Repeated Medical PG Question- 68

#ANATOMY(NEET-PG)

Which of the following muscle not attached to the marked area "A" of humerus?

A. Supraspinatus

B. Infraspinatous 

C. Teres minor

D. Subscapularis

Answer: D. Subscapularis

Expaination:

PARTS OF HUMERUS:

• It is longest bone of upper limb and has upper end, lower end & shaft.

1. UPPER END (Proximal end):

• HEAD (articulates with glenoid cavity)

• The upper end of humerus has a head, which is separated from greater & lesser tuberclebyanatomical neck.

• The upper end of humerus is the growing end.

• Surgical neck separates proximal end from the shaft.

• There is intertubercular sulcus(bicipital groove) which separates lesser tubercle from greater tubercle and also forms the lateral wall of axilla.

• Attachment on proximal end are-

• Greater tubercle (or tuberosity):- Insertion of supraspinatus, Infraspinatous & teres minor.

• Lesser tubercle (or tuberosity):– Insertion of subscapularis.

2. LOWER END (Bony Features):

• Articular Part:

• Capitulum

• Trochlea

• Nonarticular Part:

• Medial Epicondyle

• Lateral Supracondylar ridge

• Medial Supracondylar ridge

• Coronoid Fossa

• Radial Fossa

• Olecranon Fossa

→ These fossa lie within the joint cavity.

→ Medial epicondyle & lateral epicondyle are outside the capsule.

→ Posterior surface of medial epicondyle has a groove lodging ulnar nerve.

• Medial epicondyle of humerus is sometimes called as “funny bone” becausre gentle tapping of it results in tingling sensation due to stimulation of ulnar nerve.

3. SHAFT:

• The shaft of humerus is cylindrical in the upper half & triangular on cross-section in the lower half.

• Contains three borders & three surfaces.

• Borders:

• Anterior Border

• Lateral Border

• Medial Border

• Surfaces:

• Anterolateral Surface(b/w anterior & lateral borders)

• Anteromedial Surface(b/w anterior & medial border)

• Posterior Surface(b/w medial & lateral borders)

• The upper part has intertubercular sulcus (bicipital groove) anteriorly.

• Bicipital groove contains long head of biceps with its synovial sheath and an ascending branch of anterior circumflex humeral artery.

• Middle third of posterior surface of shaft of the humerous has a spiral groove (radial groove)which contains radial nerve & profunda brachi vessels.