MSK Exam 2

what are the four rotator cuff msucles

supraspinatus, infraspinatus, subscapularis, teres minor

supraspinatous

- abducts the arm

- baseball pitch

subscapularis

- medially rotates arm

- wind up for baseball pitch

infraspinadus/ teres minor

- adduct and laterally rotate arm

- slow the arm at the end of baseball pitch

origin/ insertion site for rotator cuff muscles

- glenohumeral joint

- holds head of humerus in glenoid cavity (of scapula)

- muscles originate from scapula

rotator cuff muscle innervation

- supraspinatus and infraspinatus Innervated by suprascapular nerve

- teres minor: innervated by axillary nerve

- subscapularis innervated by upper and lower subscapular nerves

muscles that elevate the scapula vs those that do not

- pectoralis minor: depress and protract scapula (hunch shoulders)

- serratus anterior: protracts and stabilizes scapula

- subclavius: stabilizes and depresses scapula

- levator scapulae: elevate and inferiorly rotate scapula

- rhomboid major/ minor: elevate, retract, inferiorly rotate scapula

- trapezius: elevate, depress, retract, rotate scapula

(rhomboid, trapezius, levator elevate; subclavius and pectoralis depress)

movements and muscle groups responsible for retraction of scapula

trapezius and rhomboids

movements and muscle groups responsible for protraction of scapula

pectoralis minor and serratus anterior

biceps brachii vs triceps brachii major actions

- biceps brachii: both heads originate on scapula and span shoulder joint; assist in flexing arm

- triceps brachii: long head originates on scapula spans shoulder joint; helps extend and adduct the arm

which muscle attachments are critical for arm movements

- biceps brachii

- brachialis

- brachioradialis

- triceps brachii

- aconeus

- pronator teres

- pronator quadratus

- supinator

pronation vs supination

-pronation: palm down (pro bball player)

- supination: palm up (hold the soup)

muscles responsible for pronation

- pronator teres, pronator quadratus

- rotate radius across ulna to pronate

- located in anterior compartment of forearm

muscles responsible for supination

- supinator

- supinates forearm

- located posterior compartment forearm

quadriceps femoris group

- vastus lateralis, vastus medialis, rectus femoris

- muscles of thigh's anterior (extensor) compartment

- composite muscle w/ four heads

knee extension and muscle involvement

- muscles of thigh's anterior (extensor) compartment: quadriceps femoris

- agonist of knee extension

crural muscles for movement at ankle, foot, and toes

particularly tibialis anterior

crural muscles located in leg move foot and toes (partitioned in posterior, lateral, and anterior compartments):

- flexor/extensor digitorum longus

- flexor/extensor hallucis longus

- fibularis tertius/ longus/ brevis

- tibilias anterior * primary dorsiflexor of foot, also inverts foot * and tibialis posterior

- extensor retinaculum

- gastrocnemeis

- soleus

- triceps surae

- plantaris

- popliteus

head of humerus articulates with?

rotator cuff muscles hold humerus in place in glenoid cavity of scapula

elbow- type of joint and actions permitted

- hinge joint

- uniaxial

- angular motion

synovial joint types

plane, hinge, pivot, condylar, saddle, ball and socket (least to most mobile)

plane joint

- articular surfaces flat

- simplest, least mobile

- uniaxial: limited side to side gliding mvmt in single plane

- "gliding"

hinge joint

- convex surface w/ concave depression

- uniaxial: like the hinge of a door

- "flexion-extension"

pivot joint

- bone with rounded surface fits into ligament ring

- uniaxial: rotation on longitudinal axis

condylar joint

- oval convex surface articulating with concave surface

- biaxial

saddle joint

- convex and concave surfaces resembling saddle shape

- biaxial

ball and socket joint

- spherical head of one bone fit into cuplike socket

- multiaxial: permits mvmt in three planes

- most freely moveable type of joint

- "rotational"

diarthroses

- freely moveable joints

- all synovial joints

synarthroses

- immobile joints

- can be fibrous or cartilagenous joints

amphiarthroses

- slightly mobile

- can be fibrous or cartilagenous

3 mc types of fibrous joints

gomphoses, sutures, syndesmoses

gomphoses

- type of fibrous joint

- peg in a socket

- articulations of teeth w/ mandible and maxillae

- function as synarthroses

sutures

- type of fibrous joint

- found btwn some skull bones

- v short fibers

- interlocking irregular edges, increase stability and decr risk of fx

- function as synarthroses

- allow growth in childhood, become ossified in adult

syndesmoses

- type of fibrous joint

- bound by interosseous membrane (interosseous ligament), broad ligamental sheet

- found btwn radius and ulna / fibula and tibia

- function as amphiarthroses

- provides pivot for two long bones

knee ligaments

- patellar ligament

- oblique popliteal ligament

- fibular collateral ligament

- tibial collateral ligament

- medial and lateral meniscus

patellar ligament

extends from patella to tibial tuberosity

oblique popliteal ligament

- protects against hyperextension

fibular collateral ligament

- extend from femur to fibula

- reinforces lateral surface of joint

- prevents hyperadduction

tibial collateral ligament

- reinforces medial surface of joint

- extends from femur to tibia

- prevents hyperabduction

medial and lateral meniscus

- deep to articular capsule w/in knee joint

- c shaped fibrocartilage pads on top of tibial condyles

- cushioning btwn articular surfaces

- change shape to conform to articulating surfaces

- partially stabilize joint medially and laterally

cruciate ligaments

- cross each other

- deep to articular capsule

- ACL, PCL

ACL

- extends from posterior femur to anterior tibia

- prevents hyperextension and anterior displacement of tibia

PCL

- extends from anteroinferior femur to posterior tibia

- prevents hyperflexion and posterior displacement of tibia

connective tissue layers superficial to deep

- epimysium: dense irregular CT wrapping whole muscle

- perimysium: dense irregular CT wrapping fascicle, houses many BV and nerves

- endomysium: areolar CT wrapping individual fiber; delicate layer for electrical insulation, capillary support, binding neighboring cells

definition and example of aponeurosis

- thin flattened sheet of dense irregular tissue

- attach muscle to bone or skin to another muscle, similar to tendon

- ex: epicranial aponeurosis

types of muscle fibers

skeletal, cardiac, smooth

skeletal muscle fibers

- functions: move the body, maintain posture, protect and support, regulate elimination of materials, produce heat

- characteristics: excitability, conductivity, contractility, extensibility, elasticity

- vascularized, innervated by somatic motor neurons

- structural and functional proteins: connectin, dystrophin, nebulin

cardiac muscle fibers

- short branching fibers, one or two nuclei

- striated (contain sarcomeres)

- many mitochondria, use aerobic respiration

- intercalated discs join ends of neighboring fibers; discs contain desmosomes and gap junctions

- contractions started by heart autorhythmic pacemaker cells

- HR and contraction force influenced by ANS

smooth muscle fibers

found in variety of organ systems w/ a variety of roles:

- BV of cardio system, regulate BP and blood flow

- bronchioles of resp system, control airflow to alveoli

- intestines of digestive system, mixes and propels materials

- ureters of urinary system, preopel urine from kidneys to bladder

- uterus of F reproductive system

basic mechanics of muscle contraction

- excitation of skeletal muscle fiber at NMJ

- excitation contraction coupling of sarcolemma, t tubules, and sarcoplasmic reticulum

- sarcomere crossbridge cycling

crossbridge cycle in muscle contraction

- activated myosin heads bind to thin filaments to form crossbridges

- myosin ATPase hydrolyzes ATP, providing energy for power stroke

- process is repeated, force generated is transferred to anchoring filaments, smooth muscle cell shortens

isometric muscle contraction

- although tension is increased, insufficient to overcome resistance

- muscle length stays the same

- ex: holding a weight while arm doesn't move

isotonic muscle contraction

- muscle tension overcomes resistance, resulting in movement

- tone stays constant but length changes

NMJ

- location where motor neuron innervates muscle

- usually mid-region of muscle fiber

parts of NMJ

synaptic knob, synaptic cleft, motor end plate

synaptic knob

- extended tip of of motor neuron axon

- houses synaptic vesicles (filled w/ Ach)

synaptic cleft

- narrow fluid filled space

- separates synaptic knob from motor end plate

- acetylcholinesterase resides here

motor end plate

- specialized region of sarcolemma

- has many Ach receptors (plasma membrane protein channels)

inversion vs eversion

- inversion: occurs only at intertarsal joints of foot, sole turns medially

- eversion: occurs only at intertarsal joints of foot, sole turns laterally

adduction vs abduction

- adduction: medial movement of body part toward midline, ex arm or thigh brought midline

- abduction: lateral movement of body part away from midline, ex arm or thigh move laterally away from body midline

lateral flexion

- mvmt in anterior posterior plane

- decreases angle btwn bones (brings bones closer

together)

- ex: bending finger

hyperextension

- extension beyond normal ROM

- w/ extensive mobility joints or injury

retinacula

- retinacular fibers: ligamentous fibers of articular capsule

- reflex around femur neck

- retinacular arteries here (supply most blood to femur head/neck)

meniscus

- medial and lateral meniscus

- deep to articular capsule w/in knee joint

- c shaped fibrocartilage pads on top of tibial condyles

- cushion btwn articular surfaces

- change shape to conform to articulating surfaces

- partially stabilize joint medially and laterally

muscle attachment points

- tendons attach muscle to bone, skin, or another muscle

- attachment for axial muscles: superior (more moveable) and inferior attachment (less moveable)

- attachment for appendicular muscles: proximal (less moveable) and distal attachment (more moveable)

- ex: proximal attachment of biceps brachii is scapula, distal is radius

thenar

- forms fleshy mass at base of thumb

- flexor pollicis brevis: flex thumb

- abductor pollicis brevis: abduct thumb

- opponens pollicis: assist in opposition of thumb

hypothenar

- fleshy mass at base of little finger

- flexor digiti minimi brevis: flex little finger

- abductor digiti minimi: abduct little finger

- opponens digiti minimi: assist in opposition little finger

midpalmer group

- occupies space btwn thenar and hypothenar groups

- consists of lumbricals (flex MP joint, extend PIP DIP), dorsal interossei (abduct fingers), palmar interossei (adduct fingers), adductor pollicis (adducts thumb)

gluteal muscle actions

- two gluteal muscles and one in lateral thigh, abduct the thigh

- gluteus maximus: agonist of thigh extension, also laterally rotates thigh

- gluteus medius and minimus: deep to gluteus maximus, abduct and medially rotate thigh