Biology 210                       

Study Notes Exam 3

 

Chapter 8: Joints

 

Classification of Joints:

-      Structural Classification: Fibrous, Cartilagenous & Synovial Joints

-      Functional Classification:

o    Synarthroses: immovable joints (sutures...)

o    Amphiarthroses: slightly movable joints (symphyses...)

o    Diarthroses: freely movable joints (most joints)

 

Fibrous Joints: bones joined by fibrous tissue; no joint cavity

-      most are immovable or slightly movable

-      sutures: between bones of the skull

o    joined with short connective tissue fibers... in middle age, connective tissue ossifies forming synostoses

-      syndesmoses: bones connected by ligament; immovable or slightly movable

o    examples include connections between bones of lower arm (radius & ulna) & lower leg (tibia & fibula)

-      gomphoses: peg in socket joint; only example is tooth in bony alveolar socket

o    connected by short periodontal ligament

 

Cartilagenous Joints: bones joined by cartilage; no joint cavity

-      synchondroses: bones joined by hyaline cartilage; almost always synarthrotic

o    examples are epiphyseal plates in long bones of children, joint between costal cartilage of first rib & manubrium of sternum

-      symphyses: articular surfaces of bone covered with hyaline cartilage fused to plate of fibrocartilage

o    fibrocartilage compressible - shock absorber, but limited movement; joints are amphiarthrotic

o    examples are intervertebral joints (discs) & pubic symphysis

 

Synovial Joints: bones separated by fluid-containing joint cavity

-      all are freely movable

-      rich supply of blood vessels & nerve endings (sense stretch)

-      articular cartilage: hyaline cartilage protects bone ends

-      joint (synovial) cavity: potential space with synovial fluid

-      articular capsule: external fibrous capsule (dense irregular CT) & internal synovial membrane (loose CT)

o    synovial membrane lines all internal joint surfaces except hyaline cartilage

-      synovial fluid: occupies free spaces in joint cavity; reduces friction

o    mostly blood filtrate; viscous fluid containing hyaluronic acid

o    weeping lubrication: fluid forced from cartilage during compression & soaked back up when pressure is relieved

-      reinforcing ligaments: capsular, extracapsular or intracapsular ligaments

-      fatty pads: cushioning in some synovial joints

-      menisci (articular discs): fibrocartilage discs in some synovial joints

o    separate articular surfaces & improve fit between bones

 

Bursae: flattened fibrous sacs lined with synovial membrane & containing film of synovial fluid

-      bunion: swollen bursa at base of big toe

-      Tendon Sheath: elongated bursa wrapped around a tendon

 

Factors Influencing Stability of Synovial Joints:

-      articular surfaces: better fit = more stable

-      ligaments: generally, more ligaments = more stable... but ligaments may break if stressed; if only ligaments joining bones, poor stability

-      muscle tone: most important stabilizing factor for most joints

o    tendons kept taught by muscle tone - a low level of contractile activity in relaxed muscles

 

Types of Synovial Joints:

Plane Joints: flat articular surfaces, allow only short slipping or gliding movements

- example: joints between vertebral articular processes

 

Hinge Joints: cylindrical projection of one bone fits into trough-shaped surface on another

- example: interphylangeal joints

 

Pivot Joints: rounded end of one bone protrudes into a bony ring/sleeve on another

- example: atlas & axis articulation

Condyloid (Ellipsoidal) Joints: oval articular surfaces of one bone fit into depression of another

- example: radiocarpal joints

 

Saddle Joints: resemble condyloid joints; each bone has both concave & convex articular surfaces (like saddle); greater freedom of movement

- example: carpometacarpal joints

Ball & Socket Joints: spherical (ball-shaped) head of one bone fits into cuplike socket of another

- example: shoulder & hip joints

 

Movements of Synovial Joints:

-      Nonaxial: slipping movement only; no axis

-      Uniaxial: movement in one plane

-      Biaxial: movement in two planes

-      Multiaxial: movement in multiple planes

 

Gliding movements: flat or nearly flat bone glides over similar surface

-      intercarpal or intertarsal joints & flat articular processes of vertebrae

 

Angular movements: increase or decrease angle between 2 bones

-      includes flexion, extension, abduction, adduction & circumduction

-      Flexion: decreases angle of joint & brings bones closer together

-      Extension: increases angle of joint & moves bones away from each other

o    Hyperextension: moving head backwards beyond straight

-      Dorsiflexion: lifting foot

-      Plantar flexion: depressing foot

-      Abduction: movement of limb away from midline

-      Adduction: movement of limb toward midline

-      Circumduction: moving a limb so that it describes a cone in space

 

Rotation: turning of bone around its long axis

-      medial rotation: rotation toward the midline

-      lateral rotation: rotation away from midline

 

Special movements:

-      Supination: rotating forearm laterally so the palm faces anterior/superiorly

-      Pronation: rotating forearm medially so the palm faces posterior/inferiorly

-      Inversion: turning the sole of the foot medially

-      Eversion: turning the sole of the foot laterally

-      Protraction: nonangular anterior movement (moving jaw forward)

-      Retraction: nonangular posterior movement (moving jaw backward)

-      Elevation: lifting a body part superiorly

-      Depression: lowering a body part inferiorly

-      Opposition: touching thumb to tip of other digits

o    Opposition is a distinguishing primate characteristic

 

Common Joint Injuries:

Sprains: ligaments of joint are stretched or torn

-      partially torn ligaments can heal; fully torn ligaments require surgical repair

 

Cartilage Injuries: tearing of knee menisci or damage to articular cartilages of other joints

-      generally will not heal; cartilage fragments interfere with joint function

-      arthroscopic surgery can remove cartilage fragments

 

Dislocations: bones are forced out of alignment

-      often accompanied by a sprain, inflammation & joint immobilization

-      subluxation is partial dislocation

-      repeat dislocations of same joint common

 

Inflammatory & Degenerative Conditions:

Bursitis: inflammation of bursa; often occurs in prepatellar bursa of knee joint (housemaid's knee) & olecranon process associated bursa of elbow (student's elbow)

-      treated with anti-inflammatory agents or aspiration

 

Tendonitis: inflammation of tendon sheaths; similar symptoms & treatments

 

Arthritis: inflammation within or around a joint

-      Osteoarthritis: chronic; results from excessive breakdown of articular cartilage

o    Generally progresses slowly & is irreversible

o    Treatments include magnetic therapy & SAM-e (S-adenosylmethionine) to build up cartilage

-      Rheumatoid Arthritis: chronic; autoimmune disease

o    begins with inflammation of synovial membranes, which thickens into a pannus that destroys articular cartilages

o    scar tissue forms & ossifies, fusing bone ends (ankylosis)

o    treatments include antibiotics, anti-inflammatories, & immunosuppressants

-      Gouty Arthritis: uric acid crystals deposit in soft tissues of joints; inflammation results; may have genetic basis; treatments include anti-inflammatories & avoidance of alcohol

 

 


Chapter 9: Muscles & Muscle Tissue

 

Muscle Types:

Skeletal muscle tissue: attach to & cover bony skeleton

-      longest of muscle types; striated; under voluntary control

 

Cardiac muscle tissue: occurs only in walls of heart

-      striated; involuntary

-      pacemaker cells set rate of contraction

 

Smooth muscle tissue: occurs in walls of visceral organs (stomach, bladder), respiratory passageways & blood vessels

-      forces fluids & other substances through body channels

-      nonstriated; involuntary

-      slow & sustained contractions

 

Muscle Functions:

-      producing movement

-      maintaining posture

-      stabilizing joints

-      generating heat

 

Functional characteristics of muscles:

-      excitability (irritability): receive & respond to stimuli

-      contractility: shorten forcibly when stimulated

-      extensibility: can be stretched or extended

-      elasticity: recoil & resume resting length following stretch

 

Skeletal Muscle Anatomy:

Connective Tissue wrappings:

-      epimysium: dense irregular CT surrounding whole muscle

-      perimysium: fibrous CT surrounding individual muscle fascicles (bundles of muscle fibers (cells))

-      endomysium: reticular CT surrounding individual muscle fibers (cells)

 

Nerve & Blood Supply: each muscle generally served by 1 nerve, an artery & 1 or more veins

-      nerve ending controls muscle cell activity

-      arteries lead to winding capillaries that deliver nearly continuous oxygen; veins carry away large amounts of metabolic waste

 

Attachments: most muscles attached to bones in at least 2 places

-      origin: point of attachment to less movable (immovable) bone

-      insertion: point of attachment to more movable bone

-      direct (fleshy) attachments: epimysium of muscle fused to periosteum or perichondrium

-      indirect attachments: extension of muscle's CT in the form of tendon or aponeurosis anchors muscle to CT covering of bone or to fascia of another muscle

 

Microscopic Anatomy of Skeletal Muscle:

-      skeletal muscle cells long (hundreds of cm) & wide; multinucleate

-      sarcolemma: plasma membrane of muscle

-      sarcoplasm: like cytoplasm of normal cell; contains many glycosomes (store glycogen) & myoglobin (carries & stores oxygen)

-      myofibrils: contractile elements of skeletal muscle

o    composed of thin filaments (actin, tropomyosin & troponin complex) & thick filaments (myosin)

o    myosin composed of long central tails & laterally oriented heads (cross-bridges) that bind actin

o    tropomyosin covers myosin binding sites on actin molecules in resting muscle

o    troponin complex consists of: TnI (inhibits actin), TnT (binds tropomyosin & positions it on actin) & TnC (binds calcium to start contraction)

o    striations result from alternating dark A bands (thick filaments with overlapping thin filaments) & I bands (thin filaments)

o    A bands have lighter central H zone (no thin filaments) with central darker M line (desmin protein)

o    I bands have darker central Z disc (connexin protein)

o    Elastic filaments (composed of titin) hold thick & thin filaments in place & recoil to reform shape when muscle relaxes)

o    A sarcomere is the region of a myofibril between adjacent Z discs

-      sarcoplasmic reticulum: smooth ER of muscle cells; store calcium

o    wraps around myofibrils; terminal cisternae are cross channels at A-I junctions

o    terminal cisternae form triad with T-tubules of sarcolemma; triads sense voltage & regulate calcium release

 

Contraction of Skeletal Muscle Fiber: activation of myosin's cross bridges

-      sliding filament mechanism: during contraction, the thin filaments slide past the thick filaments so that actin & myosin overlap to a greater degree

-      nerve impulse leads to depolarization & calcium release from sarcoplasmic reticulum

-      calcium binds to TnC, which changes shape & moves tropomyosin away from myosin binding sites on actin

-      with myosin binding sites accessible on actin, activated myosin heads bind actin (cross bridge attachment)

-      as myosin heads bind actin, they pivot as they change from high-energy shape to low-energy shape, pulling thin filament toward center of sarcomere

o    ADP & P are released from myosin head

-      a new ATP molecule binds the myosin head & myosin loses hold of actin (cross bridge detachment)

-      hydrolysis of ATP to ADP + P by ATPase releases energy to return myosin to high-energy state... provides potential energy for myosin to again bind actin

 

Regulation of contraction:

-      the axon of a motor neuron forms a neuromuscular junction with a muscle fiber

-      the neurotransmitter acetylcholine (ACh) is released in synaptic vesicles from the axon terminal of the nerve cell into the synaptic cleft between the nerve cell & muscle cell

-      the motor end plate of the muscle cell has ACh receptors that bind ACh; this binding opens sodium channels in the sarcolemma... sodium rushes in & triggers an action potential in the muscle cell:

o    muscle cells are polarized with slight negative charge in resting state

o    depolarization of the muscle cell results from the excess positive charge caused by the influx of sodium ions

o    the local depolarization spreads to the rest of the muscle cell

o    repolarization occurs as potassium ions flow out of the muscle cell to restore the resting potential

-      ACh is degraded by ACh esterase in synaptic cleft

-      Excitation-contraction coupling: transmission of action potential past triads causes sarcoplasmic reticulum to release calcium ions into sarcoplasm

o    Some calcium binds to troponin... (see above)

o    Calcium signal is short-lived (30 ms); ATP-dependent calcium pump moves calcium back into sarcoplasmic reticulum

o    As intracellular calcium levels drop, tropomyosin again blocks myosin binding sites on actin... relaxation occurs

 

Muscle twitch: response of muscle to a single brief stimulus... can be measured in lab using myogram; includes:

-      latent period

-      period of contraction

o    tetanus: sustained muscle contraction - can be incomplete or complete

-      period of relaxation

 

Isotonic contractions: muscle changes in length & moves load

Isometric contractions: muscle neither shortens nor lengthens

-      example: muscle attempts to move a load requiring force greater than available

 

Muscle metabolism: muscles need constant supply of ATP

ATP Sources:

-      Direct phosphorylation: creatine phosphate converted to creatine by creatine kinase... phosphate released added to ADP to form ATP

-      Anaerobic glycolysis & lactic acid formation: 2 ATP yield per glucose

o    Lactic acid build up in muscles - causes fatigue

o    Oxygen debt: need additional oxygen to oxidize & remove lactic acid from muscle cells

-      Aerobic respiration: yields 36 or 38 ATP per glucose

 

Smooth Muscle: spindle-shaped cells with centrally located nucleus

-      has thin endomysium; no perimysium or epimysium

-      lines walls of most blood vessels & hollow organs... 2 layers in most cases: longitudinal layer & circular layer

o    2 layers alternate contraction & relaxation: leads to peristalsis - moves contents along tube

-      myofilaments: thick filaments (myosin) & thin filaments (actin & tropomyosin (no troponin))

o    intermediate filaments with dense bodies... anchor thin filaments & form intracellular cytoskeleton

 

Contraction of Smooth Muscle:

-      uses sliding filament mechanism

-      no troponin or TnC... calcium binds calmodulin & myosin light chain kinase to activate myosin

o    calcium ions bind & activate calmodulin

o    activated calmodulin activates myosin light chain kinase

o    the activated kinase transfers phosphate from ATP to myosin cross bridges (heads)

o    phosphorylated myosin heads interact with actin of thin filaments - produces shortening of the muscle

o    intracellular calcium levels drop - relaxation

 

Regulation of Smooth Muscle Contraction:

-      can use similar mechanism to skeletal muscle... neurotransmitter release at neuromuscular junction generates action potential, which leads to rise in intracellular calcium

-      however, signal can be stimulatory or inhibitory for contraction

-      can use a variety of neurotransmitters (ACh, norepinephrine...), whereas skeletal muscle cells use ACh

-      smooth muscle cells can spontaneously depolarize in response to chemical stimuli

 

 


Chapter 10: The Muscular System

 

Muscle Attachment Sites:

-      origin: site of muscle's attachment to more stationary bone

-      insertion: site of muscle's attachment to more movable bone

-      belly: fleshy part of muscle between tendons of origin & insertion

-      tendonitis (tenosynovitis): painful inflammation of tendons, tendon sheaths & synovial membranes of a joint

o    most commonly affected tendons are those of: elbow (tennis elbow), wrists, shoulders, finger joints (trigger finger), ankles & feet

o    accompanied by swelling (fluid accumulation), tenderness & pain

o    can be caused by trauma, strain or excessive exercise

 

Lever Systems & Leverage

-      bones act as levers & joints act as fulcrums in producing movement

-      lever: rigid structure that can move around a fixed point or fulcrum

-      2 forces act on lever: effort & load (resistance)

-      when load is close to fulcrum, & effort is applied far away, the lever acts at a mechanical advantage (& vice-versa)

-      1st class levers: fulcrum is between effort & load (e.g.: scissors & seesaws; atlanto-occipital joint))

-      2nd class levers: load is between fulcrum & effort (e.g.: wheelbarrow; probably no examples in body)

-      3rd class levers: effort is between fulcrum & load (e.g.: forceps; elbow joint)

o    most common levers in body

 

Fascicle arrangement: affect a muscles range of motion & power

-      5 patterns: parallel, fusiform (spindle-shaped), circular, triangular or pennate (feather-shaped)

-      longer fibers = greater range of motion; more fibers is usually associated with more power

 

Coordination within muscle groups

-      movements are often the result of several muscles acting as a group

-      most muscles are arranged in opposing pairs:

o    agonist (prime mover): contracts while antagonist stretches

o    agonist & antagonist often located on opposite sides of bone (biceps brachii & triceps brachii)

-      synergists: contract & stabilize intermediate joints (joint in between agonist & primary joint) to prevent unwanted movement

o    wrist extensors contract to prevent wrist from flexing when fingers flex

-      fixators: stabilize origin of prime mover so it acts more efficiently

o    fixators hold scapula steady while arm moves

-      static stretching: holding a muscle in lengthened position (to point of slight discomfort; 15-30 sec.) to increase range of motion

o    benefits may include improved performance, decreased risk of injury, reduced soreness & improved posture

 

 

Muscle Names: see table 11.2 page 314

 

Principal Skeletal Muscles (figures 11.1 through 11.20)

 

Muscles of the Head & Neck:

-      orbicularis oris

o    origin: muscle fibers surrounding mouth opening

o    insertion: skin at corner of mouth

o    action: closes & protrudes lips (assists in speech)

-      zygomaticus major & minor

o    origin: zygomatic bone

o    insertion: skin at angle of mouth & orbicularis oris (z. major) & upper lip (z. minor)

o    action: z. major draws mouth superiorly & laterally (smiling & laughing); z. minor raises upper lip

-      buccinator

o    origin: alveolar processes of maxilla & mandible

o    insertion: orbicularis oris

o    action: presses cheeks against teeth & lips (whistling & blowing); draws corner of mouth laterally; assists in chewing

-      platysma

o    origin: fascia over deltoid & pectoralis major muscles

o    insertion: mandible, muscles around mouth & skin of lower face

o    action: draws outer lower lip inferiorly & posteriorly (pouting) & depresses mandible

-      orbicularis oculi

o    origin: medial wall of orbit

o    insertion: circular path around orbit

o    action: closes eye

-      muscles that move eyeballs (6 muscles): superior, inferior, lateral & medial rectus muscles, & superior & inferior oblique muscles

-      masseter

o    origin: maxilla & zygomatic arch

o    insertion: angle & ramus of mandible

o    action: elevates mandible (closes mouth) & retracts mandible

-      occipitofrontalis

o    origin: epicranial aponeurosis (frontal belly); occipital bone & mastoid process of temporal bone (occipital belly)

o    insertion: skin over orbit (frontal belly); epicranial aponeurosis (occipital belly)

o    action: draws scalp anteriorly (frontal belly); draws scalp posteriorly (occipital belly)

-      temporalis

o    origin: temporal bone

o    insertion: coronoid process & ramus of mandible

o    action: elevates & retracts mandible

-      suprahyoid muscles: elevate hyoid bone

-      infrahyoid muscles: depress hyoid bone

-      sternocleidomastoid

o    origin: sternum & clavicle

o    insertion: mastoid process of temporal bone

o    action: flex cervical portion of vertebral column; extend head & elevate sternum during forced inhalation; laterally flex & rotate head side to side

 

Muscles of abdominal wall

-      rectus abdominis

o    origin: pubic crest & pubic symphysis

o    insertion: cartilage of ribs 5-7 & xiphoid process

o    action: flexes vertebral column & compresses abdomen

-      external oblique

o    origin: lower 8 ribs

o    insertion: iliac crest & linea alba

o    action: compresses abdomen & flexes vertebral column

-      internal oblique

o    origin: iliac crest, inguinal ligament & thoracolumbar fascia

o    insertion: cartilage of last 3 or 4 ribs; linea alba

o    action: compresses abdomen & flexes vertebral column

-      transverse abdominis

o    origin: iliac crest, inguinal ligament, lumbar fascia & cartilage of lower 6 ribs

o    insertion: xiphoid process, linea alba & pubis

o    action: compresses abdomen

 

Muscles used in breathing

-      diaphragm

o    origin: xiphoid process of sternum, costal cartilage of lower 6 ribs & lumbar vertebrae

o    insertion: central tendon

o    action: increases height & volume of thoracic cavity, resulting in inhalation

-      external intercostals

o    origin: superior rib

o    insertion: inferior rib

o    action: elevates ribs & increases width & depth of thoracic cavity, resulting in inhalation

-      internal intercostals

o    origin: superior rib

o    insertion: inferior rib

o    action: further decreases width & depth of thoracic cavity during forced exhalation

 

Muscles that move the pectoral girdle (primarily scapula)

-      pectoralis minor

o    origin: 2nd or 3rd through 4th or 5th ribs

o    insertion: coracoid process of scapula

o    action: abducts & inferiorly rotates scapula; elevates 3rd through 5th ribs during forced inhalation (when scapula stabilized)

-      serratus anterior

o    origin: superior 8 or 9 ribs

o    insertion: vertebral border & inferior angle of scapula

o    action: abducts & superiorly rotates scapula; elevates ribs (when scapula stabilized)

-      trapezius

o    origin: occipital bone (superior nuchal line & ligamentum nuchae) & spines of 7th cervical & all thoracic vertebrae

o    insertion: clavicle; acromion & spine of scapula

o    action: elevates scapula & helps extend head; adducts & depresses scapula & rotates scapula upward; stabilizes scapula

 

Muscles that move the humerus

-      pectoralis major

o    origin: clavicle, sternum & costal cartilage of 2nd to 6th ribs (sometimes 1st to 7th ribs)

o    insertion: greater tubercle of humerus & intertubercular sulcus of humerus

o    action: adducts & medial rotates arm at shoulder joint; flexes arm (clavicular head) & extends arm (sternocostal head)

-      latissimus dorsi

o    origin: spines of inferior 6 thoracic vertebrae & lumbar vertebrae; crests of sacrum & ilium & inferior 4 ribs

o    insertion: intertubercular sulcus of humerus

o    action: extends, adducts & medially rotates arm at shoulder joint; draws arm posteriorly & inferiorly

-      deltoid

o    origin: acromial extremity of clavicle; acromion & spine of scapula

o    insertion: deltoid tuberosity of humerus

o    action: abducts arm at shoulder joint (lateral fibers); flexes & medially rotates arm at shoulder joint (anterior fibers); extends & laterally rotates arm at shoulder joint (posterior fibers)

-      infraspinatus

o    origin: inferior to spine of scapula (infraspinous fossa)

o    insertion: greater tubercle of humerus

o    action: laterally rotates & adducts arm at shoulder joint

-      teres major

o    origin: inferior angle of scapula

o    insertion: intertubercular sulcus of humerus

o    action: extends arm & assists in adduction & medial rotation of arm at shoulder joint

-      teres minor

o    origin: inferior lateral border of scapula

o    insertion: greater tubercle of humerus

o    action: laterally rotates, extends & adducts arm at shoulder joint

 

Muscles that move the radius & ulna

-      Flexors:

-      biceps brachii

o    origin: tubercle above glenoid cavity of scapula (long head); coracoid process of scapula (short head)

o    insertion: radial tuberosity of radius (& bicipital aponeurosis)

o    action: flexes forearm at elbow joint; supinates forearm at radioulnar joints & flexes arm at shoulder joint

-      brachialis

o    origin: distal anterior surface of humerus

o    insertion: ulnar tuberosity & coronoid process of ulna

o    action: flexes forearm at elbow joint

-      brachioradialis

o    origin: lateral border & distal end of humerus

o    insertion: superior to styloid process of radius

o    action: flexes forearm at elbow joint; supinates & pronates forearm at radioulnar joints

-      Extensors:

-      triceps brachii

o    origin: inferior to glenoid cavity of scapula (long head); lateral & posterior surface of humerus (lateral head); posterior surface of humerus ( medial head)

o    insertion: olecranon of ulna

o    action: extends forearm at elbow joint & extends arm at shoulder joint

-      Pronators:

-      pronator teres

o    origin: medial epicondyle of humerus & coronoid process of ulna

o    insertion: midlateral surface of radius

o    action: pronates forearm at radioulnar joints & weakly flexes forearm at elbow joint

 

 

Muscles that move the wrist, hand, thumb & fingers

-      Flexors:

-      flexor carpi radialis

o    origin: medial epicondyle of humerus

o    insertion: 2nd & 3rd metacarpals

o    action: flexes & abducts hand at wrist joint

-      palmaris longus

o    origin: medial epicondyle of humerus

o    insertion: flexor retinaculum & palmar aponeurosis

o    action: weakly flexes hand at wrist joint

-      flexor carpi ulnaris

o    origin: medial epicondyle of humerus; coronoid process of ulna; ridge along anterior surface of radius

o    insertion: pisiform, hamate & base of 5th metacarpal

o    action: flexes & adducts hand at wrist joint

-      Extensors:

-      extensor carpi radialis

o    origin: lateral supercondylar ridge of humerus

o    insertion: 2nd metacarpal

o    action: extends & abducts hand at wrist joint

-      extensor digitorum

o    origin: lateral epicondyle of humerus

o    insertion: distal & middle phalanges of each finger

o    action: extends distal & middle phalanges of each finger at interphalangeal joints; extends proximal phalanges of each finger at metacarpophalangeal joints; extends hand at wrist joint

-      extensor carpi ulnaris

o    origin: lateral epicondyle of humerus & posterior border of ulna

o  &nb