Muscle Structure and Function Chapter 9 – Part 2 Muscles of the Arm, Leg, Face, Torso, and Neck

Muscle Attachment Does NOT move when muscle contracts Does move when

Classification of Muscle Group Actions Agonist (Prime Mover) Muscle most responsible for movement Antagonist Opposes prime mover Provides precision and control during prime mover contraction Relaxes when prime mover contracts Synergist Aid prime mover Contract at same time as prime mover

Limb muscles Muscles of the limb function in: Movement, grasping, balance Deltoid: muscle forming the rounded contour of the shoulder; moves upper arm Pectoralis major: thick, fan-shaped muscle, situated at the chest (anterior) of the human body; moves upper arm Biceps brachii: two-headed muscle that lies on the upper arm between the shoulder and the elbow; flexes arm Brachialis: muscle in the upper arm that flexes the elbow joint Brachioradialis: muscle of the forearm that flexes the forearm at the elbow; capable of both pronation and supination Palmaris longus: muscle starts up near the elbow and runs across the middle of the forearm; flexes hand Flexor carpi ulnaris: muscle of the human forearm that acts to flex and adduct the hand Flexor carpi radialis:  muscle of the human forearm that acts to flex and abduct the hand

Color Key Purple: Muscles that move the upper arm Orange: Muscles that move the forearm Brown: Muscles that flex the hand

Anterior superficial muscles of the shoulder and arm

Posterior Arm Muscles Triceps brachii:  muscle (3 heads) on the back of the upper arm; moves forearm Anconeus: small triangular elbow muscle connecting the medial side of the ulna to the lateral side of the humerus; extends forearm Extensor carpi radialis longus: found on the lateral side of the humerus, and attaching to the base of metacarpal 2 (pointer finger) Extensor carpi radialis brevis: found on the lateral side of the humerus, running alongside the radius; extends/abduct the wrist Extensor digitorium: extends the medial four digits (phalanges) of the hand Extensor digiti minimi: muscle of the forearm that extends phalanx 5 (pinky finger!) Extensor carpi ulnaris:  extend and adduct at the wrist

Color Key Orange: Muscles that move the forearm Brown: Muscles that extend the hand

Posterior superficial muscles of the arm Flexor Carpi Ulnaris Posterior superficial muscles of the arm Anconeus Extensor digiti minimi 14

Find the muscles on your body.

Anterior Upper Leg Muscles Quadriceps: 4-headed muscle made up of the vastus lateralis, vastus intermedius, vastus medialis, and rectus femoris; moves lower leg Sartorius:  assists in flexing, weak abduction and lateral rotation of the hip, and flexion of knee Gracilis: originates at the ischiopubic ramus and extends down to the tibia; responsible for hip adduction and assists knee flexion Adductor Longus: main function is to adduct the thigh

Upper Leg (Anterior) quadriceps psoas major iliacus rectus femoris vastus intermedius (under rectus femoris) vastus medials vastus lateralis

Upper Leg (Anterior) tensor fascia latae sartorius quadriceps tendon patellar ligament

Posterior Upper Leg Gluteus Maximus: located in the buttocks and is regarded as one of the strongest muscles in the human body; responsible for movement of the hip and thigh Illotibial band: works to extend, abduct, and laterally rotate the hip; knee stabilization Biceps femoris: Both heads of the biceps femoris perform knee flexion. Since the long head originates in the pelvis it is also involved in hip extension; hamstrings Semimembranosus: enabling the leg to flex and rotate, and serving as a thigh extensor; hamstrings Semitendinosis: long, superficial muscle in the back of the thigh; hamstrings

Upper Leg (Posterior) hamstring group gluteus medius biceps femoris gluteus maximus semitendinosus iliotibial band semimembranosus Upper Leg (Posterior)

Muscles of the Lower Leg Gastrocnemius: Along with the soleus muscle, it forms half of the calf muscle; function in plantar flexion of the foot and flexing the leg at the knee joint Soleus: plantar flexion of the foot; powerful musclevital in walking, running, and dancing Achilles tendon: largest and strongest tendon in the human body; connects the calcaneus to the muscles at the back of the calf Extensor digitorum: wing-shaped muscle works to extend the foot at the ankle, along with phalanx 2-5 Tibialis anterior: dorsiflexion and inversion of the ankle Fibularis longus: also known as the peroneus longus; muscle inside the outer area of the human leg, which everts (bends in an outward direction) and flexes the ankle.

calcaneal (Achilles) tendon adductor longus gracilis adductor magnus gastrocnemius soleus sartorius calcaneal (Achilles) tendon Medial Leg Muscles

Lower Lateral Leg tibialis anterior fibularis (peroneus) longus extensor digitorum retinaculum

Knee Muscles/Connections Patellar ligament: connects to two different bones, the patella and the tibia. Quadriceps tendon: attaches patella to the quadriceps muscles by the Meniscus: lateral and medial Two vital functions: Transfer the load from the upper leg to the lower leg Stabilize the knee during flexion, extension and during circular movements. The menisci move during the backward flexion and the forward extension of the knee in order to balance the change of the articular surfaces.

(with tendon & ligament removed) medial meniscus Knee Joint quadriceps tendon posterior cruciate ligament lateral meniscus patella patellar ligament anterior cruciate ligament tibial (medial) collateral ligament fibular (lateral) collateral ligament Anterior Posterior (with tendon & ligament removed)

Head and Neck Muscles There are 4 basic functions of head and neck muscles: swallowing and chewing (mastication) making facial expressions moving your neck supporting your head

Muscles of the Head and Neck

Posterior neck muscles The muscles in the neck help to support the head. How much do you think an average adult head weighs? (over 11 pounds)

Superficial Back Muscles Large, fan-shaped muscles provide force in a wide range of body positions -EX: leaning back to straight vertical and all points in between. Levator Scapulae Trapezius Supraspinitus Infraspinitus Deltoid Teres Major Latissimus Dorsi Rhomboid Major

Trunk Muscles - Thorax Elevate ribs Depress Ribs

Trunk Muscles Abdomen Flexes trunk Stabilizes Lower back Compresses

Strains vs. Sprains A strain is when you "pull" a muscle and a sprain is when you damage a ligament.  Classification of Strains and Sprains: First degree: a few fibers of the ligament/ muscle are torn and loss of function is mild Second degree: roughly half of the fibers of the ligament/ muscle are torn loss of function is moderate to severe Third degree: all or most of the fibers of the ligament/ muscleare torn and loss of function is severe RICE: Rest Ice Compression Elevation