Ch 9 Shoulder Girdle Flashcards
1
Q
What is the purpose of the shoulder and the entire upper extremity?
A
To allow the hand to be placed in various positions to accomplish the multitude of tasks the hand is capable of performing.
2
Q
What is the most mobile joint in the body?
A
The shoulder, or glenohumeral joint, it is capable of a great deal of motion.
3
Q
Shoulder Complex
A
Term used to include all of the structures involved with motion of the shoulder.
Consists of the scapula, clavicle, sternum, humerus, and rib cage, and includes the sternoclavicular joint, acromioclavicular joint, glenohumeral joint, and “scapulothoracic articulation” (includes the shoulder girdle (scapula and clavicle) and the shoulder joint (scapula and humerus))
4
Q
Scapulothoracic Articulation
A
Not a joint in the pure sense of the word. Although the scapula and thorax do not have a point of fixation, the scapula does move over the rib cage of the thorax.
The scapula and thorax are not directly attached but are connected indirectly by the clavicle and by several muscles.
-Provides increased motion to the shoulder complex.
5
Q
Shoulder complex (anterior view)
A
.
6
Q
Shoulder Girdle
A
Term often used to discuss the activities of the scapula and clavicle and, to a lesser degree, the sternum and ribs.
- The sternoclavicular and acromioclavicular joints allow shoulder girdle motions, including elevation and depression, protraction and retraction, and upward and downward rotation.
- Five muscles attach to the scapula, the clavicle, or both, providing motion of the shoulder girdle.
7
Q
Shoulder Joint
A
Aka the glenohumeral joint
- Consists of the scapula and humerus. The motions of the shoulder joint are flexion, extension and hyperextension, abduction and adduction, medial and lateral rotation, and horizontal abduction and adduction.
- Bc the shoulder joint is so mobile, it has few ligaments. The 9 muscles that cross the shoulder joint are the prime movers in shoulder joint motion.
8
Q
Plane of the Scapula
A
Due to the curved shape of the rib cage, the scapula rests about 30 degrees anterior to the frontal plane in its resting position, against the posterior thorax.
9
Q
Resting position of the scapula on the thorax (posterior view)
A
.
10
Q
Plane of the scapula (superior view)
A
.
11
Q
Bony landmarks of the left scapula
A
.
12
Q
Left clavicle
A
.
13
Q
Sternum (anterior view)
A
.
14
Q
Sternoclavicular (SC) Joint
A
Formed by the articulation between the manubrium of the sternum and the medial (sternal) end of the clavicle.
- Synovial joint that provides the shoulder girdle with its only direct attachment to the trunk.
- Shape defined as modified ball-and-socket joint, incongruent saddle joint, or plane-shaped double gliding joint. However, there is consensus that it functions as a triaxial joint, with three degrees of freedom, allowing movement in three planes of motion.
15
Q
Sternoclavicular Joint Motions
A
Of the two bones that make up this joint, the clavicle is more movable than the sternum (motions of the SC joint will be described based on the direction in which the clavicle is moving)
- Motions include elevation and depression in the frontal plane as well as protraction and retraction in the transverse plane, and rotation occurs along the longitudinal axis of the bone (the clavicle spins on the sternum).
- Basically, the clavicle moves while the sternum remains stationary.
16
Q
Ligaments of the sternoclavicular joint (left side cut away to show the disk; anterior view)
A
.
17
Q
Sternoclavicular Joint Formation
A
Synovial joint with a joint capsule
- 3 major ligaments and a joint disk
- The articular disk serves as a shock absorber, especially from forces generated by falls on the outstretched hand
- Joint capsule surrounds the joint and is reinforced by the anterior and posterior sternoclavicular ligaments.
- Disk and its ligamentous support are so effective that dislocation at the sternoclavicular joint is rare.
18
Q
Sternoclavicular Joint Articular Disk
A
Has a unique attachment that contributes to the motion of this joint.
- Upper part of the disk is attached to the posterior superior part of the clavicle, while the lower part is attached to the manubrium and first costal cartilage. Double attachment is much like that of the double hinge found on doors that swing in both directions
- To summarize the double-hinge arrangement of this joint, during elevation and depression, motion occurs between the clavicle and disk, whereas during protraction and retraction, motion occurs between the disk and the sternum.
19
Q
Shoulder Girdle Elevation and Depression
A
The convex surface of the clavicle slides inferiorly and superiorly on the concave manubrium as the clavicle’s lateral end moves up and down, respectively. This motion occurs between the clavicle and the disk.
20
Q
Shoulder Protraction and Retraction
A
The concave portion of the clavicle slides anteriorly and posteriorly on the convex costal cartilage, respectively as the clavicle’s lateral end moves forward and backward. This motion occurs between the disk and the sternum
21
Q
3 major Ligaments supporting the Sternoclavicular Joint
A
Sternoclavicular, Costoclavicular, and Interclavicular Ligaments
22
Q
Sternoclavicular Ligament (Sternoclavicular Joint)
A
Connects the clavicle to the sternum on both the anterior and posterior surfaces and is therefore divided into the anterior and posterior sternoclavicular ligaments.
-These ligaments limit anterior-posterior movement of the clavicle’s medial end. The posterior sternoclavicular ligament limits anterior motion, and the anterior sternoclavicular ligament limits posterior motion. They both reinforce the joint capsule.
23
Q
Costoclavicular Ligament (Sternoclavicular Joint)
A
A short, flat, rhomboid-shaped ligament that connects the clavicle’s inferior surface to the superior surface of the costal cartilage of the first rib. The primary purpose of this ligament is to limit the amount of clavicular elevation.
24
Q
Interclavicular Ligament (Sternoclavicular Joint)
A
Located on top of the manubrium, connecting the superior sternal ends of the clavicles. Its purpose is to limit the amount of clavicular depression
25
Acromioclavicular (AC) Joint
Connects the acromion process of the scapula and the lateral (acromial) end of the clavicle. It is a plane-shaped synovial joint that allows a gliding motion to occur, contributing toward movement in three planes of motion.
26
Ligaments of the acromioclavicular joint (anterior view).
.
27
Sternoclavicular Joint Motion
Allows much clavicular motion, the AC joint allows subtle movements of the scapula.
- Motions are minimal but allow continuity between the scapula and thorax during scapular motions.
- Primary motions at the AC joint are upward and downward rotation in the plane of the scapula. Bc of the curved shape of the rib cage, these motions occur more in the plane of the scapula than in the pure frontal plane.
- The scapular plane is oriented approximately 30 degrees forward of the frontal plane. The AC joint can also contribute toward scapular tilt in the sagittal plane, and when present, scapular winging in the transverse plane.
28
The joint capsule surrounds the articular borders of the joint and is reinforced above and below by the...
Superior and inferior acromioclavicular ligaments.
29
Acromioclavicular Ligaments
These ligaments support the joint by holding the acromion process to the clavicle, thus helping to prevent dislocation of the clavicle. Despite this reinforcement, the joint capsule is quite weak. This capsular weakness leaves the AC joint very susceptible to injury, especially with a fall on the outstretched hand or a blow to the outside of the shoulder.
30
2 accessory ligaments of the AC joint
Coracoclavicular Ligament and Coracoacromial Ligaments.
31
Coracoclavicular Ligament
Not directly located at the joint, it does provide stability to that joint and allows the scapula to be suspended from the clavicle. It connects the scapula to the clavicle by attaching to the inferior surface of the clavicle’s lateral end and to the superior surface of the scapula’s coracoid process
-Divided into a lateral trapezoid portion and the deeper medial conoid portion. Together they prevent backward motion of the scapula, and individually they limit the rotation of the scapula.
32
Coracoacromial Ligament
Does not actually cross the AC joint, but rather forms a roof over the head of the humerus and serves as a protective arch, providing support to the head when an upward force is transmitted along the humerus
-Attaches laterally on the superior surface of the coracoid process and runs up and out to the inferior surface of the acromion process.
33
Scapulothoracic Articulation
Not a joint in the pure sense of the word as there is no direct union between the bones, and there is no joint capsule
- Consists of the slightly concave anterior surface of the scapula resting on the convex posterior aspect of the rib cage. With the lack of a true joint structure to support the scapula in its normal resting position, stability comes from an indirect link to the trunk through the clavicle and several surrounding muscles.
- Provides motion necessary for normal function of the scapula.
34
Motions of the Shoulder Girdle
-Elevation and Depression
-Protraction and Retraction
-Upward and Downward Rotation
Bc these motions can be seen best by looking at the scapula, they are commonly described as either shoulder girdle or scapular motion. -At this joint, protraction and abduction are synonymous terms, as are retraction and adduction.
35
Shoulder girdle protraction and retraction is synonymous with...
Scapular abduction and adduction. Scapular rotation is the same as shoulder girdle rotation.
36
The coracoacromial ligament forms a roof over the shoulder joint.
.
37
Scapular elevation/depression and protraction/ retraction are essentially...
Linear motions.
38
All points of the scapula move...
Up and down along the thorax and away from and toward the vertebral column in parallel lines.
39
Scapular Elevation
Occurs when the scapula moves in a superior direction
40
Scapular Depression
Occurs when the scapula moves inferiorly
41
Scapular Protraction
(scapular abduction) Occurs when the scapula moves away from the posterior midline
42
Scapular Retraction
(scapular adduction) Occurs when the scapula moves back toward the posterior midline.
43
Shoulder Girdle Motions (posterior view)
.
44
Angular Motions of the Shoulder Girdle
-Including scapular upward/ downward rotation and scapular tilt. Because of the scapula’s triangular shape, one side moves one way while another side moves in an opposite or different direction.
45
Scapular Upward Rotation
The inferior angle of the scapula rotates up and away from the vertebral column,
46
Scapular Downward Rotation
The return to the resting anatomical position from the upwardly rotated position.
-The scapula does not move past anatomical position toward the vertebral column
47
Scapular Upward/Downward Rotation
It should be noted that when the inferior angle rotates up and out, the superior angle moves down, and the glenoid fossa moves up and in. Therefore, it is important to have a point of reference to define this rotation. The inferior angle is the reference point used here
48
Scapular Tilt
Occurs when the shoulder joint goes into hyperextension. The superior end of the scapula tilts anteriorly, and the inferior end tilts posteriorly. Examples of these combined motions are the “windup” or prerelease phase of a softball pitch, a bowling delivery, or a racing dive in swimming.
49
Scapular motion during upward rotation
.
50
Scapular Winging
The posterior lateral movement of the vertebral border of the scapula in the transverse plane (the vertebral border of the scapula moves away from the rib cage) This motion occurs primarily at the AC joint but is observed most often at the scapulothoracic articulation. This can be demonstrated by asking a person with a “normal” shoulder to place his or her hand on the small of the back. The vertebral border of the scapula lifts away from the rib cage. This motion can only be done in combination with several other motions. However, pathological “winging of the scapula” also occurs when the stabilizing muscles around the scapula are weak or paralyzed. Serratus anterior weakness or paralysis is a dramatic example. When a person with that condition pushes against a wall with an outstretched hand, the involved scapula will rise away from the rib cage, standing out like a small wing. Excessive winging is considered abnormal.
51
Winging of the scapula (posterior view).
This person’s right serratus anterior muscle is paralyzed. When pushing against the wall with both hands, the right scapula rises away from the rib cage, standing out like a small wing.
52
During the linear movements of scapular elevation/ depression and scapular protraction/retraction, it is possible to move the shoulder girdle (clavicle and scapula)...
Up, down, forward, or backward without moving the humerus. However, shoulder joint motions must accompany the angular motions of scapular upward/downward rotation, and scapular tilt.
53
To rotate the scapula upward, you must also...
Flex or abduct the shoulder joint. Stated another way, when there is flexion or abduction of the shoulder joint, the scapula must also rotate upward.
54
When there is extension or adduction of the shoulder joint, the scapula...
Returns to anatomical position by rotating downward.
55
Scapular tilt can only happen when the shoulder joint goes into...
Hyperextension
56
Shoulder Joint Flexion
- Upward Rotation
| - Protraction
57
Shoulder Joint Extension
- Downward Rotation
| - Retraction
58
Shoulder Joint Hyperextension
Scapular Tilt
59
Shoulder Joint Abduction
Upward Rotation
60
Shoulder Joint Adduction
Downward Rotation
61
Shoulder Joint Medial Rotation
Protration
62
Shoulder Joint Lateral Rotation
Retraction
63
Shoulder Joint Horizontal Abduction
Retraction
64
Shoulder Joint Horizontal Adduction
Protraction
65
Scapulohumeral Rhythm
A concept that further describes the movement relationship between the shoulder girdle and the shoulder joint. The first 30 degrees of shoulder joint motion is pure shoulder joint motion. However, after that, for every 2 degrees of shoulder flexion or abduction that occurs, the scapula must upwardly rotate 1 degree. This 2:1 ratio is known as scapulohumeral rhythm.
66
It is possible to demonstrate that the first part of shoulder joint motion occurs only at the shoulder joint, but further motion must be accompanied by...
Shoulder girdle motion. With a person in the anatomical position, stabilize the scapula by putting the heel of your hand against the axillary border to prevent rotation of the scapula. Instruct the person to abduct the shoulder joint. Notice that the individual is able to abduct only a short distance before shoulder joint motion is impaired.
67
Muscles with a greater horizontal pull will be more effective in...
Pulling the scapula in or out (protracting or retracting).
68
Muscles with a more equal horizontal and vertical pull will have a role in...
Both motions (protracting and retracting)
69
The muscles of the shoulder girdle are the following:
- Trapezius
- Levator scapula
- Rhomboids
- Serratus anterior
- Pectoralis minor
70
Three parts of the trapezius muscle (posterior view).
.
71
Upper Trapezius Muscle (OIAN)
O: Occipital bone, nuchal ligament on upper cervical spinous processes
I: Outer third of clavicle, acromion process
A: Scapular elevation and upward rotation
N: Spinal accessory (cranial nerve XI), C3 and C4 sensory component
72
Middle trapezius muscle (posterior view).
.
73
Middle Trapezius Muscle (OIAN)
O: Spinous processes of C7 through T3
I: Scapular spine
A: Scapular retraction
N: Spinal accessory (cranial nerve XI), C3 and C4 sensory component
74
Lower Trapezius Muscle (OIAN)
O: Spinous processes of middle and lower thoracic vertebrae
I: Base of the scapular spine
A: Scapular depression and upward rotation
N: Spinal accessory (cranial nerve XI), C3 and C4 sensory component
74
Lower Trapezius Muscle (OIAN)
O: Spinous processes of middle and lower thoracic vertebrae
I: Base of the scapular spine
A: Scapular depression and upward rotation
N: Spinal accessory (cranial nerve XI), C3 and C4 sensory component
75
Lower trapezius muscle (posterior view).
.
76
How does the trapezius work to retract the scapula?
All three parts of the trapezius muscle work together (synergists) to retract the scapula. Remember, however, that the middle trapezius muscle is the prime mover and that the upper and lower trapezius muscles can only assist. The upper and lower trapezius muscles are antagonistic to each other in elevation/ depression and are agonistic in upward rotation.
77
Rotational movement of the right scapula.
.
78
Levator scapula muscle (posterior view).
.
79
Levator Scapula Muscle (OIAN)
O: Transverse processes of first four cervical vertebrae
I: Vertebral border of scapula between the superior angle and spine
A: Scapular elevation and downward rotation
N: Third and fourth cervical nerves and dorsal scapular nerve (C5)
80
Rhomboid muscle (posterior view).
.
81
Rhomboid Muscles (OIAN)
O: Spinous processes of C7 through T5
I: Vertebral border of scapula between the spine and inferior angle
A: Scapular retraction, elevation, and downward rotation
N: Dorsal scapular nerve (C5)
82
Serratus anterior muscle (lateral view).
.
83
Serratus Anterior Muscle
O: Lateral surface of the upper eight ribs
I: Vertebral border of the scapula, anterior surface
A: Scapular protraction and upward rotation
N: Long thoracic nerve (C5, C6, C7)
84
Pectoralis Minor Muscle
O: Anterior surface, third through fifth ribs
I: Coracoid process of the scapula
A: Scapular depression, protraction, downward rotation, and tilt
N: Medial pectoral nerve (C8, T1)
85
Retraction (Prime Movers of the Shoulder Girdle)
Middle trapezius, Rhomboids
86
Protraction (Prime Movers of the Shoulder Girdle)
Serratus anterior, Pectoralis minor
87
Elevation (Prime Movers of the Shoulder Girdle)
Upper trapezius, Levator Scapula, Rhomboids
88
Depression (Prime Movers of the Shoulder Girdle)
Lower trapezius, Pectoralis minor
89
Upward Rotation (Prime Movers of the Shoulder Girdle)
Upper and lower trapezius Serratus anterior (lower fibers)
90
Downward Rotation (Prime Movers of the Shoulder Girdle)
Rhomboids, levator scapula, pectoralis minor
91
Scapular Tilt (Prime Movers of the Shoulder Girdle)
Pectoralis Minor
92
Postural Influences
With rounding of the shoulders, the scapula is pulled into a protracted position. This places the rhomboids and middle trapezius (scapular retractors) in a chronically stretched position, and as dictated by the length-tension relationship, these muscles become weak and overstretched. The pectoralis minor, however, is placed on slack as the coracoid moves anteriorly toward the ribs, and over time it adaptively shortens (adopts a shorter resting length).
93
Anatomical Relationships of Shoulder Girdle Muscles
All five shoulder girdle muscles have their origins on the trunk; three are located posteriorly (trapezius, levator scapula, rhomboids), one laterally (serratus anterior), and one anteriorly (pectoralis minor). Of the three posterior muscles, the trapezius is the most superficial. The right and left upper, middle, and lower trapezius covers most of the back in the form of a large diamond. Remove the trapezius, and the rhomboids and levator scapula lay directly underneath
94
Pectoralis minor muscle (anterior view).
.
95
Muscles of the posterior shoulder girdle.
.
96
Muscles of the anterior shoulder girdle.
.
97
Muscles of the lateral shoulder girdle.
.
98
Force Couple
Muscles pulling in different directions to accomplish the same motion.
99
Scapula Upward Rotation Force Couple
In the case of the shoulder girdle, the upper trapezius muscle pulls up, the lower trapezius muscle pulls down, and the lower fibers of the serratus anterior muscle pull outward in a horizontal direction
100
Scapula Downward Rotation Force Couple
The combined effects of the pectoralis minor muscle pulling down, the rhomboid muscles pulling in, and the levator scapula muscle pulling up is downward rotation of the scapula. This motion is accomplished when the shoulder joint is forcefully extended, as when chopping wood, paddling a canoe, or pulling down on an overhead exercise machine. Downward rotation of the scapula must accompany extension of the shoulder joint.
101
Reverse Muscle Action
The actions of the shoulder girdle muscles have been described as moving the insertion toward the origin. However, if the insertion is stabilized, the origin will move.
-It allows some of the shoulder girdle muscles to have assistive roles in other joints, primarily the head and neck.
102
The muscular force couple produces upward rotation of the scapula (posterior view).
.
103
The muscular force couple produces downward rotation of the scapula (posterior view).
.
104
Upper Trapezius role moving Head and Neck
Because of its attachment on the occiput and cervical vertebrae, the upper trapezius can play a role in moving the head and neck. When the shoulder girdle is stabilized, bilateral contaction of the upper trapezius muscles can assist in extending the head and neck. When the upper trapezius is contracting unilaterally it can laterally bend the head and neck to the same side (ipsilateral) and rotate it to the opposite side (contralateral).
105
Lower Trapezius and Pectoralis Minor Role on the Trunk
With the shoulder girdle stabilized, the lower trapezius and pectoralis minor can reverse their actions and assist in elevating the trunk. This is particularly useful during crutch walking. With the crutches planted on the floor and the hands bearing weight on the crutches, the scapula becomes stabilized, preventing the lower trapezius and pectoralis minor from depressing the scapula when they contract. Instead, their origins move the body upward toward the scapula, thus raising the body as it swings through the crutches
106
Reverse muscle action during crutch walking with hands bearing weight on crutch handles to prevent scapula and rib cage from depressing.
The pectoralis minor (A) is pulling up on the rib cage while the lower trapezius (B) pulls up on the vertebral column and pelvis to elevate the body, allowing it to swing through the crutches.
107
Levator Scapula Role on the Neck
When the scapula is stabilized, the levator scapula can move the neck. It can assist the splenius cervicis, a neck muscle, in rotating and laterally bending the neck ipsilaterally.
108
Acromioclavicular Separation
The term commonly used to describe the various amounts of ligament injury at the AC joint. In a first-degree sprain, the acromioclavicular ligament is stretched. In a second-degree sprain, the acromioclavicular ligament is ruptured, and the coracoclavicular ligament is stretched. In a third-degree sprain, both the acromioclavicular and coracoclavicular ligaments are ruptured.
109
Clavicular Fractures
Account for the most frequently broken bone in children. They usually result from a fall on the lateral aspect of the shoulder or on the outstretched hand. The clavicle usually breaks in its midportion.
110
The shoulder girdle has what kind of motions?
Both linear and angular motions.
111
What is the point of reference for scapular rotation?
The inferior angle
112
Certain shoulder girdle and shoulder joint motions are...
Connected
113
Scapulohumeral Rhythm
Shoulder girdle and shoulder combined motions of the joints.
114
In the shoulder girdle there are force couples for both upward and downward rotation where...
Muscles pulling in different directions help to accomplish the same motion.
115
Concentric and eccentric are what kind of activities?
Accelerating and decelerating activities. With isometric activity there is no joint motion.
116
Kinetic chain movement depends on...
Whether the distal segment is fixed (closed) or free to move (open)
117
Identify the structures that make up the shoulder girdle, the shoulder joint, and the shoulder complex.
xxx
118
Given that the scapula is shaped somewhat like a triangle, what landmark is commonly used to determine the direction the scapula is rotating?
xxx
119
Given that the scapula is shaped somewhat like a triangle, what direction is the landmark moving if the scapula is rotating upwardly?
xxx
120
Which shoulder girdle motions are mostly linear?
xxx
121
Which shoulder girdle motions are mostly angular?
xxx
122
Which type of scapular motion can only happen in conjunction with glenohumeral joint motions?
xxx
123
What scapular motion is always needed to allow for any overhead reaching activity at the glenohumeral joint?
xxx
124
What is scapulohumeral rhythm?
xxx
125
How is shoulder joint motion affected by the absence of scapulohumeral rhythm?
xxx
126
The trapezius muscle is usually referred to and described as consisting of three different muscles. The two rhomboid muscles (major and minor) are referred to and described as one. From a functional perspective, why is the trapezius muscle separated into three muscles?
xxx
127
The trapezius muscle is usually referred to and described as consisting of three different muscles. The two rhomboid muscles (major and minor) are referred to and described as one. From a functional perspective, why are the rhomboid muscles described as one muscle?
xxx
128
Raising your hand over your head requires the combined action of which three shoulder girdle muscles?
xxx
129
Name and define the biomechanical term used to describe the combined action in question 10.
x
130
Which joints of the shoulder complex produce movement when your hand is reached over your head?
x
131
Starting at the inferior angle and going clockwise, name the shoulder girdle muscles that attach to the posterior surface of the right scapula.
x
132
The pectoralis minor muscle is deep to what muscle?
x
133
As you look at the lateral chest wall, the serratus anterior is deep to what two muscles?
x
134
Closing a window by pulling down
Shoulder girdle motion ___________________
(Shoulder extension)
x
135
Opening a window by pulling up
Shoulder girdle motion ___________________
(Shoulder flexion)
x
136
Carrying a heavy suitcase
Shoulder girdle motion ____________________
(No shoulder motion)
xx
137
Combing your hair in the back
Shoulder girdle motion _____________________
(Shoulder flexion, lateral rotation)
x
138
Reaching across the table
Shoulder girdle motion _____________________
(Shoulder flexion)
xx
139
In questions 1 to 5, what type of contraction occurs at the shoulder girdle?
x
140
What joint motion is occurring at the shoulder girdle?
What muscles are prime movers of this shoulder girdle action?
Is this an open-chain or closed-chain activity?
x
141
Lie prone on a table with your right arm hanging over the side of the table and holding a weight in your right hand. Move your arm up and out by doing shoulder horizontal abduction.
- What shoulder girdle motion is accompanying shoulder horizontal abduction?
- What muscles are prime movers in this shoulder girdle motion?
- Is this a concentric, eccentric, or isometric contraction?
x
142
Sit in a chair that has arms; place your hands on the armrests in a position that puts your shoulders in hyperextension. Push down on the armrests and raise your buttocks off the seat of the chair.
- What shoulder girdle motion is accompanying the shoulder flexion action (from hyperextension to neutral)?
- What muscles are prime movers in this shoulder girdle motion?
- Is this a concentric or eccentric activity?
x
143
Lie in a prone position with your legs together, hands on the table next to your shoulders, with your fingers pointing forward. Push up with your hands as far as you can while straightening your elbows, bending your knees, and keeping your back straight.
- What shoulder girdle motion is occurring?
- What muscles are prime movers in this shoulder girdle motion?
- Is this an open-chain or closed-chain activity?
x
144
Using a lat pull-down machine of the Universal Gym (or some other comparable apparatus), reach up and grasp the handles. Pull down while keeping your arms moving in the frontal plane.
- What shoulder girdle motions are accompanying shoulder adduction and lateral rotation?
- What muscles are prime movers in these shoulder girdle motions?
- Is this a concentric or eccentric activity?
x
145
While standing, grasp some light weights in your hands and perform a shoulder shrug.
- What muscle(s) contract to perform this motion, and what type of contraction are they performing?
- Next, lower down from the shrug position. What muscle(s) contract to perform this motion, and what type of contraction are they performing?
x
146
A person has scapular winging. What muscle is involved?
x
