Human Anatomy Lecture 3

Appendicular Skeleton

• The appendicular skeleton's primary function is movement, comprising bones of the upper and lower limbs and girdles that attach them to the axial skeleton.

Upper Limb

• The skeleton of the upper limb consists of:
• Shoulder girdle (clavicle, scapula)
• Arm (humerus)
• Forearm (radius, ulna)
• Bones of the hand (carpal, metacarpal, phalanges)

Pectoral Girdle

• The pectoral girdle consists of 2 clavicles and 2 scapulae.
• It provides attachment for many muscles that move the upper limb.
• The girdle is light and mobile, with only the clavicle articulating with the axial skeleton.

Clavicle

• The clavicle provides attachment for muscles and holds the scapulae and arms laterally.
• It transmits compression forces from the upper limbs to the axial skeleton.
• The clavicle has two ends: lateral (joins the scapula) and medial (articulates with the manubrium and first rib).

Scapula

• The scapula has a costal surface and a dorsal surface divided into supra-spinatus and infra-spinatus fossae.
• The scapula has three angles: superior, lateral (glenoid cavity), and inferior.

Humerus

• The humerus is the largest bone in the upper limb, articulating superiorly with the scapula and inferiorly with the radius and ulna.
• It has upper and lower ends and a shaft.

Lower Limbs

• The bones of the lower limb consist of:
• Femur (thigh)
• Tibia and fibula (leg)
• Tarsals (ankle)
• Metatarsals (foot)
• Phalanges (toes)

Pelvic Girdle

• The pelvic girdle consists of paired hip bones, which unite anteriorly at the symphysis pubis and articulate posteriorly with the sacrum.
• The bony pelvis is formed by the hip bones, sacrum, and coccyx.

True and False Pelves

• The bony pelvis is divided into the false (greater) pelvis and the true (lesser) pelvis, which forms a bowl containing the pelvic organs.

Hip Bone

• The hip bone is composed of the ilium, ischium, and pubis.
• The acetabulum is a deep hemispherical socket on the lateral pelvic surface.

Sex Differences of the Pelvis

• The pelvic inlet is oval in females and heart-shaped in males due to the sacral promontory.
• The ischial spines do not project medially into the pelvis in females as they do in males.
• The pubic angle is 80-90 degrees in females and 50-60 degrees in males.

Lower Limb

• The lower limb carries the entire weight of the erect body.
• The bones of the lower limb are thicker and stronger than those of the upper limb.
• The lower limb is divided into three segments: thigh, leg, and foot.

Femur

• The femur is the largest and strongest bone in the body.

Radius and Ulna

• The radius and ulna form the forearm.
• The radius articulates with the capitulum and radial notch of the ulna.
• The radius contributes heavily to the wrist joint and distal radius articulates with the carpal bones.

Hand

• The hand consists of:
• Carpus (wrist)
• Metacarpus (palm)
• Phalanges (fingers)

Carpus

• The carpus forms the true wrist, allowing gliding movements between carpals.
• It is composed of eight marble-sized bones.

Metacarpus

• The metacarpus forms the palm, with five metacarpals radiating distally from the wrist.
• Metacarpals articulate proximally with the distal row of carpals and distally with the proximal phalanges.

Phalanges

• There are 14 phalanges in each hand, with each digit having three phalanges (proximal, middle, and distal) except for the thumb.