Appendicular Skeleton
இணையுறுப்பு எலும்புக்கூடு
The glenoid cavity is on the scapula and holds the head of the humerus — that is your shoulder joint. The acromion is the flat end of the scapula's spine that forms the point of the shoulder.
The idea
The bones of the limbs along with their girdles constitute the appendicular skeleton. Each limb is made of 30 bones. The bones of the hand (fore limb) are humerus, radius and ulna, carpals (wrist bones, 8 in number), metacarpals (palm bones, 5) and phalanges (digits, 14). Femur (thigh bone, the longest bone), tibia and fibula, tarsals (ankle bones, 7), metatarsals (5) and phalanges (digits, 14) are the bones of the leg (hind limb); a cup-shaped bone called the patella covers the knee ventrally (knee cap). Pectoral and pelvic girdle bones help in the articulation of the upper and lower limbs respectively with the axial skeleton. Each girdle is formed of two halves. Each half of the pectoral girdle consists of a clavicle and a scapula. The scapula is a large triangular flat bone situated in the dorsal part of the thorax between the second and the seventh ribs; its dorsal flat triangular body has a slightly elevated ridge called the spine, which projects as a flat expanded process called the acromion. The clavicle articulates with the acromion. Below the acromion is a depression called the glenoid cavity, which articulates with the head of the humerus to form the shoulder joint. Each clavicle is a long slender bone with two curvatures, commonly called the collar bone. The pelvic girdle consists of two coxal bones, each formed by the fusion of three bones — ilium, ischium and pubis; at the point of fusion is a cavity called the acetabulum, to which the thigh bone articulates. The two halves of the pelvic girdle meet ventrally to form the pubic symphysis containing fibrous cartilage.
Why it matters
Girdles anchor the limbs to the trunk so that limb muscles have a firm base to pull against during walking, lifting and throwing.
NEET lens
Counts: 30 bones per limb; carpals 8, metacarpals 5, phalanges 14; tarsals 7, metatarsals 5, phalanges 14; patella = knee cap; femur = longest bone. Pectoral girdle: clavicle + scapula (between 2nd and 7th ribs); acromion = flat expanded process of the spine of scapula, articulates with clavicle; glenoid cavity articulates with head of humerus (shoulder joint). Pelvic girdle: coxal bone = ilium + ischium + pubis; acetabulum receives femur; pubic symphysis has fibrous cartilage.
Clinical significance
The clavicle is one of the most commonly fractured bones in falls on an outstretched hand. Hip fractures at the neck of the femur, common in elderly people with osteoporosis, need surgery to restore walking.
Introduction
The appendicular skeleton (126 bones) is made of the limb bones and the pectoral and pelvic girdles that attach the limbs to the axial skeleton.
Core concept
Fore limb (30): humerus, radius, ulna, carpals 8, metacarpals 5, phalanges 14. Hind limb (30): femur (longest), tibia, fibula, tarsals 7, metatarsals 5, phalanges 14, patella (knee cap). Pectoral girdle (each half): clavicle (collar bone, two curvatures) + scapula (large triangular flat bone, dorsal thorax between 2nd and 7th ribs; spine → acromion; clavicle articulates with acromion; glenoid cavity below acromion articulates with head of humerus → shoulder joint). Pelvic girdle: two coxal bones, each = ilium + ischium + pubis fused; acetabulum (cavity) receives the femur; two halves meet ventrally at the pubic symphysis (fibrous cartilage).
Go deeper
Scapula is a flat bone — the same category as the cranial bones and the sternum. Floating ribs belong to the axial skeleton, not the appendicular.
From Class 10
You know your arm has a humerus and your thigh a femur. NEET adds the girdles and the exact joints they form.