Upper Extremity AnatomyEver wondered what the differences are between us humans and animals regarding the upper limb? One of them is certainly our ability to high five each other when we ace our anatomy exam. Of course, there are many more functions and movements that our upper extremity offers to us, and this is all due to its perfect anatomy that is designed to allow a large degree of mobility.
This topic page will briefly discuss the upper extremity anatomy in order to introduce you to the main regions of the upper limb, which includes: the shoulder, arm, elbow, forearm and hand.
The shoulder is where the upper limb attaches to the trunk. Its most important part is the glenohumeral joint; formed by the humerus, scapula and clavicle. The humerus anatomy is a must-know before any discussion on the glenohumeral joint, and you can learn everything about it in our article and video tutorial:
The shoulder joint is reinforced with two groups of muscles, superficial and deep. Superficial muscles include the deltoid and the trapezius, whereas the deep group contains the supraspinatus, infraspinatus, teres minor and subscapularis (rotator cuff) muscles.
Find out everything about shoulder anatomy through our fun and engaging educational content:
The arm is the area between the shoulder and the elbow. Depending on whether you’re a gym lover or not, it may be more or less important to you. But anatomically, all parts of the arm are a must-know. There is only one bone within the arm, and that is the humerus. It is the pillar on which all the other soft tissue structures rely. The muscles are grouped into anterior and posterior compartments by the septa that attach to the humerus. The anterior compartment contains the coracobrachialis, brachialis and biceps brachii muscles. While the posterior compartment contains only one muscle, the triceps brachii.
Last but not least, is the neurovascular compartment. Every single structure of the arm is innervated by the brachial plexus, a network of nerves that originate from the C5-T1 spinal nerves. Arterial blood comes from the brachial artery, which arborizes on its way down the arm giving many branches for the supply of the structures of the arm.
The elbow is another “bridge” within the upper limb that attaches the arm and the forearm. Three bones participate in the elbow joint: the humerus, the radius and the ulna. They are shaped and attached in such a way that allows the unique forearm movement of pronation and supination. In order to understand these movements, you can find everything you need to know about elbow anatomy through this video tutorial and quiz:
Here comes the part that most students consider the hardest. The twenty muscles, and two bones (radius and ulna), of the forearm.
But don’t worry, the muscles are grouped into anterior and posterior compartments, with the anterior compartment containing mostly flexors, and the posterior, extensors. Further, each compartment has layers. The anterior compartment contains superficial, intermediate and deep layers, whilst the posterior compartment contains superficial and deep layers. We know that reading about twenty muscles, two compartments and five layers can be monotonous, so we have designed these video tutorials and quizzes to make this topic more interesting, and your life easier!
The hand is probably the finest product of human evolution from the aspect of our body mechanics. The hand anatomy enables us various movements, with the spectrum ranging from rough movements, such as smashing a mosquito, to the finest movements like playing the guitar, drawing, or writing calligraphically.
To understand how this works, let’s start with the basic parts of the hand, which are:
- the wrist (carpus)
- the metacarpus
- the digits
The bony background of the hand is very interesting. The carpus contains 8 bones, the metacarpus are comprised of 5, and the digits have 15 bones. The bones within the carpus are small, irregularly shaped, and have such curious names that you may like to choose one for your instagram account: scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate and hamate bones.
Metacarpal bones, on the other hand, are easier to remember since they are named metacarpal I to V, with metacarpal I being the ‘root’ for the thumb and metacarpal V for the pinky finger. Finally the digits are supported with three consecutively attached bones called the proximal, middle and distal phalanges, all specifically named by adding I-V at the end.
When it comes to the muscles, they are called the intrinsic muscles of the hand. Meaning they both originate and insert within the hand. This is in contrast to the ‘extrinsic’ forearm muscles that originate from the forearm, and insert into the hand. The intrinsic muscles of the hand are the: palmaris brevis, interossei (palmar and dorsal), adductor pollicis, thenar, hypothenar and lumbrical muscles. You can learn everything about them in our engaging video tutorials and then test yourself in our quiz:
As far as the neurovasculature is concerned, both arteries and nerves are continuations from the neurovascular elements of the forearm. To master this topic, watch this video tutorial and take the following quiz: