Chapter 9: Muscular System II

9.5-9.9

Smooth muscle fibers

short, single central nucleus, elongated with tapered ends, myofilaments randomly organized

lack striations

lak transverse tubules

SR not well developed

Multi-unit smooth muscle

less organized cells

function as separate units

fibers function independently

iris of eye, walls of blood vessels

stimulated by neurons, hormones

Visceral Smooth Muscle

single-unit smooth muscle; cells respond as a unit

sheets of spindle-shaped muscle fibers

fibers held together by gap junctions

rhythmicity

conduct peristalsis

walls of most hollow organs

more common

Smooth muscle resembles skeletal muscle contraction in these ways

interaction between actin and myosin

both use calcium and ATP

both are triggered by membrane impulses

Smooth muscle differs from skeletal muscle contraction in these ways

smooth muscle lacks troponin; uses calmodulin instead

two neurotransmitters that affect SmMuscle; Ach & NE

hormones can inhibit or stim. smooth muscle

stretching can trigger SmMuscle contraction

SmMuscle slower to contract and relax

SmMuscle more resistant to fatigue

SmMuscle can change length without changing tautness

Cardiac Muscle

striated muscle cells

muscle fibers joined together by intercalated discs

fibers branch, contain a single nucleus

network of fibers contracts as a unit (syncytium)

self-exciting and rhythmic

longer refractory period than skeletal muscle

no sustained or tetanic contractions

Component of levers

rigid bar or rod (bones)

fulcrum or pivot on which bar moves (joint)

object moved against resistance (weight)

force that supplies energy for movement (muscles)

Origin

less moveable end

Insertion

more moveable end

Muscle of Facial Expression

epicranius, orbicularis oculi, orbicularis oris, buccinator, zygomaticus major, zygomaticus minor, platysma

Epicranius

Origin: Occipital bone

Insertion: skin around eye

Action: elevated eyebrows as when surprised

Nerve supply: facial nerve

Orbicularis oculi

Origin: maxilla and frontal bone

Insertion: skin around eye

Action: closes eye as in blinking

Nerve supply: facial nerve

Orbicularis oculi

Origin: muscle near the mouth

Insertion: Skin of central lip

Action: closes lips, protrudes lips as for kissing

Nerve supply: facial nerve

Buccinator

Origin: alveolar processes of maxilla and mandible

Insertion: orbicularis oris

Action: compresses cheeks

Nerve supply: facial nerve

Zygomaticus major & major

Origin: Zygomatic bone

Insertion: Skin and muscle at corner of mouth

Action: Elevates corner or mouth as when smiling

Nerve supply: facial nerve

Platysma

Origin: fascia in the upper chest

Insertion: skin and muscle below mouth; mandible

Action: depresses lower lip and angle of mouth as when pouting

Nerve supply: facial nerve

Muscles of mastication

massester, temporalis, medial pterygoid, lateral pterygoid

Masseter

Origin: zygomatic arch

Insertion: lateral surface of ramus of mandible

Action: elevates and protracts mandible

Nerve supply: trigeminal nerve

Temporalis

Origin: Temporal bone

Insertion: coronoid process and anterior ramus or mandible

Action: elevates anf retracts mandible

Nerve supply: trigeminal nerve

Medial pterygoid

Origin: sphenoid, palatine, and maxillary bones

Insertion: medial surface of ramus of mandible

Action: elevates mandible and moves it from side to side

Nerve supply: trigeminal nerve

Lateral pterygoid

Origin: Sphenoid bone

Insertion: anterior surface of mandibular condyle

Action: depresses and protracts mandible and moves it from side to side

Nerve supply: trigeminal nerve

Muscle that move the head and vertebral column

Sternocleidomastoid, splenius capitis, semispinalis capitis, scalenes. quadratus lumborum, erector spinae (divides into three groups), iliocostalis (later) group, illiocostallis luborum, iliocostalis thoracis, iliocostalis cervicis

Sternocleidomastoid

Origin: Anterior surface of sternum and upper surface of clavicle

Insertion: mastoid process of temporal bone

Action: Each laterally flexes neck to the same side, rotates head to the opposite side. Together they pull the head forward and down; also aid in forceful inhalation by elevating sternum and first ribs.

Nerve supply: Accessory, C2 and C3 cervical nerves

Splenius capitis

Origin: Ligamentum nuchae and spinous processes of seventh cervical and upper thoracic vertebrae

Insertion: occipital bone

Action: Individually: rotates head to the same side; together bring head into upright position

Nerve supply: Cervical nerves

Semispinalis capitis

Origin: processes of lower cervical and upper thoracic vertabrae

Insertion: Occipital bone

Action: individually: rotates head to the opposite side; together: extend head and neck

Nerve supply: cervical and thoracic spinal nerves

Scalenes

Origin: Transverse process of cervical vertebrae

Insertion: Superior and lateral surfaces of first two ribs

Action: Individually: laterally flexes head and neck to the same side; together: elevate first two ribs during forceful inhalation

Nerve supply: Cervical spinal nerves

Quadratus lumborum

Origin: Illiac crest

Insertion: upper lumbar vertebrae and twelfth (12th) rib

Action: Extends lumbar region of vertebral column

Nerve supply: thoracic and lumbar spinal nerves

Erector spinae (divides into three groups)

Iliocostalis (lateral) group: luborum, thoracis, cervicis

Longissimus (intermediate) group: thoracic, cervicis, capitis

Spinalis (medial) group: thoracic & cervicis

Iliocostalis lumborum

Origin: iliac crest

Insertion: lower six ribs

Action: extends lumbar region of vertebral column

Nerve supply: lumbar spinal nerve

Iliocostalis thoracis

Origin: lower six ribs

Insertion: upper six ribs

Action: hold spine erect

Nerve supply: thoracic spinal nerves

Iliocostalis cervicis

Origin: upper six ribs

Insertion: fourth through sixth cervical vertebrae

Action: extends cervical region of vertebral column

Nerve supply: cervical spinal nerves

Longuissimus thoracis

Origin: lumbar vertebrae

Insertion: thoracic and upper lumbar vertebrae and ribs 9 & 10

Action: extends thoracic region of vertebral column

Nerve supply: spinal nerves

Lonhissimus cervicis

Origin: fourth and fifth (4-5)thoracic vertebrae

Insertion: second through sixth (2-6) cervical vertebrae

Action: extends cervical region of vertebral column

Nerve supply: spinal nerves

Longissimus capitis

Origin: upper thoracic and lower cervical vertebrae

Insertion: mastoid process of temporal bone

Action: extends and rotates head

Nerve supply: cervical spinal nerves

Spinalis thoracis

Origin: Upper lumbar and lower thoracic vertebrae

Insertion: upper thoracic vertebrae

Action: extends vertebral column

Nerve supply: spinal nerves

Spinalis cervicis

Origin: ligamentum nuchae and seventh (7th) cervical vertebrae

Insertion: axis (1st cervical vertebrae)

Action: extends vertebral column

Nerve supply: spinal nerves

Muscles that move the pectoral girdle

Trapezius, rhomboid major, rhomboid minor, levator scapulae, serratus anterior, pectoralis minor

Trapezius

Origin: Occipital bone, ligamentum nuchae, and spinous processes of seventh cervical and all thoracic vertebrae

Insertion: Clavicle, spine, and acromion process of scapula

Action: Rotates and retracts scapula Superior portion elevates scapula, Inferior portion depresses scapula 

Nerve supply: Accessory nerve

Rhomboid major

Origin: Spinous processes of upper thoracic vertebrae

Insertion: Medial boarder of scapula

Action: Retracts, elevates, and rotates scapula

Nerve supply: Dorsal scapular nerve

Rhomboid minor

Origin: Spinous processes of lower cervical vertebrae

Insertion: medial border of scapula

Action: retracts and elevates scapula

Nerve supply: Dorsal scapular cervical nerves

Levator scapulae

Origin: transverse process of cervical vertebrae

Insertion: medial border of scapula

Action: elevates scapulae

Nerve supply: dorsal scapular and cervical nerves

Serratus anterior

Origin: anterior surfaces of upper ribs

Insertion medial boarder of scapula

Action: protracts and rotates scapula

Nerve supply: long thoracic nerve

Pectoralis minor

Origin: anterior surface of ribs 3 to 5

Insertion: coracoid process of scapula

Action: depresses and protracts scapula, elevates ribs during forceful inhalation

Nerve supply: pectoral nerve

Coracobrachialis

Origin: Coracoid process of scapula

Insertion: Medial mid-shaft of humerus

Action: flexes shoulder and adducts arm

Nerve supply: musculocutaneus nerve

Pectoralis major

Origin: Clavicle, sternum, and costal cartilages of upper ribs

Insertion: Intertubercular sulcus of humerus

Action: Flexes shoulder, adducts, and rotates arm medially

Nerve supply: pectorla nerve

Teres major

Origin: lateral border of scapula

Insertion: Intertubercular sulcus of humerus

Action: Extends shoulder, adducts, and rotates arm medially

Nerve supply: Lower subscapular nerve

Latissimus dorsi

Origin: Spines of sacral, lumbar, and lower thoracic vertebrae, iliac crest, and lower ribs

Insertion: Intertubercular sulcus of humerus

Action: Extends shoulder, adducts, and rotates arm medially, or depresses and retracts shoulder

Nerve supply: Thoracodorsal nerve

Supraspinatus

Origin: Supraspinous fossa of scapula

Insertion: Greater tubercle of humerus

Action: abducts arm

Nerve supply: Suprascapular nerve

Deltoid

Origin: Acromion process, spine of the scapula, and the clavicle

Insertion: Deltoid tuberosity of humerus

Action: Lateral portion: abducts arm; Anterior portion flexes shoulder; Posterior portion: extends shoulder

Nerve supply: axillary nerve

Subscapularis

Origin: Anterior surface of scapula

Insertion: Lesser tubercle of humerus

Action: rotates arm medially

Nerve supply: Subscapular nerve

Infraspinatus

Origin: Infraspinous fossa of scapula

Insertion: Greater tubercle of humerus 

Action: Rotates arm laterally

Nerve supply: Upper and lower suprascapular nerves

Teres minor

Origin: Lateral border of scapula

Insertion: Greater tubercle of humerus

Action: Rotates arm laterally

Nerve supply: Axillary nerve

Muscle that move the forearm

Biceps brachii, Brachialis, Brachioradialis, Triceps brachii, Supinator, Pronator teres, Pronator quadratus

Biceps brachii

Origin: Coracoid process and tubercle above glenoid cavity of scapula

Insertion: Radial tuberosity 

Action: Flexes elbow and supinates forearm and hand

Nerve supply: Musculocutaneous nerve

Brachialis

Origin: Anterior surface of humerus

Insertion: Coronoid process of ulna

Action: Flexes elbow

Nerve supply: Musculocutaneous, median, and radial nerves

Brachioradialis

Origin: Distal lateral end of humerus

Insertion: N/A

Action: Flexes elbow

Nerve supply: Radial nerve

Triceps Brachii

Origin: Tubercle below glenoid cavity and lateral and posterior surfaces of humerus

Insertion: Lateral surface of radius above styloid process

Action: Extends elbow

Nerve supply: Radial nerve

Supinator

Origin: Lateral epicondyle of humerus and proximal ulna, just distal to radial notch

Insertion: Anterior and lateral surface of radius 

Action: Rotates forearm laterally; supinates forearm and hand

Nerve Supply: Radial nerve

Pronator teres

Origin: Medial epicondyle of humerus and coronoid process of ulna

Insertion: Lateral surface of proximal 1/3 of radius

Action: Rotates forearm medially; pronates forearm and hand

Nerve Supply: Median nerve

Pronator quadaratus

Origin: Anterior distal end of ulna

Insertion: Anterior distal end of radius

Action: Rotates forearm medially; pronates forearm and hand

Nerve Supply: Median nerve

Muscles That Move the Hand

flexor carpi radialis, flexor carpi ulnaris, palmaris longus, flexor digitorum profundus, flexor digitorum superficialis, extensor carpi radialis longus, extensor carpi radialis brevis, extensor carpi ulnaris, extensor digitorum

Flexor carpi radialis

Origin: Medial epicondyle of humerus

Insertion: Base of second and third metacarpals

Action: Flexes wrist and abducts hand 

Nerve Supply: Median nerve

Flexor carpi ulnaris

Origin: Medial epicondyle of humerus and olecranon process of ulna

Insertion: Carpal and metacarpal bones

Action: Flexes wrist and adducts hand 

Nerve Supply: Ulnar nerve

Palmaris longus

Origin: Medial epicondyle of humerus

Insertion: Fascia of palm

Action: Flexes wrist

Nerve Supply: Median nerve

Flexor digitorum superficialis

Origin: Medial epicondyle of humerus, coronoid process of ulna, and radius

Insertion: Tendons of fingers

Action: Flexes wrist and joints of fingers

Nerve Supply: Median nerve

Extensor carpi radialis longus

Origin: Lateral end of humerus

Insertion: Base of second metacarpal

Action: Extends wrist and abducts hand

Nerve Supply: Radial nerve

Extensor carpi radialis brevis

Origin: Lateral epicondyle of humerus

Insertion: Base of third (3rd) metacarpal

Action: Extends wrist and abducts hand

Nerve Supply: Radial nerve

Extensor carpi ulnaris

Origin: Lateral epicondyle of humerus and proximal, posterior ulna

Insertion: Base of fifth (5th) metacarpal

Action: Extends wrist an adducts hand

Nerve Supply: Radial nerve

Extensor digitorum

Origin: Lateral epicondyle of humerus

Insertion: Posterior surface phalanges in fingers 2 to 5

Action: Extends joints of finger

Nerve Supply: Radial nerve

Muscles of the Abdominal Wall

External oblique, internal oblique, transversus abdominis, rectus abdominis

External oblique

Origin: Outer surfaces of lower 8 ribs

Insertion: Outer lip of iliac crest and linea alba

Action: Compresses abdomen, flexes and rotates vertebral column

Nerve Supply: Intercostal nerves 7 to 12

Internal oblique

Origin: Iliac crest and inguinal ligament

Insertion: Lower 3 to 4 ribs, linea alba, and crest of pubis

Action: Compresses abdomen, flexes and rotates vertebral column

Nerve Supply: Intercostal nerves 7 to 12

Transversus abdominis

Origin: Costal cartilages of lower 6 ribs, processes of lumbar vertebrae, lip of iliac crest, and inguinal ligament

Insertion: Linea alba and crest of pubis

Action: Compresses abdomen, flexes and rotates vertebral column

Nerve Supply: Intercostal nerves 7 to 12

Rectus abdominis

Origin: Crest of pubis and pubic symphysis

Insertion: Xiphoid process of sternum and ribs 5 to 7

Action: Compresses abdomen, flexes vertebral column

Nerve Supply: Intercostal nerves 7 to 12

Levator ani

Origin: Pubis and ischial spine

Insertion: Coccyx

Action: Supports pelvic viscera and compresses anal canal

Nerve Supply: Pudendal nerve

Coccygenus

Origin: Ischial spine

Insertion: Sacrum and coccyx

Action: Supports pelvic viscera and provides sphincter-like action in anal canal and vagina

Nerve Supply: S4 and S5 nerves

Pelvic diaphragm

Levator ani & Coccygeus

Urogenital disphragm

Superficial transversus perinei, Bulbospongiosus, Ischiocavernosus, External urethral sphincter, External anal sphincter

Levator ani

Origin: Pubis ischial spine

Insertion: Sacrum and coccyx

Action: Supports pelvic viscera and provides sphincter-like action in anal canal and vagina

Nerve Supply: S4 and S5 nerves

Superficial transversus perinei

Origin: Ischial tuberosity

Insertion: Central tendon

Action: Supports pelvic viscera

Nerve supply: Pudendal nerve

Bulbospongiosus

Origin: Central tendon

Insertion: Males: Corpus cavernosa of penis; Females: Corpus cavernosa of clitoris

Action: Males: Assists emptying of urethra and assists in erection of penis; Females: Constricts vagina and assists in erection of clitoris

Nerve Supply: Pudendal nerve

Ischiocavernosus

Origin: Ischial tuberosity

Insertion: Males: Corpus cavernosa of penis; Females: Corpus cavernosa of clitoris

Action: Males: Contributes to erection of the penis; Females: Contributes to erection of the clitoris

Nerve Supply: Pudendal nerve

External urethral sphincter

Origin: Margins of pubis and ischium

Insertion: Fibers of each unite with those from other side and encircle urethra

Action: Closes urethra

Nerve Supply: Pudendal nerve

External anal sphincter

Origin: Coccyx and central tendon

Insertion: Some circular fibers as well as some fibers from each side unite with those from the other side and encircle anal canal

Action: Closes anal canal

Nerve supply: Pudendal nerve

Muscles that move the thigh

Psoas major, Iliacus, Gluteus maximus, Gluteus medius, Gluteus minimus, Piriformis, Tensor fasciae latae, Pectineus, Adductor brevis, Adductor longus, Adductor magnus, Gracilis

Psoas major

Origin: Bodies and transverse processes of lumbar vertebrae

Insertion: Lesser trochanter of femur

Action: flexes hip

Nerve Supply: Branches of L1-3 nerves

Illiacus

Origin: Iliac fossa of ilium 

Insertion: Lesser trochanter of femur

Action: Flexes hip

Nerve Supply: Femoral nerve

Gluteus maximus

Origin: Sacrum, coccyx, and posterior surface of ilium

Insertion: Posterior surface of femur and fascia of thigh

Action: Extends hip

Nerve supply: Inferior gluteal nerve

Gluteus minimus

Origin: Lateral surface of ilium 

Insertion: Greater trochanter of femur

Action: Abducts and rotates thigh medially

Nerve Supply: Superior gluteal nerve

Piriformis

Origin: Anterior surface of sacrum

Insertion: Greater trochanter of femur

Action: Abducts and rotates thigh laterally

Nerve Supply: L5, S1, and S2 nerves

Tensor fasciae latae

Origin: Anterior iliac crest

Insertion: Iliotibial tract (fascia of thigh)

Action: Abducts thigh, flexes hip, and rotates thigh medially

Nerve Supply: Super gluteal nerve

Pectineus

Origin: Spin of pubis

Insertion: Femur distal to lesser trochanter

Action: Flexes hip and adducts thigh

Nerve Supply: Obturator and femoral nerves

Adductor brevis

Origin: Pubic bone

Insertion: Posterior surface of femur

Action: Adducts thigh and flexes hip

Nerve Supply: Obturator nerve

Adductor longus

Origin: Pubic bone near pubic symphysis

Insertion: Posterior surface of femur

Action: Adducts thigh and flexes hip

Nerve Supply: Obturator nerve

Adductor magnus

Origin: Ischial tuberosity

Insertion: Posterior surface of femur

Action: Adducts thigh, posterior portion extends and anterior portion flexes hip

Nerve Supply: Obturator and branch of sciatic nerves

Gracilis

Origin: Lower edge of pubic symphysis

Insertion: Proximal, medial surface of tibia

Action: Adducts thigh and flexes knee

Nerve Supply: Obturator nerve

Muscles that move the leg

Hamstring group (Biceps femoris, Semitendinosus, Semimembranosus), Sartorius, Quadriceps Femoris Group (Rectus femoris, Vastus lateralis, Vastus medialis, Vastus intermedius)

Hamstring group

Biceps femoris, Semitendinosus, Semimembranosus

Quadriceps Femoris Group

Rectus femoris, Vastus lateralis, Vastus medialis, Vastus intermedius

Biceps femoris

Origin: Ischial tuberosity and linea aspera of femur

Insertion: Head of fibular

Action: Flexes knee, rotates leg laterally, and extends hip

Nerve Supply: Tibial nerve