HAN 200 - Chapter 10 (Muscle System)

Functions of Muscles

movement, stability, control of body openings and passages, heat production, glycemic control

muscles perform...

an action--effect produced by a muscle to produce or prevent movement. usually act in groups

categories of muscle action

prime mover, synergist, antagonist, and fixator

prime mover (antagonist)

muscle that produces most of the force during a particular joint action

synergist

muscle that aids a prime mover in a movement and helps prevent rotation

antagonist

muscle that opposes the prime mover

fixator

muscle that prevents movement of bone

muscle that crosses on anterior side

produces flexion

muscle that crosses on posterior side

produces extension

muscle that crosses on lateral side of joint

produces abduction

muscle that crosses on medial side

produces adduction

naming skeletal muscles

-muscle location

-muscle shape

-muscle size

-direction of muscle fibers or fascicles

-number of origins

-location of attachments

-muscle action

fascicle arrangement

affects a muscle's power and range of motion

patterns of fascicle arrangement

parallel, convergent, pennate, circular, fusiform

fusiform muscles

thick in middle with fascicles converging on each tapered end (biceps)

parallel muscles

uniform width and parallel fascicles

triangular muscles

broad at one end and narrow at the other (pectoralis major)

pennate muscles

feather-shaped; fascicles attach obliquely on central tendon that runs full length of muscle

circular muscles

fascicles form rings around body openings and passages

innervation

name of major nerve that supplies the muscle

superficial muscles of body: anterior view

superficial muscles of body: posterior view

muscles of facial expression

risorius, orbicularis oculi, orbicularis oris, buccinator, zygomaticus, platysma

zygomaticus

smile

Risorius

grin

orbiuclar oculi

closes eyelid

orbicularis oris

puckers lips

platysma

pulls corners of mouth down

mm for chewing

temporalis, masseter, buccinator, pterygoids

muscles for tounge movement

genioglossus, hyoglossus, styloglossus

Sternochleidomastoid

flexes neck and turns head

scalenes

lateral head movements

splenius capitis and cervicis

head extension, rotation, and lateral bending

semispinalis capitis

synergist with sternocleidomastoid

erector spinae group

prime movers of back extension and lateral bending (iliocostalis [most lateral] longissimus, spinalis [most medial]

semispinalis & quadratus lumborum

synergists in extention and rotation

external intercostals

elevates ribs during inspiration

internal intercostals

depresses ribs during forced expiration

muscles of abdominal wall

external oblique (most superficial) , internal oblique, transversus abdominis (deepest), rectus abdominis

Valsalva maneuver

increase in intra-abdominal pressure / pregnant / High blood pressure should breathe through the concentric & eccentric portions of the lift to avoid this.

pelvis floor composed of

levator ani

coccygeus

urogenital diaphragm

contains external urethral sphincter (controlling urination)

extrinsic shoulder muscles

act in combination to fix shoulder girdle and move it to increase range of arm movement

pectoralis minor (anterior thorax)

protraction & downward rotation of scapula

serratus anteruir (saw tooth)

protraction of scapula (boxing muscle)

subclavius

stabilized pectoral girdle

muscles of posterior thorax

trapezius, levator scapulae, rhomboids (major and minor)

muscles of anterior thorax

pectoralis minor, serratus anterior, subclavius

Upper Trapezius

Scapular elevation and upward rotation (shrug)

middle trapezius

retracts scapula

Lower Trapezius

scapular depression

Rhomboids (major and minor)

retraction of scapula

muscles crossing shoulder joint

pectoralis major, latissimus dorsi, deltoid

rotator cuff muscles

act as synergists and fixators; originate on scapula; reinforce shoulder capsule; prevent dislocation

Supraspinatus

assists deltoid muscle in abducting arm

Infraspinatus

lateral rotation at shoulder

teres minor

shoulder external rotation

Subscapularis

shoulder internal rotation

muscles crossing the elbow joint

brachialis, biceps brachii, (chin ups vs pull ups) brachioradialis, triceps brachii

muscles of forearm

pronator teres, pronator quadratus, supinator

pronator teres and pronator quadratus

pronate forearm

supinator

synergist with biceps brachii in forearm supination

flexors

flexor carpi radialis, flexor carpi ulnaris, palmaris longus

Extensors

extensor carpi radialis longus

extensor carpi radialis brevis

extensor carpi ulnaris

muscles crossing hip and knee joints

-Most anterior compartment muscles of the hip and thigh flex the femur at the hip and extend the leg at the knee

-Posterior compartment muscles of the hip and thigh extend the thigh and flex the leg

-The medial compartment muscles all adduct the thigh

-These three groups are enclosed by the fascia lata

Movements of the Thigh (Hip Joint)

ilioposas - flexion

tensor fasciae latae

rectus femoris (hip flexion)

medial adductors (groin) and sartorius (cross leg)

thigh (hip) extensors

-Hamstring muscles - prime movers of extension

•Biceps femoris (lateral hamstring)

•Semitendinosus (medial hamstring)

•Semimembranosus (medial hamstring)

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Gluteus maximus - assists hamstrings in forceful thigh extension

thigh abductors

gluteus maximus, gluteus medius, gluteus minimus, tensor fasciae latae

Muscles of the Thigh that Move the Knee Joint

Quadriceps femoris—sole extensor of knee

Hamstring muscles—flex knee; antagonists to quadriceps femoris

Muscles of the Leg: Movements

-Ankle: dorsiflexion and plantar flexion

-Intertarsal joints: inversion and eversion of the foot

-Toes: flexion and extension

Primary toe extensors and ankle dorsiflexors

-Tibialis anterior

-Extensor digitorum longus

-Extensor hallucis longus

-Fibularis tertius (not always present)

plantar flex ankle

gastrocnemius, soleus, plantaris, popliteus, flexor digitorum longus (flex toes) , flexor hallucis longus, tibialis posterior

intrinsic muscles of foot

Help flex, extend, abduct, and adduct toes

Support arches of foot; some leg tendons assist

extensor digitorum brevis

dorsal foot muscle; helps extend toes

Layers of Plantar Muscles

superficial layer

-flexor digitorum brevis

-abductor hallucis

abductor digiti minimi

second later

-flexor accessorius

-lubricals