The humerus is the one bone within the arm and connects to the ulna and radius bones, that are bones within the forearm.
These three bones are situated as follows:
- Humerus: extends from the shoulder to the elbow, the place it joins the ulna and radius;
- Radius: extends from the elbow to the wrist, in the identical path because the thumb;
- Ulna: extends from the elbow to the wrist, in the identical path because the little finger.
Simply because the arms, forearms, shoulders and fingers are a part of thehigher limbs(ULs) of the human physique. The primary operate they carry out is mobility.
Bones are composed of the protein collagen, which gives power and suppleness, and the mineral calcium phosphate, which is chargeable for hardness. These are necessary traits for arm motion.
Humerus: bone of the arm
Within the anatomy of the higher limb, the humerus is the biggest bone. It’s a lengthy bone and, due to this fact, its width is larger than its width and thickness. The physique of the bone is roughly cylindrical in form.
On the prime, the humerus attaches to the scapula and types the shoulder joint.
On the decrease finish, it connects to the bones of the forearm, ulna and radius. The joint between the humerus, radius and ulna is the elbow, chargeable for primary arm actions, equivalent to bending.
The proximal (higher) finish has a rounded head and on the distal (decrease) finish it turns into flattened and extensive.
Be taught extra concerning the shoulder joints
Anatomy of the higher limbs
In whole, every higher limb has 32 bones:
- Arm bone: humerus;
- Bones of the forearm: radius and ulna;
- Bones of the hand: carpal bones (8), metacarpal bones (5) and phalanges (14):
- Bones of the shoulder girdle: clavicle and scapula.
The shoulder girdle is chargeable for connecting the higher limbs, elements of the appendicular skeleton, to the axial skeleton, which is the central area of the physique.
Learn additionally:appendicular skeleton
Different bones of the higher limbs
Along with the humerus, the arm bone and largest bone of the higher limb, try details about the opposite bones that make up the higher limb.
Forearm bones
The ulna is the biggest bone within the forearm, which has a beveled construction on the prime, a large triangular physique and turns into slender and cylindrical on the decrease finish.
It’s the smallest bone within the forearm, which has a discoid head, being slender on the proximal finish and extensive on the distal finish.
Bones of the shoulder girdle
The shoulder, additionally referred to as the shoulder girdle, is shaped by the clavicle and scapula bones. The clavicle is a bone labeled as lengthy and has a form much like an “s”.
The scapula, additionally referred to as the shoulder blade, is a bone labeled as flat and has a triangular form, which connects to the clavicle via ligaments.
The junction of those two bones, situated on the higher finish of the limb, is chargeable for connecting the arm to the trunk of the physique.
Hand bones
The hand, situated on the decrease finish of the higher limb, begins on the wrist and ends with the fingers. In whole, every hand has 27 bones.
The carpal area, the place the wrist is situated, has eight bones organized in two rows. They’re: Trapezoid, Trapezium, Scaphoid, Lunate, Triquetrum, Pisiform, Hamate and Capitate.
The metacarpus is the area of the palm of the hand and has 5 metacarpal bones, numbered from I to V ranging from the thumb.
The phalanges are the thumb, index, center, ring and auricular fingers. Every finger has proximal, center and distal phalanges. Nonetheless, solely the thumb has two phalanges, that are proximal and distal.
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