (short) are often used in naming muscles—as in gluteus maximus and gluteus minimus.

• Muscle location: Some muscles are named for the bone with which they are associated. For example, the tempora- lis muscle overlies the temporal bone.

• Number of origins: When the term biceps, triceps, or quad- riceps forms part of a muscle name, you can generally assume that the muscle has two, three, or four origins (respectively). For example, the biceps brachii has two origins.

• Location of the attachments: For example, the sternoclei- domastoid muscle has its origin on the sternum (sterno) and clavicle (cleido), and inserts on the mastoid process of the temporal bone.

• Muscle shape: For example, the deltoid muscle is roughly triangular (deltoid 5 triangle), and the trapezius muscle resembles a trapezoid.

• Muscle action: For example, all the adductor muscles of the anterior thigh bring about its adduction, and all the exten- sor muscles of the wrist extend the hand.

(b) Convergent

(pectoralis major)

(c) Fusiform

(biceps brachii)

(d) Parallel

(sartorius)

(a) Circular

(orbicularis oris)

(a)

(b) (c)

(d)

(f) Bipennate

(rectus femoris)

(e)

(f)

(g)

(e) Multipennate

(deltoid)

(g) Unipennate

Figure 13.1 Patterns of fascicle arrangement in muscles.

(extensor digitorum longus)

Identification of Human Muscles

While reading the tables and identifying the various human muscles in the figures, try to visualize what happens when the muscle contracts. Since muscles often have many actions, we have indicated the primary action of each muscle in blue type in the tables. Then, use a torso model or an anatomical chart to identify as many muscles as possible. If a human cadaver is available, your instructor will provide specific instructions. Then, carry out the instructions for demonstrating and palpat- ing muscles. Figures 13.2 and 13.3, pp. 196–197, are summary figures illustrating the superficial musculature of the body.

Muscles of the Head and Neck

Muscles of the Trunk

The trunk musculature includes muscles that move the ver- tebral column; anterior thorax muscles that act to move ribs, head, and arms; and muscles of the abdominal wall that play a role in the movement of the vertebral column but more impor- tantly form the “natural girdle,” or the major portion of the abdominal body wall.

Activity 2

Gross Anatomy of the Muscular System 195

Identifying Muscles of the Trunk

Read the descriptions of specific trunk muscles and identify them in the figures (Table 13.3, p. 202, and Table 13.4, pp. 204–208, and Figures 13.6–13.10, pp. 202–208), visual- izing their action when they contract. Then identify them on a torso model or anatomical chart.

Demonstrating Operations of Trunk Muscles

Now, work with a partner to demonstrate the operation of the following muscles. One of you can demonstrate the move- ment; the following steps are addressed to this partner. The other can supply resistance and palpate the muscle being tested.

1. Fully abduct the arm and extend at the elbow. Now adduct the arm against resistance. You are using the latissimus dorsi.

2. To observe the action of the deltoid, try to abduct your arm against resistance. Now attempt to elevate your shoulder against resistance; you are contracting the upper portion of the trapezius.

3. The pectoralis major is used when you press your hands together at chest level with your elbows widely abducted.

The muscles of the head serve many specific functions. For instance, the muscles of facial expression differ from most skel- etal muscles because they insert into the skin or other muscles rather than into bone. As a result, they move the facial skin, allowing a wide range of emotions to be expressed. Other muscles of the head are the muscles of mastication, which move the mandible during chewing, and the six extrinsic eye muscles located within the orbit, which aim the eye. (Orbital muscles are studied in Exercise 23.) Neck muscles provide for the move- ment of the head and shoulder girdle.

Activity 1

Identifying Head and Neck Muscles

Read the descriptions of specific head and neck muscles and identify the various muscles in the figures (Tables 13.1 and 13.2, pp. 198–201, and Figures 13.4 and 13.5, pp. 199–201), trying to visualize their action when they contract. Then iden- tify them on a torso model or anatomical chart.

Demonstrating Operations of Head Muscles
1. Raise your eyebrow to wrinkle your forehead. You are using

the frontal belly of the epicranius muscle.
2. Blink your eyes; wink. You are contracting orbicularis oculi.

3. Close your lips and pucker up. This requires contraction of orbicularis oris.

4. Smile. You are using zygomaticus.

5. To demonstrate the temporalis, place your hands on your temples and clench your teeth. The masseter can also be pal- pated now at the angle of the jaw.

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196 Exercise 13

Head

Temporalis Masseter

Facial

Epicranius, frontal belly

Orbicularis oculi Zygomaticus

Orbicularis oris

Neck

Platysma Sternohyoid Sternocleidomastoid

Thorax

Pectoralis minor

Pectoralis major Serratus anterior Intercostals

Abdomen

Rectus abdominis External oblique Internal oblique Transversus abdominis

Thigh

Tensor fascia lata

Sartorius Adductor longus Gracilis

Shoulder

Trapezius Deltoid

Arm

Triceps brachii Biceps brachii Brachialis

Forearm

Pronator teres Brachioradialis Flexor carpi radialis Palmaris longus

Pelvis/thigh

Iliopsoas Pectineus

Thigh

Rectus femoris Vastus lateralis Vastus medialis

Leg

Fibularis longus
Extensor digitorum longus Tibialis anterior

Figure 13.2 Anterior view of superficial muscles of the body. The abdominal surface has been partially dissected on the left side of the body to show somewhat deeper muscles.

Leg

Gastrocnemius Soleus

Gross Anatomy of the Muscular System 197

Arm

Triceps brachii

Brachialis

Forearm

Brachioradialis

Extensor carpi radialis longus

Flexor carpi ulnaris Extensor carpi ulnaris Extensor digitorum

Iliotibial tract

Leg

Gastrocnemius Soleus

Fibularis longus

Calcaneal tendon

Neck

Epicranius, occipital belly Sternocleidomastoid Trapezius

Shoulder

Deltoid Infraspinatus Teres major

Rhomboid major Latissimus dorsi

Hip

Gluteus medius Gluteus maximus

Thigh

Adductor magnus Hamstrings:

Biceps femoris Semitendinosus Semimembranosus

Figure 13.3 Posterior view of superficial muscles of the body.

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198 Exercise 13

Facial Expression (Figure 13.4a, b)

Epicranius— frontal and occipital bellies

Orbicularis oculi

Corrugator supercilii

Levator labii superioris

Zygomaticus—major and minor

Risorius

Depressor labii inferioris

Depressor anguli oris

Orbicularis oris

Mentalis

Buccinator

Platysma

Bipartite muscle consisting of frontal and occipital bellies, which covers dome of skull

Tripartite sphincter muscle of eyelids

Small muscle; acts with orbicularis oculi

Thin muscle between orbicularis oris and inferior eye margin

Extends diagonally from corner of mouth to cheekbone

Slender muscle; runs inferior and lateral to zygomaticus

Small muscle running from lower lip to mandible

Small muscle lateral to depressor labii inferioris

Multilayered muscle of lips with fibers that run in many different directions; most run circularly

One of muscle pair forming V-shaped muscle mass on chin

Principal muscle of cheek; runs horizontally, deep to the masseter

Unpaired, thin, sheetlike superficial neck muscle, plays role in facial expression

Frontal belly—epicranial aponeurosis; occipital belly— occipital and temporal bones

Frontal and maxillary bones and ligaments around orbit

Arch of frontal bone above nasal bone

Zygomatic bone and infraorbital margin of maxilla

Zygomatic bone

Fascia of masseter muscle

Body of mandible lateral to its midline

Body of mandible below incisors

Arises indirectly from maxilla and mandible; fibers blended with fibers of other muscles associated with lips

Mandible below incisors

Molar region of maxilla and mandible

Fascia of chest (over pectoral muscles and deltoid)

Frontal belly—skin of eyebrows and root of nose; occipital belly—epicranial aponeurosis

Tissue of eyelid

Skin of eyebrow

Skin and muscle of upper lip

Skin and muscle at corner of mouth

Skin at angle of mouth

Skin and muscle of lower lip

Skin and muscle at angle of mouth below insertion of zygomaticus

Encircles mouth; inserts into muscle and skin at angles of mouth

Skin of chin

Orbicularis oris

Lower margin of mandible, skin, and muscle at corner of mouth

With aponeurosis fixed, frontal belly raises eyebrows; occipital belly fixes aponeurosis and pulls scalp posteriorly

Closes eye, produces blinking, squinting, and draws eyebrows inferiorly

Draws eyebrows medially and inferiorly; wrinkles skin of forehead vertically

Raises and furrows upper lip;

opens lips

Raises lateral corners of mouth upward (smiling muscle)

Draws corner of lip laterally; tenses lip; zygomaticus synergist

Draws lower lip inferiorly

Zygomaticus antagonist;

draws corners of mouth downward and laterally

Closes lips; purses and protrudes lips (kissing and whistling muscle)

Protrudes lower lip;

wrinkles chin

Draws corner of mouth laterally; compresses cheek (as in whistling); holds food between teeth during chewing

Tenses skin of neck; depresses mandible; pulls lower lip back and down ➤

Gross Anatomy of the Muscular System 199

Epicranial aponeurosis

Frontal belly

Occipital belly

Temporalis

Epicranius

Corrugator supercilii Orbicularis oculi

Levator labii superioris

Zygomaticus minor and major

Buccinator Risorius Orbicularis oris Mentalis Depressor

labii inferioris Depressor anguli oris

Masseter Sternocleidomastoid Trapezius

Platysma

(a)

Splenius capitis

Frontal belly

Aponeurosis

Occipital belly

Temporalis Masseter Sternocleidomastoid

Epicranius

Orbicularis oculi

Zygomaticus minor and major

Orbicularis oris

Platysma

(b)

Figure 13.4 Muscles of the scalp, face, and neck (left lateral view). (a) Superficial muscles. (b) Photo of superficial structures of head and neck.

Instructors may assign this figure as an Art Labeling Activity using Mastering A&PTM

➤

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200 Exercise 13

Muscles of Mastication (Figure 13.4c, d)

Masseter

Temporalis

Buccinator

Medial pterygoid

Lateral pterygoid

Covers lateral aspect of mandibular ramus; can be palpated on forcible closure of jaws

Fan-shaped muscle lying over parts of frontal, parietal, and temporal bones

(See muscles of facial expression.)

Runs along internal (medial) surface of mandible (thus largely concealed by that bone)

Superior to medial pterygoid

Zygomatic arch and zygomatic bone

Temporal fossa

Sphenoid, palatine, and maxillary bones

Greater wing of sphenoid bone

Angle and ramus of mandible

Coronoid process of mandible

Medial surface of mandible, near its angle

Condylar process of mandible

Prime mover of jaw closure; elevates mandible

Closes jaw; elevates and retracts mandible

Synergist of temporalis and masseter; elevates mandible; in conjunction with lateral pterygoid, aids in grinding movements of teeth

Protracts jaw (moves it anteriorly); in conjunction with medial pterygoid, aids in grinding movements of teeth

Orbicularis oris

Buccinator

(c)

Temporalis

Masseter

Lateral pterygoid

Medial pterygoid

Masseter pulled away

Figure 13.4 (continued) Muscles of mastication. (c) Lateral view of the temporalis, masseter, and buccinator muscles. (d) Lateral view of the deep chewing muscles, the medial and lateral pterygoid muscles.

(d)

Suprahyoid Muscles

Digastric

Stylohyoid

Mylohyoid

Infrahyoid Muscles

Sternohyoid

Sternothyroid

Omohyoid

Thyrohyoid

Median raphe Anterior

By a connective tissue loop to hyoid bone

Hyoid bone

Hyoid bone and median raphe

Lower margin of hyoid bone

Thyroid cartilage of larynx

Hyoid bone; inferior border

Hyoid bone

Platysma (cut)

Mylohyoid Stylohyoid Hyoid bone

Omohyoid

(superior belly)

Sternohyoid

Sternocleido- mastoid

Omohyoid

(inferior belly)

(b)

Acting together, elevate hyoid bone; open mouth and depress mandible

Elevates and retracts hyoid bone

Elevates hyoid bone and base of tongue during swallowing

Acting with sternothyroid and omohyoid, depresses larynx and hyoid bone if mandible is fixed; may also flex skull

(See Sternohyoid above)

(See Sternohyoid above)

Depresses hyoid bone; elevates larynx if hyoid is fixed

Gross Anatomy of the Muscular System 201

Consists of two bellies united by an intermediate tendon; forms a V-shape under chin

Slender muscle parallels posterior border of digastric; below angle of jaw

Just deep to digastric; forms floor of mouth

Runs most medially along neck; straplike

Lateral and deep to sternohyoid

Straplike with two bellies; lateral to sternohyoid

Appears as a superior continuation of sternothyroid muscle

Lower margin of mandible (anterior belly) and mastoid process (posterior belly)

Styloid process of temporal bone

Medial surface of mandible

Manubrium and medial end of clavicle

Posterior surface of manubrium

Superior surface of scapula

Thyroid cartilage

Digastric

belly

Posterior belly

Stylohyoid (cut)

Thyrohyoid

Thyroid cartilage of the larynx

Thyroid gland

Sternothyroid

(a)

Figure 13.5 Anterior muscles of the neck and throat. (a) Anterior view of suprahyoid and infrahyoid muscles. (b) Cadaver photo of suprahyoid and infrahyoid muscles.

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202 Exercise 13

Sternocleidomastoid

Scalenes—anterior, middle, and posterior

Splenius

Erector spinae

Semispinalis

Quadratus lumborum

Two-headed muscle located deep to platysma on anterolateral surface of neck; indicate limits of anterior and posterior triangles of neck

Located more on lateral than anterior neck; deep to platysma and sternocleidomastoid

Superficial muscle (capitis and cervicis parts) extending from upper thoracic region to skull

A long tripartite muscle composed of iliocostalis (lateral), longissimus, and spinalis (medial) muscle columns; superficial to semispinalis muscles; extends from pelvis to head

Deep composite muscle of the back—thoracis, cervicis, and capitis portions

Forms greater portion of posterior abdominal wall

1st cervical vertebra

Manubrium of sternum and medial portion of clavicle

Transverse processes of cervical vertebrae

Ligamentum nuchae and spinous processes of C7–T6

Iliac crest, transverse processes of lumbar, thoracic, and cervical vertebrae, and/or ribs 3–6 depending on specific part

Transverse processes of C7–T12

Iliac crest and lumbar fascia

Base of occipital bone

Mastoid process

Middle scalene

Anterior scalene

Posterior scalene

Mastoid process of temporal bone and superior nuchal line of occipital bone

Anterolaterally on ribs 1–2

Mastoid process, occipital bone, and transverse processes of C2–C4

Ribs and transverse processes of vertebrae about six segments above origin; longissimus also inserts into mastoid process

Occipital bone and spinous processes of cervical vertebrae and T1–T4

Inferior border of rib 12; transverse processes of lumbar vertebrae

Simultaneous contraction of both muscles of pair causes flexion of neck, acting independently, rotate head toward shoulder on opposite side

Flex and slightly rotate neck; elevate ribs 1–2 (aid in inspiration)

As a group, extend or hyperextend head; when only one side is active, head is rotated and bent toward the same side

Extend and bend the vertebral column laterally; fibers of the longissimus also extend and rotate head

Acting together, extend head and vertebral column; acting independently (right vs. left), causes rotation toward the opposite side

Each flexes vertebral column laterally; together extend the lumbar spine and fix rib 12; maintains upright posture

Mastoid process

Sternocleido- mastoid

(a)

Splenius

capitis

Spinous processes of the vertebrae

Splenius cervicis

(b)

Figure 13.6 Muscles of the neck and vertebral column that move the head and trunk. (a) Muscles of the anterolateral neck; superficial platysma muscle and deeper neck muscles removed. (b) Deep muscles of the posterior neck; superficial muscles removed.

Gross Anatomy of the Muscular System 203

Mastoid process of temporal bone

Longissimus capitis

Iliocostalis cervicis Longissimus cervicis

Iliocostalis thoracis

Longissimus thoracis Spinalis thoracis

Iliocostalis Erector Longissimus

spinae

Iliocostalis lumborum

External oblique

(c)

Figure 13.6 (continued) (c) Deep muscles of the back. The superficial and splenius muscles have been removed. The three muscle columns (iliocostalis, longissimus, and spinalis) forming the erector spinae are shown on the left, and deeper semispinalis and quadratus lumborum are shown on the right.

Ligamentum nuchae

Semispinalis capitis

Semispinalis cervicis

Semispinalis thoracis

Spinalis

Multifidus

Quadratus lumborum

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204 Exercise 13

Thorax and Shoulder, Superficial (Figure 13.7)

Pectoralis major

Serratus anterior

Deltoid (see also Figure 13.10)

Pectoralis minor

Large fan-shaped muscle covering upper portion of chest

Fan-shaped muscle deep to scapula; deep and inferior to pectoral muscles on lateral rib cage

Fleshy triangular muscle forming shoulder muscle mass; intramuscular injection site

Flat, thin muscle deep to pectoralis major

Sternocleidomastoid

Deltoid Pectoralis major

Sternum

Biceps brachii

Clavicle, sternum, cartilage of ribs 1–6 (or 7), and aponeurosis of external oblique muscle

Lateral aspect of ribs 1–8 (or 9)

Lateral 1/3 of clavicle; acromion and spine of scapula

Anterior surface of ribs 3–5, near their costal cartilages

Fibers converge to insert by short tendon into intertubercular sulcus of humerus

Vertebral border of anterior surface of scapula

Deltoid tuberosity of humerus

Coracoid process of scapula

Prime mover of arm flexion; adducts, medially rotates arm; with arm fixed, pulls chest upward (thus also acts in forced inspiration)

Prime mover to protract and hold scapula against chest wall; rotates scapula, causing inferior angle to move laterally and upward; essential to raising arm; fixes scapula for arm abduction

Acting as a whole, prime mover of arm abduction; when only specific fibers are active, can act as a synergist in flexion, extension, and rotation of arm

With ribs fixed, draws scapula forward and inferiorly; with scapula fixed, draws rib cage superiorly

Subclavius Clavicle

Subscapularis

Pectoralis minor

Coracobrachialis

Serratus anterior

Humerus

Figure 13.7 Muscles of the thorax and shoulder acting on the scapula and arm (anterior view). The superficial muscles, which effect arm movements, are shown on the left side of the figure. These muscles have been removed on the right side of the figure to show the muscles that stabilize or move the pectoral girdle.

Thorax, Deep: Muscles of Respiration (Figure 13.8)

Gross Anatomy of the Muscular System 205

External intercostals

Internal intercostals

Diaphragm

11 pairs lie between ribs; fibers run obliquely downward and forward toward sternum

11 pairs lie between ribs; fibers run deep and at right angles to those of external intercostals

Broad muscle; forms floor of thoracic cavity; dome- shaped in relaxed state; fibers converge from margins of thoracic cage toward a central tendon

Inferior border of rib above (not shown in figure)

Superior border of rib below

Inferior border of rib and sternum, costal cartilages of last six ribs and lumbar vertebrae

Superior border of rib below

Inferior border of rib above (not shown in figure)

Central tendon

Pull ribs toward one another to elevate rib cage; aid in inspiration

Draw ribs together to depress rib cage; aid in forced expiration; antagonistic to external intercostals

Prime mover of inspiration flattens on contraction, increasing vertical dimensions of thorax; increases intra-abdominal pressure

➤

External intercostal

Internal intercostal

(a)

Foramen for inferior vena cava

Central tendon of diaphragm

Foramen for aorta

12th rib

(b)

Xiphoid process of sternum

Foramen for esophagus

Costal cartilage

Diaphragm

Lumbar vertebra

Figure 13.8 Deep muscles of the thorax: muscles of respiration. (a) The external intercostals (inspiratory muscles) are shown on the left, and the internal intercostals (expiratory muscles) are shown on the right. These two muscle layers run obliquely and at right angles to each other. (b) Inferior view of the diaphragm, the prime mover of inspiration. Notice that its muscle fibers converge toward a central tendon, an arrangement that causes the diaphragm to flatten and move inferiorly as it contracts. The diaphragm and its tendon are pierced by the great vessels (aorta and inferior vena cava) and the esophagus.

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206 Exercise 13

Abdominal Wall (Figure 13.9)

Rectus abdominis

External oblique

Internal oblique

Transversus abdominis

Medial superficial muscle, extends from pubis to
rib cage; ensheathed by aponeuroses of oblique muscles; segmented

Most superficial lateral muscle; fibers run downward and medially; ensheathed by an aponeurosis

Most fibers run at right angles to those of external oblique, which it underlies

Deepest muscle of abdominal wall; fibers run horizontally

Pubic crest and symphysis

Anterior surface of lower eight ribs

Lumbar fascia, iliac crest, and inguinal ligament

Inguinal ligament, iliac crest, cartilages of last five or six ribs, and lumbar fascia

Xiphoid process and costal cartilages of ribs 5–7

Linea alba,* pubic crest and tubercles, and iliac crest

Linea alba, pubic crest, and costal cartilages of last three ribs

Linea alba and pubic crest

Flexes and rotates vertebral column; increases abdominal pressure; fixes and depresses ribs; stabilizes pelvis during walking; used in sit-ups and curls

See rectus abdominis, above; compresses abdominal wall; also aids muscles of back in trunk rotation and lateral flexion; used in oblique curls

As for external oblique

Compresses abdominal contents

*The linea alba (white line) is a narrow, tendinous sheath that runs along the middle of the abdomen from the sternum to the pubic symphysis. It is formed by the fusion of the aponeurosis of the external oblique and transversus muscles.

Serratus anterior

Transversus abdominis

Internal oblique External oblique

Aponeurosis of the external oblique

(a)

Pectoralis major

Linea alba

Tendinous intersection

Rectus abdominis

Inguinal ligament (formed by free inferior border of the external oblique aponeurosis)

Instructors may assign this figure as an Art Labeling Activity using Mastering A&PTM

Figure 13.9 Anterior view of the muscles forming the anterolateral abdominal wall. (a) The superficial muscles have been partially cut away on the left side of the diagram to reveal the deeper internal oblique and transversus abdominis muscles.

Muscles of the Shoulder and Thorax (Figure 13.10)

Gross Anatomy of the Muscular System 207

Trapezius

Latissimus dorsi

Infraspinatus

Teres minor

Serratus anterior

Rectus abdominis

External oblique

Internal oblique

Transversus abdominis

Inguinal ligament

(b)

Most superficial muscle of posterior thorax; very broad origin and insertion

Broad flat muscle of lower back (lumbar region); extensive superficial origins

A rotator cuff muscle; partially covered by deltoid and trapezius

A rotator cuff muscle; small muscle inferior to infraspinatus

Occipital bone; ligamentum nuchae; spines of C7 and all thoracic vertebrae

Indirect attachment to spinous processes of lower six thoracic vertebrae, lumbar vertebrae, last three to four ribs, and iliac crest

Infraspinous fossa of scapula

Lateral margin of posterior scapula

Acromion and spinous process of scapula; lateral third of clavicle

Floor of intertubercular sulcus of humerus

Greater tubercle of humerus

Greater tubercle of humerus

Extends head; raises, rotates, and retracts (adducts) scapula and stabilizes it; superior fibers elevate scapula (as in shrugging the shoulders); inferior fibers depress scapula

Prime mover of arm extension; adducts and medially rotates arm; brings arm down in power stroke, as in striking a blow

Lateral rotation of arm; helps hold head of humerus in glenoid cavity; stabilizes shoulder

Same as for infraspinatus

➤

Figure 13.9 (continued) (b) Photo of the anterolateral abdominal wall.

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208 Exercise 13

Teres major

Supraspinatus

Levator scapulae

Rhomboids—major and minor

Located inferiorly to teres minor

A rotator cuff muscle; obscured by trapezius

Located at back and side of neck, deep to trapezius

Beneath trapezius and inferior to levator scapulae; rhomboid minor is the more superior muscle

Trapezius

Deltoid

Infraspinatus

Teres major

Latissimus dorsi

Posterior surface at inferior angle of scapula

Supraspinous fossa of scapula

Transverse processes of C1–C4

Spinous processes of C7 and T1–T5

Intertubercular sulcus of humerus

Greater tubercle of humerus

Medial border of scapula superior to spine

Medial border of scapula

Extends, medially rotates, and adducts arm; synergist of latissimus dorsi

Initiates abduction of arm; stabilizes shoulder joint

Elevates and adducts scapula; with fixed scapula, laterally flexes neck to the same side

Pull scapulae medially (retraction); stabilize scapulae; rotate glenoid cavity downward

Levator scapulae

Rhomboid minor

Supraspinatus

Clavicle
Spine of scapula

Rhomboid major

Teres minor

Humerus

Figure 13.10 Muscles of the shoulder and thorax (posterior view). The superficial muscles of the back are shown for the left side of the body, with a corresponding photograph. The superficial muscles are removed on the right side of the illustration to reveal the deeper muscles acting on the scapula and the rotator cuff muscles that help to stabilize the shoulder joint.

Muscles of the Upper Limb

The muscles that act on the upper limb fall into three groups: those moving the arm, those causing movement of the forearm, and those moving the hand and fingers.

The muscles that cross the shoulder joint to insert on the humerus and move the arm (subscapularis, supraspinatus and infraspinatus, deltoid, and so on) are primarily trunk muscles that originate on the axial skeleton or shoulder girdle. These muscles are included with the trunk muscles.

The second group of muscles, which cross the elbow joint and move the forearm, consists of muscles forming the mus- culature of the humerus. These muscles arise mainly from the humerus and insert in forearm bones. They are responsible for flexion, extension, pronation, and supination.

The third group forms the musculature of the forearm. For the most part, these muscles cross the wrist to insert on the dig- its and produce movements of the hand and fingers.

Gross Anatomy of the Muscular System 209 Activity 3

Identifying Muscles of the Upper Limb

Study the origins, insertions, and actions of muscles that move the forearm, and identify them (Table 13.5, p. 210, and Figure 13.11, p. 210).

Do the same for muscles acting on the wrist and hand (Table 13.6, pp. 211–212, and Figure 13.12, pp. 211–213). They are more easily identified if you locate their insertion tendons first.

Then see if you can identify the upper limb muscles on a torso model, anatomical chart, or cadaver. Complete this portion of the exercise with palpation demonstrations as outlined next.

Demonstrating Operations of Upper Limb Muscles

1. To observe the biceps brachii, attempt to flex your forearm (hand supinated) against resistance. The insertion tendon of this biceps muscle can also be felt in the lateral aspect of the cubital fossa (where it runs toward the radius to attach).

2. If you acutely flex at your elbow and then try to extend the forearm against resistance, you can demonstrate the action of your triceps brachii.

3. Strongly flex your hand, and make a fist. Palpate your con- tracting wrist flexor muscles’ origins at the medial epicondyle of the humerus and their insertion tendons, at the anterior aspect of the wrist.

4. Flare your fingers to identify the tendons of the extensor digitorum muscle on the dorsum of your hand.

13

13

210 Exercise 13

Triceps brachii

Anconeus

Biceps brachii

Brachioradialis

Brachialis

Olecranon of ulna

Lateral aspect of olecranon of ulna

Radial tuberosity

Base of radial styloid process

Coronoid process of ulna

Powerful forearm extensor; antagonist of forearm flexors (brachialis and biceps brachii)

Abducts ulna during forearm pronation; synergist of triceps brachii in forearm extension

Flexion (powerful) and supination of forearm; “it turns the corkscrew and pulls the cork”; weak arm flexor

Synergist in forearm flexion

Flexor of forearm

Spine of scapula Deltoid (cut)

Greater tubercle of humerus

Infraspinatus Teres minor Teres major

Triceps brachii

• Lateral head • Long head

Latissimus dorsi

Humerus

Olecranon of ulna

Anconeus

Instructors may assign this figure as an Art Labeling Activity using Mastering A&PTM

Large fleshy muscle of posterior humerus; three-headed origin

Short triangular muscle blended with triceps

Most familiar muscle of anterior humerus because this two-headed muscle bulges when forearm is flexed

Superficial muscle of lateral forearm; forms lateral boundary of cubital fossa

Immediately deep to biceps brachii

Clavicle

(a)

Figure 13.11 Muscles acting on the arm and forearm. (a) Superficial muscles of the anterior thorax, shoulder, and arm, anterior view. (b) Posterior aspect of the arm showing the lateral and long heads of the triceps brachii muscle.

Long head—inferior margin of glenoid cavity; lateral head— posterior humerus; medial head—distal radial groove on posterior humerus

Lateral epicondyle of humerus

Short head: coracoid process; long head: supraglenoid tubercle and lip of glenoid cavity; tendon of long head runs in intertubercular sulcus and within capsule of shoulder joint

Lateral ridge at distal end of humerus

Distal portion of anterior humerus

Supraspinatus

Deltoid Sternum

Pectoralis major

Coracobrachialis

Triceps brachii

• Lateral head • Long head

• Medial head

Biceps brachii

Brachialis

Brachio- radialis

(b)

Gross Anatomy of the Muscular System 211

Anterior Compartment, Superficial (Figure 13.12a, b, c)

Pronator teres

Flexor carpi radialis

Palmaris longus

Biceps brachii

Tendon of biceps brachii

Pronator teres

Brachio- radialis

Extensor carpi radialis longus

Flexor pollicis longus

Seen in a superficial view between proximal margins of brachioradialis and flexor carpi radialis

Superficial; runs diagonally across forearm

Small fleshy muscle with a long tendon; medial to flexor carpi radialis

Medial epicondyle of humerus and coronoid process of ulna

Medial epicondyle of humerus

Medial epicondyle of humerus

Midshaft of radius

Base of metacarpals II and III

Palmar aponeurosis; skin and fascia of palm

Tendon of biceps brachii (cut)

Supinator

Acts synergistically with pronator quadratus to pronate forearm; weak forearm flexor

Powerful flexor and abductor of the hand

Flexes hand (weak); tenses skin and fascia of palm

➤

Pronator quadratus

Flexor retinaculum

Medial head of triceps brachii

Medial epicondyle of humerus

Extensor carpi radialis longus

Flexor carpi radialis Palmaris longus Flexor carpi ulnaris

Flexor digitorum superficialis

Tendon of brachioradialis (cut)

Flexor digitorum profundus

Flexor digitorum superficialis

Flexor pollicis longus Pronator quadratus

Tendon of flexor carpi ulnaris (cut) Thenar muscles of thumb

Tendon of flexor pollicis longus

Lumbricals

Tendon of flexor digitorum superficialis

Tendon of flexor
digitorum profundus (c)

Tendon of flexor carpi radialis (cut)

Palmar aponeurosis

Superficial transverse ligament of palm

(a)

(b)

Figure 13.12 Muscles of the forearm and wrist. (a) Superficial anterior view of right forearm
and hand. (b) The brachioradialis, flexors carpi radialis and ulnaris, and

palmaris longus muscles have been removed to reveal the position of the somewhat deeper flexor digitorum superficialis. (c) Deep muscles of the anterior compartment. Superficial

muscles have been removed. (Note:
The thenar muscles of the thumb and
the lumbricals that help move the
fingers are illustrated here but are not described in Table 13.6.) ➤

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13

212 Exercise 13

Anterior Compartment, Superficial (continued)

Flexor carpi ulnaris

Flexor digitorum superficialis

Superficial; medial to palmaris longus

Deeper muscle (deep to muscles named above); visible at distal end of forearm

Medial epicondyle of humerus and olecranon and posterior surface of ulna

Medial epicondyle of humerus, coronoid process of ulna, and shaft of radius

Anterior surface of radius, and interosseous membrane

Anteromedial surface of ulna, interosseous membrane, and coronoid process

Distal portion of anterior ulnar surface

Base of metacarpal V; pisiform and hamate bones

Middle phalanges of fingers II–V

Distal phalanx of thumb

Distal phalanges of fingers II–V

Anterior surface of radius, distal end

Base of metacarpal II

Base of metacarpal III

By four tendons into distal phalanges of fingers II–V

Base of metacarpal V

Base of distal phalanx of thumb (longus) and proximal phalanx of thumb (brevis)

Metacarpal I and trapezium

Proximal end of radius

Flexes and adducts hand

Flexes hand and middle phalanges of fingers II–V

Flexes thumb (pollex is Latin for “thumb”)

Sole muscle that flexes distal phalanges; assists in hand flexion

Pronates forearm

Extends and abducts hand

Extends and abducts hand; steadies wrist during finger flexion

Prime mover of finger extension; extends hand; can flare (abduct) fingers

Extends and adducts hand

Extend thumb

Abducts and extends thumb

Synergist of biceps brachii to supinate forearm; antagonist of pronator muscles

Anterior Compartment, Deep (Figure 13.12a, b, c)

Flexor pollicis longus

Flexor digitorum profundus

Pronator quadratus

Deep muscle of anterior forearm; distal to and paralleling lower margin of flexor digitorum superficialis

Deep muscle; overlain entirely by flexor digitorum superficialis

Deepest muscle of distal forearm

Posterior Compartment, Superficial (Figure 13.12d, e, f)

Extensor carpi radialis longus

Extensor carpi radialis brevis

Extensor digitorum

Extensor carpi ulnaris

Superficial; parallels brachioradialis on lateral forearm

Deep to extensor carpi radialis longus

Superficial; medial to extensor carpi radialis brevis

Superficial; medial posterior forearm

Lateral supracondylar ridge of humerus

Lateral epicondyle of humerus

Lateral epicondyle of humerus

Lateral epicondyle of humerus; posterior border of ulna

Dorsal shaft of ulna and radius, interosseous membrane

Posterior surface of radius and ulna; interosseous membrane

Lateral epicondyle of humerus; proximal ulna

Posterior Compartment, Deep (Figure 13.12d, e, f)

Extensor pollicis longus and brevis

Abductor pollicis longus

Supinator

Muscle pair with a common origin and action; deep to extensor carpi ulnaris

Deep muscle; lateral and parallel to extensor pollicis longus

Deep muscle at posterior aspect of elbow

Gross Anatomy of the Muscular System 213

Brachioradialis
Insertion of Extensor carpi

triceps brachii Anconeus

Flexor carpi ulnaris

Extensor carpi ulnaris

Extensor digit minimi Extensor indicis

Tendons of extensor carpi radialis brevis and longus

radialis longus

Olecranon of ulna

Anconeus

Supinator

Abductor pollicis longus

Extensor pollicis longus

Extensor pollicis brevis

Extensor indicis

Extensor carpi radialis brevis

Extensor digitorum

Abductor pollicis longus

Extensor pollicis brevis

Extensor pollicis longus

Tendons of extensor digitorum

Extensor expansion

Abductor pollicis longus

Interossei

(d)

(e)

Extensor pollicis brevis

Brachioradialis

Extensor carpi radialis longus

Extensor carpi radialis brevis

(f)

Extensor digitorum

Tendon of extensor digitorum

Extensor carpi ulnaris

Figure 13.12 (continued) Muscles of the forearm and wrist. (d) Superficial muscles, posterior view. (e) Deep posterior muscles; superficial muscles have been removed. The interossei, the deepest layer of intrinsic hand muscles, are also illustrated. (f) Photo of posterior muscles of the right forearm.

Extensor digiti minimi

13

13

Since some of the muscles acting on the leg also have attach- ments on the pelvic girdle, they can cause movement at the hip joint.

Do the same for muscles acting on the foot and toes (Table 13.9, pp. 218–220, Figure 13.15, p. 219, and Fig- ure 13.16, pp. 221–222).

Then identify all the muscles on a model or anatomical chart.

Demonstrating Operations

of Lower Limb Muscles

1. Go into a deep knee bend and palpate your own gluteus maximus muscle as you extend your thigh to resume the upright posture.

2. Demonstrate the contraction of the anterior quadriceps femoris by trying to extend your leg against resistance. Do this while seated and note how the quadriceps tendon reacts. The biceps femoris of the posterior thigh comes into play when you flex your leg against resistance.

3. Now stand on your toes. Have your partner palpate the lateral and medial heads of the gastrocnemius and follow it to its insertion in the calcaneal tendon.

4. Dorsiflex and invert your foot while palpating your tibialis anterior muscle (which parallels the sharp anterior crest of the tibia laterally).

Identifying Muscles of the Lower Limb

Read the descriptions of specific muscles acting on the thigh and leg and identify them (Table 13.7, p. 216, and Table 13.8, pp. 216–217, and Figures 13.13 and 13.14, pp. 215–217), trying to visualize their action when they contract.

214 Exercise 13

Origin on the Pelvis

Iliopsoas—iliacus and psoas major

Sartorius

Medial Compartment

Adductors—magnus, longus, and brevis

Pectineus

Gracilis

Two closely related muscles; fibers pass under inguinal ligament to insert into femur via a common tendon; iliacus is more lateral

Straplike superficial muscle running obliquely across anterior surface of thigh to knee

Large muscle mass forming medial aspect of thigh; arise from front of pelvis and insert at various levels on femur

Overlies adductor brevis on proximal thigh

Straplike superficial muscle of medial thigh

Iliacus—iliac fossa and crest, lateral sacrum;
psoas major—transverse processes, bodies, and discs of T12 and lumbar vertebrae

Anterior superior iliac spine

Magnus—ischial and pubic rami and ischial tuberosity; longus—pubis near pubic symphysis; brevis—body and inferior pubic ramus

Pectineal line of pubis (and superior pubic ramus)

Inferior ramus and body of pubis

On and just below lesser trochanter of femur

By an aponeurosis into medial aspect of proximal tibia

Magnus—linea aspera and adductor tubercle of femur; longus and brevis—linea aspera

Inferior from lesser trochanter to linea aspera of femur

Medial surface of tibia just inferior to medial condyle

Flex trunk at hip joint, flex thigh; lateral flexion of vertebral column (psoas)

Flexes, abducts, and laterally rotates thigh; flexes leg; known as “tailor’s muscle” because it helps effect cross-legged position in which tailors are often depicted

Adduct and medially rotate and flex thigh; posterior part of magnus is also a synergist in thigh extension

Adducts, flexes, and medially rotates thigh

Adducts thigh; flexes and
medially rotates leg, especially
during walking ➤

Muscles of the Lower Limb

Muscles that act on the lower limb cause movement at the hip, knee, and ankle joints. Since the human pelvic girdle is com- posed of heavy, fused bones that allow very little movement, no special group of muscles is necessary to stabilize it. This is unlike the shoulder girdle, where several muscles (mainly trunk muscles) are needed to stabilize the scapulae.

Muscles acting on the thigh (femur) cause various move- ments at the multiaxial hip joint. These include the iliopsoas, the adductor group, and others.

Muscles acting on the leg form the major musculature of the thigh. (Anatomically, the term leg refers only to that portion between the knee and the ankle.) The thigh muscles cross the knee to allow flexion and extension of the leg. They include the hamstrings and the quadriceps.

The muscles originating on the leg cross the ankle joint and act on the foot and toes.

Activity 4

Gross Anatomy of the Muscular System 215 12th thoracic

12th rib Quadratus lumborum

Psoas minor Iliac crest

Pectineus

(cut)

Adductor brevis

Adductor longus

O O

vertebra

Adductor magnus

Iliopsoas

Psoas major
Iliacus 5th lumbar

I

I

I

Anterior superior iliac spine

Tensor fascia lata Pectineus

Sartorius

Quadriceps femoris • Rectus femoris

• Vastus lateralis • Vastus medialis

Tendon of quadriceps femoris

vertebra
Femur

I
O 5 origin

I 5 insertion

Adductor longus

Gracilis
Adductor magnus

(b)

O

Patella

Patellar ligament

Vastus lateralis

Vastus intermedius

Vastus medialis

(c)

Rectus femoris tendon (cut)

Patella

Patellar ligament

(a)

Figure 13.13 Anterior and medial muscles promoting movements of the thigh and leg. (a) Anterior view of the deep muscles of the pelvis and superficial muscles of the right thigh. (b) Adductor muscles of the medial compartment of the thigh. (c) The vastus muscles (isolated) of the quadriceps group.

Instructors may assign this figure as an Art Labeling Activity using Mastering A&PTM

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13

216 Exercise 13

Anterior Compartment

Quadriceps femoris*

Rectus femoris

Vastus lateralis

Vastus medialis

Vastus intermedius

Tensor fascia lata

Superficial muscle of thigh; runs straight down thigh; only muscle of group to cross hip joint

Forms lateral aspect of thigh; intramuscular injection site

Forms inferomedial aspect of thigh

Obscured by rectus femoris; lies between vastus lateralis and vastus medialis on anterior thigh

Enclosed between fascia layers of thigh

Anterior inferior iliac spine and superior margin of acetabulum

Greater trochanter, intertrochanteric line, and linea aspera

Linea aspera and intertrochanteric line

Anterior and lateral surface of femur

Anterior aspect of iliac crest and anterior superior iliac spine

Tibial tuberosity and patella

Tibial tuberosity and patella

Tibial tuberosity and patella

Tibial tuberosity and patella

Iliotibial tract (lateral portion of fascia lata)

Extends leg and flexes thigh

Extends leg and stabilizes knee

Extends leg; stabilizes patella

Extends leg

Flexes, abducts, and medially rotates thigh; steadies trunk

*The quadriceps form the flesh of the anterior thigh and have a common insertion in the tibial tuberosity via the patellar ligament. They are powerful leg extensors, enabling humans to kick a football, for example.

Origin on the Pelvis

Gluteus maximus

Gluteus medius

Gluteus minimus (not shown in figure)

Posterior Compartment

Hamstrings†

Biceps femoris

Largest and most superficial of gluteal muscles (which
form buttock mass); intramuscular injection site

Partially covered by gluteus maximus; intramuscular injection site

Smallest and deepest gluteal muscle

Most lateral muscle of group; arises from two heads

Dorsal ilium, sacrum, and coccyx

Upper lateral surface of ilium

External inferior surface of ilium

Ischial tuberosity (long head); linea aspera and distal femur (short head)

Gluteal tuberosity of femur and iliotibial tract*

Greater trochanter of femur

Greater trochanter of femur

Tendon passes laterally to insert into head of fibula and lateral condyle of tibia

Complex, powerful thigh extensor
(most effective when thigh is flexed, as in climbing stairs—but not as in walking); antagonist of iliopsoas; laterally rotates and abducts thigh

Abducts and medially rotates thigh; steadies pelvis during walking

Abducts and medially rotates thigh; steadies pelvis

Extends thigh; laterally rotates leg; flexes leg

Gross Anatomy of the Muscular System 217

Semitendinosus Medial to biceps femoris Ischial tuberosity Medial aspect of upper tibial shaft

Semimembranosus Deep to semitendinosus Ischial tuberosity Medial condyle of tibia; lateral condyle of femur

Extends thigh; flexes leg; medially rotates leg

Extends thigh; flexes leg; medially rotates leg

*The iliotibial tract, a thickened lateral portion of the fascia lata, ensheathes all the muscles of the thigh. It extends as a tendinous band from the iliac crest to the knee.
†The hamstrings are the fleshy muscles of the posterior thigh. As a group, they are strong extensors of the thigh; they counteract the powerful quadriceps by stabilizing the knee joint when standing.

Gluteus medius

Gluteus maximus

Gluteus maximus

Adductor magnus

Adductor
magnus Gracilis

Gracilis

Iliotibial tract

Biceps femoris

Long head Short head

Semitendinosus Semimembranosus

Gastrocnemius

Iliotibial tract

Biceps femoris

Long head Short head

Semitendinosus

Semimembranosus

Gastrocnemius

(b)

Figure 13.14 Muscles of the posterior aspect of the right hip and thigh.
(a) Superficial view showing the gluteus muscles of the buttock and hamstring muscles of the thigh. (b) Photo of muscles of the posterior thigh.

(a)

Instructors may assign this figure as an Art Labeling Activity using Mastering A&PTM

13

13

Review of Human Musculature

Review the muscles by watching the Human Musculature video.

218 Exercise 13

Lateral Compartment (Figure 13.15a, b and Figure 13.16b)

Fibularis (peroneus) longus

Fibularis (peroneus) brevis

Superficial lateral muscle; overlies fibula

Smaller muscle; deep to fibularis longus

Head and upper portion of fibula

Distal portion of fibula shaft

Lateral condyle and upper 2/3 of tibia; interosseous membrane

Lateral condyle of tibia; proximal 3⁄4 of fibula; interosseous membrane

Distal anterior surface of fibula and interosseous membrane

Anteromedial shaft of fibula and interosseous membrane

By long tendon under foot to metatarsal I and medial cuneiform

By tendon running behind lateral malleolus to insert on proximal end of metatarsal V

By tendon into inferior surface of first cuneiform and metatarsal I

Tendon divides into four parts; inserts into middle and distal phalanges of toes II–V

Tendon inserts on dorsum of metatarsal V

Tendon inserts on distal phalanx of great toe

Via common tendon (calcaneal) into calcaneus of the heel

Calcaneus via calcaneal tendon

Calcaneus via calcaneal tendon

Plantar flexes and everts foot

Plantar flexes and everts foot

Prime mover of dorsiflexion; inverts foot; supports longitudinal arch of foot

Prime mover of toe extension; dorsiflexes foot

Dorsiflexes and everts foot

Extends great toe; dorsiflexes foot

Plantar flex foot

Plantar flexes foot when leg is extended; crosses knee joint; thus can flex leg (when foot is dorsiflexed)

Plantar flexion; an important muscle for locomotion

Anterior Compartment (Figure 13.15a, b)

Tibialis anterior

Extensor digitorum longus

Fibularis (peroneus) tertius

Extensor hallucis longus

Superficial muscle of anterior leg; parallels sharp anterior margin of tibia

Anterolateral surface of leg; lateral to tibialis anterior

Small muscle; often fused to distal part of extensor digitorum longus

Deep to extensor digitorum longus and tibialis anterior

Posterior Compartment, Superficial (Figure 13.16a; also Figure 13.15)

Triceps surae

Gastrocnemius

Soleus

Activity 5

Refers to muscle pair below that shapes posterior calf

Superficial muscle of pair; two prominent bellies

Deep to gastrocnemius

By two heads from medial and lateral condyles of femur

Proximal portion of tibia and fibula; interosseous membrane

➤

Gross Anatomy of the Muscular System 219

Fibularis brevis

Flexor hallucis longus

Fibular retinaculum

Lateral malleolus

(a)

Patella Head of fibula

Gastrocnemius Soleus

Fibularis longus

Extensor digitorum longus

Tibialis anterior

Extensor hallucis longus

Fibularis tertius

Superior and inferior extensor retinacula

Fibularis longus

Gastrocnemius

Tibia

Tibialis anterior

Extensor digitorum longus

Soleus

Extensor hallucis longus

Fibularis tertius

Superior and inferior extensor retinacula

Extensor hallucis brevis

Extensor digitorum brevis

Metatarsal V

Figure 13.15 Muscles of the anterolateral aspect of the right leg. (a) Superficial view of lateral aspect of the leg, illustrating the positioning of the lateral compartment muscles (fibularis longus and brevis) relative to anterior and posterior leg muscles. (b) Superficial view of anterior leg muscles.

Instructors may assign this figure as an Art Labeling Activity using Mastering A&PTM

(b)

13

Making a Muscle Painting

1. Choose a male student to be “muscle painted.”

2. Obtain brushes and water-based paints from the supply area while the “volunteer” removes his shirt and rolls up his pant legs (if necessary).

3. Using different colored paints, identify the muscles listed below by painting his skin. If a muscle covers a large body area, you may opt to paint only its borders.

• biceps brachii

• deltoid

• erector spinae

• pectoralis major

• rectus femoris

• tibialis anterior

• triceps brachii
• vastus lateralis
• biceps femoris
• extensor carpi radialis longus • latissimus dorsi

• rectus abdominis
• sternocleidomastoid • trapezius
• triceps surae
• vastus medialis

4. Check your “human painting” with your instructor before cleaning your bench and leaving the laboratory.

13

220 Exercise 13 Activity 6

For instructions on animal dissections, see the dissection

exercises (starting on p. 695) in the cat and fetal pig edi- tions of this manual.

Posterior Compartment, Deep (Figure 13.16b–e)

Popliteus

Tibialis posterior

Flexor digitorum longus

Flexor hallucis longus (see also Figure 13.15a)

Thin muscle at posterior aspect of knee

Thick muscle deep to soleus

Runs medial to and partially overlies tibialis posterior

Lies lateral to inferior aspect of tibialis posterior

Lateral condyle of femur and lateral meniscus

Superior portion of tibia and fibula and interosseous membrane

Posterior surface of tibia

Middle portion of fibula shaft; interosseous membrane

Proximal tibia

Tendon passes obliquely behind medial malleolus and under arch of foot; inserts into several tarsals and metatarsals II–IV

Distal phalanges of toes II–V

Tendon runs under foot to distal phalanx of great toe

Flexes and rotates leg medially to “unlock” knee when leg flexion begins

Prime mover of foot inversion; plantar flexes foot; stabilizes longitudinal arch of foot

Flexes toes; plantar flexes and inverts foot

Flexes great toe (hallux = great toe); plantar flexes and inverts foot; the “push-off muscle” during walking

Gross Anatomy of the Muscular System 221

Plantaris

Medial

head

Lateral head

Gastroc- nemius medial head (cut)

Plantaris (cut)

Gastrocnemius

lateral head (cut)

Popliteus

Soleus (cut) Tibialis posterior

Fibula

Fibularis longus

Flexor hallucis longus

Fibularis brevis

Gastroc- nemius

Flexor digitorum longus

Soleus

Tendon of gastrocnemius

Calcaneal tendon

Medial malleolus

(a)

Lateral malleolus

Calcaneus

Tendon of tibialis posterior

Medial malleolus

Calcaneal tendon (cut)

(b)

Calcaneus

Figure 13.16 Muscles of the posterior aspect of the right leg. (a) Superficial view of the posterior leg. (b) The triceps surae has been removed to show the deep muscles of the posterior compartment.

➤

13

13

222

Exercise 13

O

O 5 origin
I 5 insertion

Tibialis posterior

Popliteus

O

I

O

Flexor hallucis longus

Flexor digitorum longus

O

I

(c)

I

I

Figure 13. 16 (continued) Muscles of the posterior compartment of the right leg. (c–e) Individual muscles are shown in isolation so that their origins and insertions may be observed.

(d)

(e)

13

REVIEW SHEET

Gross Anatomy of the Muscular System

Instructors may assign a portion of the Review Sheet questions using Mastering A&PTM

EXERCISE

Name ______________________________________________________ Lab Time/Date ____________________________________

Classification of Skeletal Muscles

1. Several criteria were given for the naming of muscles.
   For each of the criteria below, list at least two muscles that are named for the given criterion.

   1. Muscle location: __________________________________________________________________________________________

   2. Muscle shape: ____________________________________________________________________________________________

   3. Muscle size: _____________________________________________________________________________________________

   4. Direction of muscle fibers: _________________________________________________________________________________

   5. Number of origins: _______________________________________________________________________________________

   6. Location of attachments: __________________________________________________________________________________

   7. Muscle action: ____________________________________________________________________________________________

2. Match the key terms to the descriptions below.

Key: a. prime mover (agonist) b. antagonist c. synergist d. fixator e. origin f. insertion

____________________ 1. ____________________ 2. ____________________ 3. ____________________ 4. ____________________ 5. ____________________ 6.

term for the biceps brachii during forearm flexion
term that describes the relation of brachioradialis to biceps brachii during forearm flexion term for the triceps brachii during forearm flexion
term for the more movable muscle attachment
term for the more fixed muscle attachment

term for the rotator cuff muscles and deltoid when the forearm is flexed and the hand grabs a tabletop to lift the table

223

224 Review Sheet 13

Muscles of the Head and Neck

3. Using choices from the key at the right, correctly identify muscles provided with leader lines on the illustration. Key:

4. Using the key provided in question 3, identify the muscles described next.

1. buccinator

2. depressor anguli oris

3. depressor labii inferioris

4. frontal belly of the epicranius

5. levator labii inferioris

6. masseter

7. mentalis

8. occipital belly of the epicranius

9. orbicularis oculi

10. orbicularis oris

11. risorius

12. sternocleidomastoid

13. zygomaticus minor and major

used to form the vertical frown crease on the forehead

your kissing muscle
prime mover of jaw closure
tenses skin of the neck during shaving

________ 1. ________ 2. ________ 3. ________ 4.

________ 5.

used in smiling

used to suck in your cheeks

used in blinking and squinting

used to pout (pulls the corners of the mouth downward)

raises your eyebrows for a questioning expression

________ 6.

________ 7. ________ 8. ________ 9.

226 Review Sheet 13

Muscles of the Upper Limb

7. Using terms from the key on the right, correctly identify all muscles provided with leader lines in the illustration. Key:

   1. biceps brachii

   2. brachialis

   3. brachioradialis

   4. extensor carpi radialis longus

   5. flexor carpi radialis

   6. flexor carpi ulnaris

   7. flexor digitorum superficialis

   8. palmaris longus

   9. pronator teres

8. Use the key provided in question 7 to identify the muscles described below. (Some choices from the key will be used more than once.)

________ 1. flexes and supinates the forearm

________
________
________
________
________

6. flexes the hand and middle phalanges 7. pronates the forearm
8. flexes and adducts the hand
9. extends and abducts the hand

10. flat muscle that is a weak hand flexor, tenses skin of the palm

________ 2. ________ 3.

________ 4. ________ 5.

muscle located in the posterior compart- ment of the forearm

forearm flexors; no role in supination (two muscles)

musclelocatedmedialtothepalmarislongus flexes and abducts the hand

228 Review Sheet 13
General Review: Muscle Recognition

11. Identify each lettered muscle in the illustration of the human anterior superficial musculature by matching its letter with one of the following muscle names:

________
________
________
________
________
________
________
________
________
________
________
________
________
________
________
________
________
________
________
________
________
________
________
________
________
________
________
________
________
________
________
________
________

1. adductor longus 2. biceps brachii 3. brachioradialis 4. deltoid

5. extensor digitorum longus 6. external oblique
7. fibularis longus
8. flexor carpi radialis

9. flexor carpi ulnaris
10. frontal belly of epicranius 11. gastrocnemius
12. gracilis
13. iliopsoas
14. intercostals
15. internal oblique
16. masseter
17. orbicularis oculi
18. orbicularis oris
19. palmaris longus
20. pectineus
21. pectoralis major
22. pectoralis minor
23. platysma
24. pronator teres
25. rectus abdominis
26. rectus femoris
27. sartorius
28. serratus anterior
29. soleus
30. sternocleidomastoid
31. sternohyoid
32. temporalis
33. tensor fascia lata

________ 34. tibialis anterior ________ 35. transversus abdominis ________ 36. trapezius
________ 37. triceps brachii ________ 38. vastus lateralis ________ 39. vastus medialis ________ 40. zygomaticus

nn mm

a b c

d

ll

kk jj

cc

bb aa

z

e f

g

h i

j k l m

n

o p q

hh gg

ff ee

ii

dd

y x w

v
u

t

r s

________
________
________
________
________
________

________
________
________
________
________
________
________
________

________
________
________

________
________
________
________
________
________

230 Review Sheet 13
General Review: Muscle Descriptions

13.

Identify the muscles described by completing the following statements. Use an appropriate reference as needed.

1. The _______________________, ________________________, ________________________, and ______________________

   are commonly used for intramuscular injections (four muscles).

2. The insertion tendon of the _____________________________ group contains a large sesamoid bone, the patella.

3. The triceps surae insert in common into the _____________________________ tendon.

4. The bulk of the tissue of a muscle tends to lie ______________________________________ to the part of the body it causes to move.

5. The extrinsic muscles of the hand originate on the _____________________________________________________________.

6. Most flexor muscles are located on the ______________________________________ aspect of the body; most extensors are

   located ______________________________________. An exception to this generalization is the extensor-flexor musculature

   of the __________________________________________________________________________________________________.

+ Bruxism is a condition in which individuals clench and/or grind their teeth. It often occurs as they sleep, leading to jaw pain

and damaged teeth. Which muscles contract during this nocturnal event? _____________________________________________ ____________________________________________________________________________________________________________

+ Repetitive extension of the hand at the wrist and abduction of the hand can lead to lateral epicondylitis. Although sometimes called “tennis elbow,” it more often affects individuals who don’t play tennis. Based on the name lateral epicondylitis and the

action described above, which muscle would most likely have microscopic tears in the tendon? ___________________________ ____________________________________________________________________________________________________________