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By the end of this section, you will be able to:
  • Identify the divisions of the upper limb and describe the bones in each region
  • List the bones and bony landmarks that articulate at each joint of the upper limb

The upper limb is divided into three regions. These consist of the arm    , located between the shoulder and elbow joints; the forearm    , which is between the elbow and wrist joints; and the hand    , which is located distal to the wrist. There are 30 bones in each upper limb (see [link] ). The humerus    is the single bone of the upper arm, and the ulna    (medially) and the radius    (laterally) are the paired bones of the forearm. The base of the hand contains eight bones, each called a carpal bone    , and the palm of the hand is formed by five bones, each called a metacarpal bone    . The fingers and thumb contain a total of 14 bones, each of which is a phalanx bone of the hand    .

Humerus

The humerus is the single bone of the upper arm region ( [link] ). At its proximal end is the head of the humerus    . This is the large, round, smooth region that faces medially. The head articulates with the glenoid cavity of the scapula to form the glenohumeral (shoulder) joint. The margin of the smooth area of the head is the anatomical neck    of the humerus. Located on the lateral side of the proximal humerus is an expanded bony area called the greater tubercle    . The smaller lesser tubercle    of the humerus is found on the anterior aspect of the humerus. Both the greater and lesser tubercles serve as attachment sites for muscles that act across the shoulder joint. Passing between the greater and lesser tubercles is the narrow intertubercular groove (sulcus)    , which is also known as the bicipital groove    because it provides passage for a tendon of the biceps brachii muscle. The surgical neck    is located at the base of the expanded, proximal end of the humerus, where it joins the narrow shaft of the humerus    . The surgical neck is a common site of arm fractures. The deltoid tuberosity    is a roughened, V-shaped region located on the lateral side in the middle of the humerus shaft. As its name indicates, it is the site of attachment for the deltoid muscle.

Humerus and elbow joint

This diagram shows the bones of the upper arm and the elbow joint. The left panel shows the anterior view, and the right panel shows the posterior view.
The humerus is the single bone of the upper arm region. It articulates with the radius and ulna bones of the forearm to form the elbow joint.

Distally, the humerus becomes flattened. The prominent bony projection on the medial side is the medial epicondyle of the humerus    . The much smaller lateral epicondyle of the humerus    is found on the lateral side of the distal humerus. The roughened ridge of bone above the lateral epicondyle is the lateral supracondylar ridge    . All of these areas are attachment points for muscles that act on the forearm, wrist, and hand. The powerful grasping muscles of the anterior forearm arise from the medial epicondyle, which is thus larger and more robust than the lateral epicondyle that gives rise to the weaker posterior forearm muscles.

The distal end of the humerus has two articulation areas, which join the ulna and radius bones of the forearm to form the elbow joint    . The more medial of these areas is the trochlea    , a spindle- or pulley-shaped region (trochlea = “pulley”), which articulates with the ulna bone. Immediately lateral to the trochlea is the capitulum    (“small head”), a knob-like structure located on the anterior surface of the distal humerus. The capitulum articulates with the radius bone of the forearm. Just above these bony areas are two small depressions. These spaces accommodate the forearm bones when the elbow is fully bent (flexed). Superior to the trochlea is the coronoid fossa    , which receives the coronoid process of the ulna, and above the capitulum is the radial fossa    , which receives the head of the radius when the elbow is flexed. Similarly, the posterior humerus has the olecranon fossa    , a larger depression that receives the olecranon process of the ulna when the forearm is fully extended.

Questions & Answers

what is anatomy
Oyindarmola Reply
Anatomy is the identification and description of the structures of living things
Kamara
what's the difference between anatomy and physiology
Oyerinde Reply
Anatomy is the study of the structure of the body, while physiology is the study of the function of the body. Anatomy looks at the body's organs and systems, while physiology looks at how those organs and systems work together to keep the body functioning.
AI-Robot
what is enzymes all about?
Mohammed Reply
Enzymes are proteins that help speed up chemical reactions in our bodies. Enzymes are essential for digestion, liver function and much more. Too much or too little of a certain enzyme can cause health problems
Kamara
yes
Prince
how does the stomach protect itself from the damaging effects of HCl
Wulku Reply
little girl okay how does the stomach protect itself from the damaging effect of HCL
Wulku
it is because of the enzyme that the stomach produce that help the stomach from the damaging effect of HCL
Kamara
function of digestive system
Ali Reply
function of digestive
Ali
the diagram of the lungs
Adaeze Reply
what is the normal body temperature
Diya Reply
37 degrees selcius
Xolo
37°c
Stephanie
please why 37 degree selcius normal temperature
Mark
36.5
Simon
37°c
Iyogho
the normal temperature is 37°c or 98.6 °Fahrenheit is important for maintaining the homeostasis in the body the body regular this temperature through the process called thermoregulation which involves brain skin muscle and other organ working together to maintain stable internal temperature
Stephanie
37A c
Wulku
what is anaemia
Diya Reply
anaemia is the decrease in RBC count hemoglobin count and PVC count
Eniola
what is the pH of the vagina
Diya Reply
how does Lysin attack pathogens
Diya
acid
Mary
I information on anatomy position and digestive system and there enzyme
Elisha Reply
anatomy of the female external genitalia
Muhammad Reply
Organ Systems Of The Human Body (Continued) Organ Systems Of The Human Body (Continued)
Theophilus Reply
what's lochia albra
Kizito
what are the layers of the skin
Helen Reply
It is made up of three layers, the epidermis, dermis, and the hypodermis, all three of which vary significantly in their anatomy and function. The skin's structure is made up of an intricate network which serves as the body's initial barrier against pathogens, UV light, and chemicals, and mechanical
Omer
what is diabetes?
Ifeoluwa
Diabetes is a chronic (long-lasting) health condition that affects how your body turns food into energy. Your body breaks down most of the food you eat into sugar (glucose) and releases it into your bloodstream. When your blood sugar goes up, it signals your pancreas to release insulin. Insulin act
Omer
what is gastric lavage and their implications
Ifeoluwa
what is velium
chizzy
what is a purpose
chizzy
what's fibroid
Kizito
what are disorders of connective tissue
Ester Reply
Rheumatoid arthritis (RA) Scleroderma. Granulomatosis with polyangiitis (GPA) Churg-Strauss syndrome. Lupus. Microscopic polyangiitis. Polymyositis/dermatomyositis. Marfan syndrome.
Omer
arthritis vasculitis
Enitan
what is cardiac output
Okoye Reply
(CO) amount of blood pumped by each ventricle during one minute; equals HR multiplied by SV
AI-Robot
what is SV and HR stand for
David
SV- Stroke Volume HR- Heart Rate
Ebelechukwu
Cardiac output is the amount of blood pumped by the heart in one minute. It's calculated by multiplying the heart rate (the number of times the heart beats in one minute) by the stroke volume (the amount of blood pumped out by the heart with each beat). So, cardiac output = heart rate x stroke volum
Dickson

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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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