Download 213: HUMAN FUNCTIONAL ANATOMY: PRACTICAL CLASS 6

213: HUMAN FUNCTIONAL ANATOMY:
PRACTICAL CLASS 6: Hand and Foot
THE HAND
Study X-rays and the skeleton of the hand: identify the two
rows of carpal bones:
Proximal row (medial to lateral) Pisiform, triquetrum,
lunate, scaphoid
Distal row (medial to lateral) Hamate, capitate, trapezoid
trapezium
Note how each row forms a bow shape, tensioned by the
flexor retinaculum.
On your own hand palpate the bones at the ends of the
flexor retinaculum:
Medially:
Pisiform
Hook of the hamate
Laterally
Tubercle of the scaphoid
Tubercle of the trapezium
Scaphoid, lunate and triquetrum can be felt across the
dorsum and sides of the wrist
On the palm of your hand work out where the metacarpo-phalangeal joints are located. See what movements
each of your carpo-metacarpal, metacarpo-phalangeal and interphalangeal joints can perform and correlate this
with your observations of the shape of the joints.
Look at the shapes of the carpo- metacarpal, metacarpo-phalangeal and interphalangeal joints, assign the terms:
planar, bicondylar, condylar and saddle to each of these joints.
Digit
1 = Thumb
2 = Index
3 = Middle
Carpo-metacarpal
Metacarpophalangeal
Interphalangeal
Note the different arrangement of joints in the thumb.
What affect do these shapes have on the possible movements.
Planar
Bicondylar
Condylar
Saddle
4 = Ring
5 = Little
On superficial dissections of the hand, look at the palmar aponeurosis, it is the insertion of the palmaris longus
muscle, where does it attach to bone, and what do you think its action might be?
On prosections where the palmar aponeurosis has been removed, note the superficial palmar arch. Follow
the ulna artery across the front of the wrist into the palmar arch. What artery joins the other side of the
superficial palmar arch
Also study the branching pattern of the median and ulnar nerves to supply the skin of the fingers. Which fingers
receive sensory innervation from by the ulnar and median nerves?
Median?
Ulnar
.
Deep to these nerves and vessels follow
the
tendons
of
flexor
digitorum
superficialis and profundus through the
carpal tunnel and their fibrous flexor
sheaths to the bases of the middle and
distal phalanges. How are the tendons
lubricated and nourished inside these
tunnels/sheaths?
Note the lumbrical muscles arising from
the profunda tendons.
Where do the lumbricals insert?
What is the action of lumbricals
Identify the thenar and hypothenar muscle groups , each group includes an abductor, a flexor and an
opponens muscle.
Understand the different insertions (and actions) of each.
Abductor (pollicus or digiti minimi)
Flexor (pollicis or digiti minimi)
Opponens (pollicis or digiti minimi)
What is opposition?
On a deep dissection, where the long tendons have been reflected, follow the deep branches of the ulnar
nerve and artery.
The deep branch of the ulna nerve runs across the front of the metacarpal bones and interosseous muscles and
supplies all the interosseous muscles and adductor pollicis muscle.
The deep branch of the ulna artery joins the radial artery in forming the deep palmar arch.
Follow the radial artery from the front of the wrist, around behind the base of the thumb (anatomical snuff-box);
to where it passes between the first and second metacarpals and the first dorsal interosseous muscle. It enters
the palm of the hand and joins the deep palmar arch, between the two heads of adductor pollicis.
On the deepest dissections find the deep transverse metacarpal ligaments which hold the heads of metacarpals
2-3-4-5 together, does the foot have the same arrangement of deep transverse metacarpal ligaments. Identify the
lumbricals and the interosseous tendons passing behind the deep transverse metacarpal ligaments.
Extensor expansion and finger movements
On the dorsum of the hand, follow the tendons of extensor digitorum, extensor indicis, and extensor digiti
minimi; note their interconnections on the back of the hand, then note the way they spread out in the back of the
fingers.
Look at the attachments of the extensor expansion to the metacarpo-phalangeal, and proximal and distal
interphalangeal joints, see how the lumbrical and interossei muscles insert on the sides of the extensor
expansion.
Use the diagram of a digit below with the extensor expansion and the other tendons attaching to the phalanges
(listed beside the table). In the body of the table, indicate whether the muscle flexes or extends the joint, and if
the muscle is the major muscle flexing or extending the joint.
Joints
Metacarpo
Proximal
Distal
phalangeal
Interphalangeal
Interphalangeal
Palmaris longus
Flexor digitorum
superficialis
Flexor digitorum
profundus
Extensor digitorum
Lumbricals and Interossei
Does the extensor digitorum act equally on all three joints of a finger?
Adduction and abduction of the fingers
Draw diagrams of the hand, indicating which muscle is responsible for abducting, and adducting each finger.
Adductor muscle(s)
Abductor muscle(s)
Thumb
Index finger
Middle finger
Ring finger
Little finger
The importance of lumbricals and interossei in finger movements. Apart from producing abduction and
adduction of the fingers, what other actions do they have?
Carpometacarpal joints
Interphalangeal joints
Why are these actions so important
What nerve supplies all the interossei and two lumbricals?
What posture would the hand adopt if the ulnar nerve was functioning
Carpometacarpal joints
Interphalangeal joints
What is the term for this condition?
Consider some common hand grips and describe the main movements and muscles needed
for each
1. Key grip
Description
Muscles required
Could you do this grip with an the ulna nerve lesion
, Median nerve lesion
2. Cylindrical (handle) grip
Description
Muscles required
Could you do this grip with an the ulna nerve lesion
, Median nerve lesion
3. Spherical (ball) grip
Description
Muscles required
Could you do this grip with an the ulna nerve lesion
, Median nerve lesion
4. Tripod (pencil) grip
Description
Muscles required
Could you do this grip with an the ulna nerve lesion
, Median nerve lesion
THE FOOT
The actions the foot muscles on the toes are very similar to the situation in the hand:
1.
The flexor digitorum superficialis in the forearm is like the flexor digitorum
in the foot in
that they both attach to the middle phalanx of the digits.
2.
The flexor digitorum profundus in the forearm is like the flexor digitoru m
in the foot in
that they both attach to the distal phalanx of the digits.
3.
The toes have lumbricals and interossei that have the same actions as those in the hand. Except that the
axis of adduction in the foot lies along the
4.
digit instead of the 3rd digit as in the hand.
The toes also have an extensor expansion that coordinates the actions of the tarsometatarsal and
interphalangeal joints.
The lateral plantar nerve in the foot is like the
nerve in the hand in that it supplies most of the
small muscles of the foot (including all the interossei) except for three muscles on the big toe side, but is only
sensory to 1 and ½ toes on the little toe side.
The medial plantar nerve in the foot is like the
the toes, but only supplies three muscles on the big toe side.
nerve in the hand in that it is sensory to most of
ARCHES OF THE FEET
What is a flat foot?
What is the function of the arches of the foot?
Make sure you can describe some of the mechanisms which support the arches of the foot.
BONY
LIGAMENTOUS
MUSCULAR
Extrinsic muscles
Intrinsic muscles
Practical anatomy checklist
Osteology
Bones of the hand and foot
Carpals and tarsals
Joints and movements of the digits
Muscles
Intrinsic muscles of the hand and foot