Anat Flexor & Extensor Forearm (7)

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  1. An injury to the Dorsal Scapular n. would paralyze which muscles?
    • the Levator Scapula (elevates shoulder) & the Rhomboids (retracts scapula)
    • these muscles are supplied by the Dorsal Scapular n., which comes off the root of C5
    • could still elevate & retract shoulders using Trapezius muscle (supplied by the spinal accessory nerve)
  2. An injury to the Suprascapular n. would paralyze which muscles?
    • the Supraspinatus (initiates arm abduction) & Infraspinatus (abducts/laterally rotates arm)
    • these muscles are supplied by the Suprascapular n., which comes off the Superior trunk (which is derived from roots C5 & C6)
  3. Where do most of the fibers of the Musculocutaneous & Axillary n. come from?
    • roots C5 & C6
    • Image Upload 1
  4. An injury to the Musculocutaneous n. would paralyze which muscles?
    • Biceps Brachii (flexes forearm @ elbow joint)
    • Brachialis (flexes forearm @ elbow joint)
    • Coracobrachialis (flexes arm @ shoulder joint)
    • w/o these muscles, upper arm would stay in the extended position
  5. An injury to the Axillary n. would paralyze which muscles?
    • Deltoid (main abductor of the arm) & the Teres minor (lateral rotator of the arm)
    • upper limb would be stuck in the adducted position (can't abduct)
  6. Waiter's Tip Position
    • when the upper limb is adducted, extended, & medially rotated
    • Image Upload 2
    • classic physical position of Erb's Palsy due to C5 & C6 injury
  7. Erb's Palsy
    • occurs from injury to the upper Brachial Plexus (C5 & C6)
    • can happen when the roots are stretched, i.e. if the head goes one way & the corresponding shoulder goes the other
    • Image Upload 3
    • can also happen during childbirth
  8. Shoulder Dystocia
    • as the baby's head moves through the birth canal, it's shoulder can get caught on the pubic symphysis (anterior part of woman's pelvis) → stretching of the upper roots of the Brachial Plexus
    • Image Upload 4
  9. Klumpke’s Palsy
    • occurs from damage to the lower Brachial Plexus (C8 & T1)
    • can occur when you put upward traction on the brachial plexus (eg. when hanging onto a tree branch)
    • affects the Lower Trunk, Medial Cord, & the Ulnar n. (innervates many of the intrinsic hand muscles – finger add & abduction)
    • there's paralysis of intrinsic hand muscles & numbness of the C8/T1 dermatomes
    • Image Upload 5
  10. Medial Cutaneous n. of the Arm & Forearm
    • responsible for sensation along the medial side of the arm, forearm, & hand
    • would be damaged by lower brachial plexus injury
    • these areas would be numb in the case of Klumpke’s Palsy/lower brachial plexus injury
  11. Upper Limb Osteology (1 more time)
    • Shoulder Girdle – scapula, clavicle
    • Arm: Humerus
    • Forearm: radius, ulna
    • Wrist: 8 carpal bones
    • Hand: 5 metacarpals, 14 phalanges
  12. Carrying Angle
    • small angle the forearm makes with the axis of the humerus when supinated
    • angle between humerus & ulna – normally 10-15o
    • it allows the forearms to clear the hips when swinging your arms while walking & when carrying objects
    • angle DISAPPEARS when the forearm is pronated
    • Image Upload 6
  13. Medial & Lateral Epicondyles of the Humerus
    • Medial is the origin for a common flexor/pronator tendon
    • Lateral is an origin for a common extendor/supinator tendon
    • they exist above the condyles (rounded ends) of the humerus
  14. Elbow Joint
    is a 3 part joint: radiohumeral joint, humeroulnar joint, radioulnar joint (responsible for pronation/supination of the forearm)
  15. Elbow Joint Ligaments
    • Annular lig. of Radius wraps around the head of the radius (like a sleeve); radius head can pivot w/in the annular lig.
    • Image Upload 7
    • Radial Collateral lig. on the lateral side
    • Ulnar Collateral lig. on the medial side
    • Radial & Ulnar Collateral lig. are disrupted when the elbow joint becomes dislocated
    • Image Upload 8
  16. Bursae of the Elbow Joint
    • Subcutaneous Olecranon bursa: lies between the skin & the olecranon (reduces friction btwn the skin & the bony surface)
    • Subtendinous Olecranon bursa: inserts between the triceps tendon & the distal end of the humerus
    • Image Upload 9
  17. Olecranon Bursitis
    • can be caused by banging elbow
    • leads to pain & swelling
    • can be drained by needle if it doesn't go away on its own
  18. Subluxation of the Radial Head (Nursemaid's Elbow)
    • dislocation of the radius from the end of the humerus (capitulum)
    • head of the radius POPS OUT of the sleeve of the Annular ligaments (of the Radius)
    • Image Upload 10

    Image Upload 11
  19. Colles' Fracture
    • fracture of the distal end of the radius
    • is an extension fracture of the radius
    • Image Upload 12
    • usually happens when someone falls forward & uses their hand/wrist in the extended position to break their fall – a lot of force is applied to the distal end of the radius
    • Image Upload 13
    • "dinner-fork" deformity
    • if the hand is in the extended (stop sign) position then the extensor muscles of the forearm pull the hand posteriorly
  20. Smith's Fracture
    • flexion fracture of the radius
    • Image Upload 14
    • happens when a person falls backward & uses their hand/wrist the flexed position to brace themselves
    • have an anterior displacement of the wrist/hand in this type of fracture
  21. Nightstick fracture (Ulna)
    • fracture of the ulna
    • can happen from falling on a hard surface with the forearm
    • can screw in a plate to hold the bone in place & allow it to heal over time
    • Image Upload 15
  22. Wrist Osteology
    • contains 8 carpal bones arranged in 2 rows, a proximal row & a distal row
    • they don't lie in a flat plane, they form a concavity called the Carpal Tunnel
    • tendons from the forearm (+ Median n.) can pass through this tunnel into the hand & then insert on the digits
  23. Proximal Row of the Wrist Bones (lateral → medial)
    • Scaphoid: under the thumb, articulates w/ Radius
    • Lunate: articulates w/ Radius
    • Triquitrum
    • Pisiform: rounded bone shaped like a pea
    • thumb → pinkie
    • Some Lunatics Try Psychedelics
    • Image Upload 16
  24. Distal Row of the Wrist Bones (lateral → medial)
    • Trapezium
    • Trapezoid
    • Capitate
    • Hamate: has a hook on it
    • thumb → pinkie
    • Tall Tales Can Hurt
    • Image Upload 17
  25. Metacarpal Bones
    • bones it the main part of the hand
    • 1st is the one that connects to the thumb, 5th is the pinkie's
  26. Phalanges
    • bones of the digits
    • thumb just has 2 (proximal, distal)
    • other 4 fingers have 3 phalanges: proximal, middle, & distal phalanx
  27. Metacarpophalangeal Joints (MCP)
    formed by the rounded heads of the metacarpal bones joining w/ the shallow cavities on the proximal ends of the 4 phalanges (not the thumb)
  28. Proximal Interphalangeal Joints (PIP)
    joints between the proximal & middle phalanges
  29. Distal Interphalangeal Joints (DIP)
    between the middle phalanges & the distal phalanges
  30. What is the most commonly fractures bone when someone falls?
    • the Scaphoid bone of the wrist (fall on your thumb/lateral part of your hand/wrist)
    • is difficult to heal b/c the area is not very vascular – may take months
    • Image Upload 18
    • surgeons will often put a pin in to stabilize the fracture
  31. Styloid Process
    • protuberance on the Ulna created by ligaments that run from the distal part of the ulna to the wrist
    • Image Upload 19
    • Ulna DOESN'T articulate w/ any of the wrist bones directly: allows the hand to more easily ADDuct than ABDuct
  32. Cubital Fossa
    • part of the elbow area where the Brachial a. running down the medial part of the arm divides into the Radial & Ulnar a.
    • top: line btwn lateral & medial epicondyles
    • left: brachioradialis muscle
    • right: pronator teres muscle
    • biceps & deeper the brachialis tendon passes through attaching to the radial & ulnar tuberosity respectively
    • Image Upload 20
  33. What forms the roof/covering of the Cubital Fossa?
    • skin, fascia, & bicepetal aponeurosis
    • these help protect the brachial artery & median n. lying deep in the cubital fossa
  34. Collateral Arteries in Elbow Joint
    provide anastamonic connections between the brachial, ulnar, & radial arteries

    1. superior & inferior ulnar collateral arteries: come off the brachial ~midway down the humeral shaft; go posterior & anterior to the medial epicondyle

    2. anterior & posterior ulnar recurrent arteries: branches from the ulnar a. that go BACK up to medial part of the elbow

    • 3. radial recurrent artery: runs back, anterior to the lateral epicondyle; joins up w/ a branch of the deep brachial artery called the radial collateral artery (lateral collateral circulation)
    • Image Upload 21
  35. Anterior Forearm Muscles
    • they FLEX, adduct, & abduct the hand at the wrist joint
    • they flex the fingers & thumb
    • 2 muscles in particular pronate the forearm
    • these muscles are arranged in 3 layers: deep, middle, & superficial
    • Median & Ulnar nerves supply the muscles in the ANTERIOR compartment of the forearm
    • Image Upload 22
  36. Deep Layer of Anterior Forearm Muscles
    • Flexor Digitorum Profundus (originates at the Ulna, has 4 tendons that attach at the DISTAL phalanxes of the 4 digits)
    • Flexor Pollicis Longus (flexes the THUMB at the interphalangeal joint)
    • FLEX the digits
    • Image Upload 23
  37. What nerve innervates the Flexor Digitorum Profundus (FDP)?
    • has a DUAL innervation
    • its lateral half is supplied by the Ant. Interosseous n. (digits 2 & 3) [a deep branch of the median n.]
    • its medial half is supplied by the Ulnar n. (digits 4 & 5)
  38. Flexor Pollicis Longus Muscle
    • originates on the radius, sendings one tendon across the wrist joint, & inserts on the 2nd phalanx of the thumb
    • ONLY muscle that can flex the thumb at the IP (Interphalangeal) joint
  39. Middle Layer of Anterior Forearm Muscle
    • Flexor Digitorum Superficialis
    • FLEXES the digits
    • originates partly on the common flexor/pronator tendon & also on the radius→ muscle belly gives rise to 4 tendons that cross the wrist joint → cross the metacarpophalangeal joints → insert on the middle 4 phalanges
    • Image Upload 24
    • supplied entirely by the Median n.
  40. Superficial Layer of Anterior Forearm Muscles
    • Flexor Carpi Radialis (FCR)
    • Flexor Palmaris Longus (PL)
    • Flexor Carpi Ulnaris (FCU)
    • FLEX the hand at the wrist
    • originate from a common flexor/pronator tendon on the medial epicondyle → cross the wrist joint anteriorly → attach at either the carpal bones (FCR & FCU) or the base of the metacarpals (PL)
    • Image Upload 25
    • the Flexor Carpi Ulnaris is supplied by the Ulnar n.; the other 2 (Carpi Radialis & Palmaris Longus) are supplied by the Median n.
    • Image Upload 26
  41. Palmar Aponeurosis
    • very thick fascia in the palm of the hand that helps protect underlying structures (nerves & BVs)
    • at it's apex is where the Flexor Palmaris Longus (PL) really attaches (doesn't really attach to the metacarpals)
    • Image Upload 27
  42. Pronator Teres
    • pronates the forearm & helps flex it at the elbow
    • originates on the medial epicondyle of humerus (specifically the common flexor tendon) & the Ulna (has 2 heads)
    • inserts midway down on the radius shaft
    • another anterior muscles of the forearm that lies in the superficial layer
    • Image Upload 28
    • supplied by the Median n.
  43. Brachioradialis ("Beer drinker's muscle")
    • FLEXES the forearm at the elbow joint
    • originates on the lateral epicondyle → crosses the elbow joint anteriorly → inserts on the distal part of the radius
    • supplied by the Radial n., which we usually associate w/ muscles that extend (is the exception to the rule that the Radial n. usually extends)
    • can see it pop out when you try to flex your forearm against resistance – it helps the biceps & brachialis to FLEX to forearm at the elbow joint
    • Image Upload 29
    • also lies in the superficial layer of the anterior forearm
  44. Pronator Quadratus Muscle
    • runs from the distal Ulna to the distal Radius
    • when it (& the pronator teres) contracts, it PULLS the radius medially, PRONATING the forearm
    • supplied by the Anterior Interosseous n. (the deep branch of the Median n.)
  45. Supinator Muscle
    • has 2 heads of origin: 1 on the lateral epicondyle, 1 that comes from the Ulna (wraps around the radius shaft)
    • pivots the Radius around laterally, SUPINATING the forearm
    • supplied by the Radial n.
  46. What 3 muscles are supplied by the Anterior Interosseous nerve?
    • 1. flexor pollicis longus
    • 2. pronator quadratus
    • 3. the radial half of flexor digitorum profundus
  47. Flexor Retinaculum
    • thickened layer of fascia that turns the concavity of the wrist carpal bones into a tunnel
    • bridges between the trapezium & the hamate bone + the scaphoid & the pisiform
    • keeps the 9 tendons (flexor digitorum profundus & superficialis, & the flexor pollicus longus) that pass through the carpal tunnel FIRMLY in place
    • Image Upload 30
    • Image Upload 31
  48. Carpal Tunnel Syndrome
    • numbness & tingling in part of the blue area of the hand due to compression of the Median nerve that passes through the carpal tunnel (area of sensation supplied by the Median n.)
    • Image Upload 32
    • space in the tunnel is VERY tight – any inflammation due to overuse of the flexor tendons → compression
    • Image Upload 33
  49. Posterior Forearm Muscles
    • they EXTEND, adduct, & abduct the hand at the wrist joint
    • they extend the fingers & thumb
    • they supinate the forearm (supinator muscle)
Card Set
Anat Flexor & Extensor Forearm (7)
Exam 1
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