Study Guide - University of Florida



Musculoskeletal System Study Guide

Students:

This Study Guide is for your use in this lesson on the Musculoskeletal System. The guide contains much of the information you should be familiar with, not only to pass this lesson, but to prepare you for the musculoskeletal section of the PCAT exam.

The guide contains high-resolution pictures and text summaries regarding many parts of the Musculoskeletal System. At the end of the Study Guide you will find links to movies of various body parts in motion. They are an excellent source for information for your Team Project.

I hope you find this guide valuable. Please don’t hesitate to provide me with feedback.

Humerus

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Ulna

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Radius

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Clavicle

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Sternum

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Hip Bone

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Femur

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Tibia

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Fibula

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Patella

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Anterior Deltoid

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Posterior Deltoid

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Pectoralis major: sternal head

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Triceps brachii

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Biceps brachii

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Quadriceps

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Hamstrings

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Motion Activities

Walking Jogging Push-Ups

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Sit-Ups Stand from Sitting Walking Upstairs

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The primary actions of the anterior deltoid are the flexion and internal rotation of the arm at the shoulder. Common injuries are contusions, muscle spasms and muscle strain.

The hip bone or innominate bone (meaning “no name”) is comprised of three bones that ossify into one. These three bones include the ilium, ischium, and pubis, each of which partakes in the formation of the socket of the true hip joint, the acetabulum. The ilium is the wing-shaped area of the hip bone that has a rather broad crest. The ischium consists of the tuberosities, upon which one sits, and the ischial spine: a small projection of bone that separates the greater and lesser sciatic notches. Anteriorly and inferior to the ilium is the pubis, joining its companion pubis from the opposite side to form the pubic symphysis.

The sternum is composed of three sections: the manubrium, the body, and the xiphoid process. The uppermost portion is the manubrium while the inferior part is the xiphoid process. The body of the sternum overlies the heart and is the point at which compressions are provided during cardiopulmonary resuscitation.

The clavicle acts as a strut to suspend the upper extremity from the chest wall. It is short, but quite thick and is not a straight bone. On its sternal end, the clavicle has a convex shape (bowing away from the body) while nearer the acromial end the clavicle becomes concave (bowing toward the body). The curved shape of the bone is an important feature in understanding the movements of the scapula and humerus. A direct blow or even a fall on the outstretched arm can fracture the clavicle.

The fibula is the smaller of the two bones of the leg. It lies laterally to the tibia and bears virtually no body weight.

The radius is the lateral bone of the forearm when the body is in anatomical position. During pronation of the forearm, the distal end of the radius moves medially, thus making the alignment of the two forearm bones somewhat confusing. The radius is always on the thumb side of the forearm regardless of position. The proximal end of the radius is a round shape, allowing the pronation/supination movement of the forearm. This rounded end of the bone is called the radial head.

The humerus is the longest bone of the upper limb. It serves to provide great mobility of the limb through its articulation at the shoulder joint. The humerus is vulnerable to injury due to its length and location, and may often fracture. One anatomical concern with such a fracture is the presence of the radial nerve on the bone. On the posterior side of the humerus there is a groove called the “spiral groove”. This long groove is where the radial nerve lies on its path through the arm. A fracture in the mid-shaft of the humerus could disrupt the spiral groove and injure the radial nerve.

The ulna is quite large proximally and quite small distally. It is the more medial bone of the forearm when the forearm is in the anatomical position. During pronation, the radius rotates around the ulna making the ulna appear to lie laterally to the radius. The general arrangement will always place the ulna on the little finger side of the forearm regardless of position.

The patella is the largest sesamoid bone of the human body. It is enveloped by the quadriceps tendon from the proximal aspect of the knee joint and this soft tissue becomes the patellar ligament inferior to the patella.

The femur is the longest bone in the human body. It has a unique shape, being long but acutely angled at its proximal end. The rounded proximal end is called the femoral head, and the neck of the femur connects the head to the shaft, making an angle between the neck and the shaft of approximately 125°.

The tibia is the major weight bearing bone of the leg - the fibula shares very little in that capacity.

Primary actions of the pectoralis major are the adduction, internal rotation, and extension of the arm at the shoulder. Common injuries are muscle strain, muscle spasms, and muscle rupture.

TB: long head primary actions are the extension and adduction of the arm at the shoulder as well as the extension of the arm at the elbow.

TB: lateral head primary action is the extension of the arm at the elbow.

Common injuries for both are avulsion fractures, contusions, laceration (in fractures of the humerus), muscle rupture, muscle spasms, muscle strains and tendon rupture.

The primary actions of the anterior deltoid are the flexion and internal rotation of the arm at the shoulder. Common injuries are contusions, muscle spasms and muscle strain.

Biceps brachii: long head

Biceps brachii: short head

Both muscles primary action is the flexion of the forearm at the elbow. Both muscles secondary actions are to assist flexion of the arm at the shoulder and supination of the forearm.

Common injuries for both are muscle shortening, muscle spasm, muscle strain, tendonitis and tendon rupture.

Rectus femoris: primary action is extension of the leg at the knee; secondary action is to assist with flexion of the thigh at the hip.

Sartorius: primary action is to assist other muscles with flexion, external rotation, and abduction of the thigh at the hip, and flexion and internal rotation of the knee.

Vastus lateralis: primary action is the extension of the leg at the knee.

Vastus medialis: primary action is the extension of the leg at the knee.

Common injuries for all are contusions, muscle spasms, muscle strain, and tendonitis.

Gluteus maximus: the ‘gluts’ have two primary actions, the abduction and extension of the thigh at the hip; and three secondary actions, assisting with the external rotation of the thigh at the hip, helping to stabilize the knee in extension of the thigh at the hip, and the extension of the pelvis at the hip.

Common injuries are contusions, muscle spasms and muscle strains.

Biceps femoris: long head primary actions are flexion and external rotation of the leg at the knee, and extension of the thigh at the hip.

Biceps femoris: short head primary actions are flexion and external rotation of the leg at the knee.

Common injuries of the biceps are contusions, muscle shortening, muscle spasm, muscle strain, and tendonitis.

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