Names of Muscles are Descriptive• Relative size

– Pectoralis major: major = large size• Shape

– Deltoid: like a delta or triangle• Location

– Extensor digitorum: digits = fingers or toes

• Action– Extensor digitorum: extension

• Number of attachments– Biceps brachii: biceps = 2 heads

• Direction of fibers– External obliques: oblique =

anglular

Muscle Facts• The human body has over 600

distinct skeletal muscles– The face contains over 60

muscles• 40 of which are used to frown• 20 of which are used to smile

– The stapedius in the middle ear is the smallest muscle in the body

– The gluteus maximus in the buttock is the largest muscle in the body

– The sartorius in the thigh is the longest muscle in the body

Temporomandibular Joint (TMJ)• Articulation between the

mandibular condyle of the mandible and the mandibular fossa of the temporal bone

• Strain of the joint may be caused by – Grinding the teeth– Hyperextending the lower jaw

• The condition of having strained the joint is called temporomandibular joint syndrome or TMJ syndrome

• Symptoms include headache, earache, and pain in the jaw, neck, or shoulder

Muscles of Facial Expression (p. 195)• Enable communication through

facial expressions of surprise, sadness, anger, fear, disgust, and pain

• Examples: – Epicranius – lifts eyebrow

• Made up of the frontalis & occipitalis

– Orbicularis oris – closes lips– Orbicularis oculi – closes eyes– Buccinator – compresses

cheeks– Zygomaticus – raises corner of

mouth– Platysma – draws angle of

mouth downward

Muscles of Mastication (p. 195)• Enable chewing movements• Three pairs of these muscles

are used in biting movements:– Masseter – elevates the

mandible– Temporalis – elevates the

mandible– Sphenomandibularis

• Newly discovered muscle• Extends about an inch and

a half from behind the eyes to the inside of the jawbone

• Thought to help produce the movements of chewing

Muscles That Move the Head (p. 196)• Result from the actions of paired

muscles in the neck and upper back

• Examples:– Sternocleidomastoid

• Pulls head to one side• Pulls head toward chest• Raises sternum

– Splenius capitis• Rotates head• Bends head to one side• Brings head upright

– Semispinalis capitis• Extends head• Bends head to one side• Rotates head

Muscles That Move the Pectoral Girdle• See page 196• Closely associated with

muscles that move the arm• Examples:

– Trapezius• Rotates scapula & raises

arm• Raises scapula• Pulls scapula medially• Pulls scapula and shoulder

downward– Rhomboid major

• Raises and adducts scapula– Levator scapulae

• Elevates scapula

Muscles That Move the Pectoral Girdle• See page 196• Continued

– Serratus anterior• Pulls scapula

anteriorly and downward

– Pectoralis minor• Pulls scapula

anteriorly and downward

• Raises ribs

Muscles That Move the Arm (p. 198)• The arm is one of the more

freely movable parts of the body

• Muscles connect the humerus to many other parts including the pectoral girdle, ribs, and vertebral column

• Examples:– Coracobrachialis

• Flexes and adducts arm– Pectoralis major

• Pulls arm anteriorly and across chest

• Rotates humerus• Adducts arm

Muscles That Move the Arm (p. 198)• Arm muscles (continued)

– Teres major• Extends humerus• Adducts and rotates arm

medially– Latissimus dorsi

• Extends and adducts arm• Rotates humerus inwardly• Pulls shoulder downward

and posteriorly– Supraspinatus

• Abducts arm– Deltoid

• Abducts arm, • Extends or flexes humerus

Muscles That Move the Arm (p. 198)• Arm muscles (continued)

– Subscapularis• Rotates arm medially

– Infraspinatus• Rotates arm laterally

– Teres minor• Rotates arm laterally

Muscles That Move the Forearm (p. 199)• Muscles that connect the

radius or ulna to the humerus or pectoral girdle produce most of the forearm movements

• Examples:– Biceps brachii

• Flexes forearm at the elbow• Rotates hand laterally

– Brachialis• Flexes forearm at elbow

– Brachioradialis• Flexes forearm at elbow

– Triceps brachii• Extends forearm at elbow

Muscles That Move the Forearm (p. 199)• Forearm muscles (continued)• Examples:

– Supinator• Rotates forearm at elbow

– Pronator teres• Rotates forearm medially

– Pronator quadratus• Rotates forearm medially

Muscles That Move the Hand (p. 200)• Muscles that move the hand

originate from the distal end of the humerus and from the radius and ulna

• Two major groups:– Flexors – anterior forearm– Extensors – posterior

forearm• Examples

– Flexor carpi radialis• Flexes and abducts the

wrist– Flexor carpi ulnaris

• Flexes and adducts wrist

Muscles That Move the Hand (p. 200)• Hand muscles (continued)

– Palmaris longus• Flexes wrist

– Flexor digitorum profundus

• Flexes distal joints of fingers

– Extensor carpi radialis longus

• Extends wrist • Abducts hand

– Extensor carpi radialis brevis

• Extends wrist• Abducts hand

Muscles That Move the Hand (p. 200)• Hand muscles (continued)

– Extensor carpi ulnaris• Extends and adducts

wrist– Extensor digitorum

• Extends fingers

Muscles of Abdominal Wall (p. 201)• Bone supports the walls of the

chest and pelvis, but not the walls of the abdomen

• The anterior and lateral walls of the abdomen are composed of layers of broad, flat muscles– Connect the rib cage and vertebral

column to the pelvic girdle• Linea alba

– Band of tough connective tissue– Extends from the xiphoid process

of the sternum to the symphysis pubis

– Attachment for abdominal muscles

Muscles of Abdominal Wall (p. 201)• Abdominal muscles (continued)

– External obliques• Tenses abdominal wall• Compresses abdominal

contents– Internal obliques

• Tenses abdominal wall• Compresses abdominal

contents– Transverse abdominis

• Tenses abdominal wall• Compresses abdominal

contents

Muscles of Abdominal Wall (p. 201)• Abdominal muscles (continued)

– Rectus abdominis• Tenses abdominal wall• Compresses abdominal

contents• Flexes vertebral column

Muscles of Pelvic Outlet (p. 202)• Two muscular sheets

span the outlet of the pelvis– Pelvic diaphragm

• Deeper• Forms the floor of

the pelvic cavity– Urogenital

diaphragm • More superficial• Fills the space

within the pubic arch

Muscles of Pelvic Outlet (p. 202)• Pelvic Diaphragm

– Levator ani• Supports pelvic viscera• Provides sphincter-like action

in anal canal and vagina• Urogenital Diaphragm

– Superficial transversus perinei• Supports pelvic viscera

– Bulbospongiosus• Males: assists emptying of

urethra• Females: constricts vagina

– Ischiocavernosis• Assists function of

bulbospongiosus

Muscles of Pelvic Outlet (p. 202)

Muscles That Move the Thigh (p. 203)• Attached to the femur and to some

part of the pelvic girdle• Occur in anterior and posterior

groups– Anterior groups primarily flex the

thigh– Posterior groups extend, abduct,

and rotate the thigh• Examples:

– Psoas major• Flexes thigh

– Iliacus• Flexes thigh

Muscles That Move the Thigh (p. 203)– Gluteus maximus

• Extends thigh– Gluteus medius

• Abducts and rotates thigh medially– Gluteus minimus

• Abducts and rotates thigh medially

Muscles That Move the Thigh (p. 203)– Tensor fasciae latae

• Abducts, flexes, and rotates thigh medially

– Adductor longus• Adducts, flexes, and rotates

thigh laterally– Adductor magnus

• Adducts, extends, and rotates thigh laterally

– Gracilis• Adducts thigh• Flexes and rotates lower limb

medially

Muscles That Move the Leg (p. 204)• Connect the tibia or fibula to the

femur or the pelvic girdle• Can be separated into two major

groups– Those that flex the knee– Those that extend the knee

• Examples:– Sartorious

• Flex leg and thigh• Abducts thigh• Rotates thigh laterally• Rotates leg medially

Muscles That Move the Leg (p. 204)• Hamstring group

– Biceps femoris• Flexes leg• Extends thigh

– Semitendinosus• Flexes leg• Extends thigh

– Semimembranosus• Flexes leg• Extends thigh

Muscles That Move the Leg (p. 204)• Quadriceps femoris group

– Rectus femoris• Extends leg at knee

– Vastus lateralis• Extends leg at knee

– Vastus medialis• Extends leg at knee

– Vastus intermedius• Extends leg at knee

Muscles That Move the Foot (p. 205)• Attach the femur, tibia, and

fibula to the bones of the foot• Move the foot upward

(dorsiflexion) or downward (plantarflexion)

• Turn the sole of the foot medially (inversion) or laterally (eversion)

• Examples:– Tibialis anterior

• Dorsiflexes and inverts the foot

– Fibularis tertius• Dorsiflexes and everts the

foot

Muscles That Move the Foot (p. 205)– Extensor digitorum longus

• Dorsiflexion and eversion of foot

• Extension of toes– Gastrocnemius

• Plantarflexion of foot• Flexion of leg at knee

– Soleus• Plantar flexion of foot

Muscles That Move the Foot (p. 205)– Flexor digitorum longus

• Plantarflexion and inversion of foot

• Flexion of the four lateral toes

– Tibialis posterior• Plantarflexion• Inversion of foot

– Fibularis longus• Plantarflexion• Eversion of foot• Supports arch of foot