WRIST COMPLEX

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WRIST COMPLEX

• Bones and Joints of the Wrist

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Proximal Row of Carpal Bones

• Review- testable
• Scaphoid
• Most lateral.
• Forms floor of anatomical snuff box.
• Most commonly fractured wrist bone.
• Fractures may compromise radial artery in
  snuff box.
• Articulates with radius.

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Proximal Row of Carpal Bones

• Lunate
• Articulates with radius
• Triquetral
• Articulates with ulna (via articular (ulnar)
  disc) during extreme ulnar deviation.
• Pisiform
• Sesamoid bone
• Forms in tendon of the flexor carpi ulnaris

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Distal Row of Carpal Bones

• Trapezium
• Most lateral
• Trapezoid
• Capitate
• Hamate

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Distal Row of Carpal Bones

• Entire complex enclosed in a common synovial
  membrane.
• Articulations are plane joints that perform
  gliding motions.

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Radiocarpal Joint

• Condyloid (ellipsoidal) synovial joint.
• Two degrees of freedom.
• Articular surfaces
• Scaphoid (convex)
• Lunate (convex)
• Distal radius
• Two concave fossae (lateral and medial)
• Triquetral (convex)
• Only during extreme ulnar deviation

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Radiocarpal Joint Ligaments

• Lateral (radial) collateral ligament.
• Medial (ulnar) collateral ligament.
• Dorsal radiocarpal ligament.
• Palmar radiocarpal ligament.
• Strengthen capsule

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Radiocarpal Joint Functions

• Some flexion and extension
• Ulnar deviation

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Radiocarpal Joint Arteries

• Articular arteries
• Arise from dorsal and palmar carpal arches.

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Radiocarpal Joint Nerves

• Anterior interosseous branch of median nerve.
• Posterior interosseous branch of radial nerve.
• Dorsal and deep branches of the ulnar nerve.

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Radiocarpal Joint Injuries

• Colles fracture
• Scaphoid fracture
• Usually at waist
• Compromises radial artery in snuffbox

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Midcarpal Joint

• Made up of intercarpal joints
• Between proximal and distal rows of carpals
  and between carpals.
• Movements
• Some flexion and extension.
• Radial deviation (abduction).
• Especially due to movement of head of capitate
  in its socket.
• Enclosed within synovial capsule.

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Midcarpal Joint

• Ligaments
• Dorsal ligaments.
• Palmar ligaments.
• Interosseous ligaments.
• Nerves and arteries
• Same as for radiocarpal.

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Palmar Structure Sequence(radial to ulnar)

• Radius
• Radial artery
• Flexor carpi radialis tendon
• Median nerve
• Under palmaris longus tendon

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Palmar Structure Sequence(radial to ulnar)

• Flexor digitorum superficialis tendons
• Ulnar artery
• Ulnar nerve
• Flexor carpi ulnaris tendon

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HAND
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Carpometacarpal Joints

• Plane synovial joints
• Motion
• None for digits 2-3
• Limited for 4
• More mobile for 5

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Carpometacarpal Joints

• Saddle (sellaris) joint between metacarpus and
  trapezium
• Movements
• Abduction/adduction
• Flexion/extension
• Circumduction
• Opposition

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Metacarpophalangeal Joints

• Condyloid synovial joints
• Movements
• Flexion/extension
• Abduction/adduction
• Some opposition at MCP 5
• Capsular ligaments
• Palmar ligaments (pads)
• Collaterals

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Interphalangeal Joints

• Synovial hinge joints
• Only flexion/extension allowed
• Ligaments
• Strong collaterals
• Proximal interphalangeal joints (PIPs)
• Distal interphalangeal joints (DIPs)

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Dorsal Venous Drainage

• Dorsal venous arch drains hand dorsum.
• Medially drains into basilic.
• Laterally drains into cephalic.

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Lymphatic Drainage

• Medial via lymph vessels accompanying basilic
  vein to
• Supratrochlear nodes to
• Lateral axillary nodes.
• Lateral via lymph vessels accompanying cephalic
  vein to
• Infraclavicular nodes to
• Lateral axillary nodes.

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Arterial Supply to Dorsum

• Via dorsal arterial arch from
• Radial and ulnar arteries.
• Dorsal metacarpals.
• Dorsal digitals.

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Muscles of Dorsum of Hand

• Long extensor tendons.
• Dorsal interosseous muscles (4)
• Attachments
• DAB
• Abductors
• Middle finger is reference
• Middle finger has two
• First and fifth digits have none.

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Long Extensors
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Superficial Palm

• Palmar aponeurosis
• Flexor retinaculum
• Palmaris brevis

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Palmar Aponeurosis

• Triangular layer of deep fascia located between
  two eminences.
• Provides protection for superficial vessels,
  nerves, and tendons.
• Anchored to skin and flexor retinaculum.
• Splits into four slips that blend with fibrous
  flexor sheaths of four medial digits (II V).

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Flexor Retinaculum

• Transverse carpal ligament.
• Laterally attaches to tubercles of scaphoid and
  trapezium.
• Medially attaches to hook of hamate and pisiform.

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Palmaris Brevis Muscle

• O Flexor retinaculum and palmar aponeurosis.
• I Skin on medial side of palm.
• A Tenses skin on palm.

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Carpal Tunnel Contents

• Long flexor tendons of
• Flexor digitorum superficialis
• Flexor digitorum profundus
• Flexor pollicis longus
• Median nerve
• Note ulnar nerve and artery pass through Guyons
  canal.

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Long Flexors
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Intrinsic Muscles of the Thumb

• Thenar eminence
• Adductor pollicis
• Innervation
• Deep branch of ulnar nerve (C8, T1).

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Thenar Eminence Muscles

• Abductor pollicis brevis
• Flexor pollicis brevis
• Opponens pollicis
• Innervation
• Recurrent branch of median nerve (C8, T1).

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Thenar Muscles
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Hypothenar Eminence

• Intrinsic muscles for digit V.
• Abductor digiti minimi
• Flexor digiti minimi brevis
• Opponens digiti minimi
• Innervation
• Ulnar nerve

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Hypothenar Muscles
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Long Digital Flexors

• Flexor digitorum superficialis
• Flexor digitorum profundus

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Flexor Digitorum Superficialis

• Flexes PIP (and MCP and wrist).
• Each tendon passes through fibrous flexor sheath.
• Each tendon bifurcates opposite proximal phalanx.
• Each tendon inserts on middle phalanx.

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Flexor Digitorum Profundus

• Flexes DIP (and PIP and MCP).
• More active than superficialis.
• Each tendon inserts on distal phalanx.

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Vinculae

• Small vascular bundles connecting palmar surface
  of phalanges with long flexor tendons.
• Long and short

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Long Flexors
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Dorsal Interossei

• Four bipennate muscles.
• Each arises via two heads from adjacent sides of
  two metacapals.

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Dorsal Interossei

• Insertion
• Onto extensor expansions and
• Radial sides of proximal phalanges 2 and 3
• Ulnar sides of proximal phalanges 3 and 4.
• Note digit has two dorsal interossei.
• Abducts MP joints of digits 2-4
• Reference is line through middle finger.

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Interossei Muscles
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Palmar Interossei

• Four unipennate muscles
• First is sometimes considered part of flexor
  pollicis brevis.
• Supply each digit except third
• Reference is middle finger.
• Innervation for all interossei (incl. dorsal)
• Ulnar nerve

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Lumbricals

• Four small, narrow, elongated muscles.
• Each arises from the radial side of a flexor
  digitorum profundus tendon.
• Innervation
• Two on radial side
• Median nerve
• Two on ulnar side
• Ulnar nerve
• Flex MCP joints and extend IP joints.

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Arterial Supply to Hand

• Superficial palmar arch
• Continuation of ulnar artery.
• Deep palmar arch
• Continuation of radial artery.

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Route of Radial Artery

• Smallest terminal branch of brachial artery.
• Passes proximally deep to brachioradialis muscle.
• Distally the artery lies against the radius
  lateral to the tendon of the flexor carpi
  radialis, where it can be felt (radial pulse).
• Passes across scaphoid in anatomical snuff box.

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Route of Radial Artery

• Wraps around the dorsum of first metacarpus
• Gives off arteries to the thumb and index
  finger.
• Pierces the first dorsal interosseous muscle and
  reappears in the palm of the hand.
• Gives rise to the deep palmar arch.

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Deep Palmar Arch
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Boundaries of the Anatomical Snuff Box

• Lateral (anterior)
• Tendons of the
• Abductor pollicis longus.
• Extensor pollicis brevis.
• Medial (posterior)
• Tendon of the
• Extensor pollicis longus.

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Ulnar Nerve in the Hand

• Enters hand superficial to flexor retinaculum.
• Superficial branch
• Muscular branch to palmaris brevis
• Cutaneous to palmar aspect of ulnar side of
  little finger and adjacent sides of little and
  ring fingers, including tips and dorsum.

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Ulnar Nerve in the Hand

• Deep branch
• Supplies hypothenar muscles, all interossei,
  two ulnar side lumbricals, and adductor
  pollicis.

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Nerve Supply to Hand
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Median Nerve in the Hand

• Enters palm deep to flexor retinaculum.
• Divides into lateral and medial branches
• Lateral branch
• To thenar muscles and first lumbrical.
• Cutaneous to anterior surface of thumb and
  radial side of index finger.
• Medial branch
• To second lumbrical.
• Cutaneous to adjacent sides of digits 2-4,
  including nail-bed and finger tips.

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Spaces in the Hand

• Thenar space
• Located between the palmar side of the
  adductor pollicis muscle and the long flexor
  tendons to the index finger and the thumb.
• Midpalmar space
• Located between metacarpals 4-5 and the long
  flexor tendons to digits 4-5.

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Clinical Notes

• Mallet finger
• Avulsion by long flexor tendon.
• Results in hyperflexion of DIP.
• Dupuytrens contracture
• Progressive fibrosis of palmar aponeurosis.
• Results in marked flexion of fingers at MP
  joints.
• Colles fracture.
• Fracture of scaphoid.

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Clinical Notes

• Median nerve injury
• Loss of thumb opposition.
• Atrophy of thenar muscles.
• Ape hand.
• Ulnar nerve injury
• Paralysis and atrophy of interossei.
• Guttering
• Loss of thumb adduction.
• Clawhand.

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EXTENSOR MECHANISM
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Components

• Hood
• Lateral bands
• To bases of distal phalanges.
• Central band
• To base of middle phalanx.
• Function
• Flexion at MCP joint.
• Extension at PIP, DIP joints.

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Functional Notes

• Extension of the PIP is always accompanied by the
  simultaneous extension of the DIP.
• When the PIP is flexed, the DIP may be extended
  or flexed

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Clinical Notes

• If lateral bands detach
• Lateral bands will flex the PIP and
  hyperextend the DIP.