Bones of the Upper Limb

Anna Melby

11 Bones of the Upper Limb

Anatomical Terms

Before beginning to study anatomy of the bones, it is important to define some anatomical terms. When studying anatomy, it is important to have terms of direction that specify the relative positions of structures. Below is a list of the terms of direction we will use in this class. They are given in pairs because they define opposite directions along a particular axis.

Anatomy Terms of Direction

anterior/posterior
ventral/dorsal
medial/lateral
superior/inferior
cranial/caudal
proximal/distal

The terms of direction are illustrated in the figure below.

three bodies illustrating sectional planes (left) and anatomy terms of direction — Sectional planes and anatomy terms of direction. **Back endplate figure in Human Physiology: An Integrated Approach by Dee Silverthorn, 8^th edition (2019).**

Another useful definition is anatomical position. The person in the figure above is drawn in anatomical position. In anatomical position, the limbs are extended straight and the palms face anteriorly. Anatomical position is a reference position that can be used to define limb movements. We will use this along with the sectional planes to define the actions of the muscles. Anatomical position is also key in defining the medial and lateral positions of the bones in the forearm (lower arm).

In addition to the terms of direction, it is useful to know the meaning of certain terms used to describe features on the bones. Muscle attachment points create rough spots where the tendon knits into the bone. In the joint, cartilage on the surface of the bone (articular cartilage) creates a smooth region known as a condyle. Below are definitions of terms we will use.

Glossary of Terms in Bone Anatomy

process: a projection that sticks out from the bone

tuberosity: a rough raised portion of bone where tendon of muscle attaches

condyle: smooth region that forms a joint with another bone; in life, covered with articular cartilage

epicondyle: a small projection above a condyle

head: proximal rounded extension of bone, may be separated from the shaft of the bone by a neck

articulation: joint

diaphysis: shaft of a long bone

epiphysis: end of the bone; growth plate is located in the epiphysis of growing bones

Using features of the bones and the terms of direction, you will learn how to distinguish whether a bone is from the left or right side of the body.

Bones of the Upper Limb

For reference, the figure below shows how all the bones of the upper limb fit together.

bones of the shoulder and arm — Anterior view of the arrangement of bones in the shoulder and arm. **Figure 3.1 in Human Anatomy, Color Atlas and Textbook by J.A. Gosling et al., 6^th edition (2017).**

The arm is attached to the trunk by the pectoral girdle, or shoulder girdle. The bones of the shoulder girdle are the clavicle and scapula.

The figure below shows a superior view of the clavicle.

The figure below shows anterior and posterior views of the scapula. The large ridge on the posterior side of the scapula is called the spine. The glenoid cavity is the shallow depression on the lateral side of the bone that articulates (forms a joint with) the head of the humerus.

anterior (left) and posterior (right) views of the scapula — Anterior and posterior views of the scapula.

This lateral view shows the surface of the glenoid cavity.

lateral view of the scapula showing the surface of the glenoid cavity — Lateral view of the scapula showing the glenoid cavity. **Adapted from Figure 3.86 in Human Anatomy, Color Atlas and Textbook by J.A. Gosling et al., 6^th edition (2017)**

In life, the glenoid cavity is covered with articular cartilage. Because the glenoid cavity is so shallow, there is also a small ridge of fibrocartilage around the edge (called the glenoid labrum), which helps to stabilize the humerus.

The figure below shows how the humerus fits together with the bones of the shoulder girdle.

anterior (left) and posterior (right) views of the bones in the shoulder joint — The bones in the shoulder joint. **Adapted from Figure 3.53 (left) and 3.62 (right) in Human Anatomy, Color Atlas and Textbook by J.A. Gosling et al., 6^th edition (2017).**

The humerus is the bone of the upper arm. The rounded head of the humerus is a key feature that tells you which is the medial side and proximal end of the bone.

anterior (left) and posterior (right) views of the humerus — Anterior and posterior views of the humerus. Red arrows indicate the head of the humerus at the proximal end (top). A yellow arrow points to the location of the deltoid tuberosity. The orange bracket outlines the condyle; pink arrows indicated the lateral epicondyle; cyan arrows indicate the medial epicondyle. A purple asterisk indicates the olecranon fossa in the posterior view.

The distal end of the humerus articulates with the two bones of the forearm (lower arm): the radius and the ulna. The condyle on the distal humerus has a complex shape. Above the condyle are the medial epicondyle and the lateral epicondyle. The medial epicondyle is a fairly large projection. This is what we call the “funny bone”: the ulnar nerve wraps around the medial epicondyle. If you hit this part of the bone, you will feel pain in the medial part of your lower arm.

anterior (left) and posterior (right) views of the distal humerus — Anterior and posterior views of the distal humerus. Pink arrows indicate the lateral epicondyle; cyan arrows indicate the medial epicondyle.

The olecranon fossa is a depression located on the posterior side of the distal humerus. This depression is where the olecranon process of the ulna fits.

The deltoid tuberosity is a V-shaped rough area on the lateral surface of the humerus. This is the insertion (distal attachment) for the deltoid muscle.

full humerus (left) and closeup of lateral surface showing deltoid tuberosity — The deltoid tuberosity is a V-shaped, low rough projection on the lateral surface of the humerus. The yellow box in the full view on the left indicates the region that is enlarged in the figure on the right. The red arrows in the lateral view on the right indicate the deltoid tuberosity.

The two bones of the forearm are the radius and the ulna. When the arm is in anatomical position (palm facing forward), the radius is lateral and the ulna is medial.

anterior view (left) and posterior view (right) of the bones of the forearm articulated with the humerus — Anterior and posterior views of the bones of the forearm articulated with the humerus (H). In the anterior view one can see that the radius (R) is lateral to the ulna (U). The red arrow in the posterior view indicates the olecranon process of the ulna. **Adapted from Figure 3.34 (left) and 3.73 (right) in Human Anatomy, Color Atlas and Textbook by J.A. Gosling et al., 6^th edition (2017).**

The radial tuberosity is a rough projection near the proximal end of the radius. This is the insertion for the biceps brachii muscle.

radius with radial tuberosity labeled — The radius. The major prominence near the proximal end is the radial tuberosity.

The olecranon process is the large curved proximal end of the ulna. This forms the bony part of the elbow.

view of the full ulna (top) with enlarged views of the medial (left, bottom) and lateral (right, bottom) sides of the proximal end of the bone — The ulna. Top, full view. Bottom, medial (left) and lateral (right) views of the proximal end of the bone showing the olecranon process (red arrows). The asterisk in the lateral view marks the radial notch, a smooth indentation where the ulna articulates with the radius.

Optional Videos

Below are links to videos in the Acland’s Video Atlas of Anatomy. They are helpful in allowing you to get a sense of the bones in three dimensions. They also will introduce you to the movements around the joints, which we will be studying in our class about muscle anatomy.

1.1.2 The clavicle and scapula

1.1.4 The shoulder joint and its movements

1.2.2 Bones of the arm and forearm

11 Bones of the Upper Limb

Anatomical Terms

Bones of the Upper Limb

Optional Videos

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