Hand Anatomy Quiz

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Questions and Answers

What type of joint is the Carpometacarpal Joint (CMC)?

Hinge joint

Non-axial plane joint (correct)

Pivot joint

Ball-and-socket joint

Which finger has a CMC joint articulation with the trapezium?

Index finger

Ring finger

Small finger

Thumb (correct)

Which phalange is represented as D3 in the nomenclature?

Ring finger

Long (Middle) finger (correct)

Index (Pointer) finger

Small finger

In making a tight fist, which MCP joints remain stationary?

2nd and 3rd Signup and view all the answers

What is the more distal aspect of the metacarpal referred to as?

Head Signup and view all the answers

Which metacarpal joint combination allows for slight mobility?

4th CMC Signup and view all the answers

What describes the mobility and stability of the 2nd and 3rd CMC joints?

Low mobility, high stability Signup and view all the answers

Which of the following describes the relationship between metacarpals and phalanges?

Metacarpals form the base of the thumb Signup and view all the answers

What type of joint is the interphalangeal joint (IP)?

Uniaxial Hinge Joint Signup and view all the answers

Which motion is NOT associated with the metacarpophalangeal (MCP) joints?

Opposition Signup and view all the answers

Which fingers are involved when the middle finger is the point of reference for abduction?

Second, Fourth and Fifth fingers Signup and view all the answers

What structure helps prevent hyperextension at the MCP joints?

Volar plate Signup and view all the answers

What type of joint is found at the base of the thumb?

Saddle Joint Signup and view all the answers

How many interphalangeal joints does the thumb have?

1 Signup and view all the answers

Opposition of the thumb involves which combination of movements?

Flexion and Abduction Signup and view all the answers

What is the function of the flexor retinaculum?

Hold tendons close to the wrist Signup and view all the answers

What is the primary function of the extrinsic muscles of the hand?

Finger motion Signup and view all the answers

Which structure is associated with the function of allowing various grasp patterns?

Bony skeleton arrangement Signup and view all the answers

What is the innervation of the Flexor Digitorum Superficialis muscle?

Median nerve Signup and view all the answers

Which muscle is responsible for flexing all joints of the thumb?

Flexor Pollicis Longus Signup and view all the answers

What does the Extensor Pollicis Brevis muscle primarily extend?

MCP joint of the thumb Signup and view all the answers

Which two nerves innervate the Flexor Digitorum Profundus muscle?

Median nerve and Ulnar nerve Signup and view all the answers

Which muscle's action is primarily radial abduction of the thumb?

Abductor Pollicis Longus Signup and view all the answers

What is the origin point of the Flexor Digitorum Superficialis?

Medial epicondyle of the humerus Signup and view all the answers

What is the primary role of the palmar carpal ligament?

Holds flexor muscles in place Signup and view all the answers

Which ligaments blend distal fibers together?

Palmar carpal ligament Signup and view all the answers

What passes through the carpal tunnel formed by the transverse carpal ligament?

Median nerve and nine tendons Signup and view all the answers

Where does the extensor retinaculum attach laterally?

Radius Signup and view all the answers

How many compartments does the extensor retinaculum divide into?

6 Signup and view all the answers

What muscle is associated with the first dorsal compartment?

Abductor Pollicis Longus Signup and view all the answers

What shape does the palm assume when relaxed?

Cupped Signup and view all the answers

Which structure is known as the extensor hood?

Extensor Expansion ligament Signup and view all the answers

What is the primary action of the Extensor Indicis?

Extension of the MCP joint of the 2nd finger Signup and view all the answers

Which tendons form the anatomical snuff box?

Abductor Pollicis Longus and Extensor Pollicis Longus Signup and view all the answers

What is the primary action of the Extensor Digiti Minimi?

Extension of the MP joint of the 5th finger Signup and view all the answers

Which nerve innervates the Extensor Digitorum?

Radial nerve Signup and view all the answers

How many joints comprise the thumb?

3 Signup and view all the answers

Which of the following describes the location of the anatomical snuff box?

Deep depression on the dorsal base of the thumb Signup and view all the answers

What is the action of the Flexor Pollicis Longus?

Flexion of the thumb at all joints Signup and view all the answers

What is the origin of the Flexor Digitorum Superficialis?

Medial epicondyle of humerus and coronoid process of ulna Signup and view all the answers

What is an intrinsic muscle?

An intrinsic muscle is a muscle that originates and inserts within the same region, allowing for precise movements. Signup and view all the answers

Explain the difference between the thenar muscles and hypothenar muscles. Provide an example of each.

The thenar muscles are located at the base of the thumb and facilitate its movement, while the hypothenar muscles are located at the base of the little finger. An example of a thenar muscle is the Abductor Pollicis Brevis, and an example of a hypothenar muscle is the Abductor Digiti Minimi. Signup and view all the answers

What hand muscle does not have a bony attachment? To what two tendons does it attach?

The Lumbricals do not have a bony attachment. They attach to the flexor digitorum profundus tendon and the extensor digitorum tendon. Signup and view all the answers

The flexor pulley system consists of only annular pulleys.

False Signup and view all the answers

What is the primary function of the flexor tendon pulley system?

Maintain flexor tendons close to the joint's axis of motion Signup and view all the answers

What is a mallet finger?

A mallet finger is a finger joint deformity caused by disruption of the terminal extensor tendon distal to the DIP joint. Signup and view all the answers

What characterizes a swan neck deformity?

A swan neck deformity is characterized by hyperextension at the PIP joint and flexion at the DIP joint. Signup and view all the answers

What causes De Quervain’s Disease?

De Quervain’s Disease is caused by inflammation and thickening of the sheath containing the Extensor Pollicis Brevis and Abductor Pollicis Longus. Signup and view all the answers

Which of the following injuries is characterized by a common hand injury among athletes involving an acute tear?

Skier's thumb Signup and view all the answers

What symptoms are associated with Carpal Tunnel Syndrome?

Numbness and tingling in the thumb, index, and middle fingers Signup and view all the answers

The ulnar claw is characterized by an inability to extend all digits.

True Signup and view all the answers

What is the primary function of the Flexor Digitorum Superficialis?

Flexion of PIP joints Signup and view all the answers

Which joint type do the Carpometacarpal joints belong to?

Non-axial plane joints Signup and view all the answers

How many bones comprise one thumb?

Two Signup and view all the answers

What is the main function of extrinsic muscles of the hand?

Finger motion Signup and view all the answers

What does CMC stand for in joint nomenclature?

Carpometacarpal Signup and view all the answers

Which muscle primarily abducts the thumb?

Abductor Pollicis Longus Signup and view all the answers

Which ligaments form the carpal tunnel?

Flexor retinaculum and transverse carpal ligament Signup and view all the answers

The joint type for Interphalangeal joints is _____ hinge joint.

uniaxial Signup and view all the answers

What is the anatomical snuffbox?

A deep depression at the base of the thumb formed by tendons. Signup and view all the answers

Which nerve innervates the majority of intrinsic muscles of the hand?

Ulnar nerve Signup and view all the answers

Which of the following is an intrinsic muscle of the hand?

Abductor Pollicis Brevis Signup and view all the answers

The middle finger can perform adduction.

False Signup and view all the answers

What movements occur at the thumb CMC joint?

Flexion, extension, palmar abduction, adduction, opposition, reposition Signup and view all the answers

What is the purpose of the Volar plate?

Prevents hyperextension Signup and view all the answers

Study Notes

Hand Nomenclature

Thumb = D1
Index (Pointer) = D2
Long (Middle) = D3
Ring = D4
Small = D5

Bones of the Hand: Ray

Metacarpal base is more proximal
Metacarpal head is more distal
Metacarpal neck is below the head

Joint Structures

Carpometacarpal Joint (CMC)
- Articulation between metacarpal and carpal bones
Metacarpophalangeal Joint (MCP or MP)
- Articulation between metacarpal and proximal phalanx
Interphalangeal Joint (IP)
- Proximal IP (PIP)
- Distal IP (DIP)

CMC Joints

Non-axial plane (irregular) synovial joint
Thumb CMC: articulation between trapezium and 1st metacarpal. High Mobility, Low Stability.
Index CMC: articulation between trapezoid and base of 2nd metacarpal. Low Mobility, High Stability.
Long CMC: articulation between capitate and base of 3rd metacarpal. Low Mobility, High Stability.
Ring CMC: articulation between hamate and base of 4th metacarpal. Slight Mobility, High Stability.
Small CMC: articulation between hamate and base of 5th metacarpal. Slight Mobility, High Stability.
The 5th CMC joint is the most mobile of the fingers and allows for a small amount of finger opposition.

“Knuckles” (MCP Joints)

Biaxial Condyloid Joints
Rounded metacarpal heads articulate with concave base of phalanges
Motions: Flexion/Extension/Hyperextension/Abduction/Adduction
Volar plate prevents hyperextension

MCP Joints: Motions

Middle finger is reference point for abduction and adduction
Abduction: fingers move away from the middle finger.
Adduction: fingers move towards the middle finger.

Interphalangeal Joint (IP)

Uniaxial Hinge Joints
Motions: Flexion/Extension
Digit 1 (Thumb): 1 IP Joint
Digits 2-5: 2 IP Joints (PIP and DIP)

Thumb CMC Joint

Trapezium articulates with 1st metacarpal
Saddle Joint (Concave & Convex)
- Note: Sometimes described as a modified ball and socket joint, which implies motion in all three planes.
Rotation at the CMC joint with opposition is involuntary and occurs due to joint shape. It is considered an accessory motion.

Thumb CMC Joint: Motions

Flexion/Extension: Occurs in frontal plane.
Palmar Abduction/Adduction: Occurs in sagittal plane.
Opposition/Reposition: Opposition (flexion and abduction with rotation) is a combination of motions. Reposition is the return to anatomical position.

Bones and Landmarks

5 MCPs
5 Proximal Phalanges
4 Middle Phalanges
5 Distal Phalanges
Proximal end of metacarpal/phalanx: base
Distal end of metacarpal/phalanx: head

Ligaments and Other Structures

Flexor retinaculum: fibrous band spanning the anterior wrist, holds tendons close to the wrist during flexion and prevents carpal bone separation.
Splits into: Palmer Carpal Ligament and Transverse Carpal Ligament

Ligaments and Other Structures: Carpal Tunnel

Median nerve
FDS
FDP
FPL

Ligaments and Other Structures: Extensor Retinaculum

Fibrous band crossing dorsal side of wrist
Attaches medially to the ulnar styloid and laterally to the triquetrum, pisiform, and radius
Function: Holds extensor tendons close to wrist during extension.
Divided into 6 sections (tunnels) called dorsal compartments.

Ligaments of the Hand and Other Structures: Dorsal Compartments

1st Compartment: Abductor Pollicis Longus (APL), Extensor Pollicis Brevis (EPB)
2nd Compartment: Extensor Carpi Radialis Longus (ECRL), Extensor Carpi Radialis Brevis (ECRB)
3rd Compartment: Extensor Pollicis Longus (EPL)
4th Compartment: Extensor Digitorum Communis (EDC), Extensor Indicis Proprius (EIP)
5th Compartment: Extensor Digiti Minimi (EDM)
6th Compartment: Extensor Carpi Ulnaris (ECU)

Ligaments of the Hand and Other Structures: Extensor Expansion Ligament

“Extensor Hood”
Triangular aponeurosis covering dorsal and sides of proximal phalanx of fingers

Arches of the Hand

Longitudinal Arch: Starts at wrist and goes to finger tips.
Transverse Arch: Distal - Metacarpal Heads, Proximal - CMC Joints.
Function: Allow for high level of function with various grasp patterns.

Creases

Distal Palmar Crease
Proximal Palmar Crease
Thenar Crease
Distal Wrist Crease
Proximal Wrist Crease

Extrinsics

Muscles with origin above the wrist and insertion inside the hand.
Cross the wrist and hand joints.
Primary Function: Finger motion
Secondary Function: Wrist motion

Extrinsic Muscles

Anterior: Flexor Digitorum Superficialis (FDS), Flexor Digitorum Profundus (FDP), Flexor Pollicis Longus (FPL).
Posterior: Abductor Pollicis Longus (APL), Extensor Pollicis Brevis (EPB), Extensor Pollicis Longus (EPL), Extensor Digitorum Communis (EDC), Extensor Indicis (EI), Extensor Digiti Minimi (EDM).

Flexor Digitorum Superficialis

Origin: Medial epicondyle of humerus, coronoid process, medial collateral ligament.
Insertion: Anterior margin of base of 2nd-5th middle phalanx.
Action: Flexion of PIP; secondary MCP flexion (2nd-5th Digits).
Nerve: Median nerve.

Flexor Digitorum Profundus

Origin: Medial olecranon, anterior and medial ulna, interosseous membrane.
Insertion: Base 2nd-5th distal phalanges
Action: Flexion of DIP, secondary MCP and PIP flexion (2nd-5th Digits).
Nerve: Median nerve (2nd and 3rd), Ulnar nerve (4th and 5th).

Relationship of Profundus and Superficialis Insertions

Profundus tendons pass through the superficialis tendons.

Flexor Pollicis Longus

Origin: Radius, anterior surface, interosseous membrane
Insertion: Distal phalanx of thumb
Action: Flexion of all thumb joints
Nerve: Anterior Interosseous (Median)

Abductor Pollicis Longus

Origin: Posterior radius, interosseous membrane, middle ulna
Insertion: Base of thumb metacarpal
Action: Radial abduction of thumb
Nerve: Radial nerve

Extensor Pollicis Brevis

Origin: Posterior distal radius
Insertion: Base of proximal phalanx of thumb
Action: Extends MCP joint of thumb
Nerve: Radial nerve

Extensor Pollicis Longus

Origin: Middle posterior ulna and interosseous membrane
Insertion: Base of distal phalanx of thumb
Action: Extension of thumb IP joint.
Nerve: Radial nerve

Anatomical Snuff Box

Deep depression on dorsal base of thumb
Borders:
- Radial (Lateral) Side:
  - Abductor Pollicis Longus
  - Extensor Pollicis Longus
- Ulnar (Medial) Side:
  - Extensor Pollicis Brevis
Bone found in depression: Scaphoid bone

Extensor Digitorum

Origin: Lateral epicondyle of humerus
Insertion: Base of middle and distal phalanx of 4 fingers (extensor mechanism)
Action: Extension of all 3 joints of fingers.
Nerve: Radial nerve.

Extensor Indicis

Origin: Distal Ulna
Insertion: Base of distal phalanx of 2nd finger
Action Extension of MCP joint of 2nd finger
Nerve: Radial nerve

Extensor Digiti Minimi

Origin: Lateral epicondyle of humerus
Insertion: Base of proximal phalanx of small finger
Action: Extension of MP joint of 5th finger
Nerve: Radial nerve

Sensory Innervations

Median Nerve: Palmar surface of thumb, index, middle, and radial half of ring finger.
Ulnar Nerve: Palmar surface of small finger and ulnar half of ring finger, dorsal surface of all fingers except thumb.
Radial Nerve: Dorsal surface of the thumb, index, middle, and radial half of ring finger

Review Questions

1. Which thumb and finger motions occur in the frontal plane? Flexion/Extension of the fingers and thumb.
2. Which thumb and finger motions occur in the sagittal plane? Palmar abduction/adduction of the thumb.
3. Which thumb and finger motions occur in the transverse plane? Thumb rotation during opposition.
4. How many bones comprise a thumb? 4
5. How many bones comprise a finger? 3
6. How many joints comprise the thumb? 3 (CMC, MCP, IP)
7. How many joints comprise a finger? 3 (MCP, PIP, DIP)
8. Which thumb opposition motion is considered an accessory motion? Rotation
9. Which tendons and nerve run through the carpal tunnel? FDS, FDP, FPL, and Median nerve
10. What is an extrinsic muscle? A muscle that originates outside the hand.
11. What is the “anatomical snuff box”? Which muscles act as the borders of this area? It's the depression between the tendons of Abductor Pollicis Longus, Extensor Pollicis Brevis, and Extensor Pollicis Longus.

Flexor Digitorum Superficialis

Origin: Medial epicondyle of humerus, coronoid process of ulna, and radial tuberosity.
Insertion: Base of middle phalanx of digits 2-5.
Action: Flexion of PIP joints
Nerve: Median nerve

Flexor Digitorum Profundus

Origin: Medial and anterior ulna, coronoid process, medial olecranon, and interosseous membrane.
Insertion: Base of distal phalanxes 2-5.
Action: Flexion of DIP joint.
Nerve: Median nerve (2nd and 3rd) and ulnar nerve (4th and 5th).

Flexor Pollicis Longus

Origin: Interosseous membrane, anterior surface of radius.
Insertion: Base of distal phalanx of thumb.
Action: Flexion of thumb at all joints.
Nerve: Anterior Interosseous (Median) nerve.

Bones of the Hand: Ray

Metacarpals: Each finger has one metacarpal bone.
Metacarpal Base: The more proximal aspect of the metacarpal.
Metacarpal Head: The more distal aspect of the metacarpal.
Metacarpal Neck: Located below the metacarpal head.

Carpometacarpal Joints (CMC)

Type of Joint: Non-axial plane (irregular) synovial joint.
Articulation: The CMC joints connect the proximal end of a metacarpal to the distal row of carpal bones.
Thumb CMC: High mobility, low stability.
Index, Long, Ring, and Small CMC: Low mobility, high stability.
The 5th CMC joint: The most mobile of the finger CMC joints, allowing for a small amount of opposition.

Metacarpophalangeal Joints (MCP or MP)

Type of Joint: Biaxial condyloid joints.
Articulation: The MCP joints connect the distal ends of metacarpals with the proximal phalanges.
Motions: Flexion, extension, hyperextension, abduction, and adduction.

Interphalangeal Joints (IP)

Type of Joint: Uniaxial hinge joints.
Motions: Flexion and extension.
Digit 1 (Thumb): Has 1 IP joint.
Digits 2-5: Have 2 IP joints (Proximal IP [PIP] and Distal IP [DIP]).

Thumb CMC Joint

Articulation: Trapezium articulates with the base of the 1st metacarpal.
Type of Joint: Saddle joint (sometimes described as a modified ball and socket joint).
Motions: Flexion/extension, palmar abduction/adduction, opposition/reposition.

Ligaments and Other Structures: Flexor Retinaculum

Location: A fibrous band stretching across the anterior wrist in a mediolateral (horizontal) direction.
Functions:
- Holds tendons close to the wrist during flexion.
- Prevents the separation of the carpal bones.
Components: Divided into the palmar carpal ligament and the transverse carpal ligament.

Ligaments and Other Structures: Palmar Carpal Ligament

Location: More proximal and superficial.
Attachments: Connects to the styloid processes of the radius and ulna, crossing over the flexor muscles.
Distal fibers: Blend with the transverse carpal ligament.

Ligaments and Other Structures: Transverse Carpal Ligament

Location: Deeper and more distal.
Attachments: Connects to the pisiform and hook of the hamate on the medial side, and the scaphoid and trapezium laterally.
Function: Forms a tunnel through which the median nerve and 9 extrinsic flexor tendons pass.

Ligaments of the Hand and Other Structures: Extensor Retinaculum

Location: Fibrous band crossing the dorsal side of the wrist.
Attachments: Connects to the ulnar styloid medially and the triquetrum, pisiform, and radius laterally.
Function: Holds extensor tendons close to the wrist during extension.
Divisions: Divided into six sections (tunnels) called dorsal compartments.

Ligaments of the Hand and Other Structures: Dorsal Compartments

Compartment 1: Abductor Pollicis Longus (APL) and Extensor Pollicis Brevis (EPB).
Compartment 2: Extensor Carpi Radialis Longus (ECRL) and Extensor Carpi Radialis Brevis (ECRB).
Compartment 3: Extensor Pollicis Longus (EPL).
Compartment 4: Extensor Digitorum Communis (EDC) and Extensor Indicis Proprius (EIP).
Compartment 5: Extensor Digiti Minimi (EDM).
Compartment 6: Extensor Carpi Ulnaris (ECU).

Ligaments of the Hand and Other Structures: Extensor Expansion Ligament

Nickname: “Extensor Hood”.
Location: A small, triangular, flat aponeurosis covering the dorsum and sides of the proximal phalanx of the fingers.

Arches of the Hand

Longitudinal Arch: Starts at the wrist and extends to the fingertips.
Transverse Arch: Distal – Metacarpal heads; Proximal – CMC joints.
Function: Allows for a high level of function with various grasp patterns.

Creases

Distal palmar crease: Most distal horizontal crease in the palm.
Proximal palmar crease: Middle horizontal crease in the palm.
Thenar crease: Diagonal crease across the thenar eminence.
Distal wrist crease: Most distal transverse crease on the wrist.
Proximal wrist crease: Most proximal transverse crease on the wrist.

Extrinsic Muscles of Thumb & Fingers

Origin: Above the wrist.
Insertion: Inside the hand.
Functions:
- Primary: Finger motion.
- Secondary: Wrist motion (weak).

Anterior Extrinsic Muscles

Flexor Digitorum Superficialis (FDS):
- O: Medial epicondyle of humerus (common flexor origin), coronoid process, and medial collateral ligament.
- I: Anterior margin of the base of the 2nd-5th middle phalanges.
- A: Flexion of PIP joints; secondary MCP flexion (2nd-5th digits).
- N: Median nerve.
Flexor Digitorum Profundus (FDP):
- O: Medial olecranon, anterior and medial ulna, and interosseous membrane.
- I: Base of the 2nd-5th distal phalanges.
- A: Flexion of DIP, secondary MCP and PIP flexion (2nd-5th digits).
- N: Median nerve (2nd and 3rd) and ulnar nerve (4th and 5th).
Flexor Pollicis Longus (FPL):
- O: Radius, anterior surface, and interosseous membrane.
- I: Distal phalanx of thumb.
- A: Flexes all joints of the thumb.
- N: Anterior interosseous (median) nerve.

Posterior Extrinsic Muscles

Abductor Pollicis Longus (APL):
- O: Posterior radius, interosseous membrane, and middle ulna.
- I: Base of the thumb metacarpal.
- A: Radial abduction of thumb.
- N: Radial nerve.
Extensor Pollicis Brevis (EPB):
- O: Posterior distal radius.
- I: Base of the proximal phalanx of thumb.
- A: Extends MCP joint of thumb.
- N: Radial nerve.
Extensor Pollicis Longus (EPL):
- O: Middle posterior ulna and interosseous membrane.
- I: Base of distal phalanx of thumb.
- A: Extension of thumb IP joint.
- N: Radial nerve.
Extensor Digitorum Communis (EDC):
- O: Lateral epicondyle of humerus.
- I: Base of middle and distal phalanx of 4 fingers (extensor mechanism).
- A: Extension of all three joints of fingers.
- N: Radial nerve.
Extensor Indicis (EI):
- O: Distal ulna.
- I: Base of distal phalanx of 2nd (index) finger and dorsal expansion.
- A: Extension of MCP joint of 2nd (index) finger.
- N: Radial nerve
Extensor Digiti Minimi (EDM):
- O: Lateral epicondyle of humerus.
- I: Base of proximal phalanx of small (5th) finger and dorsal expansion.
- A: Extension of MP joints of 5th finger.
- N: Radial nerve.

Anatomical Snuff Box

Location: Deep depression on the dorsal base of the thumb.
Borders:
- Radial (Lateral) Side: Abductor Pollicis Longus and Extensor Pollicis Longus.
- Ulnar (Medial) Side: Extensor Pollicis Brevis.

Intrinsic Muscles of the Hand

Origin: Within the hand.
Insertion: At or distal to the carpal bones.
Functions:
- Motion of thumb and fingers.
- Responsible for precision and fine motor control.

Intrinsic Muscles of the Hand - Thenar Muscles

Location: Form the thenar eminence.
Function: Act to move the thumb.

Intrinsic Muscles of the Hand - Hypothenar Muscles

Location: Form the hypothenar eminence.
Function: Act primarily on the little finger.

Intrinsic Muscles of the Hand - Deep Palm Muscles

Function:
- Act to move the lumbricals and interossei, as well as one thumb muscle.
- Located between the thenar and hypothenar eminences.

Intrinsic Muscles of the Hand (Thenar)

Flexor Pollicis Brevis (FPB):
- O: Trapezium and flexor retinaculum.
- I: Proximal phalanx.
- A: Flexion of the MCP joint of the thumb.
- N: Median nerve.
Abductor Pollicis Brevis (APB):
- O: Scaphoid, trapezium, and flexor retinaculum.
- I: Proximal phalanx.
- A: Abducts the thumb.
- N: Median nerve.
Opponens Pollicis (OP):
- O: Trapezium and flexor retinaculum.
- I: First metacarpal.
- A: Opposes the thumb.
- N: Median nerve.

Intrinsic Muscles of the Hand (Hypothenar)

Flexor Digiti Minimi (FDM):
- O: Hamate and flexor retinaculum.
- I: Base of proximal phalanx of the 5th finger.
- A: Flexes the CMC and MCP of the 5th finger.
- N: Ulnar nerve.
Abductor Digiti Minimi (ADM):
- O: Pisiform and tendon of flexor carpi ulnaris.
- I: Proximal phalanx of the small (5th) finger.
- A: Abducts the MP of the 5th finger.
- N: Ulnar nerve.
Opponens Digiti Minimi (ODM):
- O: Hamate and flexor retinaculum.
- I: 5th metacarpal.
- A: Opposition of the small (5th) finger.
- N: Ulnar nerve.

Intrinsic Muscles of the Hand (Deep Palm)

Adductor Pollicis (AP):
- O: Capitate, base of the 2nd metacarpal, and palmar surface of the 3rd metacarpal.
- I: Base of the proximal phalanx of the thumb.
- A: Adducts the thumb.
- N: Ulnar nerve.
Dorsal Interossei (DAB):
- O: 2 metacarpal bases - adjacent.
- I: Base of proximal phalanx and dorsal apparatus and EDC.
- A: Abduct fingers at MCP, flex MP joint, extend PIP.
- N: Ulnar nerve.
Palmar Interossei (PAD):
- O: Base and shaft of a metacarpal.
- I: Base of proximal phalanx, dorsal expansion, and EDC.
- A: Adduct fingers at MCP.
- N: Ulnar nerve.
Lumbricals:
- O: Tendon of flexor digitorum profundus.
- I: Tendon of extensor digitorum muscle
- A: Flex the MCP, extend IP.
- N: Median nerve (1st & 2nd), Ulnar nerve (3rd & 4th).

Flexor Ligamentous Structures

Collateral ligaments: Located on the lateral aspect of the DIP, PIP, and MCP joints.
- Radial Collateral Ligaments: Stabilizes laterally.
- Ulnar Collateral Ligaments: Stabilizes medially.

Pulley System

Location: A fibro-osseous tunnel on the palmar aspect of the hand through which the deep and superficial flexor tendons pass.
Components:
- Palmar Aponeurosis Pulley
- Five Annular Pulleys (A1 to A5)
- Three Cruciform Pulley
Function: Maintain flexor tendons close to the joint’s axis of motion and prevent bowstringing.
Thumb: Only has 2 pulleys (A1 and A2).

Annular Ligaments

A2 and A4 are crucial for preventing the tendons from bowstringing, which is the sideways displacement of tendons
A1, A3, and A5 over the MP, PIP, and DIP joints respectively, originating from the palmar plate

Cruciform Pulleys

Prevent the tendon sheath from collapsing or expanding during finger movement
C1 is located just distal to the A2 pulley
C2 is located between the A3 and A4 pulleys
C3 is located distal to the A4 pulley

Trigger Finger Stages

Stage 1: characterized by tenderness
Stage 2: characterized by clicking and catching
Stage 3: characterized by a tendon becoming stuck

Extensor Mechanism

The extensor mechanism is an extension of the extensor digitorum communis (EDC) tendon on the dorsum of each phalanx
The extensor indicis (EI) and extensor digiti minimi (EDM) insert into the extensor mechanism of the second and fifth digits, respectively.
The EDC, central tendon, lateral bands, extensor hood, and oblique retinacular ligament make up the extensor mechanism.

Extensor Mechanism Functions

The EDC tendon attaches by a tendinous slip to the proximal phalanx, allowing for MP joint extension
The central tendon (slip) attaches to the base of the middle phalanx and allows for PIP joint extension
The lateral bands run on either side of the dorsal midline and rejoin before attaching to the distal phalanx, extending the DIP joint
The extensor hood surrounds the MP joint laterally, medially, and dorsally, receiving tendinous fibers from the lumbricals and interossei
The ORL attaches at the sides of the proximal phalanx and digital tendon sheaths and proceeds to the distal portion of the lateral bands

Extensor Mechanism Dysfunctions

Mallet finger: Disruption of the terminal extensor tendon distal to the DIP joint causing the finger joint to deform
Boutonniere deformity: Injury to the central slip leading to PIP joint flexion and DIP joint hyperextension
Swan Neck Deformity: Laxity of the volar plate or an imbalance of muscle forces (extension > flexion) at the PIP causing hyperextension at the PIP and flexion at the DIP
Intrinsic Minus Hand: Weakness of the intrinsic muscles of the hand

Flexor Pollicis Brevis

Originates from the flexor retinaculum and trapezium
Inserts into the proximal phalanx of the thumb
Action: Flexes the thumb at the MCP joint
Innervation: Median nerve

Abductor Pollicis Brevis

Originates from the trapezium, scaphoid, and flexor retinaculum
Inserts into the proximal phalanx of the thumb
Action: Abducts the thumb
Innervation: Median nerve

Opponens Pollicis

Originates from the flexor retinaculum, trapezium, and scaphoid
Inserts into the lateral surface of the proximal phalanx of the first metacarpal
Action: Opposes the thumb
Innervation: Median nerve

Flexor Digiti Minimi

Originates from the hamate and flexor retinaculum
Inserts into the base of the distal phalanx of the 5th finger
Action: Flexes the 5th finger at all joints, also flexes the CMC and MCP of the 5th finger
Innervation: Ulnar nerve

Abductor Digiti Minimi

Originates from the ligament tendon of the flexor carpi ulnaris, hamate, lunate, and pisiform
Inserts into the base of the proximal phalanx of the 5th finger
Action: Abducts the MP of the 5th finger
Innervation: Ulnar nerve

Opponens Digiti Minimi

Originates from the lunate, hamate, and flexor retinaculum
Inserts into the 5th metacarpal
Action: Opposes the 5th finger
Innervation: Ulnar nerve

Adductor Pollicis

Originates from the capitate, base of the 2nd metacarpal, and lateral surface of the 3rd metacarpal
Inserts into the proximal phalanx of the thumb
Action: Adducts the thumb
Innervation: Median nerve

Dorsal Interossei

Originates from the adjacent bases between the metacarpals
Inserts into the proximal bases of the phalanx, dorsal expansion, and EDC
Action: Abducts the metacarpals of digits 2-5
Innervation: Radial and Ulnar nerves

Palmar Interossei

Originates from the lateral surface of metacarpals 4 and 5 and the medial surface of 1st metacarpal, base, and shaft of the metacarpal
Inserts into the base of the proximal phalanx of digits 2, 4, and 5, the dorsal apparatus, and the EDC
Action: Adducts the metacarpals for digits 2, 4, and 5
Innervation: Median and Ulnar nerves

Lumbricals

Originates from the tendon of the flexor digitorum profundus
Inserts into the tendon of the extensor digitorum
Action: Flexes the MCP joint and extends the PIP and DIP joints of digits 2-5
Innervation: Median (2 and 3 digits) and Ulnar (4 and 5 digits)

Functional Position

MCP joints are flexed 50-70 degrees and the IP joints are slightly flexed
Allows for optimal position for the wrist and hand, improving strength and precision
The most effective position for hand use

Hand Functional Types

Grasp: the primary function of the hand, holding and manipulating objects.
Prehension: Grasping and manipulating an object
- Power grip: A forceful grasp using an isometric contraction
- Precision grip: Object is manipulated by finger movement

Grasp Patterns

Spherical: All fingers and thumb abduct around an object. Palm not involved - mostly finger tips. Example: Holding an apple.
Cylindrical: Fingers flexed around the object with the thumb wrapped around the object. Fingers adducted, object pressed against palm. Example: Holding a hammer.
Hook fist: 2nd through 5th digits flexed around an object, flexor digitorum profundus and superficialis contracting. Example: Holding a handle.

Precision Grips (Pinch)

Tripod: Involves thumb and first two digits.
Pincer/Tip to tip: Pick up small objects
Lateral prehension (key): Thumb on the lateral side of the index finger, the most powerful

Pediatric Development of Grasp

Grasp patterns develop gradually as children mature
Children develop different grasp patterns at different ages

Common Wrist and Hand Pathologies

Colles' Fracture: Occurs when an elderly person falls on an outstretched hand, causing a transverse fracture of the distal radius and posterior displacement of the distal fragment.
Smith's Fracture: A fracture of the distal radius caused by a fall on the back of the hand, resulting in an anterior displacement of the distal fragment.
Greenstick Fracture: An incomplete fracture, more often seen in children. Commonly occurs in the radius, proximal to a Colles' fracture.
Ganglion Cyst: A benign tumor mass appearing as a bump on the dorsal surface of the wrist, developed along the tendons or joints of the wrist and hand.
Carpal Tunnel Syndrome: Occurs when the median nerve is compressed within the carpal tunnel, causing numbness, tingling, and weakness in the thumb, index, and middle fingers.
De Quervain's Disease: An inflammation and thickening of the sheath containing the extensor pollicis brevis and abductor pollicis longus tendons, causing pain on the radial side of the wrist.
Trigger Finger/Stenosing Tenosynovitis: A disorder affecting the sliding mechanism of a tendon in its sheath. When a nodule or swelling develops, the tendon becomes stuck. The flexor tendons of the middle and ring fingers are most commonly affected.
Dupuytren's Contracture: A condition where the palmar aponeurosis undergoes nodular thickening. Most common in the palm, affecting the ring and little fingers, leading to flexion contractures.
Skier's Thumb/Gamekeeper's Thumb: An acute tear of the ulnar collateral ligament of the thumb, often seen in athletes.

Extensor Mechanism Dysfunction Review

Swan Neck Deformity: Characterized by hyperextension at the PIP joint and flexion at the DIP joint.
Boutonniere Deformity: Characterized by PIP joint flexion and DIP joint hyperextension.
Mallet Finger: Caused by a disruption of the terminal extensor tendon distal to the DIP joint, resulting in a deformed finger joint.

Radial Nerve Pathway and Injury

The radial nerve branches into the posterior interosseous nerve at the supinator muscle.
The radial nerve is compressed as it spirals around the humerus.
Saturday Night Palsy: Occurs when the radial nerve is compressed due to someone falling asleep with their arm over the back of a chair. This injury results in loss of wrist extensors.
Wrist Drop: Loss of wrist extension and weakened ability to release objects due to high radial nerve injury.

Median Nerve Pathway and Injury

The median nerve gives rise to the Anterior Interosseous Nerve (AIN) at the radiohumeral joint line.
The AIN supplies motor function to the deep muscles in the anterior forearm: flexor pollicis longus, pronator quadratus, and flexor digitorum profundus (II and III).
Ape Hand Deformity: Loss of thumb opposition and atrophy of the thenar eminence muscles, caused by median nerve injury.
Sign of Benediction: MCP and PIP joints of the 2nd and 3rd fingers are extended while the MCP joints of the 4th and 5th fingers are flexed when making a fist, indicating median nerve injury.
AIN Dysfunction: Inability to form an “OK” sign due to inability to flex the thumb IP joint and the index DIP joint.

Ulnar Nerve Pathway and Injury

The ulnar nerve supplies the intrinsic muscles of the hand.
Ulnar Claw: Occurs with the loss of medial two lumbricals, leading to hyperextension of the proximal phalanges and extreme flexion of the middle and distal phalanges of the 4th and 5th fingers when extending all digits.
Claw Hand: A combination of ulnar and median nerve injuries that results in a claw-like deformity of the hand.

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Description

Test your knowledge on the nomenclature and structural anatomy of the hand. This quiz covers the bones of the hand, various joints including the carpometacarpal and metacarpophalangeal joints, and their articulations. Ideal for students or professionals interested in human anatomy and kinesiology.