Anatomy of the Elbow and Wrist Muscles

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Questions and Answers

What are the three bones that make up the elbow and forearm complex?

  • Proximal radius, Distal radius, Ulna
  • Humerus, Ulna, Scapula
  • Humerus, Femur, Radius
  • Distal humerus, Ulna, Radius (correct)

Which joint configuration allows for flexion and extension in the elbow?

  • Humeroradial joint only
  • Proximal radio-ulnar joint only
  • Both humero-ulnar and humeroradial joints (correct)
  • Humero-ulnar joint only

What is the normal carrying angle of the elbow?

  • 20 degrees
  • 10 degrees
  • 25 degrees
  • 15 degrees (correct)

Which of the following describes how the ulna moves at the humero-ulnar joint during flexion and extension?

<p>The ulna rotates slightly during movements (A)</p> Signup and view all the answers

What is a characteristic feature of the elbow joint that contributes to its stability?

<p>Tight fit between trochlea and trochlear notch (D)</p> Signup and view all the answers

Which muscle is primarily responsible for wrist extension and is innervated by the radial nerve?

<p>Extensor carpi ulnaris (D)</p> Signup and view all the answers

What is the primary function of the extensor retinaculum?

<p>Prevent bowstringing of wrist extensors (D)</p> Signup and view all the answers

Which of the following wrist flexors is innervated by the ulnar nerve?

<p>Flexor carpi ulnaris (A)</p> Signup and view all the answers

Which of the following muscles act on both the wrist and the hand as part of the secondary set?

<p>Extensor digitorum (A)</p> Signup and view all the answers

Which primary wrist extensors insert at the base of the third metacarpal?

<p>Extensor carpi radialis brevis (A)</p> Signup and view all the answers

What type of joint configuration is present at the radiocarpal and midcarpal joints?

<p>Convex-on-concave (B)</p> Signup and view all the answers

Which of the following muscles would primarily contribute to ulnar deviation of the wrist?

<p>Extensor carpi ulnaris (A)</p> Signup and view all the answers

What condition is characterized by swelling of tendons at the radial styloid?

<p>De Quervain's tenosynovitis (D)</p> Signup and view all the answers

Which of the following bones is NOT included in the wrist joint structure?

<p>Humerus (B)</p> Signup and view all the answers

What is the primary function of the ligaments in the wrist?

<p>Stabilize, permit, and guide motion (A)</p> Signup and view all the answers

Which carpal bone is most commonly fractured?

<p>Scaphoid (C)</p> Signup and view all the answers

What type of joint is the radiocarpal joint?

<p>Condyloid (D)</p> Signup and view all the answers

What structure helps to stabilize the distal radioulnar joint?

<p>Triangular fibrocartilage complex (TFCC) (A)</p> Signup and view all the answers

Which movement occurs in the midcarpal joint?

<p>Same direction as the hand (B)</p> Signup and view all the answers

What structures run through the carpal tunnel?

<p>Flexor tendons and median nerve (A)</p> Signup and view all the answers

The triangular fibrocartilage complex (TFCC) is vital for which of the following functions?

<p>Transmitting forces from the hand to the forearm (A)</p> Signup and view all the answers

What stabilizes the distal radioulnar joint?

<p>Triangular Fibrocartilage Complex (D)</p> Signup and view all the answers

Which ligament is taught when excessive valgus force is applied?

<p>Medial Collateral Ligament (C)</p> Signup and view all the answers

What is the normal range of flexion for the humeroulnar and humeroradial joints?

<p>0-145 degrees (A)</p> Signup and view all the answers

Which muscle, in addition to the biceps brachii, is primarily responsible for forearm supination during forceful actions?

<p>Deltoid (B)</p> Signup and view all the answers

What happens when there is a tear of the interosseous membrane?

<p>Proximal migration of radius (A)</p> Signup and view all the answers

What type of joint movement occurs at the proximal radioulnar joint?

<p>Supination and Pronation (A)</p> Signup and view all the answers

What is the main role of the annular ligament?

<p>Keep the radius in place (D)</p> Signup and view all the answers

Which nerve is associated with elbow flexors?

<p>Musculocutaneous Nerve (B)</p> Signup and view all the answers

What is the primary function of the forearm during supination?

<p>Bringing the hand to the face (C)</p> Signup and view all the answers

Which ligaments provide stability against varus forces?

<p>Lateral Collateral Ligament (D)</p> Signup and view all the answers

What is the functional range for pronation in the forearm?

<p>0-90 degrees (B)</p> Signup and view all the answers

What is the primary function of the interosseous membrane?

<p>Transmit force proximally (C)</p> Signup and view all the answers

Which muscles are responsible for elbow extension?

<p>Triceps Brachii and Anconeous (B)</p> Signup and view all the answers

What will most likely occur if the extremes of elbow range of motion are lost?

<p>Minimal impairment (D)</p> Signup and view all the answers

Flashcards

What bones make up the elbow joint?

The elbow joint is formed by three bones: the humerus, ulna, and radius. The joint is responsible for flexing, extending, and rotating the forearm.

What is the proximal radio-ulnar joint?

The proximal radio-ulnar joint is the point where the radius and ulna connect at the elbow. It allows the hand to rotate.

What bone part connects with the trochlear notch?

The trochlea is a smooth, spoon-shaped part of the humerus that sits in the trochlear notch of the ulna. It's the primary point of contact during elbow movement.

What is the carrying angle?

The carrying angle is the slight angle between the humerus and forearm when the arm is hanging straight down. It's usually 15 degrees but can vary between individuals.

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What is the medial epicondyle?

The medial epicondyle is a bony protrusion on the inner side of the elbow, which serves as an attachment site for muscles involved in wrist flexion.

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Articular Capsule

A fibrous capsule that surrounds the elbow joint, helping to stabilize the joint and prevent excessive movement.

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Lateral Collateral Ligament

A strong ligament on the lateral side of the elbow, preventing excessive inward motion (valgus force).

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Medial Collateral Ligament

A strong ligament on the medial side of the elbow, preventing excessive outward motion (varus force).

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Annular Ligament

A ring-shaped ligament that encircles the head of the radius, holding it in place during rotation of the forearm.

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Flexion

The motion of the elbow joint where the angle between the upper arm and forearm decreases, bringing the hand closer to the shoulder.

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Extension

The motion of the elbow joint where the angle between the upper arm and forearm increases, straightening the arm.

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Supination

The motion of the forearm where the palm faces up.

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Pronation

The motion of the forearm where the palm faces down.

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Proximal Radioulnar Joint

The movement of the radius over the ulna during pronation and supination.

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Interosseous Membrane

A strong, fibrous membrane connecting the radius and ulna along their length, providing stability and transferring forces.

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Triangular Fibrocartilage Complex (TFCC)

A complex of ligaments and cartilage at the distal radioulnar joint, providing stability and facilitating proper movement.

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Musculocutaneous Nerve

The nerve that supplies the biceps brachii, brachialis, and coracobrachialis muscles, which play a role in elbow flexion.

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Radial Nerve

The nerve that supplies the triceps brachii and anconeus muscles, which play a role in elbow extension.

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Median Nerve

The nerve that supplies the forearm pronators and some hand flexors.

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Ulnar Nerve

The nerve that supplies the wrist flexors and hand intrinsics.

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Distal Radius

The distal radius is a bone in the forearm that articulates with the carpal bones of the wrist. It has several key features including Lister's Tubercle, Styloid Process, and Ulnar Notch.

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Distal Ulna

The distal ulna is the bone on the pinky-finger side of the forearm and forms part of the wrist joint. It has a prominent head and a styloid process that serves as the attachment site for the extensor carpi ulnaris (ECU) muscle.

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Carpal Bones

The carpal bones are eight small bones that form the wrist. They are arranged in two rows: proximal (scaphoid, lunate, triquetrum, pisiform) and distal (trapezium, trapezoid, capitate, hamate).

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Scaphoid Bone

The scaphoid is the most commonly fractured carpal bone. It is a boat-shaped bone with a proximal pole, distal pole, and neck. Poor blood supply in the proximal pole increases the risk of complications from fractures in that area.

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Lunate Bone

The lunate is the moon-shaped bone in the wrist and the most commonly dislocated carpal bone. It is crucial for transmitting forces from the hand to the forearm.

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Radiocarpal Joint

The radiocarpal joint is the main joint of the wrist, connecting the distal radius and the proximal row of carpal bones. It allows for flexion, extension, radial deviation, and ulnar deviation of the wrist.

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TFCC

The triangular fibrocartilage complex (TFCC) is a group of ligaments and cartilage that stabilizes the ulnar side of the wrist. It helps to distribute force across the wrist joint and protect the structures on that side.

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Carpal Tunnel

The carpal tunnel is a narrow passageway in the wrist through which the median nerve and tendons of the flexor muscles pass. If compressed, it can lead to carpal tunnel syndrome.

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What are the two planes of wrist movement?

The wrist joint allows for movement in two planes: flexion/extension and radial/ulnar deviation. Flexion is bending the hand towards the forearm, extension is straightening the hand away from the forearm. Radial deviation is moving the hand towards thumb side, ulnar deviation is moving the hand towards pinky side.

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What bones form the central column of the wrist?

The central column is a group of bones that runs through the center of the wrist and hand. It is crucial for wrist stability and mobility, and includes the radius, lunate, capitate, and 3rd metacarpal.

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Differentiate between primary and secondary wrist muscles.

The primary set of wrist muscles act only at the wrist, while the secondary set acts on both the wrist and the hand. This means the primary set's primary function is wrist movement, while the secondary set also influences hand movements.

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Which nerves innervate the wrist flexors and extensors?

The radial nerve innervates the wrist extensors, which helps the hand move away from the forearm, while the median and ulnar nerves control the wrist flexors, which help the hand move towards the forearm.

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What is the function of the extensor retinaculum?

The extensor retinaculum acts like a band that holds the wrist extensors in place, preventing them from slipping out of position during movement. Imagine it like a strap keeping tendons from “bowstringing” away.

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How do wrist flexors contribute to strong gripping?

Strong gripping involves the wrist flexors to counteract the force of the finger flexors, stabilizing the wrist. This allows for a more powerful and controlled grip.

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What is radial and ulnar deviation?

Radial deviation is movement of the hand towards the thumb side, while ulnar deviation is movement towards the pinky side. It is important for hand positioning and dexterity.

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What is De Quervain's Tenosynovitis?

De Quervain's tenosynovitis is inflammation of the tendons of the extensor pollicis longus and brevis. These tendons are located near the thumb side of the wrist, and the inflammation causes pain and difficulty moving the thumb.

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Study Notes

Elbow, Forearm, and Wrist Anatomy

  • The elbow/forearm complex consists of three bones (distal humerus, ulna, radius) and four joints.
  • The joints include the humero-ulnar, humeroradial, proximal radio-ulnar, and distal radio-ulnar joints.

Mid-Distal Humerus (Anterior View)

  • Trochlea: A pulley-shaped structure
  • Coronoid Fossa: A depression for the coronoid process of the ulna
  • Capitulum: A rounded knob for the radial head
  • Radial Fossa: A depression for the radial head
  • Medial Epicondyle: A bony projection on the medial side, attachment for forearm flexor muscles
  • Lateral Epicondyle: A bony projection on the lateral side, attachment for forearm extensor muscles

Mid-Distal Humerus (Posterior View)

  • Trochlea: A pulley-shaped structure
  • Olecranon Fossa: Deep depression for the olecranon process of the ulna
  • Medial Epicondyle: Attachment for forearm flexor muscles
  • Lateral Epicondyle: Attachment for forearm extensor muscles

Proximal Ulna

  • Trochlear Notch: A deep depression that articulates with the trochlea of the humerus
  • Radial Notch: A depression that articulates with the radius
  • Coronoid Process: A projection that sits in the coronoid fossa of the humerus
  • Olecranon Process: A large projection that forms the bony point of the elbow

Proximal Radius

  • Head (Fovea): A rounded structure that articulates with the capitulum of the humerus
  • Neck: A constricted area beneath the head
  • Radial Tuberosity: A roughened area for the attachment of the biceps brachii muscle

How it Fits

  • Various joints are described in relation to how the bones articulate with each other.
  • Illustrations display the precise fitting.

Joints of the Elbow and Forearm

  • The elbow consists of the humero-ulnar and humeroradial joints.
  • The elbow is a modified hinge joint where the ulna rotates slightly
  • The elbow has one degree of freedom.
  • The elbow's tight joint fit (between trochlea and trochlear notch) creates stability.

Carrying Angle

  • Normal carrying angle: 15 degrees
  • Excessive carrying angle: 25 degrees and beyond
  • Varus deformity: Medially deviated angle

Joint Stabilizers

  • Articular Capsule: Encloses the joint, providing stability.
  • Lateral Collateral Ligament: Provides stability.
  • Radial Collateral Ligament: Provides lateral stability and limits excessive varus force
  • Ulnar Collateral Ligament: Provides medial stability and limits excessive valgus force
  • Medial Collateral Ligament: Provides medial stability.
  • Anterior: Part of the capsule
  • Posterior: Part of the capsule
  • Transverse: Part of the capsule
  • Annular Ligament: Wraps around radial head, stabilizing the proximal radio-ulnar joint

Movements of the Humero-ulnar, Humeroradial, and Proximal Radio-ulnar Joint

  • Humero-ulnar/humeroradial joints: flexion (30-130 degrees), extension(0-145 degrees)
  • Proximal radio-ulnar joint: pronation (50/50, 90/90 degrees) and supination

Arthrokinematics of the Elbow

  • The humero-ulnar and humeroradial joints show a similar concave to convex relationship
  • Significant joint stability depends on the congruence of the humerus and ulna.
  • (How they move, and slide).

Function

  • The elbow controls the length of the limb for activities like feeding, reaching, throwing, and personal hygiene.
  • The loss of extreme ranges of motion (ROM) commonly leads to minimal impairment.
  • The functional range of motion (ROM) is 30-130.

Arthrokinematics of the Forearm

  • The radius moves over a fixed ulna.
  • The annular ligament holds the radial head in place.
  • The distal radio-ulnar joint involves radius rolling and sliding over the ulna.
  • The connection provides stability.

Forearm Arthrokinematics

  • The forearm has one degree of freedom
  • Pronation: 0-90 degrees, supination: 0-80 degrees

Forearm Function

  • Bringing hand to face for feeding, washing, or shaving
  • Pronation moves the hand to move objects from chair or put on table.

Interosseous Membrane

  • The radius and ulna are linked by the interosseous membrane.
  • It supports extrinsic forearm muscles and transfers force to other body parts.
  • This membrane is susceptible to tears and injuries.

Triangular Fibrocartilage Complex (TFCC)

  • This complex comprises cartilage and ligaments between the ulna and carpal bones.
  • It stabilizes the distal radio-ulnar joint.
  • The TFCC plays an important role in wrist and forearm motion.

Nerve Innervation

  • Musculocutaneous nerve: bicep brachii, coracobrachialis, brachialis
  • Radial nerve: triceps, anconeous, wrist extensors
  • Median nerve: hand flexors, forearm pronators
  • Ulnar nerve: wrist flexors, hand intrinsics

Muscles that Move the Elbow

  • Flexors include biceps brachii and brachialis (musculocutaneous nerve); brachioradialis(radial nerve)
  • Brachialis is deep and attaches to the ulna
  • Brachioradialis is on the lateral side and helps position the forearm.

Elbow Extensors

  • Triceps brachii; long, lateral, and medial heads
  • Anconeus (from lateral epicondyle of humerus to proximal ulna) provides medial-lateral stability in the elbow joint

Forearm Supinators

  • Supinator (radial nerve), and biceps Brachii - Supinator helps with lesser movements of the forearm
  • Biceps also plays an important role in forceful supination

Forearm Pronators

  • Pronator teres and pronator quadratus (median nerve)
  • Pronator quadratus stabilizes the distal radio-ulnar joint and guides arthrokinematic motions.

Wrist Joint

  • The wrist joint has multiple bones

The Wrist

  • Distal Radius bones: Lister's tubercle, styloid process, ulnar notch
  • Distal Ulna: concave head, prominent head, styloid process
  • Carpal bones: eight total bones (scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate, and hamate)
  • Scaphoid: easily fractured
  • Lunate: often dislocates
  • Triquetrum: movable and prominent
  • Pisiform: sesamoid bone

Radiocarpal Joint

  • Proximal: concave radius, articular disc
  • Distal: Convex scaphoid, lunate, and triquetrum
  • Bi-concave, bi-convex shape
  • Two degrees of freedom.

Midcarpal Joint

  • Between proximal and distal carpal rows
  • Biaxial synovial joint
  • Concave-convex relationship

Other Structures of the Wrist

  • Stabilizing ligaments
  • Permit and guide motion
  • Limit joint motion
  • Transmit forces from hand to forearm
  • Prevent dislocation

Triangular Fibrocartilage Complex (TFCC)

  • Made up of multiple parts
  • It stabilizes Distal RU joint
  • Reinforces the ulnar side of the wrist
  • Helps in transferring wrist compression forces
  • 60% compression supported by radius, 40% by TFCC

The Carpal Tunnel

  • Formed by concave carpal bones and transverse carpal ligament
  • Contains nerves and tendons running through the area

Pathologies of the Elbow, Forearm, and Wrist

  • Elbow: concussions, fractures, bursitis, overstretch injuries, sprains/strains, lateral epicondylitis, medial epicondylitis, myositis ossificans, pulled elbow
  • Wrist: fractures, rheumatoid arthritis, strains, dislocations, sprains/tears, hyperpronation/hypersupination, carpal tunnel syndrome, extensor intersection syndrome, ulnar nerve entrapment

De Quervain's Tenosynovitis

  • Caused by inflammation of tendons around the radial styloid
  • repetitive motions (grasping, pinching, pulling)

Radial Nerve Palsy

  • Caused by radial nerve compression
  • Results in wrist drop

Cubital Tunnel Syndrome

  • Ulnar nerve impingement
  • Often results in chronic compression and repetitive trauma
  • Leads to tingling, numbness, weakness, and atrophy

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