hand anatomy
TRANSCRIPT
Hand Anatomy
Peninsula Hospital Center
Palmar Spaces
• Thenar Space• Midpalmar Space• Hypothenar Space• Radial Bursa• Ulna Bursa• Parona Space
Radial, Ulna and Perona Space
Digits
• Osteology – Fingers• proximal (P1), middle (P2), and distal (P3) phalanges
– Thumb • Proximal and distal phalanges
MCP Joint
• Triaxial condyloid joint– Range of motion: 15° of hyperextension to 90° of flexion– Metacarpal head has trapezoidal shape
• cam effect ? on the collateral ligaments• Taut MCP joint flexion• Lax in extension.
– Thumb: Metacarpal head a single broad condyle• Sesamoids volar plate.• Ulnar collateral ligament (UCL)
– Proper – Accessory portions
PIP Joint
• The PIP joint hinge joint• Head of proximal phalanx
– Two condyles – Intercondylar notch– Intercondylar notch articulates with the median ridge at the base
of the middle phalanx– Collateral ligaments Taut throughout range of motion – Proper collateral ligament
• Origin head of the proximal phalanx• Insertion lateral tubercle of the base
– Accessory collateral ligament—Inserts into the volar plate. – Volar plate—A thick, fibrocartilagenous floor that originates within the A2 pulley and
inserts into the “rough area” at the base of P2. It supports the insertion of the accessory collateral ligament and prevents PIP joint hyperextension.
PIP Joint
• Accessory collateral ligament– Inserts into the volar plate– Volar plate• Origin: A2 pulley • Insertion: Base of P2• Function: Supports the insertion of the accessory
collateral ligament and prevents PIP joint hyperextension.
DIP Joint
• Distal interphalangeal joint is stabilized by– Collateral ligaments– Terminal extensor tendon insertion– FDP insertion– Volar plate
Dorsal Surface of Finger
• Extensor apparatus • Extensor tendons divided into anatomic zones• Trifurcates at P1 base• Central portion insertion P2 as the central slip. • Lateral slips converge middle phalanx insertion P3
Dorsal Surface
• Dorsal stabilizing structures – Sagittal bands: origin at MCP joint volar plate and the base of P1
• Function: Stabilize extrinsic extensor tendon at the dorsal MCP joint• Indirectly MCP joint extension
– Triangular ligament• Function: Stabilize conjoined lateral bands over the base of P2 and prevent
volar subluxation.
– Transverse retinacular ligament• Function: Stabilize conjoined lateral bands to prevent dorsal subluxation
– The oblique retinacular ligament (ORL) links the PIP and DIP joints. • Origin: Fibro-osseous gutter at the A2 pulley and middle third of P1 (volar)
to insert into the terminal extensor tendon (dorsal).
Volar Finger
• Fascia– Grayson and Cleland ligaments– The flexor tendons five anatomic zones – FDS flattens and bifurcates at A1– FDS further divides into medial and lateral slips
Vascular Supply
• Vascular supply: Direct vascular supply and synovial diffusion
• Direct Vascular Supply: Transverse digital arteries and a direct arterial supply from intraosseous vessels at tendinous insertions• Synovial diffusion: Rely on intratendinous canaliculi for
synovial diffusion
Zones of Flexor Tendons
Flexor Tendon Pulleys
• The A1, A3, and A5 pulleys take their origin from palmar plates of the MCP, PIP, and DIP joints, respectively
• A2 and A4 pulleys originate from the proximal and middle phalanges
• A2 and A4 pulleys are the most important pulleys biomechanically
Dorsal Thumb
• MCP joint– EPL tendon is ulnar to EPB– EPL, EPB stabilized by sagittal band
• Volar Thumb • FPL emerges from interval between adductor pollicis
and the thenar• Flexes interphalangeal (IP) joint.
Volar Thumb
– Flexor tendon sheath/pulleys • A1, oblique and A2 pulleys comprise the pulley system
of the thumb. • A1 pulley at MCP joint• Oblique pulley fibers distal and radial direction at
proximal phalanx• A2 pulley: origin IP joint volar plate• A1 and oblique pulleys most important biomechanically• Radial digital nerve risk during A1 pulley release.
Hand Osteology
• CMC Joint– biconcave-convex
• TM joint– Biconcave-convex (two opposing saddles) – Stability by dorsal ligamentous complex• Dorsooradial ligament • Posterior oblique ligament• Deep anterior oblique ligament
Dorsal Hand and Extensor Tendons
• Juncturae tendinae • Extensor indicis proprius (EIP) and extensor digiti
minimi (EDM) are most commonly ulnar EDC tendons • Most common extensor pattern to little finger two
EDM tendons and no EDC tendon. • Extensor digitorum brevis confused with a soft-tissue
tumor.
Intrinsic Muscles
• Interossei (dorsal and volar)• Lumbrical• Thenar• Hypothenar muscles.
Interossei Muscles
• Origin: metacarpal diaphyses• Dorsal to the deep transverse intermetacarpal
ligament• Innervation: ulnar nerve• First interosseous muscle sometimes
innervated by median nerve
Interossei Muscles
• Four dorsal interossei: bipennate, superficial and deep muscle belly– Superficial Insertion lateral tubercle abduction of
digit– Deep lateral tendon Insertion Extensor Apparatus Flex MCP Joint
• Volar interossei : Unipennate – Origin: Metacarpal Shaft; Insertion: Extensor apparatus– Function: Flex MCP joint and adduct index, ring, and
little fingers
Lumbricals
– Origin: FDP tendon– Insertion: Radial lateral band of the extensor
apparatus– Action: extend the PIP and DIP joints through the
oblique fibers– Innervation: Median Nerve (1st and 2nd) and
unipennate• Ulna nerve (3rd and 4th) and bipennate.
Thenar Muscles
Muscle Innervation
APB Median Nerve
FPB Sup Median; Deep Ulna
Opponens Pollicis Median Nerve
Adductor Pollicis Ulna Nerve
Hypothenar MusclesHypothenar Muscles Innervation
Abductor Digiti Minimi Ulna Nerve
Flexor Digiti Minimi Ulna Nerve
Opponens Digiti Minimi Ulna Nerve
Hand 3
Hand 4
Hand 5
Hand 6
Hand 7
Finger 1
Finger 2
Hand 8
Hand 9
Paronychia
Felon
Webspace
Hand Spaces