Classification of skeleton: Appendicular-1

Appendicular Skeleton

The shoulder girdle, which houses the upper limbs, and the pelvic girdle, which houses the lower limbs, make up the appendicular skeleton.

Upper Extremities

The axial skeleton connects and supports the 64 bones that make up the bones of the upper extremities. The upper extremity can also be divided into the following four groups:

• Shoulder girdle or pectoral girdle
• Fore arm
• Arm
• Hand

Shoulder (Pectoral) Girdle

• The arm is supported by the shoulder girdle. There are two scapula and two clavicles in it. The upper extremity bones are joined to the axial skeleton by the shoulder girdles. They serve as points of attachment for numerous muscles.
  • Clavicle (Collar Bone)
    • The long, thin bone is the clavicle. It has a shaft in the center and two ends on the periphery: an acromial end and sternal end, respectively (laterally). The sterno-clavicular joint is created when the sternal end articulates with the sternum's manubrium. Together with the acromion process of the scapula, the acromial end creates the acrominoclavicular joint. The only bone connection between the axial skeleton and the upper limbs is the clavicle. It is the first bone to osseously begin. The only long bone that is horizontal and is referred to as the "beauty bone" is this one.
  • Scapula (Shoulder Blade)
    • The second to seventh ribs are covered by the scapula, a flat, triangular-shaped bone. The scapula is located on the upper back, above the ribs and connected to them via muscles on the posterior chest wall. The superior, medial (vertebral), and lateral (axillary) boundaries are the three sides of the triangle. The spine, a transverse ridge on the posterior surface, extends past the scapula's lateral border and hangs over the glenoid cavity. The acromian process is the name given to the prominent overhangs that can be felt through the skin as the shoulder's highest point. The acrominoclavicular joint, formed by the acromian process and the clavicle, aids in the mobility of the shoulder girdle. Muscles that move the shoulder joint are attached to the bone by a projection called the coracoids process.

Arm

• The bone in the arm is called the humerus. From the shoulder to the elbow, it reaches. The upper extremity's largest bone is this one. The glenohumeral joint is formed by the proximal end of the humerus, which has a rounded head, articulating with the glenoid cavity of the scapula. Greater and smaller tubercles are two rough protrusion that are located close to the head. The term "anatomical neck" refers to the tissue that divides the head from the tubercles. The biceps muscle tendons occupy the intertubercular groove (Sulcus or bicipital groove), which divides the lesser tubercle from the greater tubercle. Because it is the most frequently fractured location of the proximal end of the humerus, the line dividing the upper end from the shaft is known as the surgical neck. The radial groove for the radial nerve is located posteriorly, whereas the deltoid tuberosity is located laterally for attachment of the deltoid muscle. The majority of the forearm muscles attach distally to the medial and lateral epicondyles, which are two rough prominences. The capitulum, trochlea, olecranon fossa, coronoid fossa, and radial fossa are all parts of the humeral condyle.

Fore Arm

• The two bones that make up the forearm are the ulna and the radius. The radius is medial to the ulna. The two bones are parallel when the forearm is in its natural posture, which is with the palm of the hand facing forward. They link together at the elbow joint with the humerus and the wrist joint with the carpal bones. The superior and inner radio-ulnar joints are formed by how they also articulate with one another. The interosseous membrane is a ligament that connects the shafts of the radius and ulna. Ulna: The medial and longer of the two forearm bones, the ulna serves as the forearm's stabilizing bone. Olecranon process, located posteriorly on the top end of the ulna, and coronoid process, located anteriorly, both resemble beaks. The trachlea of the humerus is encircled by the semilunar trochlear notch created between the two processes. The ulna's shaft is thick and cylindrical at its proximal end, but as it extends distally, it tapers and loses diameter. The disc-like head of the ulna with a conical ulnar styloid process is a small but abrupt enlargement at the distal end of the ulna. The wrist joint does not involve the ulna.
  • Radius
    • The shorter and more lateral of the two forearm bones is the radius. A short head, neck, and medially oriented tuberosity are seen on its proximal end. Disc-like head articulates with humeral capitulum. In contrast to the ulna, the radius' shaft enlarges gradually as it moves distally. The medial side of the distal end develops an ulnar notch. The radius has a styloid process on the side. The brachioradialis muscle and ligament are attached to the wrist by the styloid process.

Hand

• The carpal or wrist bones, metacarpal bones, and phalanges are the bones of the hand.
  • Carpal Bones
    • Eight carpal bones are located in two rows, each with four bones. They shape the wrist. They are, going inward from the outside:
      • Scaphoid, lunate, triquetrum, and posiform are in the proximal row.
      • Trapezium, trapezoid, capitate, and hamate in the distal row.

There is only a small amount of movement between the bones because they are tightly fitted together and held in place by ligament. The wrist can move up and down as well as side to side thanks to these short bones.

• Metacarpal Bone
  • The skeletal anatomy of the palm of the hand is composed of 5 metacarpal bones. From the thumb side inwards, they are numbered. The distal end connects to the phalanges, while the proximal ends connect to the carpal bones.
• Phalanges/Finger Bone
  • Three phalanges are present in each finger and two in the thumb, totaling 14 phalanges. Proximal, middle, and distal phalanges are the names given to them. By means of hinge joints, they articulate with the metacarpal bones and with one another. Fingers are able to participate in secure grips thanks to these bones.

Lower Extremities

There are 62 bones in the lower extremities. The hip girdle connects it to the axial skeleton. The following groups can be used to categorize the bones in the lower extremities.

• Hip bone (pelvic girdle)
• Leg
• Thigh
• Foot

Hip Bone (Pelvic Girdle)

• The sacrum and two innominate (hip) bones together make up the pelvic girdle. The basin-like structure is known as the pelvis. The viscera of the pelvic cavity are shielded by the pelvic girdle, which also supports the trunk on the legs.
  • Innominate Bone
    • The ileum, ischium, and pubis are the three fused bones that make up each hip bone. The acetabulum, which fits the head of the femurs, has these three bones fused together.
  • Ilium
    • The largest, uppermost, flattened portion of the hip bone is called the ilium. It creates the hip's apex, which is a broad, extended prominence. It is made up of a lower body and a superior ala (using). The pubis and ischium are joined by the body of the ilium to form the acetabulum. Strong anterior superior and anterior inferior iliac spines on the ilium's anterior surface serve as attachment points for the ligaments and tendons of lower limb muscles. The long, curved, and thickened superior border of the ala of the ilium, or the iliac crest, runs posteriorly from the anterior superior iliac spine (ASIS) and terminates at the posterior superior iliac spine (PSIS). The crest functions as a protective "bumper" and is a crucial location for the aponeurotic attachment of deep fascia and thin, sheet-like muscles. The iliac tubercle, a protrusion on the iliac crest's external lip, is located 5–6 cm posterior to the ASIS. The greater sciatic notch's superior end is marked by the posterior inferior iliac spine.
  • Ischium
    • The lowest and sturdiest part is called the ischium. It descends from the acetabulum and enlarges into the ischial tuberosity, a substantial tuberosity that supports the body when seated. The ischiopubic ramus, a bone bar that forms the inferomedial boundary of the obturator foramen, is formed when the inferior ramus of the pubis and the ramus of the ischium join. At the inferior edge of this notch, a large, triangular ischial spine provides. ligamentous affixation
  • Pubis
    • The hip bone's anterior section is known as the pubis. Its body is triangular and features superior and inferior rami. At the pubic symphysis, the bodies of the two pubic bones meet. The obturator foramen is formed by the pubis and ischium.