Mod 2: Lecture 5 - Hand

Question 1

Osteology of the hand

Answer 1

• Metacarpals: found in the palm/hand
• — 5 metacarpals, one per finger
• — numbered 1-5 with the thumb as 1 and pinky as 5
• Phalanges
• — Digit 1: thumb - proximal and distal phalanx
• — Digits 2-5: proximal, middle and distal phalanx

Question 2

Clinical Correlation: Boxer’s Fracture

Answer 2

• fracture of the fifth metacarpal
• — metacarpal of the pinky
• caused by making a closed fist and hitting a hard object
• — a trained boxer can hit currently, the fracture is usually found in untrained people

Question 3

Articulations of the Digits and Thumb

Answer 3

• Carpometacarpal (CMC)
• Metacarpophalangeal (MCP or MP)
• Proximal Interphalangeal (PIP)
• Distal Interphalangeal (DIP)
• Interphalangeal Joint of the Thumb

Question 4

1. Carpometacarpal Joint

2. Metacarpophalangeal Joint

Answer 4

1. • saddle (1st digit/thumb)
     - gliding (digits 2-5)
     - between the carpals and metacarpals
2. • condyloid (digits 2-5)
     - hinge (digit 1)
     - between the metacarpal and proximal phalanx

Question 5

1. Proximal Interphalangeal Joint
2. Distal Interphalangeal Joint
3. Interphalangeal Joint of the Thumb

Answer 5

1. • hinge
     - between the proximal phalanx and middle phalanx for digits 2-5
2. • hinge
     - between the middle phalanx and distal phalanx for digits 2-5
3. • hinge
     - between the proximal and distal phalanx of the first digit
     - only two bones in the thumb so it has only one joint

Question 6

Movement of the Digits (2-5)

Answer 6

• Flexion/Extension
• — MP, PIP, and DIP joints
• Abduction/Adduction
• — MP joints
• — coronal plane: in the hand the midline runs through the third digit (middle finger)
• — abduction: spreading the fingers apart, away from the middle finger
• — adduction: putting the fingers back together, closer to the middle finger

Question 7

Movements of the Thumb

Answer 7

• Abduction/Adduction
• Flexion/Extension
• Opposition

Question 8

Abduction/Adduction of the Thumb

Answer 8

• CMC joint
• occurs in a plane perpendicular to the palm
• if you had your hand in a puppet and were opening (ab) and closing (ad) the mouth

Question 9

Flexion/Extension of the Thumb

Answer 9

• occurs in a plane parallel to the palm
• CMC, MP, and IP joints
• ext: gliding the thumb laterally away from the hand
• flex: gliding the finger across the palm

Question 10

Opposition of the Thumb

Answer 10

• CMC Joint
• bringing the thumb and pinky together across the hand
• a combination of flexion and extension

Question 11

Stabilizing Ligaments of the Digits

Answer 11

• Collateral Ligament
• — has a cord-like part and a fan-like part
• — on either side of fingers to reinforces the IP joints
• — prevent lateral deviation
• Palmar Ligament
• — over the IP joint on the palm side of the finger
• — prevents against too much hyperextension (pulling the finger back)
• — also called volar plate

Question 12

Clinical Correlation: Swan Neck Deformity

Answer 12

• laxity or rupture of the volar plate (palmar ligament) which causes slippage of the collateral ligaments
• Result: PIP hyperextension and DIP flexion
• — at the PIP joint (middle knuckle), the middle phalanx goes up bc the joint goes down
• — but at the DIP joint (last knuckle), the distal phalanx drops back down bc the joint goes up

Question 13

Non-Manipulative Prehension Patterns

Answer 13

• The function of the extrinsic muscles
• – start someplace other than the hand, so have greater area for a bigger muscle belly and thus have a stronger contraction
• Gross grasp hand positions
• Hook Grip: bending four fingers (digits 2-5), but not the thumb, like when holding onto a briefcase
• Spherical Grip: a curve of all five digits, like holding a baseball before you throw it
• Cylindrical Grip: fingers wrap tightly together with thumb overlap, like holding a roll of paper or a weight

Question 14

Manipulative Prehension Patterns

Answer 14

• Function of the intrinsic muscles
• Fine motor prehension patterns
• Palmar Pinch: pad to pad between the thumb (digit 1) and index finger (digit 2)
• — can also be the pad of digit 1 to the pads of digits 2 and 3
• Lateral Pinch: pad of the thumb (digit 1) to the side of the index finger (digit 2)
• Tip-to-Tip Pinch: the tip of the thumb (digit 1) to the tip of the index finger (digit 2)

Question 15

Extrinsic Hand Muscles

Answer 15

• Flexor ___ ___
• — digitorum superficialis
• — digitorum profundus
• Extensor ___ ___
• — digitorum
• — indicis proprius
• — digiti minimi

Question 16

Extrinsic Thumb Muscles

Answer 16

• Extensor pollicis I/b
• Abductor pollicis longus
• Flexor pollicis longus

Question 17

Extrinsic Flexors: a)FDS, b)FDP

1. Attachments
2. Action
3. Innervation

Answer 17

1a. - bifurcation at the PIP joint, insert on the middle phalanx
- somewhere in the arm
1b. - below the PIP joint, goes between the FDS’s bifurcation
- just past the DIP joint, inserts on the distal phalanx
2a. flexion of the PIP joint
2b. flexion of the DIP joint
3a. median nerve
3b. median and ulnar nerves

Question 18

Flexor Sheath

Answer 18

• stabilizes the tendons of the hand/digits
• Membranous Portion
• Retinacular Portion

Question 19

Membranous Portion of the Flexor Sheath

Answer 19

• inner portion
• promotes tendon gliding
• same structure as a bursa: double layered sac around the tendon with a little fluid in the middle
• — visceral layer and parietal layer

Question 20

Retinacular Portion of the Flexor Sheath

Answer 20

• outer portion, continuous with ligamentous stuff around the muscle
• stabilize the tendon
• — similar to eyelets on the fishing pole that hold the line as it comes up the pole
• — keeps the tendon close to the bone
• — if ruptured: bowstring of the tendon - it sticks out, hangs away from the bone
• 5 annular pulleys
• 3 cruciform pulleys

Question 21

Clinical Correlation: Trigger Finger

Answer 21

• a bent finger that will not unbend
• — like it is pulling a trigger
• nodule/lump on one of the flexor tendons
• — the tendon will have trouble traveling under the flexor sheath
• — the tendon gets stuck
• — the patient feels a pulling and a popping as the pass is forced past the sheath

Question 22

Extrinsic Extensors: a) ED, b) EIP, c) EDM

1. Attachements
2. Action
3. Innervation

Answer 22

1a,b,c. - extensor expansion
2a.
3a,b,c. radial nerve

Question 23

Extensor Expansion

Answer 23

• aka extensor hood aka extensor mechanism
• non-contractile
• a slip of connective tissue on the dorsal side of the finger that couples the PIP and DIP joints
• allows PIP/DIP extension without MP extension via intrinsic muscles
• site of attachment for extensor muscles so they can act on the PIP and DIP joints

Question 24

Clinical Correlation: Boutonniere Deformity

Answer 24

• rupture of the central tendon through which the PIP joint protrudes
• Result: PIP flexion, DIP extension
• — finger bent at the middle knuckle and bent back/straight at the last knuckle

Question 25

Clinical Correlation: Mallet Deformity

Answer 25

- extensor tendon laxity due to overstretching or rupture which results in decreased efficiency of the extensor hood - --- the tendon is too long for the muscle to pull back bc it is overstretched - Result: inability to extend the DIP - --- finger bent at the last knuckle

Question 26

Extrinsic Muscles of the Thumb: a) EPL, b) EPB, c) APL, d) FPL 1. Attachments 2. Action 3. Innervation

Answer 26

1c. - base of first metacarpal 3a,b,c. radial nerve 3d. median nerve

Question 27

Anatomical Snuff Box

Answer 27

- formed by the extensor pollicis brevis, extensor pollicis longus, and abductor pollicis longus - at the base of the thumb, a triangular depression between tendons - -- extensor pollicis longus tendon on the medial side - --- extensor pollicis brevis and abductor pollicis longus tendons on the lateral side

Question 28

Intrinsic Hand Muscles: 4 Compartments

Answer 28

- Thenar: by the thumb - Hypothenar: by the pinky - Adductor: by the thumb, but behind the thenar - Central: by the middle of the palm - small muscles for fine motor or manipulative prehension - --- begin and end in the hand

Question 29

Intrinsic Muscles - Thumb: | Innervations

Answer 29

- Thenar Group - --- OP, AbPB, AdP, FPB - ---- primarily innervated by the median nerve, with one innervated by the ulnar nerve

Question 30

Intrinsic Muscles - 5th Digit (Pinky): Innervations

Answer 30

- Hypothenar Group - --- ODM, AbDM, FDM (B) - --- innervated by the deep branch of the ulnar nerve

Question 31

Adductor Compartment

Answer 31

- Adductor Pollicis | - innervated by the ulnar nerve

Question 32

Central Compartment: Lumbricals 1. Attachments 2. Action 3. Innervation

Answer 32

- there are four - --- one per finger, with none on the thumb - --- the index finger is number one 1. - FDP tendon - extensor hood 2. - flex at MP and extend at PIP/DIP 3. -median nerve: thenar side, lumbricals 1 and 2 - ulnar nerve: hypothenar side, lumbricals 3 and 4

Question 33

Central Compartment: a) Dorsal Interossei b) Palmar Interossei 1. Attachments 2. Action 3. Innervation

Answer 33

a) Dorsal - there are four, one in each space between digits including the thumb 2a. abduction - spread fingers 3a. ulnar nerve b) Palmar - there are three, one between each finger, with none on the thumb 2b. adduction - bring fingers together 3b. ulnar nerve

Question 34

Cutaneous Innervation of the Hand

Answer 34

- sensory distribution in the skin - Ulnar Nerve: 5th digit and 1/2 of 4th digit on both the dorsal and palmar sides - Radial Nerve: - --- the whole dorsal side of the 1st digit - --- from the wrist to the PIP joint on the dorsal side of the 2nd, 3rd, and 1/2 of the 4th digits - Median Nerve: - --- the palmar side of the 1st, 2nd, 3rd, and 1/2 of the 4th digits - --- the dorsal side of the 2nd, 3rd, and 1/2 of the 4th digits from the PIP joint to fingertip

Question 35

Prehension: Power Grip

Answer 35

- palmar grasp - accomplished by interactions of the intrinsic and extrinsic muscles working together - refers to forcible motions of the digits acting against the palm - fingers are wrapped around an object with counterpressure from the thumb - --- like gripping the monkey bars

Question 36

Muscles involved in Power Grip

Answer 36

- long flexor muscles to the fingers - the intrinsic muscles of the digits - extensors of the wrist

Question 37

Extension/Flexion of the wrist and power grip

Answer 37

- extension of the wrist increases the distance over which the flexors of the fingers act, producing a stronger grasp - --- when you first swing onto the monkey bar - as flexion increases at the wrist, the grip becomes weaker and more insecure - ---- when you lost momentum and are hanging off the bar about to drop