Hand bones: A delicate bone structure

Hands are an extremely important part of the human body. Indeed, the hand performs simple operations such as grasping a large object. However, in addition, the hand also undertakes activities that require sophistication such as holding a pen to write, opposing thumbs. It is also the site of much sensory feedback to the body. So how is the hand structured to take on such a delicate function? All will be answered in the following article.

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• 1. Position of the hand
• 2. Structure of the hand
• 3. Hand skeletal system
• 4. Wrist bone mass
• 5. Hand bones
• 6. Finger bones
• 7. Sesame bone
• 8. Joints in the hand
• 9. Function of the hand

1. Position of the hand

Apparently, the hand is at the end of an arm. As for the limit, the hand goes from the furthest wrist crease to the tips of the fingers. The hand is divided into two parts: palm and back of hand. When the hand is cupped inward, it is called the palm, and the outside is called the back of the hand.

2. Structure of the hand

A hand has 5 fingers, each finger has its own name to distinguish it

• The thumb is also known as the I finger. This is the first finger from right to left when the palm is up or from left to right when the palm is facing down. As the name suggests, the thumb has the largest diameter of the 5 fingers.
• The index finger, also known as the second finger, is the next finger of the thumb.
• The middle finger, or third finger, is the finger located in the middle of the five fingers. This is the next finger of the index finger.
• The little finger, or the fourth finger, is the finger next to the middle finger. In life, we often call it by another familiar name that is ring finger.
• The little finger is the V finger, the last finger of the hand. As the name implies, this is the smallest of the 5 fingers.

Of the five fingers, the thumb is the one with the largest range of motion and the most delicate. Excluding the thumb, the remaining 4 fingers can grasp objects in the palm of the hand. However, only the thumb can perform the opposite finger movements. Therefore, the thumb plays an important role in the delicate movements of the hand.

See also: Structure and function of the hand.

3. Hand skeletal system

The musculoskeletal system of the hand is very complex and delicate. You know, in humans, each hand has 27 bones. In particular, the wrist bone has 8 bones, the hand bone has 5 bones, and the 5 fingers have a total of 14 bones. Let's find out in detail how these bones are structured!

Model illustration of bones in the hand.

4. Wrist bone mass

The wrist bones are the bones that connect the bones of the forearm and hand. There are 8 bones in all, arranged in two rows: upper and lower rows, equally divided into 4 rows each. From the outside to the inside, there are 4 bones in the upper row: the clavicle, the lunate, the pyramid, and the pea. The lower row consists of 4 bones: trapezius, corpus callosum, fibula, and hook bone. These bones are fastened together into a deep socket and by complex systems of ligaments.

When flexing the hand, the 4 bones of the upper row join the bones of the forearm. Meanwhile, the 4 bones of the lower row follow the knuckles of the hand and fold into the 4 bones of the upper row.

In general, each bone has 6 faces. There are disjoint faces, that is, the back of the hand and the palm of the hand. The remaining faces abut the bones above, below or beside it.

In general, the bones of the wrist can be compared to a ball bearing located between the two bones of the forearm and the five bones of the hand. So the wrist is moved in a flexible and soft way. The wrist bones are less likely to break. However, when fracture is usually in the isthmus of the clavicle or dislocation of the lunate.

Illustration of the bones of the wrist, palm, and back of the hand.

5. Hand bones

The hand bone mass consists of 5 long bones, numbered according to the number of the fingers, going from I to V. The first metacarpal bone begins in the thumb. Knuckle bones II, III, IV, V in the index, middle, ring, and little bones, respectively. Each skeleton has three faces: inner, outer, and posterior. Corresponds to 3 banks: inner, outer and posterior. The upper end of the bone is called the base, the lower end is the crest.

Body slightly curved anteriorly, triangular prism with 1 posterior and 2 lateral faces. Thus adapting the palm to the grip function. The bony base has an articulating interface with the bones of the wrist. Meanwhile, the crest is spherical in shape, to match the proximal base of the fingers.

6. Finger bones

Each finger has 3 vertebrae: proximal, middle and distal in the order from the knuckles down. Except for the thumb, there are only two segments: the proximal and the distal. Similar to the bones of the hand, each knuckle has 3 parts: base, body and tip.

6.1. Proximal knuckles

Body slightly bent forward. There are two sides: the front is flat, the back is more round. The base is in the form of a concave joint, articulating with the crest of the knuckle of the hand. Meanwhile, the crest is below, abutting to the medial base.

6.2. Middle finger knuckle

The body is curved like a proximal segment, has two faces. Pulley-shaped base, matched with proximal vertebrae. The inferior tip abuts the base of the distal vertebrae.

6.3. Distal knuckles

The body of the distal knuckle is very small. The base articulates with the tip of the middle knuckle. Horseshoe-shaped crest, smooth back, rough front.

The knuckles as well as the bones of the hand are very fragile. Because they are located just under the skin of the back of the hand, which is often used for cover. When broken, these bones are prone to angulation, displacement, reduction or loss of flexion and extension of the fingers. And it is possible to make the fingers overlap when the hand is closed.

Illustration of bony regions of the hand.

7. Sesame bone

This is a small, round or oval bone. They are usually located around joints or in tendons. With the role of increasing the firmness of joints and strength of tendons. In the hand, there is only sesamoid bone around the joint. The sesamoid bone is often seen in the knuckles - fingers, fingers - fingers. The thumb always has two sesamoid bones on either side of the metatarsal joint.

8. Joints in the hand

We have just covered the basic skeletal structures in the hand region. Obviously, the hand area is small but has a very large number of bones. So, in order to have a soft, delicate hand movement, these bones need to be perfectly articulated. Thanks to the joints, our hands can grasp and release, operate flexibly, and perform sophisticated gestures with ease. Let's learn about the joints in the hand area.

8.1. Interphalangeal joints

The interphalangeal joint is also known as the interphalangeal joint. These are the joints between the fingers. Each finger has two different interdigital joints. The proximal interphalangeal joint connects the proximal and distal vertebrae. Similarly, the distal interphalangeal joint connects the medial and distal vertebrae.

 The thumb has only one joint, because the thumb has only two knuckles. These are hinge joints, they allow movement in one plane. Mainly flexing and stretching movements. Both sides are made very strong by ligaments, so they are limited by other movements.

8.2. Hand-finger joint

The joint that connects the bones of the hand to the bones in the fingers. The knuckles of the four fingers on the hand except the thumb are convex joints. While the knuckle joint is a hinge joint.

8.3. Wrist intervertebral joint

Are joints present between the bones of the wrist

8.4. Wrist-hand joint

The joints between the bones of the wrist and hand.

8.5. Wrist rotator

It is the joint between the lower face of the lower head of the radial bone (the radial bone is one of the 2 bones of the forearm) and the bones of the wrist. The lower surface of the lower head of the radial bone is a triangular articular cavity, in the middle there is a small ridge dividing the cavity into two faces. The outer surface of the triangle abuts the shinbone. Meanwhile, the inner face is quadrangle, abutting the lunate bone.

The wrist rotator cuff is mainly a flexion and extension movement. With a folding amplitude of about 90o, and stretching about 60o. In addition, it can be closed at 45° and 30° form. Wrist is more flexed than extended and more adducted than flexed. Therefore, the bones of the wrist are close together when extended and flexed, and loose when flexed and closed.

Illustration of the mandibular rotator cuff and the wrist and hand joints.

9. Function of the hand

The main function of the hand is to grasp objects as well as to perform delicate operations. For example, holding a pen, writing, drawing, pinching fingers to pick up a coin... Things seem very simple in life, but it is a delicate and meticulous process that nature bestows on the table. hand.

Fingerprints are used to identify an individual.

In addition, each of us has a difference in the palm of our hand. In the palm of the hand there are palm lines. The presence of palm lines has a role to help people's activities when holding objects better. And the skin on the underside of the fingertips has fingerprints, which is a very special area. Fingerprints are a mark like no other. So it is used to identify each person.

Palm color is also important. Normally the palm is bright pink. Pale palms may be related to anemia. Or yellow palms can signal liver disease. Or lipstick palms can signal cirrhosis of the liver.

The shape and color of the fingers not only have an aesthetic role, but it also has a predictive role for your health. For example, normally fingernails are ruddy, but in cases of iron deficiency anemia, we see pale nails.

See also:  Abnormalities of toenails .

Palm color can predict your health status.

Thus, we have learned interesting information about the structure and characteristics of the bones of the hand. Hands play an important role in human activities. Therefore, understanding the structure of our hands will better protect it. Hope readers have had useful knowledge from the article. Thank you for always accompanying SignsSymptomsList!

Doctor Nguyen Thanh Xuan