Clavicle Bone Anatomy
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Humerus Bone Anatomy
Introduction to Humerus bone anatomy:
- The
humerus is a long bone that supports the upper arm (upper arm bone). It extends from the shoulder joint to the elbow joint.
Anatomy of the Humerus bone:
- At its
proximal end, the humerus is attached to the axial skeletal by the shoulder girdle or pectoral girdle, which consists of the scapula and clavicle bones. The rounded humeral head fits into the glenoid fossa (cavity) of the scapula. This shallow depression on the lateral side of the scapula allows the shoulder joint to be very mobile but also reduces its stability.
- A long, cylindrical shaft (body) makes up the
middle part of the humerus. Most of the shaft’s surface is smooth except for the deltoid tuberosity, which is located near the midpoint of the lateral margin. The shaft is an attachment site for several muscles that move the upper arm and lower arm.
Distally, the humerus joins medially with the ulna and laterally with the radius at the elbow joint.
- The humeroulnar joint is formed by the pulley-shaped trochlea of the humerus and the trochlear notch of the ulna. The humeroradial joint is formed by the rounded capitulum of the humerus and the concave superior surface of the radial head.
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- Muscles from the shoulder girdle help stabilize the joint and control the front-to-back, side-to-side, and rotational movements of the humerus.
Anterior Markings of the Humerus Bone:
Head (Caput humeri) is a large, rounded, prominence that extends medially from the bone’s proximal end. It articulates with the glenoid fossa of the scapula to form the glenohumeral joint or shoulder joint.
Greater tubercle (Tuberculum majus) is a large, roughened area located lateral to the head. The supraspinatus, infraspinatus, and teres minor muscles attach to this elevation.
Lesser tubercle (Tuberculum minus) is a roughened area located medial to the greater tubercle. It serves as the insertion site for the subscapularis muscle.
Intertubercular Groove or Sulcus (Sul-cus intertubercularis) is a narrow, longitudinal depression between the greater and lesser tubercles. This indentation, which is also called the bicipital groove, is a passageway for the tendon of the long head of the biceps brachii. The pectoralis major, teres major and latissimus dorsi muscles also attach here.
Anatomical Neck (Collum anatomicum) is a grooved constriction between the head and tubercles that serves as an attachment point for the articular (joint) capsule.
Surgical Neck (Collum chirurgicum hu-meri) is an region inferior to the tubercles where the bone narrows and fractures often occur.
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Shaft or Body (corpus humeri) is the elongagted, cylinder shaped middle portion of the bone. Its relatively smooth surface is the insertion point for muscles that move the upper arm and the origin point for muscles that move the lower arm.
Deltoid Tuberosity (Tuberositas deltoidea) is a raised, roughened area located on the lateral side of the shaft at its midpoint. It is an attachment point for the deltoid muscle.
Lateral Epicondyle (Epicondylus lateralis) is a rounded projection at the distolateral end of the humerus. The posterior surface of the lateral epicondyle serves as an attachment point for some of the muscles that extend the wrist and fingers of the hand.
Lateral Supracondylar Ridge (Crista su-pracondylaris lateralis) is the roughened margin located above the lateral epicondyle. The brachioradialis muscle attaches along this edge of the bone.
Medial Epicondyle (Epicondylus medialis) is a rounded projection at the distomedial end of the humerus. Some of the muscles that flex the forearm, wrist, and fingers attach to anterior surface of this marking.
Capitulum (Capitulum humeri) is a small, knob-like prominence on the distolateral end of the humerus. It articulates with the head of the radius bone at the elbow joint.
Trochlea (Trochlea humeri) is a pulley-shaped formation located medial to the capitulum. This region articulates with the trochlear notch of the ulna bone at the elbow joint.
Coronoid Fossa (Fossa coronoidea) is a depression located superior to the anterior aspect of the trochlea. This region provides space for the coronoid process of the ulna when the forearm is flexed.
Radial Notch (Fossa radialis) is a small depression located superior to the capitulum. This region provides space for the head of the radius when the forearm is flexed.
Posterior Markings of the Humerus Bone:
Head (Caput humeri) is a large, rounded, prominence that extends medially from the bone’s proximal end. It articulates with the glenoid fossa of the scapula to form the glenohumeral joint or shoulder joint.
Greater Tubercle (Tuberculum majus) is a large, roughened area located lateral to the head. The supraspinatus, infraspinatus and teres minor muscles attach to this elevation.
Anatomical Neck (Collum anatomicum) is a grooved constriction between the head and tubercles that serves as an attachment point for the articular (joint) capsule.
Surgical Neck (Collum chirurgicum hu-meri) is an region inferior to the tubercles where the bone narrows and fractures often occur.
Shaft or Body (corpus humeri) is the elongagted, cylinder shaped middle portion of the bone. Its relatively smooth surface is the insertion point for muscles that move the upper arm and the origin point for muscles that move the lower arm.
Deltoid Tuberosity (Tuberositas deltoidea) is a raised, roughened area located on the lateral side of the shaft at its midpoint. It is an attachment point for the deltoid muscle.
Radial groove or sulcus (Sulcus nervi) is a shallow depression that runs diagonally along the lateral posterior surface of the bone, next to the deltoid tuberosity. It forms a partial passageway for the radial nerve and deep brachial artery.
Lateral Epicondyle (Epicondylus lateralis) is a rounded projection at the distolateral end of the humerus. The posterior surface of the lateral epicondyle serves as an attachment point for some of the muscles that extend the wrist and fingers of the hand.
Lateral Supracondylar Ridge (Crista su-pracondylaris lateralis) is the roughened margin located above the lateral epicondyle. The brachioradialis muscle attaches along this portion of the bone.
Medial Epicondyle (Epicondylus medialis) is a rounded projection at the distomedial end of the humerus. Some of the muscles that flex the forearm, wrist, and fingers attach to anterior surface of this marking.
Trochlea (Trochlea humeri) is a pulley-shaped formation located medial to the capitulum. This region articulates with the trochlear notch of the ulna bone at the elbow joint.
Olecranon fossa (Fossa olecrani) is a prominent, triagular-shape depression on the distal posterior surface, superior to the trochlea. This area accepts the olecranon process of the ulna when the forearm is extended.
Test yourself:
- Proximal end:
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- Middle:
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- Distal end:
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- Anterior view:
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- Posterior view:
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