MUSCLE TISSUE
NERVE AND MUSCLE CELLS ARE CAPABLE OF TRANSMITTING ELECTROCHEMICAL IMPULSES ALONG THEIR MEMBRANES ( EXCITABILITY )
ALL CELLS IN THE BODY POSSESS MEMBRANE POTENTIAL, BUT ONLY NERVE AND MUSCLE CELLS UTILIZE THIS CHARACTERISTIC TO GENERATE
ACTION POTENTIALS
1. MUSCLE TISSUE IS EXCITABLE AND PRODUCES ELECTRICAL IMPULSES IN RESPONSE TO STIMULUS
2. MUSCLE TISSUE IS EXTENSIBLE AND CAN BE STRETCHED. WHEN THE ENDS OF A STRETCHED MUSCLE ARE RELEASED, IT RECOILS TO ITS ORIGINAL SIZE ( ELASTICITY )
CATEGORIES OF MUSCLE FIBERS
1. STRIATED MUSCLE FIBERS (SKELETAL AND CARDIAC MUSCLE)
2. SMOOTH MUSCLE FIBERS
FUNCTIONS
SKELETAL MUSCLES ARE PRIMARILY FOR LOCOMOTION. OTHER FUNCTIONS INCLUDE MAINTENANCE OF POSTURE AND BODY TEMPERATURE AND SUPPORT OF SOFT TISSUES.
MUSCLE STRUCTURE
MUSCLE IS MADE UP OF BUNDLES, OR FASCICULI, OF SKELETAL MUSCLE CELLS.
A COLLAGENOUS CONNECTIVE TISSUE LAYER ( EPIMYSIUM ) COVERS THE ENTIRE MUSCLE.
THE EPIMYSIUM FOLDS INTO THE BELLY OF THE MUSCLE AS THE PERIMYSIUM AND SEPARATES MUSCLE INTO BUNDLES OF MUSCLE CELLS (FASCICLE )
AN EXTENSION OF THE PERIMYSIUM, CALLED ENDOMISYIUM, PLUNGES DEEP INTO EACH FASCICLE AND SURROUNDS INDIVIDUAL MUSCLE FIBERS
THE EPIMYSIUM EXTENDS AS A STRONG CORD CALLED THE TENDON WHICH BLENDS INTO THE PERIOSTEUM OF THE ATTACHED BONE.
ALSO WE HAVE APONEUROSIS, BROAD FLAT SHEET OF CONNECTIVE TISSUE THAT ATTACHES A MUSCLE TO SKELETON OR ANOTHER MUSCLE
SKELETAL MUSCLES ATTACH TO BONES AND OTHER TISSUES BY TENDONS
FOR THE MUSCLE TO PRODUCE A COORDINATED ACTION, ONE END OF IT MUST SERVE AS AN ATTACHMENT SITE WHILE THE OTHER END MOVES THE INTENDED BONE.
THE LESS MOVABLE END OF THE MUSCLE IS CALLED THE ORIGIN
THE OPPOSITE END THAT MOVES THE BONE IS CALLED THE INSERTION
STRUCTURE OF SKELETAL MUSCLE FIBER
SKELETAL MUSCLES ARE COMPOSED OF CELLULAR STRUCTURES CALLED MUSCLE FIBERS
EACH MUSCLE FIBER IS A COMPOSITE OF MANY CELLS THAT FUSED DURING EMBRYONIC DEVELOPMENT
THE CELL MEMBRANE OF A MUSCLE FIBER IS CALLED THE SARCOLEMMA
CONNECTING SARCOLEMMA TO THE INTERIOR OF THE FIBER ARE MANY TRANSVERSE TUBULES ( T TUBULES ) WHICH FUNCTION IN PASSING CONTRACTION STIMULI TO DEEPER REGIONS OF THE MUSCLE FIBER.
THE CELL MEMBRANE OF A MUSCLE FIBER IS CALLED THE SARCOLEMMA
CONNECTING SARCOLEMMA TO THE INTERIOR OF THE FIBER ARE MANY TRANSVERSE TUBULES ( T TUBULES ) WHICH FUNCTION IN PASSING CONTRACTION STIMULI TO DEEPER REGIONS OF THE MUSCLE FIBER.
EACH MYOFIBRIL CONSISTS OF SEVERAL DIFFERENT KIND OF PROTEINS ARRANGED IN 3,000 THIN AND 1,500 THICK FILAMENTS
THIN FILAMENTS ARE MOSTLY COMPOSED OF THE PROTEIN ACTIN
THICK FILAMENTS ARE MADE OF MYOSIN
FILAMENTS ARE ARRANGED IN REPEATING PATTERNS CALLED
SARCOMERES
DISTINGUISHABLE REGIONS
THIN FILAMENTS CONNECT AT THE Z LINES ON EACH END OF SARCOMERE
AREAS NEAR Z LINES THAT CONTAIN ONLY THIN FILAMENTS ARE I BANDS
BETWEEN I BANDS IS THE A BAND, AREA WITHIN THE LENGTH OF THICK FILAMENTS
EDGES OF A BAND ARE THE ZONE OF OVERLAP WHERE THICK AND THIN FILAMENTS BIND DURING MUSCLE CONTRACTION.
THE MIDDLE REGION OF A BAND IS THE H BAND ( H ZONE ) AND CONTAINS ONLY THICK FILAMENTS
M LINE IS IN THE CENTER OF BAND A, ATTACHES THICK FILAMENTS
THIN FILAMENTS
CONSISTS OF TWO INTERWINING STRANDS OF ACTIN ( G ACTIN FORMS THE ACTIN FILAMENT, AND F ACTIN LOOKS LIKE A TWISTED PEARL NECKLACE )
ON G ACTIN SUBUNITS ARE ACTIVE SITES WHERE MYOSIN BIND
THE OTHER TWO PROTEINS ARE TROPOMYOSIN AND TROPONIN
Tropomyosin follows actin filaments and blocks active sites
Troponin holds tropomyosin in position and has binding sites for calcium
THICK FILAMENTS
ARE MADE OF THE PROTEIN MYOSIN
EACH SUBUNIT CONSISTS OF TWO STRANDS: TWO INTERWINED TAIL REGIONS AND TWO GLOBULAR HEADS
THE NEUROMUSCULAR JUNCTION
EVERY SKELETAL MUSCLE FIBER IS CONTROLLED BY A MOTORNEURON AT A SINGLE
NEUROMUSCULAR JUNCTION
THE NEUROMUSCULAR JUNCTION IS WHERE THE NERVE FIBER CONTACTS THE MUSCLE FIBER
IS USUALLY MADE AT APPROXIMATELY THE MIDPOINT OF THE FIBER SO THAT THE ACTION POTENTIAL GENERATED IN THE FIBER WILL REACH THE OPPOSITE ENDS OF THE FIBER AT ABOUT THE SAME TIME
THE END OF A NEURON, THE AXON, EXPANDS TO FORM A BULBOUS SYNAPTIC KNOB CONTAINING CHEMICAL MESSENGER MOLECULES CALLED ACETYLCHOLINE.
A SMALL GAP, THE SYNAPTIC CLEFT, SEPARATES SYNAPTIC KNOB FROM A FOLDED AREA OF SARCOLEMMA, THE MOTOR END PLATE.
THE SURFACE OF THE AXON TERMINAL BRANCH WITHIN THE CLEFT IS CALLED THE PRESYNAPTIC MEMBRANE.
THE INFOLDED SARCOLEMMA ON THE OTHER SIDE OF THE SYNAPTIC CLEFT IS THE POSTSYNAPTIC MEMBRANE.
1. ACTION POTENTIAL TRAVELS AND REACHES SYNAPTIC KNOB.
2. SYNAPTIC VESICLES RELEASE ACETYLCHOLINE INTO SYNAPTIC CLEFT
3. ACh HOOKS UP RECEPTORS ON POSTSYNAPTIC MEMBRANE.
4. AN ACTION POTENTIAL DEVELOPS IN SARCOLEMMA OF MUSCLE FIBER.
ONCE A.P. IS INITIATED IN THE SARCOLEMMA
1. Action potential moves inward to the T-TUBULE SYSTEM.
2. CALCIUM IONS are released by the SARCOPLASMIC RETICULUM
2. ACh is inactivated by ACETILCHOLINESTERASE.
USUALLY
WHEN A MUSCLE PULL IN ONE DIRECTION, AN ANTAGONISTIC MUSCLE PULL IN THE OPPOSITE DIRECTION TO PRODUCE RESISTANCE AND PROMOTES A SMOOTH MOVEMENT.
MUSCLE OPERATES IN ANTAGONISTIC SETS, WHEN A MUSCLE PRODUCES MOVEMENT IN ONE DIRECTION, ANOTHER MUSCLE PULLS IN THE OPPOSITE DIRECTION. ( THE PRIME MOVER AND THE ANTAGONIST )
MUSCLES THAT HELP THE PRIME MOVER ARE CALLED SYNERGIST.
NAMING MUSCLES
MUSCLES ARE NAMED AFTER THE BONES THEY ATTACH TO, BODY REGIONS, MUSCLE SHAPES, MUSCLE ACTIONS, ORIGINS, AND INSERTIONS.
NAMES ARE OFTEN COMPOUND NAMES ( temporalis muscle, occipitalis, sternocleidomastoid )
THE SIZE OF A MUSCLE IS OFTEN REFLECTED IN ITS NAME ( gluteus maximus, gluteus minimus )
THE DIRECTION OF MUSCLE FASICLES IS ALSO USED ( abdominus rectus, transversus abdominis, obliques )
MANY MUSCLES ARE NAMED AFTER THEIR ORIGIN ( triceps, has 3 origins; biceps, quadriceps )
SHAPE OF THE MUSCLE ( deltoid, trapezium )
OTHERS ARE NAMED BASED ON THEIR ACTIONS ( flexor carpi ulnaris, levator scapulae )
BODY MUSCLES
MUSCLES OF THE HEAD AND THE NECK
MUSCLES OF FACIAL EXPRESSION
EPICRANIUS
FRONTALIS
OCCIPITALIS
ORBICULARIS OCULI
CORRUGATOR SUPERCILII
ORBICULARIS ORBIS
BUCCINATOR
DEPRESSOR LABII
LEVATOR LABII
RISORIUS
ZYGOMATICUS MAJOR
ZYGOMATICUS MINOR
PLATYSMA
MUSCLES OF THE EYE
THESE OCULOMOTOR MUSCLES ARE LOCATED ON THE OUTSIDE OF THE EYE, AND INSERT ON THE SCLERA, THE WHITE, FIBROUS COVERING ON THE EYE
( EXTRINSEC MUSCLES )
INTRISECT MUSCLES ARE THE INTERNAL MUSCLES OF EYE AND ARE INVOLVED IN FOCUSING EYE FOR VISION
EXTRINSIC MUSCLES OF THE EYE
SUPERIOR RECTUS
INFERIOR RECTUS
MEDIAL RECTUS
LATERAL RECTUS
SUPERIOR OBLIQUE
INFERIOR OBLIQUE
MUSCLES OF MASTICATION
MASSETER
TEMPORALIS
PTERYGOIDEUS INTERNUS
PTERYGOIDEUS EXTERNUS
BUCCINATOR
MUSCLES OF THE TONGUE
PALATOGLOSSUS
GENIOGLOSSUS
STYLOGLOSSUS
HYPOGLOSSUS
MUSCLES OF THE ANTERIOR NECK
THESE MUSCLES INSERT ON THE
HYOID BONE
SUPRAHYOID MUSCLES
GENIOHYOID
STYLOHYOID
MYLOHYOID
DIGASTRIC
INFRAHYOID MUSCLES
OMOHYOID
STERNOHYOID
STERNOTHROYD
THYROHYOID
MUSCLES
THAT MOVE THE HEAD
ARE LONG, SLENDER MUSCLES
EACH CONSISTS OF SEVERAL DIVISIONS ARISING FROM DIFFERENT POINTS.
ANTERIOR MUSCLES
STERNOCLEIDOMASTOID attach to sternum, clavicle, mastoid process of temporal bone. ACTS TO FLEX THE HEAD.
POSTERIOR MUSCLES
SCALENUS
SEMISPINALIS
SPLENIUS
MUSCLES OF THE CHEST, ABDOMEN, AND SPINE
ANTERIOR MUSCLES OF THE CHEST
PECTORALIS MAJOR
PECTORALIS MINOR
SUBCLAVIUS
SERRATUS ANTERIOR
MUSCLES OF RESPIRATION
INTERNAL AND EXTERNAL
INTERCOSTAL MUSCLES
ASSIST THE DIAPHRAGM DURING BREATHING
DIAPHRAGM
FORM THE THORACIC FLOOR
SEPARATES THORACIC AND ABDOMINOPELVIC CAVITIES
ORIGINATES AT MANY POINTS, MUSCLE FIBERS MEET AT A CENTRAL TENDON.
WHEN THE MUSCLE CONTRACTS, IT PULLS DOWN UPON THE CENTRAL TENDON AND LOWERS THE THORACIC FLOOR. THIS INCREASES THE VOLUME OF THORACIC CAVITY
CONTRACTING DIAPHRAGM EXPAND THORAX AND AIR IS INHALED INTO THE LUNGS
ABDOMINAL MUSCLES
RECTUS ABDOMINIS ( divided by a fibrous line called The Linea alba )
EXTERNAL OBLIQUE MUSCLE
INTERNAL OBLIQUE MUSCLE
TRANSVERSE ABDOMINIS
POSTERIOR MUSCLES OF THE CHEST
TRAPEZIUS
LATISSIMUS DORSI
MUSCLES OF THE POSTERIOR SPINE
LONGISSIMUS ( capitis, cervicis, and thoracis )
ILIOCOSTALIS
( BOTH ARE CALLED COLLECTIVELY SACROSPINALIS MUSCLE )
SEMISPINALIS CAPITIS AND SPLENIUS CAPITIS
SCALENES
QUADRATUS LUMBORUM
MUSCLES OF PELVIC REGION
COCCYGEUS
LEVATOR ANI
EXTERNAL ANAL SPHINCTER
MUSCLES OF THE SHOULDER, ARM, AND HAND
IT FUNCTION IS TO SUPPORT AND MOVE THE UPPER LIMBS.
MUSCLES OF THE SHOULDER HELD TO ANCHOR THE HUMERUS TO THE SCAPULA AND ALSO TO STABILIZE SCAPULA ON POSTERIOR CHEST
MUSCLES OF UPPER ARM FLEX AND EXTEND THE ARM
MUSCLES OF FOREARM MOVE THE WRIST AND THE HAND
MUSCLES OF THE SHOULDER
SUPRASPINATUS
INFRASPINATUS
SUBSCAPULARIS
TERES MINOR
TERES MAJOR
RHOMBOIDEUS
LEVATOR SCAPULAE
DELTOID ( anterior, posterior and middle portion )
MUSCLES OF THE UPPER ARM
BICEPS BRACHI
BRACHIALIS
CORACOBRACHIALIS
TRICEPS BRACHII
MUSCLES OF THE FOREARM
SUPINATOR
PRONATOR TERES AND PRONATOR QUADRATUS
SUPERFICIAL FLEXORS OF THE WRIST ( Flexor carpi radialis, Palmaris Longus, Flexor carpi ulnaris )
FLEXOR DIGITORUM SUPERFICIALIS
EXTENSORS OF THE HAND AND FINGERS ( Extensor carpi ulnaris, Extensor digitorum, Extensor carpi radialis brevis and Extensor carpi radialis longus )
BRACHIORADIALIS
INTRINSIC MUSCLES OF THE HAND
CONTROL MOVEMENTS OF FINGERS AND THUMB
LOCATED ON THE HAND ITSELF
1. MUSCLES OF THE THENAR EMINENCE.- Flexor pollicus brevis, Abductor pollicus brevis, Opponens pollicus, Adductor pollicis
2. MUSCLES OF THE HYPOTHENAR EMINENCE.- Opponens digiti minimi, Flexor digiti minimi, Abductor digiti minimi.
MUSCLES OF THE PELVIS, LEG, AND FOOT
THEY HELP SUPPORT THE MASS OF THE BODY AND STABILIZE THE PELVIC GIRDLE
FLEXORS OF THE LEG ARE ON THE POSTERIOR THIGH, AND EXTENSOR MUSCLES ARE LOCATED ANTERIORLY.
ABDUCTORS ARE FOUND ON THE LATERAL SIDE OF THE THIGH, AND ADDUCTORS ARE ON THE MEDIAL SIDE.
MUSCLES OF THE PELVIS AND GLUTEAL REGION
ILIOPSOAS ( Psoas major and Iliacus )
DEEP LEG ROTATORS ( Internal and external obturators, and Piriformis )
TENSOR FASCIAE LATAE
GLUTEAL MUSCLES ( Gluteus maximus, Gluteus medius, and Gluteus Minimus )
MUSCLES OF THE UPPER LEG
ADDUCTORS OF THE THIGH ( Pectineus, Gracilis, and the Adductor Muscle group adductor magnus, adductor longus and adductor brevis- )
SARTORIUS
QUADRICEPS FEMORIS GROUP ( Rectus femoris, vastus medialis, vastus lateralis, and vastus intermedius )
MUSCLES OF POSTERIOR THIGH
THE HAMSTRINGS ( Semitendinous, Semimembranous, and Biceps Femoris )
MUSCLES OF LOWER LEG
TIBIALIS ANTERIOR
EXTENSOR MUSCLES OF THE TOES ( Extensor hallucis long and Extensor digittorum longus )
MUSCLES OF POSTERIOR LOWER LEG ( Gastrocnemius, Soleus, Tibialis posterior and Flexor hallucis longus
MUSCLES OF THE FOOT
DIGITORUM BREVIS ( Extensor and flexor digitorum brevis )
HALLUCIS MUSCLES OF THE FOOT ( Abductor hallucis and Flexor hallucis brevis )
ABDUCTOR DIGITIS MINIMI