Humerus
(Redirected from Humeral head)
Description
General
- The humerus is a long bone that has both a shaft (diaphysis) and two regions of articulation (epiphysis)
- The humerus is the longest bone in the upper extremity.
- The proximal or upper portion of the humerus consists of the bone's large rounded head joined to the body by a constricted portion called the neck and two eminences the greater and lesser tubercles.
Proximal Humerus
- Head
- Hemispheric head covered in articular cartilage
- Articulates with the glenoid fossa
- Forms that lateral half of the glenohumeral joint
- Anatomical neck
- Just below the head
- Represents the distal attachment of the joint capsule
- Greater tubercle
- Three smooth, flat impressions located posterosuperiorly
- Attachments from superior to inferior: supraspinatus, infraspinatus, teres minor
- Lesser tubercle
- Located anterior to the to the anatomical neck
- Attachments: subscapularis
- Intertubercular sulcus
- Also known as the bicipital groove
- Indentation between the greater and lesser tubercle
- Long head of the biceps brachii can be found in the groove
- Tendon of pectoralis major attaches to the lateral lip
- Tendon of teres minor attaches to the medial lip
- Latissimus dorsi attaches to the posterior aspect
- Surgical neck
- Narrowing just below the tubercles
- Close proximty to axillary nerve, posterior circumflex humeral artery
- Represents transition to shaft
Humeral Shaft
- Proximal half is cylindrical, distal half is triangular
- Anterior Border
- Begins at the greater tubercle, runs downward almost to the end of the bone
- Proximal end is continuous with the lateral lip of the intertubercular sulcus
- Lateral border
- Begins just distal to the greater tubercle
- Thickens distally to form the lateral supracondylar ridge
- Middle portion of the lateral border is adjacent to the rough V shaped area referred to as the deltoid tubercle/tuberosity.
- Medial border
- Forms the medial supracondylar ridge distally
- Radial groove: shallow groove that interrupts the lateral border in its medial third.
- Contains radial nerve, deep brachial artery
- Anterolateral surface
- Limited between the anterior, lateral borders
- Deltoid attaches to the proximal smooth surface, deltoid tuberosity on middle surface
- Lateral brachialis originates from the distal part of this surface, proximal two third of the lateral supracondylar ridge
- Anteromedial surface
- Located between the anterior and medial borders
- Begins proximally at the floor of the intertubercular sulcus.
- Coracobrachialis attaches around its mid-portion
- Brachialis covers distal half
- Posterior surface
- Bounded by the medial, lateral borders
- Covered mostly by the medial head of the triceps brachii
- Proximal third also gives attachment to the lateral head of the triceps brachii.
Distal Humerus
- General
- Trochlea
- The trochlea has a surface shaped like a pulley
- Covers the anterior, posterior and inferior surfaces of the medial condyle of the humerus
- Articulates with ulna at trochlear notch
- Elbow extension: posterior, inferior aspects articulate with ulna
- Elbow flexion: anterior, inferior parts articulate with ulna
- Capitellum
- Convex and rounded projection that articulates with the head of the radius
- Covers the anterior, inferior surfaces of the lateral condyle of the humerus
- Extension: inferior surfrace in contact with humerus
- Flexion: radial head slides towards anterior aspect humerus
- Medial Epicondyle
- Blunt landmark superomedial to the medial condyle
- Ulnar Nerve passes posterior
- The common flexor tendon attaches here
- Composed of flexor carpi ulnaris, Palmeris Longus, flexor carpi radialis, Pronator Teres
- Lateral Epicondyle
- Landmark superolateral to the lateral condyle
- Attachment site of the common extensor tendon
- Composed of brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis, Extensor digitorium, extensor digiti minimi, extensor carpi ulnaris, Anconeus
- Olecranon Fossa
- The olecranon fossa is a deep hollowed area on the posterior surface, superior to the trochlea.
- In elbow extension, the tip of the ulnar olecranon process lodges into this fossa.
- Coronoid Fossa
- Located superior to trochlea on the anterior surface
- Coronoid process of ulna lodges here in elbow flexion
- Radal Fossa
- Located on anterior humerus
- Head of the radius sits here with the elbow in full flexion
Osteology
- Humeral Head
- Four growth center: head, shaft, greater tubercle, lesser tubercle[3]
- Typically fuses between ages 14-20
- Contributes about 80% of longitudinal growth of humeral shaft
Vascular Supply
- Proximal
- Anterior circumflex humeral artery
- Posterior circumflex humeral artery
Innervation
Clinical Significance
Proximal
- Humeral Head Epiphysiolysis
- Proximal Humerus Fracture
- Glenohumeral Dislocation
- Glenohumeral Arthritis
Shaft
Distal
- Capitellum Fracture
- Terrible Triad of Elbow
- Lateral Condyle Fracture (Peds)
- Medial Condyle Fracture (Peds)
- Panners Disease (AVN of the Capitellum)
See Also
References
- ↑ Image courtesy of https://www.theskeletalsystem.net/
- ↑ 2.0 2.1 Case courtesy of Piotr Gołofit, Radiopaedia.org, rID: 53034
- ↑ www.wheelessonline.com/ortho/anatomy_of_proximal_humeral_physis. Accessed March 7, 2010.