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

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 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

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 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

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

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 Transverse abdominis

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 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

Muscles That Move the Thigh (p. 203) Gluteus maximus Extends thigh Gluteus medius Abducts and rotates thigh medially Gluteus minimus

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 Semimembranosus

Muscles That Move the Leg (p. 204) Quadriceps femoris group Rectus femoris Extends leg at knee Vastus lateralis Vastus medialis Vastus intermedius

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 Eversion of foot Supports arch of foot