Anatomy
  • Anatomy

    Anatomy of the Shoulder

    The two main bones of the shoulder are the humerus and the scapula (shoulder blade).

    The joint cavity is cushioned by articular cartilage covering the head of the humerus and face of the glenoid. The scapula extends up and around the shoulder joint at the rear to form a roof called the acromion, and around the shoulder joint at the front to form the coracoid process.

    The end of the scapula, called the glenoid, meets the head of the humerus to form a glenohumeral cavity that acts as a flexible ball-and-socket joint.

    The joint is stabilized by a ring of fibrous cartilage surrounding the glenoid called the labrum.

    Ligaments connect the bones of the shoulder, and tendons join the bones to surrounding muscles. The biceps tendon attaches the biceps muscle to the shoulder and helps to stabilize the joint.

    Four short muscles originate on the scapula and pass around the shoulder where their tendons fuse together to form the rotator cuff.

    All of these components of your shoulder, along with the muscles of your upper body, work together to manage the stress your shoulder receives as you extend, flex, lift and throw. 

    Anatomy of the Elbow

    The elbow is a hinge joint made up of the humerus, ulna and radius.

    The unique positioning and interaction of the bones in the joint allows for a small amount of rotation as well as hinge action. This rotation is easily noticed during activities such as hand-to-mouth eating motions.

    The primary stability of the elbow is provided by the ulnar collateral ligament, on the medial (inner) side of the elbow. However, one of the most common injuries to the elbow occurs on the lateral, or outer, side of the elbow -- it is called Lateral Epicondylitis, or Tennis Elbow.

    Anatomy of the Ankle

    The ankle is a complex mechanism. What we normally think of as the ankle is actually made up of two joints: the subtalar joint, and the true ankle joint. The true ankle joint is composed of three bones, seen above from a front, or anterior, view: the tibia which forms the inside, or medial, portion of the ankle; the fibula which forms the lateral, or outside portion of the ankle; and the talus underneath. The true ankle joint is responsible for up and down motion of the foot.

    Beneath the true ankle joint is the second part of the ankle, the subtalar joint, which consists of the talus on top and calcaneus on the bottom. The subtalar joint allows side to side motion of the foot.

    The ends of the bones in these joints are covered by articular cartilage. The major ligaments of the ankle are: the anterior tibiofibular ligament, which connects the tibia to the fibula; the lateral collateral ligaments, which attach the fibula to the calcaneus and gives the ankle lateral stability; and, on the medial side of the ankle, the deltoid ligaments, which connect the tibia to the talus and calcaneus and provide medial stability.

    These components of your ankle, along with the muscles and tendons of your lower leg, work together to handle the stress your ankle receives as you walk, run and jump. 

    Anatomy of the Spine

    The normal anatomy of the spine is usually described by dividing up the spine into three major sections: the cervical, the thoracic, and the lumbar spine. (Below the lumbar spine is a bone called the sacrum, which is part of the pelvis). Each section is made up of individual bones called vertebrae. There are 7 cervical vertebrae, 12 thoracic vertebrae, and 5 lumbar vertebrae.

    An individual vertebra is made up of several parts. The body of the vertebra is the primary area of weight bearing and provides a resting place for the fibrous discs which separate each of the vertebrae. The lamina covers the spinal canal, the large hole in the center of the vertebra through which the spinal nerves pass. The spinous process is the bone you can feel when running your hands down your back. The paired transverse processes are oriented 90 degrees to the spinous process and provide attachment for back muscles.

    There are four facet joints associated with each vertebra. A pair that face upward and another pair that face downward. These interlock with the adjacent vertebrae and provide stability to the spine. The vertebrae are separated by intervertebral discs which act as cushions between the bones.

    Each disc is made up of two parts. The hard, tough outer layer called the annulus surrounds a mushy, moist center termed the nucleus. When a disc herniates or ruptures, the soft nucleus spurts out through a tear in the annulus, and can compress a nerve root. The nucleus can squirt out on either side of the disc or in some cases both sides.

    The amount of pain associated with a disc rupture often depends upon the amount of nucleus that breaks through the annulus, and whether it compresses a nerve. To help alleviate the pain, a Laminotomy/Microdiscectomy may be performed.

    Anatomy of the Hand & Wrist

    The hand is composed of many small bones called carpals, metacarpals and phalanges. The two bones of the lower arm -- the radius and the ulna -- meet at the hand to form the wrist.
    The Median and Ulnar nerves are the major nerves of the hand, running the length of the arm to transmit electrical impulses to and from the brain to create movement and sensation. 

    Anatomy of the Knee

    The bones of the knee, the femur and the tibia, meet to form a hinge joint. The joint is protected in front by the patella (kneecap). The knee joint is cushioned by articular cartilage that covers the ends of the tibia and femur, as well as the underside of the patella. The lateral meniscus and medial meniscus are pads of cartilage that further cushion the joint, acting as shock absorbers between the bones.

    Ligaments help to stabilize the knee. The collateral ligaments run along the sides of the knee and limit sideways motion. The anterior cruciate ligament, or ACL, connects the tibia to the femur at the center of the knee. Its function is to limit rotation and forward motion of the tibia. (A damaged ACL is replaced in a procedure known as an ACL Reconstruction.) The posterior cruciate ligament, or PCL (located just behind the ACL) limits backward motion of the tibia.

    These components of your knee, along with the muscles of your leg, work together to manage the stress your knee receives as you walk, run and jump.

    Anatomy of the Hip

    The hip is a ball-and-socket joint where the head of the femur articulates with the cuplike acetabulum of the pelvic bone.

    The head of the femur and the socket are covered with a layer of smooth cartilage which cushions the joint, and allows the bones to move on each other with very little friction.