L8: The Arm: Osteology and Musculature

Question 1

Distal End of the Humerus

Answer 1

Question 2

Distal end of the Humerus

Answer 2

Question 3

Distal End of the Humerus

Answer 3

Question 4

Answer 4

Question 5

Answer 5

Question 6

Answer 6

Question 7

Answer 7

Question 8

Anterior (Flexor) Compartment contains 3 muscles (BBC):

• _________
• _________
• _________
• Innervated predominantly by the _____________

Answer 8

Anterior (Flexor) Compartment contains 3 muscles (BBC):

• Biceps Brachii
• Brachialis
• Coracobrachialis
• Innervated predominantly by the musculocutaneous nerve.

Question 9

Posterior (Extensor) Compartment contains one muscle: ___________

•Innervated by the ________

Answer 9

Posterior (Extensor) Compartment contains one muscle: Triceps Brachii

•Innervated by the radial nerve

Question 10

Biceps Brachii

Answer 10

Origin:

• Short Head: Coracoid Process of the Scapula
• Long Head: Supraglenoid Tubercle of the Scapula
  
  • Enters intertubercular (bicipital) groove
  • Held in the groove by the transverse humeral ligament

Insertion: Long and short converge on the radial tuberosity & bicipital aponeurosis

Innervation: Musculocutaneous Nerve

Actions:

• Flexor of the forearm at the elbow joint
• Powerful supinator of the forearm when the elbow joint is flexed
• Flexion of the glenohumeral joint as the 2 heads of the muscle cross the joint

Question 11

Answer 11

Question 12

_____________:

• Characteristic deformity following rupture of the tendon of biceps brachii
• On flexing the elbow, a prominent bulge of the muscle belly is seen as its unrestrained fibers contract

Answer 12

Popeye Deformity:

• Characteristic deformity following rupture of the tendon of biceps brachii
• On flexing the elbow, a prominent bulge of the muscle belly is seen as its unrestrained fibers contract

Question 13

Brachialis

Origin, Insertion, Innervation, Action

Answer 13

Origin: Distal half of anterior surface of humerus

Insertion: Coronoid Process and Ulnar Tuberocity

Innervation: Musculocutaneous Nerve, small lateral part by Radial Nerve

Actions: Flexes forearm at elbow

Question 14

Corocobrachialis

Origin, Insertion, Innervation, Action

Answer 14

Origin: Tip of Coracoid Process of the Scapula

Insertion: Middle ⅓ Medial surface of Humerus

Innervation: Musculocutaneous Nerve *Penetrates Muscle!

Actions: Flexes & Adducts arm

Question 15

Triceps Brachii

Origin, Insertion, Innervation, Action

Answer 15

Origin:

• Long Head: Infraglenoid Tubercle
• Lateral Head: Posterior Surface of Humerus inferior to Radial Grove
• Medial Head: Posterior Surface of Humerus inferior to Radial Grove

Insertion: (all 3 heads converge into large tendon)

• Superior surface of Olecranon of Ulna
• Fascia of forearm

Innervation: Radial Nerve

Actions: Extends Forearm

Question 16

Anconeus

Origin, Insertion, Innervation, Action

Answer 16

Origin: Lateral Epicondyle of Humerus

Insertion: Lateral side of Olecranon and U_pper ¼ of posterior surface Ulna_

Innervation: Radial Nerve ( Posterior Interosseeoues nerve)

Action: Extends the forearm. Tenses capsule of elbow joint preventing pinching