Appendicular Skeleton[1]
The appendicular skeleton includes the upper and lower limbs (i.e., the arms and legs) and includes the bones that attach each limb to the axial skeleton. Refer back to Figure 6.19 in Section 6.4 for an illustration of the appendicular skeleton.
Bones of the Upper Limbs
The bones of the upper limbs include the bones of the arms, wrists, and hands. The shoulder attaches the upper limbs to the axial skeleton. See Figure 6.38 for an illustration of the bones of the upper limbs.
Figure 6.38 Bones of the Upper Limbs (“Human_arm_bones_diagram.svg” by LadyofHats Mariana Ruiz Villarreal is licensed in the Public Domain.)
Bones of The Shoulder (Pectoral Girdle)
The shoulder connects the arms to the axial skeleton, forming the pectoral girdle. The bones of the pectoral girdle include the following:
- Clavicle: The bone connecting the sternum to the scapula, also known as the collarbone
- Scapula: The bone commonly known as the shoulder blade
- Acromion: A bony extension from the scapula that forms the highest superior point or “tip” of the shoulder
See Figure 6.39 for a detailed illustration of the bones of the pectoral girdle.
Figure 6.39 Pectoral Girdle (Source: Figure 8.3 in https://openstax.org/books/anatomy-and-physiology-2e/pages/8-1-the-pectoral-girdle)
A:”802_Pectoral_Girdle” by OpenStax College is licensed under CC BY 3.0
Bones of the Arms
There are three bones in each arm including the following:
- Humerus: The upper arm bone.
- Radius: The bone on the lateral or thumb side of the forearm.
- Ulna: The bone on the medial or pinky finger side of the forearm.
Bones of the Wrists and Hands
The bones of the hand and wrist include the carpals, metacarpals, and phalanges:
- Carpals: There are eight carpal bones that make up the wrist bones. They are the scaphoid, lunate, triquetrum (triangular), pisiform, trapezium, trapezoid, hamate and capitate.
- Metacarpals: A group of five bones making up the palm of hand.
- Phalanges: The 14 bones that make up the fingers (and toes). A single finger bone is called a phalanx. Each finger (except the thumb) is composed of three bones: the distal phalanx, middle or intermediate phalanx, and proximal phalanx. The exception is the thumb, which only has two bones, the distal and proximal phalanges.
See Figure 6.40 for a detailed illustration of the bones of the wrist, hand, and fingers.
Figure 6.40 Bones of the Hand, Wrist, and Fingers (“806_Hand_and_Wrist.jpg” by OpenStax College is licensed under CC BY 3.0)
A:”806_Hand_and_Wrist” by OpenStax College is licensed under CC BY 3.0
Bones of the Lower Limbs
The pelvic girdle (hip and pelvis) attaches the lower limbs to the axial skeleton. The bones of the lower limb include bones of the legs and the feet.
Bones of the Hip and Pelvis
The hip serves as the attachment point for each lower limb at the acetabulum, the large cup-like socket that holds the head of the femur. Each adult hip bone is formed by three separate pelvic bones, the ilium, ischium, and pubis, that fuse together during the late teenage years:
- Ilium: The ilium is the superior region that forms the largest part of the hip bone. It is attached to the sacrum at the sacroiliac joint. If you place your hands on your hips, you can feel the curved, superior margin of the ilium, which is the iliac crest.
- Ischium: The ischium forms the inferior region of each hip bone and supports the body when sitting.
- Pubis (or pubic bone): The pubis forms the anterior (front) portion of the hip. The pubis curves medially, where it joins to the pubis of the opposite hip bone at a specialized joint called the pubic symphysis.
See Figure 6.43 for an illustration of the hip and pelvis.
Figure 6.43 Bones of the Hip and Pelvis (Pelvic Girdle) (Source: “Pelvic_girdle_illustration.svg” by U.S. National Cancer Institute is licensed under CC BY-SA 4.0)
The pelvis refers to the entire structure formed by the hip bones, the sacrum, and the coccyx. See Figure 6.44 for an illustration of the pelvis.
Figure 6.44 Pelvis (“807_Pelvis.jpg” by OpenStax College is licensed under CC BY 3.0)
The shape of the pelvis is different for males and females. In general, the bones of the male pelvis are thicker and heavier because they have adapted to support a male’s typically heavier physical build. Because the female pelvis has adapted for childbirth, it is wider than the male pelvis. The shape and size of the pelvis can be used during forensic assessment to identify if skeletal remains are male or female. See Figure 6.45 for a comparison of the female and male pelvis.
Figure 6.45 Comparison of the Female and Male Pelvis (Source: https://openstax.org/books/anatomy-and-physiology-2e/pages/8-3-the-pelvic-girdle-and-pelvis)
A:”809_Male_Female_Pelvic_Girdle” by OpenStax College is licensed under CC BY 3.0
See Table 6.6 for an overview of the differences between the female and male pelvis.
Table 6.6 Overview of Differences between the Female and Male Pelvis[2]
| Female Pelvis | Male Pelvis | |
| Pelvic Weight | Bones of the pelvis are lighter and thinner | Bones of the pelvis are thicker and heavier |
| Pelvic Inlet Shape | Pelvic inlet has a round or oval shape | Pelvic inlet is heart-shaped |
| Subpubic Angle | Subpubic angle is greater than 80 degrees | Subpubic angle is less than 70 degrees |
| Pelvic Outlet Shape | Pelvic outlet is rounded and larger | Pelvic outlet is smaller |
Bones of the Leg
The bones of the leg include the femur, patella, tibia and fibula.
Femur
The femur, or thigh bone, is the single bone of the upper leg. It is the longest and strongest bone of the body, and accounts for approximately one-quarter of a person’s total height.
Some features of the proximal femur include the following:
- Femoral head: The rounded, proximal end is the head of the femur, which articulates with the acetabulum (hip socket) of the pelvis to form the hip joint.
- Femoral neck: The narrowed region below the head is the neck of the femur, which is a common area for fractures.
- Greater trochanter: The greater trochanter is the large, upward, bony projection located above the base of the neck. The greater trochanter can be felt just under the skin on the lateral side of your upper thigh.
- Lesser trochanter: The lesser trochanter is a small, bony prominence that lies on the medial side of the femur, just below the neck.
Some features of the distal femur include the following:
- Lateral condyle: The smooth surface that forms the distal and posterior sides of the lateral expansion of the distal femur.
- Lateral epicondyle: The rough area on the outer, lateral side of the lateral condyle.
- Medial condyle: The smooth, articulating surface that forms the distal and posterior sides of the medial expansion of the distal femur.
- Medial epicondyle: A roughened area of the distal femur located on the medial side of the medial condyle.
- Patellar surface: A smooth groove located on the anterior side of the distal femur, between the medial and lateral condyles that is the site of articulation for the patella.
See Figure 6.41 for an illustration of the femur and its features.
Figure 6.41 Femur and Its Features (Source: Figure 8.16 at https://openstax.org/books/anatomy-and-physiology-2e/pages/8-4-bones-of-the-lower-limb#fig-ch08_04_01)
A:”810_Femur_and_Patella” by OpenStax College is licensed under CC BY 3.0
Patella
The patella is a small, sesamoid bone located in the anterior knee, commonly referred to as the kneecap.
Tibia
The tibia is the medial bone of the lower leg, commonly called the shin bone, and the main weight-bearing bone. The distal end of the tibia forms the medial malleolus, which forms the bony protrusion on the medial side of the ankle.
Fibula
The fibula is the thinner, lateral bone of the lower leg. The distal end of the fibula forms the lateral malleolus, which forms the bony protrusion on the lateral side of the ankle.
Bones of the Ankles and Feet
The major bones of the ankles and feet include the tarsals, metatarsals, and phalanges:
- Tarsals: The tarsals are a group of seven bones in the posterior half of the foot. The tarsals include the calcaneus (heel bone), talus, navicular, medial (1st) cuneiform, intermediate (2nd) cuneiform, lateral (3rd) cuneiform and cuboid bones.
- Metatarsals: A group of five bones found in the anterior half of the foot
- Phalanges: Group of 14 bones that make up the toes (and fingers). The hallux is the great toe. Like the fingers, the toes are composed of three bones called the distal phalanx, middle or intermediate phalanx, and proximal phalanx, with the exception of the great toe, which only has two bones, the distal and proximal phalanges.
See Figure 6.42 for an illustration of the bones of the ankles and feet.
Figure 6.42 Bones of the Feet (“812_Bones_of_the_Foot.jpg” by OpenStax College is licensed under CC BY 3.0)
- Unless otherwise indicated, this work is a derivative of Ernstmeyer, K., & Christman, E. (Eds.). (2024). Medical terminology 2e. Open RN | WisTech Open. https://wtcs.pressbooks.pub/medterm/ ↵
- Unless otherwise indicated, this chapter is a derivative of Betts, J. G., Desaix, P., Johnson, E., Johnson, J. E., Korol, O., Kruse, D., Poe, B., Wise, J., Womble, M. D., & Young, K. A. (2022). Anatomy and physiology 2e. OpenStax. https://openstax.org/books/anatomy-and-physiology-2e/pages/1-introduction ↵
Area which serves to attach the upper limb to the sternum of the axial skeleton, consisting of the clavicle and the scapula.
Collarbone.
The bone commonly known as the shoulder blade.
A bony extension from the scapula that forms the highest superior point or “tip” of the shoulder.
The upper arm bone.
The bone on the lateral or thumb side of the forearm.
The bone on the medial or pinky finger side of the forearm.
Eight bones making up the wrist.
Group of five bones making up the palm of hand.
The 14 bones that make up the fingers (and toes).
Single finger bone.
The large cup-like socket that holds the head of the femur.
The superior region that forms the largest part of the hip bone.
Superior margin of the ilium.
The inferior region of each hip bone and supports the body when sitting.
The anterior (front) portion of the hip.
A cartilaginous joint in the pelvis that connects the two pubic bones.
The entire structure formed by the hip bones, the sacrum, and the coccyx.
The rounded, proximal end is the head of the femur, which articulates with the acetabulum (hip socket) of the pelvis to form the hip joint.
The narrowed region below the head of the femur, which is a common area for fractures.
The large, upward, bony projection located above the base of the neck.
A small, bony prominence that lies on the medial side of the femur, just below the neck.
The smooth surface that forms the distal and posterior sides of the lateral expansion of the distal femur.
The rough area on the outer, lateral side of the lateral condyle.
The smooth, articulating surface that forms the distal and posterior sides of the medial expansion of the distal femur.
A roughened area of the distal femur located on the medial side of the medial condyle.
A smooth groove located on the anterior side of the distal femur, between the medial and lateral condyles that is the site of articulation for the patella.
A small, sesamoid bone located in the anterior knee, commonly referred to as the kneecap.
Distal end of the tibia.
Distal end of the fibula.
A group of seven bones in the posterior half of the foot.
A group of five bones found in the anterior half of the foot.
The great toe.
