The humerus (/ˈhjuːmərəs/; pl.: humeri) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a rounded head, a narrow neck, and two short processes (tubercles, sometimes called tuberosities). The shaft is cylindrical in its upper portion, and more prismatic below. The lower extremity consists of 2 epicondyles, 2 processes (trochlea and capitulum), and 3 fossae (radial fossa, coronoid fossa, and olecranon fossa). As well as its true anatomical neck, the constriction below the greater and lesser tubercles of the humerus is referred to as its surgical neck due to its tendency to fracture, thus often becoming the focus of surgeons.
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👉 Humerus in the context of Coracoid
A coracoid is a paired bone which is part of the shoulder assembly in all vertebrates except therian mammals (marsupials and placentals). In therian mammals (including humans), a coracoid process is present as part of the scapula, but this is not homologous with the coracoid bone of most other vertebrates.
In other tetrapods, it joins the scapula to the front end of the sternum and has a notch on the dorsal surface which, along with a similar notch on the ventral surface of the scapula, forms the socket in which the proximal end of the humerus (upper arm bone) is located. The acrocoracoid process is an expansion adjacent to this contact surface, to which the shoulderward end of the biceps brachii muscle attaches in these animals. In birds (and generally theropods and related animals), the entire unit is rigid and called scapulocoracoid. This plays a major role in bird flight. In other dinosaurs, the main bones of the pectoral girdle were the scapula (shoulder blade) and the coracoid, both of which directly articulated with the clavicle.
- ⭐ Core Definition: Humerus
- 👉 Humerus in the context of Coracoid
- Humerus in the context of Scapula
- Humerus in the context of Plantigrade
- Humerus in the context of Shoulder
- Humerus in the context of Elbow
- Humerus in the context of Glenohumeral joint
- Humerus in the context of Long bone
- Humerus in the context of Scapulocoracoid
Humerus in the context of Scapula
The scapula (pl.: scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on either side of the body being roughly a mirror image of the other. The name derives from the Classical Latin word for trowel or small shovel, which it was thought to resemble.
In compound terms, the prefix omo- is used for the shoulder blade in medical terminology. This prefix is derived from ὦμος (ōmos), the Ancient Greek word for shoulder, and is cognate with the Latin (h)umerus, which in Latin signifies either the shoulder or the upper arm bone.
Humerus in the context of Plantigrade
In terrestrial animals, plantigrade locomotion means walking with the toes and metatarsals flat on the ground. It is one of three forms of locomotion adopted by terrestrial mammals. The other options are digitigrade, walking on the toes and fingers with the heel and wrist permanently raised, and unguligrade, walking on the nail or nails of the toes (the hoof) with the heel/wrist and the digits permanently raised. The leg of a plantigrade mammal includes the bones of the upper leg (femur/humerus) and lower leg (tibia and fibula/radius and ulna). The leg of a digitigrade mammal also includes the metatarsals/metacarpals, the bones that in a human compose the arch of the foot and the palm of the hand. The leg of an unguligrade mammal also includes the phalanges, the finger and toe bones.
Among extinct animals, most early mammals such as pantodonts were plantigrade. A plantigrade foot is the primitive condition for mammals; digitigrade and unguligrade locomotion evolved later. Among archosaurs, the pterosaurs were partially plantigrade and walked on the whole of the hind foot and the fingers of the hand-wing. Out of the plantigrade animals, only a few, such as humans, kangaroos and certain rodents, are obligate bipeds, while most others are functional bipeds.
Humerus in the context of Shoulder
The human shoulder is made up of three bones: the clavicle (collarbone), the scapula (shoulder blade), and the humerus (upper arm bone) as well as associated muscles, ligaments and tendons.
The articulations between the bones of the shoulder make up the shoulder joints. The shoulder joint, also known as the glenohumeral joint, is the major joint of the shoulder, but can more broadly include the acromioclavicular joint.
Humerus in the context of Elbow
The elbow is the region between the upper arm and the forearm that surrounds the elbow joint. The elbow includes prominent landmarks such as the olecranon, the cubital fossa (also called the chelidon, or the elbow pit), and the lateral and the medial epicondyles of the humerus. The elbow joint is a hinge joint between the arm and the forearm; more specifically between the humerus in the upper arm and the radius and ulna in the forearm which allows the forearm and hand to be moved towards and away from the body.The term elbow is specifically used for humans and other primates, and in other vertebrates it is not used. In those cases, forelimb plus joint is used.
The name for the elbow in Latin is cubitus, and so the word cubital is used in some elbow-related terms, as in cubital nodes for example.
Humerus in the context of Glenohumeral joint
The shoulder joint (or glenohumeral joint from Greek glene, eyeball, + -oid, 'form of', + Latin humerus, shoulder) is structurally classified as a synovial ball-and-socket joint and functionally as a diarthrosis and multiaxial joint. It involves an articulation between the glenoid fossa of the scapula (shoulder blade) and the head of the humerus (upper arm bone). Due to the very loose joint capsule, it gives a limited interface of the humerus and scapula and is the most mobile joint of the human body.
Humerus in the context of Long bone
The long bones are those that are longer than they are wide. They are one of five types of bones: long, short, flat, irregular and sesamoid. Long bones, especially the femur and tibia, are subjected to most of the load during daily activities and they are crucial for skeletal mobility. They grow primarily by elongation of the diaphysis, with an epiphysis at each end of the growing bone. The ends of epiphyses are covered with hyaline cartilage ("articular cartilage"). The longitudinal growth of long bones is a result of endochondral ossification at the epiphyseal plate. Bone growth in length is stimulated by the production of growth hormone (GH), a secretion of the anterior lobe of the pituitary gland.
The long bone category includes the femora, tibiae, and fibulae of the legs; the humeri, radii, and ulnae of the arms; metacarpals and metatarsals of the hands and feet, the phalanges of the fingers and toes, and the clavicles or collar bones. The long bones of the human leg make up nearly half of adult height. The other primary skeletal component of height are the vertebrae and skull.
Humerus in the context of Scapulocoracoid
The scapulocoracoid is the unit of the pectoral girdle that contains the coracoid and scapula.The coracoid itself is a beak-shaped bone that is commonly found in most vertebrates with a few exceptions.The scapula is commonly known as the shoulder blade. The humerus is linked to the body via the scapula, and the clavicle is connected to the sternum via the scapula as well.
Therian mammals lack a scapulocoracoid.