Humerus
Dr. R. Menaka
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Humerus of Ox
It is long bone and directed obliquely downwards and backwards.
It presents a shaft and two extremities
Shaft:
It is twisted in appearance and has four surfaces.
Anterior Surface- somewhat triangular area
Posterior Surface- nutrient foramen is located on the distal part
Medial Surface- Teres tubercle is present and gives attachment with the teres major muscle.
Lateral Surface- The musulo-spiral groove is present and covered by brachialis muscle in the living status.
The crest of humerus is present between the lateral surface and anterior surface. Deltoid tuberosity is located on the middle of the crest of humerus.
The deltoideus muscle is inserted with deltoid tuberosity. The triceps and teres minor muscle is inserted on the upper part of the crest of humerus.
Proximal Extremity:
It presents an articular head, two tuberosities and a bicipital groove.
The articular head is smooth and convex which articulates with the glenoid cavity of scapula and forms shoulder joint.
Two tuberosities are lateral and medial. The lateral tuberosity is larger than the medial tuberosity. Between the tuberosity, the bicipital groove is present.The tendon of biceps brachii passes through the bicipital groove. The lateral tuberosity has summit and convexity. The summit overhangs on the bicipital groove. The tendon of supraspinous muscle is inserted with the summit of lateral tuberosity. The infraspinous muscle is inserted with the convexity of the lateral tuberosity. The medial tuberosity is divided in to anterior and posterior. The anterior part forms the medial boundary of the bicipital groove. The posterior part gives attachment of subscapularis muscle. The bicipital groove also known as inter tuberal groove.
Distal Extremity:
The distal extremity of humerus has
Modified condyles – medial (larger) and lateral (smaller), epicondyles, olecranon fossa, coronoid fossa and condyloid crest.
The medial and lateral condyles articulate with the radius and ulna. Then forms the elbow joint. This articular surface divided by ridge.
The medial epicondyle gives origin of the following muscles.
The lateral epicondyle gives origin of –ulnaris lateralis
The condyloid crest gives origin of the following muscles
The olecranon fossa articulates with olecranon process of ulna during extreme extension and coronoid fossa articulates with
coronoid process of radius during extreme flexion.
Humerus of horse:
The musculo-spiral groove is deep and spirally curved (more twisted appearence)
The deltoid tuberosity is better developed.
The bicipital groove is further divided by a ridge.
The ridge of distal articular surface is less prominent.
Humerus of dog:
It is long and slender and less twisted.
The deltoid tuberosity is ridge like
The lateral tuberosity is single.
The olecranon fossa and coronoid fossa usually communicates by supratrochlear foramen.
Humerus of pig:
Musculo spiral groove is shallow
supratrochlear foramen is present
Humerus of rabbit:
The deltoid tuberosity is ridge like
Musculo spiral groove is shallow
supratrochlear foramen is present
Humerus of fowl:
Proximally humerus articulates with scapula and coracoid
Pneumatic foramen is present.
The shaft is less twisted