Mod 2: Lecture 3 - Arm, Elbow and Cubital Region

Question 1

Cubital means

Answer 1

elbow

Question 2

Distal Humerus

Answer 2

• Condyles: articulating surfaces
• — Capitulum: articulates with the radius
• — Trochlea: articulates with the ulna
• Epicondyles
• — Two: Medial and Lateral
• — primarily sites of muscle attachment
• Fossae
• — Three: radial, coronoid, olecranon

Question 3

Radius and Ulna

1. proximal ends
2. distal ends

Answer 3

1. • both articulate with the distal humerus
     - ulna is longer proximally
     - end of ulna is much bigger, has a hook
     - end of radius is a flat little cap
2. • radius is longer distally
     - radius has a slanted triangular end
     - ulna has a little bumpy end

Question 4

Radius and Ulna

1. rotation
2. joined by

Answer 4

1. • radius rotates around the ulna
     - — supination and pronation
2. • they are joined by interosseus membrane
     - — syndesmosis joint
     - proximal and distal radial-ulnar joints

Question 5

Features of the Radius

Answer 5

1. Head: little flat cap
2. Neck: short, skinny area under the head
3. Radial Tuberosity: bump right under the neck, site of biceps attachment
4. Shaft of Radius
5. Styloid Process: the tip of the triangular distal end, pointed projection
6. Ulnar notch: the tip of the other side of the distal radius, where the radius meets the ulna

Question 6

Features of the Ulna

Answer 6

1. Olecranon Process
2. Trochlear (Semilunar) Notch
3. Coronoid Process
4. Tuberosity
5. Radial Notch
6. Shaft of Ulna
7. Head of Ulna
8. Styloid Process

Question 7

Features of the Ulna:

1. Olecranon Process
2. Trochlear Notch
3. Coronoid Process

Answer 7

1. the superior tip of the hook at the proximal end
2. the inside curve of the hook, where the ulna joins the trochlea of the humerus
3. the inferior tip of the hook at the proximal end

Question 8

Features of the Ulna:

4. Tuberosity
5. Radial Notch

Answer 8

4. a bump a little below the hook on the same side as it, site of attachment for the brachialis muscle
5. bump on the lateral side (in anatomical position), right underneath the hook, where the radius meets the ulna on the proximal ends

Question 9

Features of the Ulna:

6. Shaft
7. Head
8. Styloid Process

Answer 9

6. the long middle part
7. the distal end
8. the little pointy bump off of the distal end

Question 10

Articulations

Answer 10

• Three which share a joint capsule
• — Humeroulnar
• — Humeroradial
• — Proximal Radioulnar
• Distal Radioulnar

Question 11

1. Humeroulnar Joint
2. Humeroradial Joint
3. Proximal Radioulnar

Answer 11

• these three share a joint capsule
  1. - Hinge
• Flexion/Extension of the elbow
• medial side
  2. - Modified hinge
• flexion/extension
• supination/pronation - some spinning of radial head
• lateral side
  3. - Pivot
• supination/pronation
• between the radius and ulna on the proximal ends

Question 12

Distal Radioulnar

Answer 12

• Pivot
• supination/pronation
• between the radius and ulna on the distal ends

Question 13

Arthrokinematics of the Elbow

1. In extension…
2. In flexion…

Answer 13

1. the olecranon process is in close approximation to the distal humerus in the olecranon fossa
2. the olecranon process pulls away from the distal humerus, as the coronoid process and radius approach their respective fossae
   - – the radius and coronoid process get closer to the the humerus

Question 14

Arthrokinematics: supination/pronation

Answer 14

• Supination occurs as the radial head spins on the capitulum of the humerus
• the radius rotates around the ulna
• the radius is the only bone that moves, the ulna is fixed
• includes these joints:
• — humeroradial
• — proximal and distal radioulnar

Question 15

Supporting Structures: Elbow Region - Annular Ligament

Answer 15

• Encircles the head of the radius
• — forms 4/5 of a circle
• — the radial notch of the ulna forms the other 1/5
• Attaches to the margins of the radial notch
• Holds the head of the radius against the ulna
• Protects against the distal dislocation of the radius
• — holds the radius up so it stays in its place at the joint
• — distal dislocation is down toward the wrist
• Stabilizes the proximal radioulnar joint
• — holds the radius to the ulna

Question 16

Supporting Structures: Lateral Collateral Ligament

Answer 16

• From the lateral epicondyle of the humerus to the annular ligament of the radius
• Protects against varus (medial) deviation of the forearm
• taut in full extension

Question 17

Supporting Structures: Medial Collateral Ligament

Answer 17

• From the medial epicondyle of the humerus to the coronoid process and olecranon process of the ulna
• Protects against valgus (lateral) deviation of the forearm
• Posterior fibers taut in flexion
• Transverse (oblique) fibers from olecranon to coronoid process deepen socket for trochlea

Question 18

Muscles Acting on the Elbow: Flexion/Extension

Answer 18

• Anterior Compartment:
• — Biceps Brachii
• — Brachialis
• — Nerve: Musculocutaneous
• Posterior Compartment:
• — Triceps Brachii
• — Anconeus
• — Brachioradialis
• — Nerve: Radial

Question 19

Biceps Brachii

1. Attachments
2. Action
3. Innervation

Answer 19

1. • both heads: radius via bicipital aponeurosis
     - short head: coracoid process of the scapula
     - long head: supraglenoid tubercle
2. • flexes elbow (flex humerus)
     - supinates the forearm
3. musculocutaneous nerve

Question 20

Brachialis

1. Attachments
2. Action
3. Innervation

Answer 20

• deep to the biceps muscle
  1. - distal, anterior humerus
• coronoid process of the ulna
  2. flexes the forearm
  3. musculocutaneous nerve

Question 21

Triceps Brachii

1. Attachments
2. Action
3. Innervation

Answer 21

1. • all heads: olecranon of the ulna
     - long head: infraglenoid tubercle
     - lateral head: posterior superior humerus
     - medial head (deep): posterior inferior humerus
2. extend elbow (LH-ext in shoulder)
3. radial nerve

Question 22

Anoconeus

1. Attachments
2. Action
3. Innervation

Answer 22

1. • lateral epicondyle of humerus
     - olecranon of ulna
2. extends the forearm and aids in pronation of the forearm
3. radial nerve

Question 23

Brachioradialis

1. Attachments
2. Action
3. Innervation

Answer 23

1. • lateral supracondylar ridge of distal humerus
     - lateral, distal radius
2. flexes elbow
3. radial nerve
   - originates in the posterior compartment and shares the innervation of the posterior compartment, but rotates to the front of the muscle so its action is similar to the muscles of the anterior compartment

Question 24

Muscles Acting on the Radioulnar Joints

Answer 24

• Supinators
• — Supinator Muscle
• — Biceps Brachii
• Pronators
• — Pronator Teres
• — Pronator Quadratus

Question 25

Supinator Muscle

1. Attachments
2. Action
3. Innervation

Answer 25

1. • lateral epicondyle of humerus, crest of ulna
     - anterior, lateral, and posterior surface of radius
2. supinates the forearm
3. radial nerve

Question 26

Pronator Teres

1. Attachments
2. Action
3. Innervation

Answer 26

1. • coronoid process and medial epicondyle
     - lateral surface of radius
2. pronates and flexes the forearm
3. median nerve

Question 27

Cubital Fossa

Answer 27

• triangular hollow area on the anterior aspect of the elbow

Question 28

Boundaries of the Cubital Fossa

Answer 28

• superiorly: an imaginary line connecting the medial and lateral epicondyles
• medially: pronator teres
• laterally: brachioradialis

Question 29

Cubital Fossa:

1. Floor
2. Roof

Answer 29

1. formed by the brachialis and supinator

2. formed by deep fascia, subcutaneous tissue, and skin of the anterior elbow

Question 30

Contents of the Cubital Fossa

Answer 30

• terminal part of the brachial artery
• (deep) accompanying veins of the arteries
• biceps brachii tendon
• median nerve