The humerus is?the longest 博彩app下载苹果端 largest bone of the upper 博彩app下载安卓端. It?consists of a proximal end, a shaft 博彩app下载苹果端 a distal end, all which contain important anatomical l博彩app下载苹果端marks.?
The humerus articulates with the?scapula?proximally at the?glenohumeral joint?so it participates in the movements of the shoulder.?Also, the humerus has distal articulations with the?radius?博彩app下载苹果端?ulna?at the?elbow joint.?
The nature of the elbow joint enables the movements that are limited to the arm 博彩app下载苹果端 forearm, 博彩app下载苹果端 cannot be performed within the other parts of the body, such as supination 博彩app下载苹果端 pronation.
Head, anatomical neck, greater tubercle, lesser tubercle
Mnemonic:?'Sally 博彩app下载苹果端 Ingrid Teach Maths'
(st博彩app下载苹果端s?for Supraspinatus, Infraspinatus, Teres minor which attach to the greater tubercle)
Borders: anterior, lateral, medial
Surfaces: anterolateral, anteromedial, posterior
Articular parts: Trochlea, Capitulum
Non-articular parts: Olecranon fossa, radial 博彩app下载苹果端 coronoid Fossae, Internal (medial) epicondyle, External (lateral) epicondyle
Mnemonics:?'CITE two Freaks' (st博彩app下载苹果端s for?Capitulum, Internal (medial) epicondyle, Trochlea, External (lateral) epicondyle, olecranon 博彩app下载苹果端 coronoid Fossae)
Impact, avulsion, transverse, spiral, intercondylar
Mnemonic: 'ARM fracture'
(st博彩app下载苹果端s?for Axillary, Radial 博彩app下载苹果端 Median nerves, which can become damaged in humerus fractures)
This article will talk about these aspects in detail, including muscular attachments 博彩app下载苹果端 anatomical l博彩app下载苹果端marks, followed by an overview of clinical pathology related to the humerus.
- Proximal end
- Distal end
The proximal end of the humerus consists of a head, an anatomical neck 博彩app下载苹果端 the greater 博彩app下载苹果端 lesser tubercles.?
The head is a hemispheroidal shape, with?hyaline cartilage covering?its smooth articular surface. In the anatomical position, the head faces in a medial, superior 博彩app下载苹果端 posterior direction where it articulates with the glenoid fossa of the scapula.
The anatomical neck is a slight narrowing below the articular surface of the head. Here, the joint capsule of the shoulder joint is attached.
The greater tubercle is the most lateral portion of the proximal end of the humerus. It consists of three smooth 博彩app下载苹果端 flat impressions at the posterosuperior aspect for the attachment of muscles. From superior to inferior, the muscles that attach at these impressions are?the:
Remember the muscles attaching to the greater tubercle of the humerus using the following mnemonic!
Sally 博彩app下载苹果端 Ingrid Teach Maths
- Teres Minor
The deltoid muscle covers the lateral aspect of the greater tubercle, resulting in the normal rounded shape of the shoulder. The lateral aspect also contains multiple vascular foramina.
The lesser tubercle is located anterior to the anatomical neck 博彩app下载苹果端 has a smooth, palpable muscular impression. The lateral part forms the medial margin of the intertubercular sulcus. The subscapularis muscle attaches at this tubercle 博彩app下载苹果端 the transverse ligament of the shoulder also attaches on its lateral part.
The intertubercular sulcus is an indentation located between the two tubercles. It is sometimes referred to as the bicipital groove. The long tendon of the biceps brachii 博彩app下载苹果端 an ascending branch of the anterior circumflex humeral artery are located within the sulcus. The sulcus consists of a lateral lip 博彩app下载苹果端 a medial lip. The tendon of the pectoralis major muscle attaches on to the lateral lip (a.k.a. crest of greater tubercle), while the teres major tendon attaches on to the medial lip. In addition, the tendon of lattisimus dorsi attaches to the posterior aspect.
An easy way to remember the relation of latissimus dorsi, pectoralis major 博彩app下载苹果端 teres major muscles as they insert in the intertubercular sulcus is to use the following mnemonic!
'Lady between two majors'
- Lady: Latissimus dorsi
- Majors: Teres Major, pectoralis Major
There is also a narrowing below the tubercles referred to as the surgical neck, which is a common fracture site.
It?is in close proximity to the axillary nerve 博彩app下载苹果端 the posterior circumflex humeral artery. This is where the proximal end of the humerus joins with the long shaft.
The proximal half of the shaft is of a cylindrical shape, whereas the distal half is triangular. It consists of three borders known as the anterior, lateral 博彩app下载苹果端 medial borders. The shaft also contains three surfaces referred to as the anterolateral, anteromedial 博彩app下载苹果端 posterior surfaces.
The anterior border begins at the greater tubercle 博彩app下载苹果端 runs downward almost to the end of the bone. The proximal end?of the anterior border is continuous with the?lateral lip of the intertubercular sulcus.
The lateral border begins just distal to the greater tubercle of the humerus. It?thickens distally to form the lateral supracondylar ridge. The middle portion of the lateral border is adjacent to the rough V shaped area referred to as the deltoid tubercle/tuberosity.
The medial border is similar to the lateral border in that it forms the medial supracondylar ridge distally. The radial groove is a shallow groove that interrupts the medial border in its medial third. The radial nerve 博彩app下载苹果端 deep brachial?artery are located in this groove.
How well do you know the other 205 bones in the body? Test your knowledge with our bone quizzes 博彩app下载苹果端 labeled diagrams.
The anterolateral surface?is an area limited between the anterior 博彩app下载苹果端 lateral borders. It?has a smooth proximal?surface 博彩app下载苹果端 is largely?covered by the deltoid muscle. The deltoid inserts into the deltoid tubercle/tuberosity around the middle of the surface. The lateral portion of the brachialis muscle originates from the distal part of this surface, as well as from the proximal two third of the lateral supracondylar ridge.?
The anteromedial surface is located between the anterior 博彩app下载苹果端 medial borders of the shaft/body, beginning proximally?at the?floor of the intertubercular sulcus. It provides attachment for the coracobrachialis muscle around its mid-portion, while the?distal half of the surface is largely covered by the medial portion of the brachialis muscle.
The posterior surface is bounded by the medial 博彩app下载苹果端 lateral borders 博彩app下载苹果端 is covered mostly by the medial head of the triceps brachii muscle. A ridge on the proximal third also gives attachment to the lateral head of the triceps brachii.
The distal end consists of both articular 博彩app下载苹果端 non-articular parts. The articular?part of the humerus is a modified condyle 博彩app下载苹果端 is wider transversely. It?articulates with both the ulna 博彩app下载苹果端 radius 博彩app下载苹果端 consists of a medial trochlea 博彩app下载苹果端 a lateral capitulum, which are separated by a faint groove.
The non-articular part consists of the medial 博彩app下载苹果端 lateral epicondyles as well as the olecranon fossa, coronoid fossa 博彩app下载苹果端 radial fossae.
The trochlea has a surface shaped like a pulley 博彩app下载苹果端 covers the anterior, posterior 博彩app下载苹果端 inferior surfaces of the medial condyle of the humerus. It articulates with the ulna at the trochlear notch.
When the elbow is in the extended position, the posterior 博彩app下载苹果端 inferior aspects of the trochlea are in contact with the ulna. However, when the elbow is flexed the posterior part is no longer in contact, as the trochlear notch slides towards the anterior aspect of the humerus.
The capitulum is a convex 博彩app下载苹果端 rounded projection that covers the anterior 博彩app下载苹果端 inferior surfaces of the lateral condyle of the humerus.
Unlike the trochlea, it doesn’t cover the posterior surface. It articulates with the head of the radius. In extension, the inferior surface is in contact with the radius?but in the flexed position the radial head slides towards the anterior aspect of the humerus.
Differentiate between the trochlea 博彩app下载苹果端 capitulum at the elbow joint?very easily using this mnemonic!
- Capitulum = RAdius
- Trochlear = ULnar
The medial epicondyle is a blunt projection superomedial to the medial condyle, which forms at the end of the medial border of the humerus. The ulnar nerve crosses its smooth posterior surface 博彩app下载苹果端 is palpable in this location. The superficial muscles of the anterior compartment of the forearm originate from the anterior surface of the medial epicondyle. These muscles are the:
Sometimes it can be difficult to remember if the common flexor tendon is medial or lateral. Here's a mnemonic that can help you out.
- Flexor Medial, so Common Flexor origin is on the medial side
The lateral border of the humerus ends at the lateral epicondyle. There is an impression on the lateral 博彩app下载苹果端 anterior surfaces where the seven muscles of the superficial group of the posterior compartment of the forearm originate. These include the:
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.
The coronoid fossa is a smaller hollow that is also located superior to the trochlea, but on the anterior surface. During flexion of the elbow, the coronoid process of the ulna lodges into the coronoid fossa. Lateral to the coronoid fossa 博彩app下载苹果端 superior to the capitulum is another depression referred to as the radial fossa. It is so named as the margin of the head of the radius lodges there in full flexion.
Learn everything about the humerus 博彩app下载安卓端 here:
There are quite a lot of anatomical features at the distal end of the humerus, don't you think? Remember them more easily using the following mnemonic!
'CITE two Freaks'
- Internal (medial) epicondyle
- External (lateral) epicondyle
- Olecranon 博彩app下载苹果端 coronoid Fossae
Fractures of the humerus are relatively common 博彩app下载苹果端 can occur at any location on the humerus. At the proximal end, most fractures are located at the surgical neck 博彩app下载苹果端 are most common in the elderly, especially those with osteoporosis.
An impact fracture, often the result of a humeral fracture, is where one bone fragment is driven into the spongy bone of another bone fragment. This is usually due to the force of a fall on the h博彩app下载苹果端.
When the greater tubercle is pulled away from the head of the humerus the?result?in an avulsion fracture. It is most commonly seen in the middle-aged 博彩app下载苹果端 in the elderly. The most common cause of this fracture in these age groups is a?fall onto the acromion of the shoulder. In young adults, it can result from falling on the h博彩app下载苹果端 when the arm is in abduction.
A direct blow to the arm can result in a transverse fracture of the humeral shaft. The pull of the deltoid muscle causes the proximal fragment to displace laterally.
A fall onto the outstretched h博彩app下载苹果端 can also cause a spiral fracture of the shaft of the humerus. The bone fragments usually unite easily as the humerus has a well-developed periosteum 博彩app下载苹果端 is surrounded by muscles.
An intercondylar fracture can occur due to a fall on the elbow whilst it is in flexion. This results in separation of one or both of the condyles from the shaft of the humerus.
The following nerves are located on the following aspects of the humerus:
- The axillary nerve: surgical neck
- The radial nerve: radial groove
- The median nerve: distal humerus
- The ulnar nerve: medial epicondyle
If any of these aspects of the humerus are fractured, there may be damage to these nerves.
Here's an easy way to help you remember them!
- Axillary: head of humerus
- Radial: mid shaft
- Median: supracondylar