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Lab Manual - Flexor Compartment of the Forearm, Superficial Hand, and Elbow Joint
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Lab Manual - Flexor Compartment of the Forearm, Superficial Hand, and Elbow Joint |
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Learning Objectives:
Upon completion of this session, the student will be able to:
1. Review the
bony landmarks. (Play movie; View images:
N 420, 421, 436, 439, 440, 450, 451, 452, 456, TG 2-03A, 2-03B, 2-04, 2-21, 2-22, 2-31, 2-32)
Review bony processes of the humerus, radius
and ulna previously examined. Identify supinator crest, posterior border,
and interosseous
crest of ulna. Identify the dorsal radial tubercle and interosseous
crest of radius. Locate grooves at the distal end of radius which
accommodate tendons as they cross the wrist. Examine an articulated hand,
noting arrangements of carpals, metacarpals, and
phalanges.
Identify proximal, middle and distal
phalanges.
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Bones
of the elbow |
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Bones
of the elbow
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Bones
of the forearm |
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Bones
of the forearm
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Bones
of the wrist
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Wrist
bones
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Identify
the scaphoid, lunate,triquetrum, pisiform, trapezium, trapezoid, capitate, hamate, and hook of hamate. (Handy Mnemonic: Some Lovers Try Positions That They Can't Handle)
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Surface
anatomy of the anatomical snuffbox
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Examine the anterior part of the
antebrachial fascia and, in its distal part, the palmar
carpal ligament spanning between the distal end of the radius and
ulna. Note differences between this and the extensor retinaculum.
What muscles
lie within this fascial plane?
What muscles
lie deep to it?
Where are the
arteries, veins and nerves in relation to it?
With what is
it continuous distally?
Remove the
antebrachial fascia, leaving the palmar carpal ligament intact.
2. On flexor side
of forearm, separate and dissect the various muscular layers and trace the
median and ulnar nerves. (Play movie; View images: N434, 445, 446, 447, 448, 449, 450, 451, 460, 461, 465, 466, 468, 472, 475, 476, 481, TG 2-19, 2-21, 2-22, 2-23, 2-24, 2-25, 2-27A, 2-27B, 2-28B, 2-28C2-30, 2-33, 2-34, 2-36, 2-37A, 2-37B2-38, 2-39, 2-40, 2-41, 2-48, 2-49A, 2-49B, 2-51A, 2-51B)
The forearm flexor muscles are arranged in
three layers. Dissect each layer separately.
LAYER 1. Pronator
teres. Note two heads of origin, relation of median nerve. What
structures cross its insertion?
The tendons
of flexor carpi radialis,palmaris
longus, and flexor carpi ulnaris lie within the
palmar carpal ligament at the wrist. Trace them through the palmar carpal
ligament. Note points of insertion on a skeleton, but do not trace the tendons
into the palm. Do you have a palmaris longus?
The flexor
carpi ulnaris has two heads of origin; note the ulnar nerve entering the
forearm between these two heads. Cut the insertion of pronator teres from the
radius, leaving a short (1 cm) stump, and reflect toward the ulnar border of
the forearm to expose the next (second) layer of muscle. This maneuver also
reveals the deep head of pronator teres and the course
of the median nerve between the two heads. Do any structures lie between the
first two layers of muscles?
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Pronation of the hand |
LAYER 2. Flexor digitorum
superficialis. Trace its origin along the oblique line of the radius to the
coronoid process of the ulna and to the medial epicondyle of the humerus. Note
the fibrous arch spanning between radius and ulna.
What passes
beneath this arch?
Trace three or
four tendons as they pass beneath the palmar carpal ligament. Do not
trace into palm. What is their arrangement?
Locate the
median nerve in relation to the tendons at the wrist.
LAYER 3. Incise the radial origin of flexor
digitorum superficialis and reflect. Dissect flexor pollicis longus, flexor digitorum profundus and pronator
quadratus (deep to the tendons of the above muscles). Trace
tendons to the wrist but do not invade the palm. Compare the arrangement of the
tendons of flexor digitorum superficialis and profundus as they enter the
wrist. Note the anterior interosseous artery, vein and nerve.
Return to the cubital fossa and trace the
brachial artery as it divides into radial and ulnar
arteries. Where is the point of bifurcation?
Trace the
radial artery. Define its course and relations. Follow the radial artery as it
courses through the "anatomical snuffbox" to the dorsum
of the hand.
NOTE specifically the relations
at the wrist between the radial artery and the flexor carpi radialis and the
brachioradialis in the palmar carpal ligament. This is a pulse point. Palpate
on your partners. The grouping of the radial artery and superficial radial
nerve under cover of brachioradialis constitutes a convenient dividing line
between forearm flexor and extensor muscle groups.
Follow the ulnar artery, noting course and
specific relations to median and ulnar nerves and to muscles. Locate it at the
wrist between the flexor carpi ulnaris and flexor digitorum superficialis, deep
to the palmar carpal ligament. This is a pulse point; palpate on your partners.
Identify the following branches: common interosseous, anterior interosseous, posterior interosseous; note the muscular
branches. Consider the collateral circulation of the
elbow between branches of brachial, deep brachial, radial and
ulnar arteries. Note the accompanying veins (venae comitantes). Consider the
blood supply to the entire forearm.
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Angiogram
of collateral vessels
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Median nerve. Trace through the
forearm, noting specific relations to pronator teres, the fibrous arch of
flexor digitorum superficialis, the ulnar artery, its location between flexor
digitorum superficialis and profundus. Where do muscular branches to the flexor
muscles arise?
Locate
precisely at the wrist. Locate theanterior interosseous nerve; where does it arise?
What muscles does it supply? Relations?
Ulnar nerve. Trace through the
forearm; note specific relations to flexor carpi ulnaris, to flexor digitorum
superficialis and profundus, and to the ulnar artery. Precisely locate at the
wrist. What muscles does it supply? Where do these branches leave the ulnar
nerve?
Locate the dorsal
cutaneous branch of the ulnar nerve (previous dissection). Organize the
innervation of the muscles of the forearm into simple groupings.
3. Open the hand, look at creases, and
skin the palm (do not cut the recurrent branch of median n.). (Play movie; View images:
N 447, 448, 459, 460,461, 465, 466, 468, 472A, 472B, 459, 460, 462, TG 2-24, 2-25, 2-33A, 2-33B, 2-34A, 2-34B, 2-38A, 2-38B, 2-40)
PALM OF THE HAND. Remove the skin from the
palm of the hand. If the digits are more than slightly flexed, it is difficult
if not impossible to dissect the digits and palm. To make the dissection
easier, the flexor digitorum superficialis and profundus and flexor pollicis
longus should be transected in the forearm. Sever them at different levels
(proximal to distal) so that their tendons can be distinguished from each
other. Be careful not to cut the median nerve directly beneath flexor digitorum
superficialis. It should then be possible to straighten the digits, thus making
the dissection easier. Note the dense attachment to deep fascia and dense
subcutaneous tissue.
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Bones of the hand |
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Bones
of the hand
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Wrist
bones
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Locate the palmar
digital branches of the median and ulnar
nerves along the borders of the digits. Determine area of
distribution. Do they supply any portion of the dorsal side of the digit? How
much? Significance? What do they accompany?
Scrape the subcutaneous fat from the deep
fascia of the palm. In the thenar eminence do not clean completely down to the
muscle until the recurrent (motor) branch of
the median nerve has been located. Define the parts of the deep fascia:
thenar fascia, hypothenar fascia, palmar
aponeurosis and fibrous flexor digital
sheaths. Characterize each, define boundaries and extent.
Palmar aponeurosis. Using a sharp scalpel,
clean its surface thoroughly to display fibrous structure and orientation of
fibers. What is its relation to palmaris longus, the palmar carpal ligament and
the flexor retinaculum?
Identify the
superficial transverse metacarpal ligament and transverse fasciculi; note the
gaps between them. What can be seen in these gaps?
Note the
digital fibers extending to the sides of the digits and the flexor digital
sheaths.
4. Reflect the palmar aponeurosis
distalward and identify neurovascular structures. (Play movie; View images:
N 447, 448, 459, 460, 461, 462, 465,466, 468, 462, 459, 460, 462, TG 2-33, 2-34, 2-36, 2-37A, 2-37B, 2-38, 2-39, 2-40)
Clean the subcutaneous fat from the digits
and expose the fibrous flexor digital sheaths. Note attachments and structures.
Reflect the palmar aponeurosis distalward,
separating it from the palmaris longus and the flexor retinaculum, defining the
distal border of the latter. As you reflect, note the septa at its medial and
lateral margins that extend to the second and fifth metacarpals. Continue
reflecting and note septa extending to metacarpals II-V. These form
compartments for the flexor tendons in the central compartment of the palm.
What is the carpal tunnel and its
associated syndrome?
Pick up the median nerve at the proximal
border of the flexor retinaculum then cut the retinaculum following the median
nerve to the distal border of the flexor retinaculum. Identify the recurrent
(motor) branch of the median nerve at the distal border of the flexor
retinaculum; trace it into the thenar muscles. Trace the superficial palmar
branch of the radial artery to the thenar compartment. Does it continue beyond?
Where?
Define
the common and proper digital
branches of the median nerve, and areas of distribution. How do
median and ulnar nerves share in the cutaneous innervation of the digits
(review)?
Note the
change in relationship of palmar nerves and arteries as they reach the digits.
Trace the ulnar artery and nerve into the
palm across the flexor retinaculum to the interval between the hook of the
hamate and the pisiform. Note their bifurcation here. Trace the superficial ulnar
artery into the superficial palmar arterial
arch; note its position, relation, and distribution (common and proper digital arteries). What artery
completes the superficial palmar arterial arch?
Trace
the superficial ulnar nerve into common and proper digital nerves. (Review pattern of
distribution.)
5. Examine the
muscles of the thenar and hypothenar compartments. (Play movie; View images:
N 461, 462, 465, 466, TG 2-34A, 2-34B, 2-35, 2-37, 2-38)
Consider the basic compartmental structure of
the hand and dissect each compartment separately (thenar
compartment, hypothenar
compartment, central compartment, adductor-interosseous
compartment).
Examine the thenar fascia; open and remove.
Dissect abductor pollicis brevis and flexor pollicis brevis. Does the flexor
pollicis brevis have a deep head?
Examine opponens
pollicis (deep to the other thenar muscles) and the insertion
of adductor pollicis (not a thenar
compartment muscle). Note the position of the tendon of flexor pollicis longus surrounded by
the radial bursa.
Examine the hypothenar fascia; open and
remove. Dissect abductor digiti minimi, flexor digiti minimi (brevis), and opponens
digiti minimi. Innervation of hypothenar muscles?
Note relations
of the deep ulnar nerve and artery to
the origins of these muscles.
6. Cut the flexor
retinaculum and pull the long flexor tendons toward the fingertips. (Play movie; View images:
N 450, 450, 460, 461, 462, 463, 464,465, 466, 475, TG 2-21, 2-31, 2-34A, 2-34B, 2-35, 2-37A, 2-37B, 2-38, 2-45, 2-48)
Examine the flexor retinaculum. Determine
its attachments and extent. Review its relationships with the palmar carpal
ligament, palmaris longus and palmar aponeurosis. Examine the contents of the
carpal tunnel. How is it formed?
Examine
tendons of flexor digitorum superficialis and profundus; note their relative
positions in the canal and the ulnar
bursa. Into which digital sheath does the bursa continue
distally?
Pull the long
flexor tendons toward the fingers from beneath the superficial palmar arterial
arch and trace the tendons of the long flexors to the flexor digital sheaths.
Incise a sheath longitudinally, noting the synovial lining and the manner of
insertion of flexor digitorum superficialis and profundus tendons into the
middle and distal phalanges, respectively. What are vincula?
If you have
not already done so, cut the tendons of flexor digitorum superficialis and
profundus near the wrist (but at different distances from the retinaculum),
pull distally and separate. Identify the lumbrical
muscles, noting origin; trace to their insertion into extensor
expansions; innervation?
Consider
function.
Return to the carpal tunnel and trace the
flexor pollicis longus tendon to its insertion. Note the radial bursa.
Locate the flexor carpi radialis tendon. Is
it in the carpal tunnel? What happens to it?
Trace it to
its insertion. Trace the median nerve and bring all of its branches in the hand
into continuity (motor and sensory).
Pull the tendons of the long flexors
distally to expose the adductor-interosseous compartment. Clean the adductor pollicis muscle and
identify its oblique andtransverse heads. Clear the anterior
interosseous fascia from interosseous muscles and identify the deep palmar arterial arch; note the
accompanying deep branch of the ulnar nerve.
Plastinated specimens are available for the study of joints. Review joints on plastinated speciments. If you wish to perform joint dissections, please do so on one limb only.
7.
Open the elbow by removing the anterior and posterior capsules. (Play movie; View images: N 431, 432, 438, 438, 439, 454, 455, TG 2-17, 2-18, 2-43A, 2-43BC, 2-44A, 2-44B, 2-44C)
Elbow joint. The elbow joint
consists of the humeroulnar,
humeroradial (true elbow articulations), and the proximal radioulnar articulation. Though contained in a
single cavity, they move independently.
Remove
the muscles on both the posterior and anterior surfaces of the joint. Do not
enter the joint cavity at this time. Examine carefully the biceps tendon at its
insertion, noting associated bursae and dual action at elbow joint and proximal
radioulnar joint. Clean the capsule and define the ulnar collateral, radial collateral and annular ligaments. Remove the capsule
anteriorly and posteriorly to expose the joint surfaces, leaving the ligaments
intact. Examine actions. Consider the action of pronators and supinators. What
is a "pulled elbow"?
Examine
the interosseous membrane and note the direction of its fibers. What is the
significance of their direction?
Examine the distal radioulnar joint and its articular disc. Determine the action of
the proximal radioulnar joint and its axis of rotation. Do the same for the
distal radioulnar joint. How does the combined motion of these two joints
affect the position of the hand?
8.
Dissect the wrist by making a frontal section through the distal radius and
ulna, carpals and proximal metacarpals. (Play movie; View images: N 453, 454, 455A, 455B, 458, TG 2-44A, 2-44B, 2-44C, 2-45)
Radiocarpal (wrist)
joint.
Remove all tendons and muscles of the wrist and hand, and identify the capsule, dorsal radiocarpal, palmar radiocarpal, ulnar collateral and radial collateral
ligaments.
Section
the wrist in the frontal plane, in the following manner. Flex the wrist
and hand. Saw through the distal end of the radius and ulna, continuing through
both the proximal and distal rows of carpals and the proximal end of the four
ulnar metacarpals. The procedure may require sawing in more than one plane to
expose all joints. This section exposes the distal radioulnar, the radiocarpal, the intercarpal, midcarpal, carpometacarpal, and the
intermetacarpal articulations. Note the extent of each synovial cavity and the
interosseous intercarpal ligaments. Consider the combined actions of the
"greater wrist" in flexion, extension, adduction, abduction, and
circumduction. How do these articulations combine to provide these actions at
the "wrist"?
Examine
the carpometacarpal articulation of the thumb (saddle type).
Examine
the deep transverse
metacarpal ligaments. Note that each one lies between interosseous and lumbrical muscle tendons for
that digit. What are their relationships to the extensor expansion and fibrous
flexor sheath?
Open any of the metacarpophalangeal and interphalangeal joints, noting the capsule and
collateral ligaments.
Elbow dislocation Elbow dislocation Growth plates Updated: 25 Oct 2011
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