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What features are on the dorsal surface of the hand?
- extensor tendons
- knuckles
- anatomical "snuff box"
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What bone makes the knuckles?
heads of metacarpals
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What is the lateral boundary of the anatomical "snuff box"?
tendons of abductor pollicis and extensor pollicis brevis
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What is the medial boundary of the anatomical "snuff box"?
the tendon of extensor pollicis longus
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What structures are contained within the anatomical "snuff box"?
radial a. and the styloid process of the radius
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What are the palmar surface features of the hand?
- palmar and digital creases
- thenar eminence of thumb
- hypothenar eminence of 5th digit
- abundance of sweat glands and absence of hair
- well-patterned ridges on ventral surface of distal phalanges (fingerprints)
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What is the function of fingerprints?
to prevent slippage of grasped objects
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Where are the carpometacarpal joints?
between the carpal bones and the metacarpal bones
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Where are the intermetacarpal joints?
Between metacarpal bones at the proximal ends
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Where are the metacarpophalangeal joints?
between the metacarpal bones and the phalanges
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How manyinterphalangeal joints does the thumb have?
one
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What are the muscles of the thenar eminence?
- abductor pollicis brevis
- flexor pollicis brevis
- opponens pollicis
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What does it mean when a muscle is an intrinsic muscle of the hand?
the origin and insertion of the muscle are both in the thumb
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Which of the thenar muscles has a different innervation? Which nerve?
the deep head of flexor pollicis brevis --ulnar N
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Which muscles are the hypothenar muscles?
- palmaris brevis
- abductor digit minimi
- flexor digiti minimi brevis
- opponens digiti minimi
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Which of the hypothenar muscles has a different insertion? Where?
opponens digiti minimi --shaft of 5th metacarpal
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Which hypothenar muscle has a differnt innervation? Which nerve?
palmaris brevis --ulnar n. or its superficial branch
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What muscles does the median nerve supply?
- abductor pollicis brevis
- flexor policis brevis
- opponens pollicis
- lateral lumbricales
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What groups can the interossei muscles be divided into?
dorsal and palmar groups
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Where are the interossei muscles found?
between the metacarpal bones
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How many palmar interossei muscles are there?
3
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How many dorsal interossei muscles are there?
4
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Which digit has no palmar interossei mucles?
3rd digit
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How many dorsal interossei muscles insert on the 3rd digit?
2
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How many lumbricales muscles are there?
4
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Which lumbricales does the median nerve innervate?
lumbricales 1 and 2
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Do the interossei and the lumbricales assist in the same action?
yes
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Extenso expansion attaches to...
all 3 phalanges
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What becomes impaired if you injure the dense connective tissues of the hand?
- impaired maual dexterity
- requires long periods of time to heal
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What is the palmar aponeurosis?
a thickening of the deep fascia in the central area of the palm
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What does the palmar aponeurosis overlie?
long flexor tendons and other soft tissues
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Proximally, what is the palmr aponeurosis continuous with?
flexor retinaculum
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Distally, what does the palmar aponeurosis divide into?
four longitudinal bands that attach to the bases of the proximal phalanges and fue with fibrous digital sheaths of each of the four figers
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Which muscle inserts into the palmar aponeurosis?
palmaris longus
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What is the function of the palmar aponeurosis?
- gripping objects
- protects structures
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What is the palmar aponeurosis made of?
collagen fibers
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A lateral/thenar compartment is formed where?
by a septum at the lateral border of palmar aponeurosis extended deeply to the 1st metacarpal
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At the medial border of the palmar aponeurosis, a fibros medial septum extends dorsally t the 5th metacarpal forming...
a medial/hypothenar compartment on the medial side of the septum
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What is contained in the lateral compartment?
thenar muscles
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What is contained in the medial compartment?
hypothenar muscles
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What lies between the medial and lateral septa?
a central compartmen containing flexor tendons and their sheaths, superficial palmar arch and braches of the median and ulnar nerves
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Where is the oblique septum located?
lateral border of the palmar aponeurosis, passes deeply and obliquely to the 3rd metacarpal
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What compartment does the oblique septum divide?
central compartment
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What are the divisions of the central compartment (by the oblique septum) called?
lateral and medial mid-palmar spaces
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Does the adductor pollicis muscle have its own compartment?
yes
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What is the flexor retinaculum?
a heavy thickening of the anterior antebrachial fascia at the level of the wrist joint
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What structures course deep to the flexor retinaculum?
median nerve and all the flexor tendons (except palmaris longus tendon)
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The flexor retinaculum along with the carpal bones forms the:
carpal tunnel
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What is the extensor retinaculum?
a thickening of the posterior antebrachial fascia
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Where is the extensor retinaculum located?
from lateral border of radius to medial border of the ulna and the triquetrum and pisiform
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How many typical compartments of the extensor retinaculum are there?
6
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What forms the 6 typical compartments of the extensor retinaculum?
septa from the retinaculum to the underlying bone
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What is the function of synoival sheaths?
provides friction-less environment for the tendons
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What are synovial sheaths filled with?
synovial fluid
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In relationship to the flexor retinaculum, where do the flexor digitorum superficialis and flexor digitorum profundus pass?
deep to the flexor retinaculum
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What are osteobribrous flexor sheaths?
synovial membrane so tendons can slide freely over each other and bone
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Where do the osteofibrous digital tendon sheaths begin?
level of MP joint
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Where do the osteofibrous digital tendon sheaths teminate?
proximal to base of distal phalanges
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What are the two layers of the osteofibrous digital tendon sheaths?
- outer fibrous layer
- inner synovial laye
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What connects the tendon to the osteofibrous sheath on the anterior surface of the phalanx?
two strands of connective tissue --vincula tendinum
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Is the proximal or distal vinculum longer?
proximal vinculum is longer
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How are the long flexor tendons supplied with blood?
by small blood vessels from the periosteum of the phalanges that pass through the long and short vincula
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What is contained in a osseofibrous tunnel?
a muscle tendon surrounded by fluid
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What is the purpose of the osseofibrous tunnel?
prevents friction of tendons on bone
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What is the osseofibrous tunnel made of?
dense connective tissue
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Do the flexor tendons share a common flexor sheath?
yes
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Do the extensor tendons share a common extensor sheath?
no
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Which extensor tendons share a common sheath?
only tendons within the same compartment
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What is found between the four tendons of the extensor digitorum?
intertendinous connections
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The expanded tendon of insertion on the dorsal side of the hand is knon as:
the extensor hood or the dorsal digital expansion
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The distal prolongation of the extensor hood is known as the:
extensor aponeurosis
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Flexion(extension) of distal phalanges is usually accompanied by an equal amount of...
flexion (extension) of the middle phalanges
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Which nerve supply cutaneous innervation to the hand?
radial, ulnar and median nerves
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What is the major branch of the median nerve in the forearm?
anterior interosseous nerve
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What muscles does the anterior interosseous nerve supply?
all the extrinsic flexors (except flexor carpi ulnaris and ulnar half of flexor digitorum profundus)
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What nerve innervates the flexor digitorum profundus and the flexor carpi ulnaris?
ulnar n.
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Which nerve supplies all the extensor muscles?
radial nerve and its main branch --posterior interosseous n.
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All intrinsic muscles of the hand are supplied by the ular nerve except:
- abductor pollics brevis
- flexor pollicis brevis (superficial head)
- opponenes pollicis
- lumbricales (1 and 2)
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What arteial supplies the hand?
- superficial palmar arch
- deep plamar arch
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What is the superficial palmar arch a continuation of?
ulnar artery
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What is the deep palmar arch a continuation of?
radial artery
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What arteries come off the superficial palmar arch?
common digital arteries
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What do the common digital arteries divide to form?
proper palmar digital arteries
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What arteries come off the deep palmar arch?
palmar metacarpal arteries
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What arteries do the palmar meacarpal arteries communicate with?
common digital arteries
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At the creases of the fingers, the skin is firmly bound to what?
subcutaneous tissue beneath
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What occurs if there is an incision across a crease of the fingers?
- produces musch scar tissue
- remarkable reduction in range of motion
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What might cause the palmar aponeurosis to become abnormally thickened?
fibrous bands that extend from the aponeurosis to the bases of the phalanges
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What happens when fibrous bands extend from the palmar aponeurosis to the base of the phalanges?
Dupuytren's contracture
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What is Dupuytren's contracture?
- when fingers are pulled into flexion, the aponeurosis becomes contracted so that the flexed MP joints cannot be straightened
- caused by extension of the palmar aponeurosis
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What is the cause of Dupuytren's contracture?
may be a hereditary predisposition
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What is a good thing about having different compartments in the hand when one gets infected by a puncture?
- when one compartment becomes infected the accumulated pus is contained within that compartment by the septa
- if infection site is properly treated, infection rarely spreads to other compartments, but could spread to forearm
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Do the deep and superficial palmar arches anastomosis with each other?
yes
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What does injury to the median nerve in the forearm or at the wrist produce?
paralysis of thenar muscles
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What is a sign of injury to the median nerve in the forearm or at the wrist?
loss of opposition of the thumb
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Which muscles could produce a close imitation of opposition when the median nerve is injuried?
abductor pollicis longus, adductor and the deep intrinsic flexor and the interossei
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Where does the recurrent branch of the median nerve lie?
superficial, on thenar eminence
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What happens if the recurrent branch of the median nerve is severed by minor laceration?
render the thumb useless as most of the thenar muscles are paralyzed
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What happens when the median nerve at the wrist is injuried?
- paralysis of most of the thenar muscles
- sensory impairment in most of the fingers
- subsequent atrophy of the thenar muscles
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Which nerve injury caused "ape hand" deformity?
median nerve at the wrist
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What is "ape hand deformity?
when thenar muscles become flattened because of atrophy caused by a median nerve injury at the wrist
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What occurs with injury to the ulnar nerve at the wrist?
- loss of sensation in the 5th finger and ulnar half of the 4th finger
- impaired abduction and adduction of 5th finger
- paralysis of adductor pollicis, the 3rd and 4th lumbricales and the interossei
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What causes furrows between the metacarpals?
subsequent atrophy of aductor pollicis, 3rd and 4th lumbricales and interossei caused by ulnar nerve injury at the wrist
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What is "claw hand"?
- when the hand has furrows between the metacarpals
- - causd by: subsequent atrophy of aductor pollicis, 3rd and 4th lumbricales and interossei caused by ulnar nerve injury at the wrist
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Does the radial nerve supply any of the intrinsic muscles of the hand? If so, which ones?
no
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What des the radial nerve supply?
all the extensors of the wrist and digits
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What occurs with injury to the radial nerve in the arm or forearm?
- prduces inability to extend the wrist
- the hand remains flexed and flaccid --wrist drop
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What is wrist drop?
- injury to the radial nerve
- hand remains flexed and flaccid
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What movements do the MP joints allow?
flexion and extension, abduction and adduction of fingers
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Do the heads of the metacarpals have a concave or convex shape?
convex
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Do the bases of the proximal phalanges have concave or convex shape?
concave
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Are abduction and adduction possible when the interphalangeal joints are flexed?
no
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How many phalanges are there?
14
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How many phalanges does the thumb have?
2
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What texture is the dorsal sufaces of proximal and middle phalanges?
smooth, rounded, and coveed by extensor expansion
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The palmar surface of the proximal and middle phalanges make the floor of...
the osteofibrous tunnels
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What runs through the osteofibrous tunnels?
flexor tendons
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What is the texture of the dorsal distal phalanges?
smooth area, just deep to fingernail
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the palmar distal phalanges are under the...
area for the finger pad
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What texture is the finger pad?
rough, due to attachment of fibrous bands that attach skin to the distal phalanges
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What type of joints are the inerphalangeal joints (PIP and DIP)?
hinge joints
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What movements are allowed with hinge joints?
extension and flexion
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