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Flashcards in Mod 2: Lecture 5 - Hand Deck (37)
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Osteology of the hand

- 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


Clinical Correlation: Boxer's Fracture

- 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


Articulations of the Digits and Thumb

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


1. Carpometacarpal Joint
2. Metacarpophalangeal Joint

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


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

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


Movement of the Digits (2-5)

- 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


Movements of the Thumb

- Abduction/Adduction
- Flexion/Extension
- Opposition


Abduction/Adduction of the Thumb

- 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


Flexion/Extension of the Thumb

- 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


Opposition of the Thumb

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


Stabilizing Ligaments of the Digits

- 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


Clinical Correlation: Swan Neck Deformity

- 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


Non-Manipulative Prehension Patterns

- 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


Manipulative Prehension Patterns

- 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)


Extrinsic Hand Muscles

- Flexor ___ ___
---- digitorum superficialis
---- digitorum profundus
- Extensor ___ ___
---- digitorum
---- indicis proprius
---- digiti minimi


Extrinsic Thumb Muscles

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


Extrinsic Flexors: a)FDS, b)FDP
1. Attachments
2. Action
3. Innervation

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


Flexor Sheath

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


Membranous Portion of the Flexor Sheath

- 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


Retinacular Portion of the Flexor Sheath

-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


Clinical Correlation: Trigger Finger

- 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


Extrinsic Extensors: a) ED, b) EIP, c) EDM
1. Attachements
2. Action
3. Innervation

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


Extensor Expansion

- 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


Clinical Correlation: Boutonniere Deformity

- 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


Clinical Correlation: Mallet Deformity

- 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


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

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


Anatomical Snuff Box

- 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


Intrinsic Hand Muscles: 4 Compartments

- 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


Intrinsic Muscles - Thumb:

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


Intrinsic Muscles - 5th Digit (Pinky): Innervations

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