MUSCULAR SYSTEM Structure of the Muscles

Muscles Comprise a large part of the human body Comprise a large part of the human body –Nearly half our body weight comes from muscle tissue  If you weigh 140 lbs, 60 lbs is from muscle attached to bones Over 650 different muscles Over 650 different muscles

Responsibilities of Muscle System 3 main: 3 main: 1. Body movement (voluntary and involuntary) 2. Body form and shape, to maintain posture 3. Body heat, to maintain body temperature

Types of Muscle 3 types: 3 types: –Skeletal –Smooth –Cardiac Described as: Described as: –Striated –Spindle shaped –nonstriated

Skeletal (figure 7-1 pg 123) Attached to the _________ Attached to the _________ Called striped or striated b/c they have cross bandings (striations) of alternating light and dark bands running perpendicular to the length Called striped or striated b/c they have cross bandings (striations) of alternating light and dark bands running perpendicular to the length Voluntary muscle b/c contains nerves under voluntary control Voluntary muscle b/c contains nerves under voluntary control Multinucleate Multinucleate Sarcolemma is the muscle cell membrane and the cytoplasm is sarcoplasm Sarcolemma is the muscle cell membrane and the cytoplasm is sarcoplasm

Smooth (visceral) figure 7-2 Small and spindle shaped Small and spindle shaped Single nuclei Single nuclei No striations No striations Unattached to bones Unattached to bones Involuntary muscles; controlled by the autonomic nervous system Involuntary muscles; controlled by the autonomic nervous system Found in the walls of internal organs Found in the walls of internal organs

Cardiac figure 7-3 Found only in the ____________ Found only in the ____________ Striated, branched, and involuntary Striated, branched, and involuntary Membranes of adjacent cells are fused at intercalated discs Membranes of adjacent cells are fused at intercalated discs Requires continuous supply of oxygen to function Requires continuous supply of oxygen to function Cardiac muscle cells begin to die after 30 seconds of no oxygen Cardiac muscle cells begin to die after 30 seconds of no oxygen

Sphincter/Dilator Muscles Special circular muscles in the openings b/t the esophagus and stomach; stomach and small intestine; and in the walls of the anus, urethra, and mouth Special circular muscles in the openings b/t the esophagus and stomach; stomach and small intestine; and in the walls of the anus, urethra, and mouth Open and close to control the passage of substances Open and close to control the passage of substances

Look at table 7-1 pg 125 Look at table 7-1 pg 125 Summarizes the characteristics of the 3 major muscle types Summarizes the characteristics of the 3 major muscle types

Naming Skeletal Muscles Named by location, size, direction, number of origins, location of origin and insertion, and action; Named by location, size, direction, number of origins, location of origin and insertion, and action; However, not all muscles are named in this manner However, not all muscles are named in this manner Look at figures 7-6 and 7-7 pg 130 and look how the muscles are named Look at figures 7-6 and 7-7 pg 130 and look how the muscles are named

Location…………………. Location…………………. Size……………………….. Size……………………….. Direction of fibers……. Direction of fibers……. Number of origins……. Number of origins……. Location of origin and insertion………………… Location of origin and insertion………………… Action flexor…………… Action flexor…………… Extensor……………………… Extensor……………………… Depressor…………………… Depressor…………………… Frontalis – forehead Gluteus maximus – largest muscle in the buttock External abdominal oblique – edge of the lower rib cage Biceps – two-headed muscle in humerus Sternocleidomastoid – origin in sternum Flexor capri ulnaris – flexes the wrist Extensor carpi ulnaris – extends the wrist Depressor anguli oris – depresses the corner of the mouth; raises and lowers body parts

There are 656 muscles in the human body There are 656 muscles in the human body 327 antagonistic muscle pairs and 2 unpaired muscles 327 antagonistic muscle pairs and 2 unpaired muscles –Unpaired muscles: orbicularis oris and the diaphragm The muscles can be divided and subdivided into the following regions The muscles can be divided and subdivided into the following regions –Head, neck, and trunk and extremities

Head Muscles Muscles of expression Muscles of expression Muscles of mastication (chewing) Muscles of mastication (chewing) Muscles of the tongue Muscles of the tongue Muscles of the pharynx Muscles of the pharynx Muscles of the soft palate Muscles of the soft palate

Neck Muscles Muscles moving the head Muscles moving the head Muscles moving the hyoid bone and the larynx Muscles moving the hyoid bone and the larynx Muscles moving the upper ribs Muscles moving the upper ribs

Trunk and Extremity Muscles Muscles that move the vertebral column Muscles that move the vertebral column Muscles that move the scapula Muscles that move the scapula Muscles of breathing Muscles of breathing Muscles that move the humerus Muscles that move the humerus Muscles that move the forearm Muscles that move the forearm Muscles that move the wrist, hand, and finger digits Muscles that move the wrist, hand, and finger digits Muscles that act on the pelvis Muscles that act on the pelvis Muscles that move the femur Muscles that move the femur Muscles that move the leg Muscles that move the leg Muscles that move the ankles, feet, and toe digits Muscles that move the ankles, feet, and toe digits

Muscles of the Head and Neck Control human facial expressions such as: Control human facial expressions such as: –What are some examples? (think of feelings) –Refer to table 7-2 and figure 7-8 Muscles of mastication control the mandible, raising it to close the jaw and lowering it to open the jaw. Muscles of mastication control the mandible, raising it to close the jaw and lowering it to open the jaw. –Refer to table 7-3 and figure 7-8 Muscles that move the head cause extension, flexion, and rotation Muscles that move the head cause extension, flexion, and rotation –Refer to table 7-4 and figure 7-8

Muscles of the Upper Extremities Help to move the scapula and humerus and forearm, wrist, hand, and fingers Help to move the scapula and humerus and forearm, wrist, hand, and fingers Refer to table 7-5 and figure 7-9 Refer to table 7-5 and figure 7-9

Muscles of the Trunk Control breathing and the movements of the abdomen and the pelvis Control breathing and the movements of the abdomen and the pelvis Refer to table 7-6 and figure 7-10 Refer to table 7-6 and figure 7-10

Muscles of the Lower Extremities Assist in the movement of the femur, leg, ankle, foot, and toes Assist in the movement of the femur, leg, ankle, foot, and toes Hamstrings comprised of: semitendinosus, biceps femoris, and semimembranosus muscles Hamstrings comprised of: semitendinosus, biceps femoris, and semimembranosus muscles Tendons of these muscles attach posteriorly to the tibia and fibula (can be felt behind the knee) Tendons of these muscles attach posteriorly to the tibia and fibula (can be felt behind the knee) Responsible for flexing the knee Responsible for flexing the knee Refer to table 7-7 and figure 7-11 Refer to table 7-7 and figure 7-11