Wrist and Hand Anatomy PDF

Wrist and hand: pages 101-118 Surface Anatomy of the hand: skin ridges aid in reducing slippage when grasping objects. The radial artery pulse may be felt if pressing the distal end of the radius between the FCR and APL tendons. The FCU serves as a guide to the ulnar nerve and artery and palmaria t...

Wrist and hand: pages 101-118 Surface Anatomy of the hand: skin ridges aid in reducing slippage when grasping objects. The radial artery pulse may be felt if pressing the distal end of the radius between the FCR and APL tendons. The FCU serves as a guide to the ulnar nerve and artery and palmaria tendon as a guide to median nerve. Palmar Arch: ○ Superficial: 1.5 cm distal to the deep palmar arch. ○ Deep: lies at the level of the bases of the metacarpals. Wrist: indicate the proximal border of the flexor retinaculum ○ Proximal: the proximal wrist crease is the first visible crease on the wrist. ○ Middle: the middle wrist crease is the 2nd visible crease on the wrist ○ Distal: the most distal wrist crease. Palmar creases: help folding the skin over the hand and prevent slipping. ○ Radial longitudinal: travels almost horizontally medial to the thumb “root” ○ Proximal (transverse): crease superior to the thenar crease and inferior to the distal transverse. ○ Distal: most distal crease, inferior to the indicis minimi. ○ Proximal digital: most proximal crease in all digits (inferior to proximal phalanx) ○ Middle digital: medial crease in all digits (superior to proximal phalanx inferior to middle phalanx). ○ Distal digital: distal crease in all digits ( inferior to distal phalanx and superior to middle phalanx). Hand Bones: Carpal bones 8 total: ○ Proximal row: scaphoid, lunate, tricutreum, pisiform ○ Distal row: trapezium, trapezoid, Capitater, Hamate Metacarpals: ○ Base: most proximal border of the metacarpal ○ Shaft: long portion of the metacarpal connecting base to head ○ Head: most distal border of the metacarpal, area where metacarpal articulates with Phalanx in the MCP joint. Phalanges: ○ Base: most proximal border of the phalange. Articulates with the metacarpal at the MCP joint. ○ Shaft: long(ish) structure of the phalanx connecting the base to the head. ○ Head: most distal border of the phalanx. May articulate with the next phalange in the IP joint only if we are not discussing the head of the distal phalanx. Hand structure: Areas: ○ Thenar: muscular elevation at the base of the thumb. ○ Hypothenar: muscular elevation at the base of the 5th digit. Grips: ○ Power: when digits apply force against the palm. Allows for carrying heavy objects.  ○ Hook: less forceful than power grip, fingers act similarly to it though however with no contact to the palm. Used to carry a brief case. ○ Precision: grip that allows for quick manipulation of an object. Example: holding a pencil, manipulating a coin etc. ○ Pinching: type of grip where we compress something between the thumb and index finger. ○ Position of rest: used when the fingers or hand are not actively doing anything. Carpal Tunnel: area between the flexor retinaculum superficially and the tubercules of the scaphoid and trapezoid on the lateral side and the pisiform and hook of hamate on the medial side. Carpal tunnel syndrome refers to median nerve entrapment in the carpal tunnel. Osteofibrous canal of the wrist Boundaries: ○ Floor: carpi bones (scaphoid and trapezoid laterally and pisiform and hamate medially) ○ Roof: flexor retinaculum Contents: ○ Median nerve ○ Tendons:Flexor Pollicie Longus, Flexor digitorium superficialis and flexor digitorium profundus. Guyon’s Canal: anatomical fibro-osseous canal located on the medial side of the hand and extends between the proximal border of the pisiform bone and distally to the hook of hamate. This canal is a common entrapment site for the ulnar nerve. Also known as ulnar canal /tunnel Boundaries: ○ Roof: volar (palmar) ligaments ○ Floor: flexor retinaculum ○ Medial wall: pisiform, pisohamate ligament, abductor digits minimi ○ Lateral wall: hook of hamate, flexor retinaculum Contents: ulnar nerve, and ulnar artery Anatomical Snuff box: also known as the radial fossa. Located at the level of the carpal bones and best seen when the thumb is extended. A triangular depression on lateral aspect of dorsum of hand Boundaries: ○ Posterior border: extensor pollicis longus tendon ○ Anterior border: extensor pollicis brevis, abductor pollicis longus tendons ○ Proximal border: radius Styloid process ○ Floor: scaphoid, and trapezium bones ○ Roof: skin Contents: radial artery, superficial branch of the radial nerve, cephalic vein Fascia & Compartments of Palm Palmar fascia: continuous with antebrachial fascia and the fascia of the dorsum of the hand. Thin over the thenar and Hypothenar eminences Palmar aponeurosis: a strong, well defined part of the deep fascia of the palm. It covers the soft tissues and overlies the flexor tendons. Extension of the palmar is longus tendon, becomes continuous with the fibrous digital sheaths.  Fibrous digital sheaths: ligamentous tubes that enclose the synovial sheaths, the superficial and deep flexor tendons and the tendon for the flexor pollicis longus in their passage along the palmar aspect of their respective fingers. Medial fibrous septum: extends deeply from the medial border of the palmar aponeurosis to the 5th metacarpal. Lateral fibrous septum: extends deeply from the lateral border of the palmar aponeurosis to the 3rd metacarpal. Hypothenar compartment: medial to the medial fibrous septum, contains the Hypothenar muscles and is bound anteriorly by the Hypothenar fascia. Thenar compartment: lateral to the lateral fibrous septum, contains the thenar muscles and is bound anteriorly by the thenar fascia. Central compartment: compartment between the Hypothenar and thenar compartments. Bound anteriorly by the palmar aponeurosis, contains the flexor tendons and their sheaths, the lumbricals, the superficial palmar arterial arch and the digital vessels and nerves. Adductor compartment: the deepest muscular plane of the palm. Contains the adductor pollicis. Distal Radio-Ulnar joint: occurs between radius and ulna Joint type: Pivot synovial joint. Radial moves around the relatively fixed distal end of the ulna. Capsule: it surrounds the radio-ulnar joint, but is deficient superiorly. This is because the synovial membrane extends there to form the sacciform recess of the distal radio-ulnar joint. This accommodates the movement of the radius over the ulna. Ligaments: the anterior and posterior ligaments strengthen the fibrous layer of the joint capsule of the distal radio-ulnar joint. These ligaments are relatively weak and move from the radius to the ulna obliquely anteriorly or obliquely posteriorly Movements: ○ Pronation: the distal end of the radius moves (rotates) anteriorly and medially crossing over the ulna anteriorly. ○ Supination: the radius uncrosses from the ulna by having its distal end rotate posteriorly and laterally. Getting the bones back in parallel. Blood supply: supplied by the anterior and posterior interosseous arteries. Nerve supply: supplied by the anterior and posterior interosseous nerves. Radiocarpal joint: Joint type: condyloid synovial joint Capsule: the fibrous layer of the joint capsule surrounds the wrist joint and is attached to the distal ends of the radius and ulna, as well as the proximal row of carpals. The synovial membrane lines the internal surface of the fibrous membrane and is attached to the margins of the articular surfaces. Contains an articular disc just distal to the ulna and proximal to the carpal bones. Ligaments: ○ Palmar radiocarpal: pass from the radius to the 2 rows of carpals. Strong ligaments allow the hand to follow the radius during supination of the forearm. ○ Dorsal radiocarpal: also strong. Allowing the hand to follow the radius during pronation of the forearm ○ Ulnar collateral: strengthens joint medially. Attaches to the ulnar Styloid process and triquetrum  ○ Radial collateral: strengthens joint laterally. Attaches to the radial Styloid process and scaphoid. Movements: movements can be augmented by the mid carpal and inter carpal joints. The movements are: ○ Flexion/extension: more ROM for flexion than extension. ○ Abduction/adduction: more ROM for adduction than abduction. Most adduction on the wrist joint while most abduction from a neutral position at the mid carpal joint. ○ Circumduction: sequential movements of flexion, adduction, extension, abduction or the reverse. Blood supply: supplied by branches of the dorsal and palmar carpal arches Nerve supply: supplied by the interosseous branch of the median nerve, posterior interosseous branch of the radial nerve and the dorsal and deep branches of the ulnar nerve. Intercarpal joints: Joint type: plane synovial Four joints: ○ In between proximal and distal carpals (2): joints between the carpal bones on the proximal row and between the carpal bones of the distal row ○ Midcarpal: a complex joint between the proximal row and distal row metacarpals. ○ Pisotriquetral: articulation of the pisiform with the palmar surface of the triquetrum. Capsule: a articular cavity exists between the Intercarpal and carpometarcapal joints (except for the thumb). The fibrous layer of the capsule surrounds the IC joints, which helps unite the carpals. The synovial membrane lines the fibrous layer and attaches to the margins of the carpals’ articular surfaces. Ligaments: the carpals are United by anterior, posterior and interosseous ligaments. Movements: joint permits gliding movement between carpals. This allow for increased movement at the wrist joint. Blood supply: dorsal and palmar carpal arches Nerve supply: anterior interosseous branch of the median nerve and the dorsal and deep branches of the ulnar nerve. Carpometacarpal & Intermetacarpal joints: Joint type: ○ 1st CMC: saddle type synovial joint ○ All other CMC: plane type synovial joints ○ Intermetarcapal: plane type synovial joints Capsulae: four the 4 CMC joints (excluding 1st) and the three Intermetacarpal joints are enclosed on the same joint capsule in the palmar and dorsal surfaces. The fibrous layer is lined internally by a common synovial membrane. For the first CMC the fibrous layer is attached to the margins of the articular surface. Ligaments: ○ Palmar: unite the bones in the region of the joints ○ Dorsal: unite the bones in the region of the joints, ○ Interosseous: unite the bones in the region of the joints.  ○ Transverse Metacarpal: there are 2 types (superficial and deep) associated with the distal ends of the metacarpals. Limit movement at the CMC and IM joints by limiting separation of metacarpal’s heads. Movements: thumb one is special and will be covered later. Only 4th and 5th digits CMC joints have mobility and allow for flexing and rotating. Blood supply: they are supplied by peri-articular arterial anastomoses of the wrist and hand Nerve supply:anterior interosseous branch of the median nerve, posterior interosseous branch of the radial nerve and the dorsal and deep branches of the ulnar nerve. 1 CMC joint movements: Extension: extensor pollicis longus, extensor pollicis brevis, abductor pollicis longus Flexion: flexor pollicis longus, flexor pollicis brevis Abduction: abductor pollicis longus, abductor pollicis brevis Adduction: adductor pollicis and 1st dorsal interosseous Opposition: opponents pollicis (more muscles) Metacarpophalangeal and Interphalangeal joints: Joint type: both are condyloid type of synovial joints Capsule: each MCP and IP joint is enclosed by a joint capsule. The synovial membrane lines the fibrous layer and attaches to the margins of each joint. Ligaments: ○ Collateral: strengthens the MCP and IP joint capsule is strengthened by 2 of this ligament (medial and lateral). They do not allow fingers to abduct while fully flexed. ○ Palmar (plates): thinner fan like portion of the collateral ligament. Forms the palmar aspect of the joint capsule. ○ Deep transverse MC: holds the heads of the metacarpals together. Movements: ○ 1st digit MCP: flexion/extension ○ 2nd-5th digits MCP: flexion/ extension and abduction/ adduction ○ IP joints: only flexion/ extension in all Blood supply: deep digital arteries arising from the superficial palmar arches Nerve supply: digital nerves from the ulnar and median nerves. Intrinsic muscles of the hand: Thenar muscles: ○ Opponents pollicis brevis: Proximal attachment: flexor retinaculum and tubercules of scaphoid and trapezium. Distal attachment: lateral side of 1st metacarpal Innervation: recurrent branch of median nerve (C8-T1) Main action: opposes thumb. ○ Abductor pollicis brevis: Proximal attachment:flexor retinaculum and tubercules of scaphoid and trapezium. Distal attachment:lateral side of base of proximal phalanx of thumb. Innervation:recurrent branch of median nerve (C8-T1) Main action: abducts thumb and helps oppose it ○ Flexor pollicis brevis superficial head:  Proximal attachment:flexor retinaculum and tubercules of scaphoid and trapezium. Distal attachment:lateral side of base of proximal phalanx of thumb. Innervation:recurrent branch of median nerve (C8-T1) Main action: flexes thumb ○ Flexor pollicis brevis deep head: Proximal attachment:flexor retinaculum and tubercules of scaphoid and trapezium. Distal attachment:lateral side of base of proximal phalanx of thumb. Innervation:deep branch of ulnar nerve (C8, T1) Main action: flexes thumb Adductor muscles: ○ Adductor pollicis oblique head: Proximal attachment: bases of 2nd and 3rd metacarpals, capitate, and adjacent carpals Distal attachment: medial side of base of proximal phalanx Innervation:deep branch of ulnar nerve (C8, T1) Main action:adducts thumb ○ Adductor pollicis transverse head: Proximal attachment: anterior surface of shaft of 3rd metacarpal Distal attachment:medial side of base of proximal phalanx Innervation:deep branch of ulnar nerve (C8, T1) Main action: adducts thumb Hypothenar muscles: ○ Abductor digiti minimi: Proximal attachment:pisiform Distal attachment: medial side of base of proximal phalanx of 5th digit Innervation:deep branch of ulnar nerve (C8, T1) Main action: abducts 5th digit; assists in flexion of its proximal phalanx ○ Flexor digiti minimi brevis: Proximal attachment: hook of hamate and flexor retinaculum Distal attachment:medial side of base of proximal phalanx of 5th digit Innervation:deep branch of ulnar nerve (C8, T1) Main action: flexes proximal phalanx of 5th digit ○ Opponents digiti: Proximal attachment:hook of hamate and flexor retinaculum Distal attachment:medial border of 5th metacarpal Innervation:deep branch of ulnar nerve (C8, T1) Main action:draws 5h metacarpal anteriorly and rotates it, bringing 5th digit to opposition with thumb. Lumbricals/central muscles: ○ 1st and 2nd lumbricals: Proximal attachment:lateral 2 tendons of flexor digitorium profundus (as unnipenate muscles) Distal attachment: lateral sides of extensor expansions of 2nd-5th digits  Innervation: Median Nerve (C8-T1) Main action: flex metacarpophalangeal joints, extend interphalangeal joints. ○ 3rd and 4th lumbricals: Proximal attachment: medial 3 tendons of flexor digitorium profundus (as bippenate muscles Distal attachment:lateral sides of extensor expansions of 2nd-5th digits Innervation:deep branch of ulnar nerve (C8, T1) Main action:flex metacarpophalangeal joints, extend interphalangeal joints. Interosseous muscles: ○ Dorsal interossei (1st-4th): Proximal attachment:adjacent sides of 2 metacarpals (as bippenate muscles) Distal attachment: bases of proximal phalanges; extensor expansions of 2nd-4th digits Innervation:deep branch of ulnar nerve (C8, T1) Main action: abduct 2nd-4th digits, help lumbricals ○ Palmar interossei (1st-3rd): Proximal attachment:palmar surfaces of 2nd, 4th and 5th metacarpals (as unipennate muscles) Distal attachment:bases of proximal phalanges; extensor expansions of 2nd, 4th and 5th digits Innervation:deep branch of ulnar nerve (C8, T1) Main action: adduct 2nd, 4th and 5th digits. Help lumbricals Long Flexor tendons sheaths: Common flexor sheath (ulnar bursa): deep to flexor retinaculum. The FDS and FDP tendons enter central compartment to be then directed to the digital synovial sheaths Digital synovial sheaths: one for each finger, allows for free and smooth movement of the tendons and fingers,