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Musculoskeletal Anatomy > Hand Anatomy > Flashcards

Hand Anatomy Flashcards

0
Q

How many metacarpals

A

5

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1
Q

How many carpal bones?

A

8- scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate, hamate

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2
Q

How many phalanges?

A

14- proximal, middle & distal for digits 2-5, only proximal and distal for 1st phalange

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3
Q

What kind of joints are in the hand?

A
  • Metacarpal-phalangeal (MCP): synovial joints, condyloid, allows flex-extension & adduction-abduction
  • Interphalangeal (IP): synovial joints, PIPs (proximal interphalangeal joint) and DIPs (distal interphalangeal joint), bi-condyloid facets allow flexion-extension and little adduction-abduction
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4
Q

What are the ligaments of the fingers?

A
  • Palmar (volar)- thickened anterior portions of the joint capsules of MCP & IP joints
  • Deep Transverse- interconnects MCP joints EXCEPT for the thumb, allows for greater mobility of the thumb
  • Collateral ligaments- CT bands on each side of joint, support all MCP & IP joints, at MCP joints: flexion tautens collateral ligaments which limits adduction-abduction, extension relaxes ligaments which permits adduction-abduction
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5
Q

What are the 2 important aspects of the palm?

A
  • Palmar aponeurosis: protective covering over tendons

* Superficial transverse ligament: across palmar side of MCP joints

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6
Q

What are tendon coverings made up of?

A
  • Fibrous flexor sheaths which enclose flexor tendons in fingers
  • Synovial sheaths around tendons
  • Flexor retinaculum= transverse carpal ligament, it is the ‘roof’ of the carpal tunnel
  • All are made of fibrous CT
  • Makes fluid that cuts down friction
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7
Q

What are synovial sheaths?

A
  • Wrap around the tendon to reduce friction
  • Lined with 2 types of synoviocytes:
    1. Type A are marcophage-like
    2. Type B secrete hyaluronic acid, which increases the viscosity, consists of hylauronic acid, lubricin, proteinases & collagenases
  • Synovial fluid also transports oxygen, nutrients, CO2 and waste products
  • Has thixotropic characteristics
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8
Q

Movements of the thumb

A
  • Abduction-Adduction are perpendicular to the palm

* Flexion-Extension are parallel to the palm

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9
Q

Movements of the fingers

A

*Abduction-Adduction are referenced from the middle finger

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10
Q

DAB & PAD

A
  • Dorsal abduct
  • Palmar adduct
  • Dorsal and palmar interossei are antagonists of each other
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11
Q

Importance of finger ligaments

A
  • Fibrous flexor sheaths act as a pulley system to assist action of flexor muscles/tendons on phalanges
  • Link ligaments provide a connection between flexor tendon sheaths and dorsal expansions to coordinate movements
  • Holds tendons close to each other and close to the bone
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12
Q

Trigger finger

A

Occurs when chronic irritation causes a nodule to form along the flexor tendon, this nodule prevents smooth action of the tendon and may even lock finger in flexed position

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13
Q

Bowstring phenomenon

A
  • What happens if tendon sheath ruptures

* Will see the tendon essentially pulling off the bone

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14
Q

Swan neck

A
  • Starts as mallet finger

* Brings PIP into extension

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15
Q

Boutonniere

A

Extensor tendon disrupted= collateral ligament slips under axis of joint= PIP inflection because no opposing force, but collateral ligament pulls up and give extension of DIP

16
Q

Median nerve

A
  • Cutaneous: 3 1/2 digits and thenar eminence
  • Forearm muscles: pronator teres, palmaris lonus, flexor carpi radialis, flexor digitorum superificialis and 1/2 of profundus, pronator quadratus, flexor pollicis longus
  • Hand muscles: all thenar muscles except the adductor pollicis, lumbricals 1, 2
  • Power grip: muscles provide forceful grip
17
Q

Carpal Tunnel

A
  • Space formed by flexor retinaculum/transverse carpal ligament spanning across carpal bones (flexor retinaculum lies deep to palmar aponeurosis)
  • Structures in the carpal tunnel: median nerve, flexor digitorum superficialis, flexor digitorum profundus, flexor pollicis longus
  • Structures NOT in the carpal tunnel: ulnar nerve, radial and ulnar arteries, palmaris longus, flexor carpi ulnaris, flexor carpi radialis
18
Q

Carpal Tunnel Syndrome

A
  • Median nerve is compressed
  • Carpal tunnel size is reduced due to local inflammation or tenosynovitis, fluid overload, dislocation of carpal bones, arthritis
  • Often associated with diabetes mellitus, which also compromises nerve function
  • Symptoms include loss of sensation over median nerve distribution, loss of function of thenars and lumbricals 1, 2, thenar wasting (ape hand)
19
Q

Testing the median nerve

A
  • Tinel’s or Phalen’s test
  • Sensory testing- tunin fork, 2-point discrimination
  • Strength testing- thenar musculature
  • It is possible to have a negative electromyograph and still have carpal tunnel syndrome (CTS)
20
Q

Ulnar nerve

A
  • Cutaneous: 1 1/2 digits, ulnar side of palm and dorsum of hand
  • Forearm muscles: flexor carpi ulnaris, 1/2 of flexor digitorum profundus
  • Hand muscles: hypothenars, adductor pollicis, lumbricals 3 & 4, dorsal and palmar interossei
  • Precision grip: intrinsic hand muscles produce fine movement of the fingers (b/c many more hand muscles innervated by ulnar)
21
Q

Tunnel of Guyon or Ulnar Tunnel

A
  • Space between pisiform and hook of hamate, interconnected by pisohamate ligament (extension of flexor carpi ulnaris tendon)
  • Floor of tunnel is the flexor retinaculum
  • Roof of tunnel is the palmar carpal ligament (extension of forearm deep fascia)
  • In the tunnel: ulnar nerve (splits into deep and superficial branches), ulnar artery and veins
22
Q

Ulnar nerve entrapment

A
  • Claw hand due to lack of MCP flexion and IP extension in fingers, 2 fingers remain extended b/c 2 of the lumbricals are innervated by the median nerve
  • Atrophy of interossei
  • Cutaneous loss of 1 1/2 digits
23
Q

Testing the Ulnar nerve

A
  • Tinel’s over the Tunnel of Guyon
  • Sensation testing over ulnar nerve distribution
  • Instruct patient to cross one’s fingers; this requires intact interossei function
  • Can do EMG and nerve conduction studies
24
Q

Testing the radial nerve

A
  • Wrist and elbow extension
  • Sensation around dorsum of thumb
  • Nerve conduction studies
  • Doesn’t innervate anything intrinsically in the hands
  • ‘Waiters’ hand

Musculoskeletal Anatomy (9 decks)

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