Q.1 How will you determine the side to which the humerus belongs?
- The upper end is rounded and forms the head. The lower end is flattened from before backward.
- Head is directed medially and backward.
- Lesser tubercle projects from the front of the upper end.
- The anterior aspect of the upper end shows a vertical groove called the intertubercular sulcus.
Q.2 What is the anatomical position of the humerus in the body?
- Head is directed medially, upwards and backward.
- The medial epicondyle is directed medially and slightly backward.
Q.3 What are the contents of the intertubercular sulcus (Bicipital groove)?
- The tendon of the long head of biceps.
- Synovial sheath of the tendon.
- Ascending branch of anterior circumflex humeral artery.
Q.4 What are the structures attached to intertubercular sulcus?
- To medial lip: Teres major, insertion.
- To floor: Latissimus dorsi, insertion.
- To lateral lip: Pectoralis major, insertion.
Q.5 How the tendon of the pectoralis major is inserted?
- It is inserted by a bilaminar tendon on the lateral lip of the bicipital groove, the two laminae are continuous with each other inferiorly.
Q.6 What are the muscles inserting on greater tubercle?
- Supraspinatus: On upper impression.
- Infraspinatus: On middle impression.
- Teres minor: On lower impression.
Q.7 Which muscle is inserted into lesser tubercle?
Q.8 What is the ‘anatomical neck’ and ‘surgical neck’ of the humerus?
- Anatomical neck: Surrounds the margin of head. Provides attachment to the capsular ligament which is deficient inferiorly on the medial side.
- Surgical neck: Lies at the upper end of the shaft, below the epiphyseal line. It is a common site for fracture.
Q.9 What are the structures related to the surgical neck of the humerus?
- Axillary nerve • Anterior and posterior circumflex humeral vessels
Q.10 Name the structures related to the radial groove of shaft of humerus.
- Radial nerve and
- Profunda brachii vessels
Q.11 Which muscle originates from medial supracondylar ridge?
- Pronator teres, from the lower end of the medial supracondylar ridge
Q.12 Which muscle originates from lateral supracondylar ridge?
- Brachioradialis: From upper two-thirds.
- Extensor carpi radialis longus: From lower one-third.
Q.13 Which muscles arise from the lateral epicondyle of the humerus (common extensor origin)?
- Extensor carpi radialis brevis
- Extensor digitorum
- Extensor digiti minimi
- Extensor carpi ulnaris
Q.14 Which muscles also arise from the lateral epicondyle of humerus except from common extensor origin?
Q.15 What is the angle of ‘Humeral torsion’?
- It is an angle formed by the superimposition of long axes of upper and low articular surfaces of the humerus.
- It is about 164 degrees.
- It is greater in men and in adults.
Q.16 What are fossae present in the lower end of the humerus?
- Olecranon fossa: Posteriorly, just above trochlea. Accommodates the olecranon process in extended elbow.
- Radial fossa: Anteriorly, above capitulum. Accommodates radial head in flexed elbow.
- Coronoid fossa: Anteriorly, above trochlea. Accommodates coronoid process of ulna in flexed elbow.
Q.17 Why the fracture of the humerus at the junction of the upper and middle third leads to delayed union?
- Because of poor blood supply at the junction.
Q.18 Which nerve is most commonly involved in the supracondylar fracture of the humerus?
Q.19 What are the ossification centers for the lower end of the humerus and at what age they appear?
- Capitulum: First year
- Medial epicondyle: Fifth year
- Medial part of trochlea: Ninth year
- Lateral epicondyle: Twelfth-year Medial epicondyle fuses with the shaft at 20th year and others fuse together to form a single epiphysis, which fuses with the shaft at 15 years of age.