Module 8 Upper Body Movements

acromion

flattened bony process extending laterally from scapular spine

agonist

muscle responsible for producing a particular motion

antagonist

muscle that opposes the action of an agonist

ball-and-socket joint

synovial joint formed between spherical end of one bone and depression of a second bone

bi

two

biceps brachii

two-headed muscle that flexes the forearm and flexes the arm at the shoulder

condyloid joint

synovial joint where shallow depression at the end of one bone receives a rounded end from a second bone

contractility

ability to shorten (contract) forcibly

biceps brachii

two-headed muscle that flexes the forearm and flexes the arm at the shoulder

condyloid joint

synovial joint where shallow depression at the end of one bone receives a rounded end from a second bone

head of the humerus

smooth, rounded region on the medial side of the proximal humerus

agonist

muscle responsible for producing a particular motion

antagonist

muscle that opposes the action of an agonist

ball-and-socket joint

synovial joint formed between spherical end of one bone and depression of a second bone

fixator

synergist that stabilizes the origin of the agonist

flexor carpi ulnaris

muscle that flexes and adducts the hand at the wrist

glenohumeral joint

shoulder joint formed by the articulation between the glenoid cavity of the scapula and the head of the humerus

glenoid cavity

shallow depression located on the lateral scapula, between the superior and lateral borders

condyloid joint

synovial joint where shallow depression at the end of one bone receives a rounded end from a second bone

head of the humerus

smooth, rounded region on the medial side of the proximal humerus

agonist

muscle responsible for producing a particular motion

antagonist

muscle that opposes the action of an agonist

ball-and-socket joint

synovial joint formed between spherical end of one bone and depression of a second bone

bi

two

antagonist

muscle that opposes the action of an agonist

ball-and-socket joint

synovial joint formed between spherical end of one bone and depression of a second bone

fixator

synergist that stabilizes the origin of the agonist

flexor carpi ulnaris

muscle that flexes and adducts the hand at the wrist

medial border of the scapula

elongated, medial margin of the scapula

medial epicondyle of the humerus

enlarged projection located on the medial side of the distal humerus

motor unit

motor neuron and the group of muscle fibers it innervates

muscle tension

force generated by the contraction of the muscle

muscle tone

low levels of muscle contraction that occur when a muscle is not producing movement

myogram

instrument used to measure twitch tension

olecranon process

expanded posterior and superior portions of the proximal ulna

opponens digiti (minimi)

muscle that brings the little finger across the palm to meet the thumb

pectoral girdle

shoulder girdle, made up of the clavicle and scapula

pectoralis major

thick, fan-shaped axial muscle that covers much of the superior thorax

pectoralis minor

muscle that moves the scapula and assists in inhalation

prime mover

principle muscle involved in an action

pronator teres

pronator that originates on the humerus and inserts on the radius

recruitment

increase in the number of motor units involved in contraction

relaxation phase

period after twitch contraction when tension decreases

rhomboid major

muscle that attaches the vertebral border of the scapula to the spinous process of the thoracic vertebrae

spine of the scapula

prominent ridge passing mediolaterally across the upper portion of the posterior scapular surface

supinator

muscle that moves the palm and forearm anteriorly

supraglenoid tubercle

small bump located at the superior margin of the glenoid cavity

synergist

muscle whose contraction helps a prime mover in an action

tetanus

continuous fused contraction

biceps brachii

two-headed muscle that flexes the forearm and flexes the arm at the shoulder

condyloid joint

synovial joint where shallow depression at the end of one bone receives a rounded end from a second bone

triceps brachii

three-headed muscle that extends the forearm

agonist

muscle responsible for producing a particular motion

antagonist

muscle that opposes the action of an agonist

ball-and-socket joint

synovial joint formed between spherical end of one bone and depression of a second bone

activation gate

part of the voltage-gated Na+ channel that opens when the membrane voltage reaches threshold

axon

single process of the neuron that carries an electrical signal away from the cell body

axon hillock

tapering of the neuron cell body that gives rise to the axon

axon segment

single stretch of the axon insulated by myelin and bounded by nodes of Ranvier

axon terminal

end of the axon, where there are usually several branches extending toward the target cell

axoplasm

cytoplasm of an axon

dendrite

branchlike process that extends from the neuron cell body and functions as a contact for incoming signals

depolarization

change in a cell membrane potential from rest toward zero

external oblique

superficial abdominal muscle with fascicles that extend inferiorly and medially

facial nerve

cranial nerve VII extending from brain stem area to the facial muscles

bi

two

intertubercular groove (sulcus)

narrow groove located between the greater and lesser tubercles of the humerus

latent period

time when a twitch does not produce contraction

lateral epicondyle of the humerus

small projection located on the lateral side of the distal humerus

internal oblique

flat, intermediate abdominal muscle with fascicles that run perpendicular to those of the external oblique

jugular foramen

irregularly shaped opening located in the lateral floor of the posterior cranial cavity

lateral pterygoid

muscle that moves the mandible from side to side

linea alba

white, fibrous band that runs along the midline of the trunk

masseter

main muscle for chewing that elevates the mandible

mastication

chewing

mastoid process

large bony prominence on the inferior, lateral skull, just behind the earlobe

membrane potential

distribution of charge across the cell membrane

nerve

cord-like bundle of axons located in the peripheral nervous system

neuron

neural tissue cell responsible for generating and propagating electrical signals

oblique

at an angle

orbicularis oculi

circular muscle that closes the eye

facial nerve

cranial nerve VII extending from brain stem area to the facial muscles

ball-and-socket joint

synovial joint formed between spherical end of one bone and depression of a second bone

bi

two

trapezius

two-headed muscle that flexes the forearm and flexes the arm at the shoulder

condyloid joint

synovial joint where shallow depression at the end of one bone receives a rounded end from a second bone

triceps brachii

three-headed muscle that extends the forearm

agonist

muscle responsible for producing a particular motion

spinal cord

organ of the central nervous system found within the vertebral cavity

splenius capitis

neck muscle that inserts into the head region

sternocleidomastoid

major muscle that laterally flexes and rotates the head

stylomastoid foramen

opening located on inferior skull, between the styloid process and mastoid process

styloid process

downward projecting, elongated bony process located on the inferior aspect of the skull

synapse

narrow junction across which a chemical signal passes from neuron to the next

synaptic cleft

small gap between cells in a chemical synapse

temporalis

muscle that retracts the mandible

threshold

membrane voltage at which an action potential is initiated

orbicularis oculi

circular muscle that closes the eye

orbicularis oris

circular muscle that moves the lips

origin

end of a skeletal muscle that is attached to another structure in a fixed position