HUMERUS BONE

DEVELOPMENT:
  • Ossified from eight centers, one for each of the following parts: body(8th week of fetal life;primary center), head(1st yr.), greater tubercle(2nd yr.), lesser tubercle(5thyr.), capitulum, trochlea, and one for each epicondyle.
  • At birth the humerus is ossified in nearly its whole length, only the extremities remaining cartilaginous.
  • 6th yr. head and tubercles unite-> large epiphysis + body(12yr)
  • The lower end of the humerus end of the 2nd year ossification begins in the capitulum->(medialward) articular end of the bone; center for the medial part of the trochlea at 12 Ossification begins at 5 in medial epicondyle & at lateral at 13
  • About 16 to 17 yr, the lateral epicondyle and both portions of the articulating surface unites with the body, and at the 18 to medial epicondyle.
  • Multiplying factor for estimating stature from humerus in male is 5-6
OSTEOLOGY :
  • It is longest bone of upper limb and has upper end, lower end & shaft
-UPPER END:
  • HEAD (articulates with glenoid cavity)
  • ANATOMICAL NECK.
  • LESSER TUBERCLE
  • GREATER TUBERCLE .
  • There is intertubercular sulcus(groove like structure) which separates lesser tubercle from greater tubercle and also forms the lateral wall of axilla
  • The narrow line separating the upper end of humerus from shaft is called SURGICAL NECK.
  • -LOWER END (Bony Features)
Articular Part:
  1. Capitulum
  2. Trochlea
Nonarticular Part:
  1. Medial Epicondyle
  2. Lateral Supracondylar ridge
  3. Medial Supracondylar ridge
  4. Coronoid Fossa
  5. Radial Fossa
  6. Olecranon Fossa
-SHAFT: Contains three borders & three surfaces.
  • Borders:
  1. Anterior Border
  2. Lateral Border
  3. Medial Border
  4. Anterolateral Surface(b/w anterior & lateral borders)
  5. Anteromedial Surface(b/w anterior & medial border)
  6. Posterior Surface(b/w medial & lateral borders)
Side Determination:
  1. Upper end: Rounded.
  2. Lower end: Expanded from side to side & flattened from before backwards.
  3. Head: Directed posterior & medially upwards.
  4. Lesser Tubercle: Projects from the front of the upper end & is limited laterally by the intertubercular sulcus.
MUSCLE ATTACHMENTS OF HUMERUS:

Insertion muscles (upper humerus) Intertubercular sulcus Greater tubercle Pectoratis major, Latissmus dorsi & Teres major
Supraspinatus, Infraspinatus & Teres minor
Lesser tubercle Lesser tubercle
Origin muscles (lower humerus) Medial Origin muscles (lower humerus)
Lateral Lateral

  • Rotator cuff (Musculotendinous cuff): Fibrous sheath formed by the four flattened tendons of Subscapularis, Infraspinatus, Teres minor and Supraspinatus (SITS)
  • Gives strength to the capsule of shoulder joint all around except inferiorly
  • I.m. injections in the deltoid should be given in the lower half of the muscle to avoid injury to axillary nerve
BLOOD SUPPLY:
  • ARTERY
  • Nutrient arteries:Humerus - profunda brachii [Brachial artery]
  • VEINS
  • Preaxial vein of upper limb - Cephalic vein
  • Postaxial vein of upper limb - Basilic vein
NERVE SUPPLY:
  • Three Nerves are directly related to the Humerus.
  • AXILLARY Nerve at the Surgical neck.
  • RADIAL Nerve passes through the Radial groove( spiral groove of humerus)
  • Note:radial nerve is formed by: Axons from Roots: C5 to T1 Brachial plexus
  • Trunks: Superior, Medial and Inferior
  • Cord: Posterior
  • Axons pass through Spiral groove of humerus
  • Fibrous arch attachment of triceps to humerus
  • Lateral intermuscular septum below deltoid insertion
  • Arcade of Frohse: Above supinator and below elbow
  • Branches
  • Above elbow
  • – Above spiral groove (humerus)
  • ULNAR Nerve behind the medial epicondyle.
Exam Question
  • Multiplying factor for estimating stature from humerus in male is 5-6
  • There is intertubercular sulcus (groove like structure) which separates lesser tubercle from greater tubercle and also forms the lateral wall of axilla
  • Intertubercular sulcus of humerus gives attachment to pectoralis major, latissmus dorsi & teres major
  • RADIAL Nerve passes through the Radial groove( spiral groove of humerus)
  • Nerves of humerus are radial, ulnar & axillary nerve.
Don't Forget to Solve all the previous Year Question asked on HUMERUS BONE