Surface anatomy of the flexor retinaculum:
Attachements and structures pass under / over / through it.
Distal wrist crease – proximal border of flexor retinaculum
Medially – pisiform and hook of hammate
Laterally – scaphoid and trapezium
Carpal tunnel
9 tendons and one nerve
8 tendons share a sheath – FDP, FDS
Median nerve (lateral)
Flexor pollicis longus (most lateral)
FCR is not under carpal tunnel but is under flexor retinaculum.
Palmaris Longus blends on top
Ulnar artery and nerve pass above
Arterial supply of the hand.
Ulnar artery
Superficial palmar arch – mainly ulna
3 common palmar digital arteries anastamose with palmar metacarpal arteries
Each divide into pair of palmar digital arteries.
Deep palmar arch
Palmar metacarpal arteries.
Radial artery
Curves behind snuffbox and enters hand passing between the two heads of 1st dorsal interosseous muscles then between two heads of adductor pollicis.
End with anastamosis with deep palmar arch – mainly radial. (over metacarpal)
Princip pollicis artery
Palmar metacarpal arteries
Innervation of the muscles of the hand.
Median – LOAF
Lateral 2 lumbricals
Opponens pollicis
Abductor pollicis brevis
Flexor pollicis brevis
Ulnar – all other intrinsic muscles of hand
Medial 2 lumbricals
Interossi
Hypothenar – abductor digiti minimi, flexor digiti minimi brevis, opponens digiti minimi
Adductor pollicis
Deep head of flexor pollicis brevis
Radial – from forearm.
Extensor pollicis longus, brevis, abductor pollicis longus
Sensory innervation of the hand.
Radial – 1st dorsal webspace, lateral 3.5 fingers’ dorsally up to DIP joints
Medial – lateral 3.5 fingers’ on palmar side and dorsally up to DIP joint
Ulna – medial 1.5 fingers palmar and dorsal surface
Median passes under two heads of pronator teres
Ulnar passes under the 2 heads of flexor carpi ulnaris
Actions of the interossei and the lumbricals.
PAD (Palmer Interossei Aduction)
DAB (Dorsal Interossei Abduction)
Wrist joint.
Proximal wrist crease
Condyloid/ellipsoid Synovial joint between distal radius and scaphoid, lunate and triquetrum (with articular disc of distal radioulnar joint)
Radial and ulnar collateral ligaments, palmar and dorsal radiocarpal ligaments
Flexion/extension, radial and ulna deviation, and circumduction
Innervated by radial, Ulna and median nerves
Blood supply of the scaphoid.
End arterial supply from distal branches of radial artery
Flows distal to proximal
Movements of the thumb
Saddle synovial joint
Trapezium and 1st metacarpal – separate articular cavity
Angular movements in any plane – flexion/extension, abduction/adduction, circumduction, restricted axial rotation
All three nerves
Arterial supply from anastamosis of wrist and hand
MCP/PIP/DIP Joints
PIP and DIP – Hinge synovial joints
Flexion, extension
MCP – condyloid synovial joint
Flexion/extension, abduction/adduction
Deep transverse metacarpal ligaments hold the heads of medial 4 metacarpal heads together.
Supplied by digital arteries.
Hand compartments
Palmar aponeurosis (deep fascia)
Fibrous digital sheaths
Medial fibrous septum – from palmar aponeurosis to 5th metacarpal
Medial to this is the hypothenar compartment
Lateral fibrous septum – from palmar aponeurosis to 3rd metacarpal
Lateral to this is the thenar compartment
Between the two septum – central compartment – flexor tendons, sheaths, lumbricals, superficial palmar arch, digital vessels and nerves.
Mid palmar space is cont to ant compt of forearm via carpal tunnel
Intrinsic hand muscles
Thenar
Flexor pollicis brevis
Superficial and deep part
Origin – distal flexor retinaculum and trapezium tubercle
Insertion – base of proximal phalynx
Innervation – median nerve
Deep part = First palmar interossei – origin – ulnar side of first metacarpal, inserts – ulnar side of base of proximal phalynx. Ulnar innervarion
Abductor pollicis brevis
Contributes to bulk of thenar eminence, middle
Origin – distal flexor retinaculum and scaphoid tubercle, sometimes trapezium tubercle
Inserts – radial side of base of first phalynx and capsule of MCP.
Median nerve
Opponens Pollicis
Deep to the above two, most medial
Origin – distal flexor retinaculum and trapezium tubercle
Inserts – length of thumb metacarpal on radial side.
Median nerve
Blood – superficial palmar arch
Hypothenar
Opponens digiti minimi – deep
Abductor digiti minimi – most superficial, origin pisiform/FCU
Flexor digiti minimi brevis – medial
Non thenar
Adductor pollicis
Transverse and oblique head. Deep to the others
Origin transverse head – ant body of 3rd metacarpal
Origin oblique head – base of 2nd and 3rd metacarpals and capitate and trapezoid.
Common insertion – ulnar side of base of proximal phalynx of thumb.
Ulnar nerve
Blood – deep palmar arch between the two heads from radial artery
Lumbricals 4
Arise from FDP tendons–> dorsal hood
1&2 unipentate, 3&4 bipentate.
Interossei
4 dorsal and 3 palmar. Dorsal are bipentate, palmar are unipentate.