The Muscular System Primary Function of the Muscular

The Muscular System

Primary Function of the Muscular System n n n Locomotion movement of substances through the body structure and support for organs and tissues

Muscle Tissue: 3 Types n Muscle Tissue enables the movement of body structures. Smooth, Cardiac, Skeletal

Muscle Types: Smooth Muscle n Smooth muscle is non-striated, and acts in a number of involuntary processes in the body. Some of these processes include:

Muscle Types: Smooth Muscle n n n allows the expansion and contraction of arteries and veins lines the bladder and reproductive tracts lines the entire gastrointestinal tract

Did you know? . . . n Tiny smooth muscle fibers in the skin called Arrector pili are responsible for “goose bumps. ”

Muscle Types: Cardiac Muscle n Cardiac muscle (heart muscle) is striated but functions involuntarily. It is solely responsible for propelling blood throughout the body.

Muscle Types: Skeletal Muscle n Skeletal muscle is striated, and associated with voluntary movement. It also provides structure and support for organs and tissues.

Anatomy of skeletal muscles tendon Muscle Fascicle Skeletal muscle fiber (cell)

How Do Muscles Work? n n n Individual muscle fibers are composed of small cylindrical structures called myofibrils. The functional component within the myofibril is called the sarcomere. Within the sacromere, protein filaments called actin and myosin allow the cell to expand contract in a 3 step process:

3 Steps n n n 1) Before the muscle is stimulated, actin and myosin filaments partially overlap one another. 2) A nerve cell releases a signal which causes the actin and myosin filaments to “slide” along one another and overlap even more. 3) This contracts the myofibril and subsequently the entire muscle cell. When the nervous signal changes, the filaments relax and return to their original state.

Muscle fiber sarcomere Z-line myofibril Actin myosin Thin myofilament Myosin molecule of thick myofilament

Sarcomere

Actin and Myosin: A Closer Look n Access the website below (skip to sections 6 -10) and complete the tutorial. http: //www. wiley. com/college/pratt/0471393878/st udent/animations/actin_myosin. swf

Action Potentials and the Neuromuscular Junction 1. Impulse arrives at axon terminal Ca+ ions rush in activating synaptic vesicles 2. 3. 4. Synaptic vesicles fuse with cell membrane of axon terminal ACh released ACh binds with motor end plate: deplorization occurs Impulse travels through -tubules & SR T

Actin, Myosin, and Action Potentials Putting it all Together… n Access these online animations to help visualize these processes… The Neuromuscular Junction n http: //tinyurl. com/the-neuromuscularjunction Action Potential and Muscle Contraction n http: //tinyurl. com/5 qox 4 x Sarcomere Contraction n http: //tinyurl. com/sarcomerecontraction

Did you Know? If you check out a standard lass, Muscles are a third of her body mass. Muscle (~35%) BODY COMPOSITION

The Muscular System: Key Components n Muscles move body parts because they’re attached to bones by strips of dense connective tissue called tendons.

Skeletal Muscle: Key Concepts n The place where muscle attaches to a stationary bone is called the “origin. ” The place where the same muscle attaches and “pulls” is called the “insertion. ” Origin Insertion

Skeletal Muscle: Key Concepts n Skeletal muscle can be characterized as either “extensors” (causing a joint to straighten or extend), or a “flexor” (causing a joint to bend or flex).

Challenge question n How are tendons different from ligaments?

Basic Muscle Groups You Need to Know!

Basic Muscle Groups You Need to Know!

Basic Muscle Groups You Need to Know!

Naming Skeletal Muscles Direction of Muscle Fibers Location Action Skeletal Muscle Origin & Insertion Size Shape Number Of Origins

Naming Muscles: By Direction of Muscle Fibers (Relative to the Midline) n n n RECTUS = parallel to the midline n Rectus Abdominus TRANSVERSE = perpendicular to midline n Transverse Abdominus OBLIQUE = diagonal to midline n External Oblique

Naming Muscles: Location n Structure near which muscle is found n n FRONTALIS = near FRONTAL bone OCCIPITALIS = near OCCIPITAL bone

Naming Muscles: Size n n n n Relative Size of Muscle MAXIMUS = largest n Gluteus Maximus MEDIUS = middle n Gluteus Medius MINIMUS = smallest n Gluteus Minimus LONGUS = longest n Fibularis Longus BREVIS = short n Fibularis Brevis TERTIUS = shortest n Fibularis Tertius

Naming Muscles: Number of Origins n n Number of tendons of origin BICEPS = Two n Biceps Brachii n Biceps Femoris TRICEPS = Three n Triceps Brachii QUADRICEPS = Four n Quadriceps Femoris

Naming Muscles: Shape n n n Relative Shape of the Muscle DELTOID = triangular shape Δ TRAPEZIUS = trapezoid shape SERRATUS = sawtoothed ♒ RHOMBOIDEUS = rhomboid shape TERES = round ○

Naming Muscles: Action NAME FLEXOR EXTENSOR ACTION EXAMPLE Decrease angle at a joint Flexor Carpi Radialis Increase angle at a joint Extensor Carpi Ulnaris ABDUCTOR Move bone away from midline Abductor Pollicis Longus ADDUCTOR LEVATOR Move bone toward midline Adductor Longus Produce upward movement Levator Scapulae DEPRESSOR Produce downward movement Depressor Labii Inferioris SUPINATOR Turn palm upward/anterior Supinator PRONATOR Turn palm downward/posterior Pronator Teres

Cateorigizing muscles by the Actions they Facilitate n n Prime mover– muscle with the major responsibility for a certain movement Antagonist – muscle that opposes or reverses a prime mover Synergist – muscle that aids a prime mover in a movement and helps prevent rotation Fixator – stabilizes the origin of a prime mover Examples __________

Head & Neck Muscles

Head & Neck Muscles n Frontalis: elevate n Orbicularis Oculi: close n n eyebrows eyelid Zygomaticus: draw angle of lip upward Buccinator: draws cheeks against teeth Orbicularis Oris: closes mouth Platysma: draws lower lip down & back n n n Cranial Aponeurosis: connects frontalis to occipitalis Temporalis: elevates mandible Occipitalis: draws scalp back Masseter: elevates mandible Sternocleidomastoid: n n Flexes head Draws head toward shoulder

Key Muscles of Facial Expression n Smiling Muscles n n n Orbicularis Oculi Nasalis Levator Labii Superioris Levator Anguli Superioris Zygomaticus Risorius n Frowning Muscles n n n Frontalis Orbicularis Oris Depressor Anguli Oris Depressor Labii Inferioris Mentalis Platysma

Muscles of the Axial Skeleton n Erector Spinae: maintain posture of back/extension n n n Semispinalis Multifidus Rotatores Respiratory Muscles n Spinalis Longissimus Iliocostalis Oblique Muscles: rotation of the vertebrae n n n Diaphragm External Intercostals Internal Intercostals—deep breaths Abdominal Muscles n n External Obliques Internal Obliques Transverse Abdominus Rectus Abdominus

Muscles of the Axial Skeleton

Muscles of Scapular Stabilization n Trapezius: n n n n Retraction Elevation Depression Upward Rotation Rhomboid—retraction Levator Scapular—Elevation Pectoralis Major—Protraction Serratus Anterior—Protraction

Anterior Muscles of Shoulder n Deltoid n n Pectoralis Major n n n Flexion/Extension Abduction/Adduction Internal’External Rotation Adduction Flexion Extension Internal Rotation Biceps Brachii—Flexion

Posterior Muscles of Shoulder n Teres Major n n Latissimus Dorsi n n Adduction Extension Internal Rotation Triceps Brachii n n Adduction Extension

Rotator Cuff Muscles (SITS) n Supraspinatus n n Abduction Infraspinatus n External Rotation q q Teres Minor q External Rotation q Internal Rotation Subscapularis

Muscles of the Elbow/Forearm n Triceps Brachii— n Bicep Brachii— Extension n n Brachialis—Flexion Brachioradialis— n n n Flexion Supination Flexion Pronator Teres Pronator Quadratus Supinator Longus

Muscles of the Wrist & Hand n n n Flexor Carpi Ulnaris Flexor Carpi Radialis Flexor Digitorum Extensor Carpi Ulnaris Extensor Carpi Radialis Extensor Digitorum Anterior (Palmar) View Posterior (Dorsal) View

Muscles of the Hip: Anterior §Medial/Adductor Muscles: §Adductor Magnus §Adductor Longus §Adductor Brevis §Gracilis §Anterior Muscles §Iliopsoas—Flexion §Pectineus— §Flexion §Adduction §Sartorius— §Flexion §Lateral Rotation

Muscles of the Hip: Gluteal ** Gluteus Minimus is under the Gluteus Medius n Gluteus Maximus— n Gluteus Medius— n Gluteus Minimus— n Tensor Fasciae Lata Extension Abduction — n n Flexion Abduction

Muscles of Anterior Thigh n “Quadriceps” n Rectus Femoris— n n n Hip flexion Knee extension Vastus Lateralis—knee extension Vastus Medialis—knee extension Vastus Intermedius— knee extension Sartorius— n n Hip & Knee Flexion Lateral Hip Rotation **Vastus Intermedius is beneath Rectus Femoris

Muscles of Posterior Thigh n “Hamstrings” n n n Responsible for Knee Flexion & Hip Extension Semimembranosus Semitendinosus Biceps Femoris Gastrocnemius n Knee Flexion

Muscles of the Lower Leg n Anterior Compartment n n Posterior Compartment n n n Tibialis Anterior — Dorsiflexion & inversion Extensor Digitorum Longus Fibularis Tertius — dorsiflexion & eversion Gastrocnemius — plantarflexion, knee flexion Soleus — plantarflexion Lateral Compartment n n Fibularis Longus — plantarflexion & eversion Fibularis Brevis — plantarflexion & eversion

Can you think of different ways in which the muscular system works with other body systems to maintain homeostasis?

Aerobic vs. Anaerobic Exercise n Muscle contraction requires ATP. When oxygen is present in sufficient amounts, the normal processes of glycolysis and cellular respiration can take place (aerobic). However, if oxygen is not present in large enough quantities to sustain vigorous muscle contraction, only a small amount of ATP is generated through glycolysis; and lactic acid forms in the absence of cellular respiration (anaerobic).

Pop Quiz! Identify Skeletal muscle groups 1 -14 n

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