Transcript Chapter 2 - Shoulder and Arm

2
Shoulder and Arm
•Agonist:
•muscle that causes specific movement or possibly several
movements to occur through the process of its own contraction
Antagonist:
muscle that acts in opposition to the specific movement
generated by the agonist and is responsible for returning a limb
to its initial position.
•Synergist
•muscle which performs, or assists in performing, the same
set of joint motions as the agonists
Shoulder Complex comprised of 3 bones:
•Clavicle : “aka” collar bone;
•acromioclavicular: joint laterally
• sternoclavicular: joint medially (single attachment between the axial and
appendicular skeleton)
•Synovial joints
•Scapula:
•16 muscles attach to scapula
•scapulothoracic joint is false joint
•Along with clavicle important in stabilization and movement of the arm
•Humerus:
•Articulates with glenoid fossa to form glenohumeral joint
•Synovial ball and socket joint.
Bones of the Shoulder and Arm
CLAVICLE – convex medially, concave laterally
Bony Landmarks
Bony Landmarks
Bony Landmarks
Intertubercular groove is also
known as the bicipital groove
Radial fossa – where the head of
radius hits the humerus
Coronoid fossa – where the
coronoid process of ulna hits the
humerus
Trochlea – medial condyle of
humerus; on both anterior and
posterior of humerus
Capitulum – lateral condyle of
humerus; only on anterior of
humerus
Bony Landmarks
Olecranon fossa – where the
olecranon process of ulna hits
the humerus
Trochlea - continues from
anterior of humerus to posterior
of humerus
(Capitulum does not)
Bony Landmark Trails
Bony Landmark Trails
Spine of the Scapula
•Superficial ridge
•Oblique angle from acromion to the medial border
•Attachment site for:
•posterior deltoid
•middle and lower trapezius
•Separates the supraspinatus and infraspinatus
fossa
Medial Border
•Runs parallel to the vertebral column
•Deep to the trapezius muscle
•Attachment site for:
•Rhomboids
•Serratus anterior
Lateral Border
Extends superiorly and
laterally from the inferior
angle of the scapula towards
the axilla (armpit)
Infraglenoid Tubercle
Located at the most superior aspect
of the lateral border
Serves as attachment site of the long
head of the triceps brachii
Infraspinous Fossa
Triangular area inferior to the
spine of the scapula
Filled with infraspinatus muscle
Supraspinous Fossa
Deep depression superior to the
spine of the scapula
Supraspinatus muscle attaches and
lies in this fossa
Subscapular Fossa
Located on the scapula’s anterior (underside) surface,
against the rib cage
Attachment site for the subscapularis muscle
Scapulothoracic joint – “pseudoarthrotic joint”; it
moves like a joint, but it is attached to the thorax by
muscle, so it is not a true joint between two bones (it is
just suspended there)
Inferior Angle
Located at the inferior end of the
medial border of the scapula
Superior Angle
Located at the superior end of the
medial border of the scapula
Acromion
Lateral aspect of the spine of the scapula
Located at the top of the shoulder
Articulates with the acromial end of the
clavicle
Clavicle
S-shaped bone that is horizontally positioned
across the upper thorax
Lateral (acromial) end articulates with the
acromion
•relatively flat
Medial (sternal) end articulates with the sternum
• rounded
Acromioclavicular Joint (AC joint)
Synovial joint / diarthrosis
Articulation between the the acromion
of the scapula and the (acromial end) of
the clavicle.
The lateral end of the clavicle is flat
and sits slightly higher than the
acromion
Sternoclavicular Joint (SC joint)
Synovial joint / diarthrosis
Where the sternum articulates
with the medial (sternal end) of
the clavicle.
Contains a fibrous disk
The medial end of the clavicle is
rounded
The S/C joint is the only bony
attachment of the upper
extremity to the axial skeleton
Coracoid Process
Anterior, beak-like projection of
scapula
Located inferior to the shaft of the
clavicle
It can be located in the deltopectoral
groove
Deltoid Tuberosity
Small, low bump
Located on the lateral side of the midhumeral shaft
Serves as attachment site of the deltoid
muscle fibers
Greater Tubercle
Located inferior and lateral to the
acromion on the proximal end of the
humerus
Attachment site for 3 of the 4 rotator
cuff muscles
•Supraspinatus
•Infraspinatus
•Teres minor
Lesser Tubercle and Intertubercular Groove
Lesser tubercle - smaller than and medial to the greater tubercle
•Attachment site for subscapularis muscle
Intertubercular groove (bicipital groove) - lies between the greater and lesser
tubercles
•Tendon of the long head of the biceps brachii muscle travels through here
Muscles of the Shoulder and Arm
Muscles of the Shoulder and Arm
Muscles of the Shoulder and Arm
Deltoid
Triangle shaped muscle
Composed of anterior, medial and
posterior fibers.
All fibers abduct the humerus.
Deltoid
Trail Guide: Deltoid
Trapezius
Divided into 3 groups:
•Upper (descending) fibers
•Middle fibers
•Lower (ascending fibers)
Upper and lower fibers act as
antagonists in elevation and depression
respectively
Trapezius
(CN XI) and C2, 3, 4
Upper, Middle and Lower
Fibers of the Trapezius
Trail Guide: Trapezius
Latissimus Dorsi
Broadest muscle of the back
Intertubercular groove of the humerus
Latissimus Dorsi
Trail Guide:
Latissimus Dorsi
Teres Major
Called the “lats little helper” because it is a
synergist with the latissimus dorsi
Teres major and minor act
antagonistically in medial and lateral
rotation
•Teres minor= laterally rotates
•Teres major= medially rotates
Latissimus Dorsi and Teres Major
Both are termed the handcuff muscles
Rotator Cuff Muscles
Supraspinatus
Infraspinatus
Teres Minor
Subscapularis
Rotator Cuff Muscles
Rotator Cuff Muscles
Stabilize head of the humerus in glenoid cavity
Rotator Cuff Muscles
Stabilize head of the humerus in glenoid cavity
Upper 2/3
Rotator Cuff Muscles
Supraspinatus
Infraspinatus
Teres Minor
Subscapularis
Rotator Cuff Tendons
Supraspinatus tendon
Infraspinatus Tendon
Teres Minor
Subscapularis
Supraspinatus Tendon
Medially rotate and extend arm(Handcuff position)
Just anterior and inferior to the acromion
Infraspinatus and Teres Minor Tendons
Flex shoulder to 90 degrees.
Deep to deltoid just inferior to the acromion
Subscapularis Tendon
Trail Guide: Rotator Cuff
Rotator Cuff Injuries
Supraspinatus is the
strongest abductor of the
shoulder
The major muscle that is
usually involved is the
supraspinatus muscle.
•Rotator Cuff Tendonitis
•Rotator Cuff Tears
•Instability Impingement
•Rotator Cuff Tendonitis
•Also known as "bursitis" or
"impingement syndrome"
•Occurs when the rotator cuff
gets irritated on the
undersurface of the acromion.
•Multiple causes(etiologies).
•Some people are born with a
"hooked" acromion that will
predispose them
•Rotator cuff weakness that
causes the humerus to ride
up and pinch the
supraspinatus tendon
•The bursa — a waterballoon type structure that
acts as a cushion between the
rotator cuff and
acromion/humerus — gets
inflamed.
•Rotator Cuff Tears
•Occurs when tendonitis in the
rotator cuff becomes chronic
and it wears down one of the
rotator cuff tendons
(Supraspinatus tendon).
•Tears can occur due to a
traumatic event as a result of
over tensioning the tendon or
shoulder instability.
•Can be a “pop” in the
shoulder, usually with
immediate pain (this is called
an "acute rotator cuff tear").
Instability
Impingement
•Dislocations
Head of the humerus completely pops out of
the socket.
•Initially most commonly due to significant
trauma (although it can occur in some
people without significant trauma)
•In time it becomes easier and easier for the
joint to dislocate.
•Most shoulder dislocations are anterior.
•Subluxations
This is the feeling that the shoulder slips
slightly out of socket, then immediately
comes back in place.
•Often happens without any major trauma.
"loose-jointed".
•Can occur in all directions
"multidirectional instability".
• Common in throwing athletes
and swimmers
Acute rotator cuff tear
Sudden tearing sensation followed by severe pain shooting from the upper shoulder area (both in front and in back) down
the arm toward the elbow.
Decreased range of motion of the shoulder because of pain and muscle spasm.
Acute pain from bleeding and muscle spasm: This may resolve in a few days.
Large tears may cause the inability abduct the arm (raise it out to the side) due to significant pain and loss of muscle power.
Chronic rotator cuff tear
Pain usually is worse at night and may interfere with sleep.
Gradual weakness and decreased shoulder motion develop as the pain worsens.
Decrease in the ability to abduct the arm.
Difficult to use the injured arm for activities that entail lifting the arm as high as or higher than the shoulder, to the front or
side.
May develop “Frozen Shoulder”
Rotator cuff tendinitis
More common in women 35-50 years of age
Deep ache in the shoulder also felt on the outside upper arm over the deltoid muscle
Point tenderness may be appreciated over the area that is injured
Pain comes on gradually and becomes worse with lifting the arm away from the body(abduction) or turning it inward
(internal rotation)
May lead to a chronic tear:
When a rotator cuff tendon becomes inflamed (tend=tendon +itis=inflammation), it runs the risk of losing its blood supply,
causing some tendon fibers to die. This increases the risk that the tendon can fray and partially or completely tear.
Rhomboid Major and Minor
Rhomboids
Trail Guide: Rhomboids
Levator Scapula
•Located along lateral and posterior side of the
neck
•Inferior portion is deep to the upper trapezius
•More superficial on the lateral side of the neck
Levator Scapula
C3 and C4
Levator Scapula
Trail Guide: Levator
Scapulae
Serratus Anterior
•Lies along the posterior and lateral rib cage
•Most of the muscle is deep to the scapula, latissimus dorsi or pectoralis major.
•Superficial portion of the muscle lies inferior to the axilla
•Works to abduct the scapula as an antagonist to the rhomboids
Serratus Anterior
External surfaces of upper eight or nine ribs
Winging of the
Scapula
Mostly due to a lesions of the long
thoracic nerve (serratus anterior).
Rarely, but may also be due to spinal accessory
nerve (trapezius) and dorsal scapular nerve
(rhomboids).
Breast Tissue
•Composed of subcutaneous fat and supported
by suspensory ligaments connecting skin with
deep fascia anterior to the pectoralis major.
•2/3 of the breast covers the pectoralis major.
•The inferior and lateral aspects cover the
serratus anterior muscle
Pectoralis Major
•Broad powerful muscle
•Divided into 3 segments
•Clavicular fibers
•Sternal fibers
•Costal fibers
•The upper fibers and lower fibers act as
antagonists to themselves
•Upper fibers= flexion at the shoulder
•Lower fibers=extension at the shoulder
Pectoralis Major
Upper fibers: Lateral pectoral
Lower fibers: Lateral and medial pectoral
Trail Guide:
Pectoralis Major
Pectoralis Minor
•Lies deep to the pectoralis major along the rib cage
•Fibers run perpendicular to pectoralis major
•Brachial plexus, axillary artery and vein cross
underneath pectoralis minor
Pectoralis Minor
Assist to elevate thorax during forced inhalation
Trail Guide:
Pectoralis Minor
Pectoralis Minor
Syndrome
Definition:
A form of Thoracic Outlet Snydrome (TOS) causing
pain, numbness, tingling, and/or weakness in the arm
and hand due to pressure against the nerves or blood
vessels that supply the arm.
Causes:
tight muscles, ligaments, bands, or bony
abnormalities in the thoracic outlet area of the body
causing pressure on nerves (most common) or blood
vessels.
Symptoms:
numbness and tingling in the fingers; pain in the
neck, shoulder, and arm; headaches in the back of the
head; weakness of the arm and dropping things from
the hand; worsening of the symptoms when elevating
the arm to do such things as comb or blow dry one's
hair or drive a car; and coldness and color changes in
the hand. Worse at night or when using the arm for
overhead activities
Subclavius (underneath clavicle)
Depress the clavicle and draw it anteriorly
Inferior surface of middle 1/3 of clavicle
Biceps Brachii
Long head (lateral) and short head (medial)
Tendon of the long head passes through the intertubercular
groove
Intertubercular groove helps stabilize the tendon
Biceps Brachii
Trail Guide: Biceps
Brachii
Triceps Brachii
•Only muscle located on the posterior arm
•Antagonist to the biceps brachii
•Three heads:
•Long head
•Lateral head
•Medial head
Triceps Brachii
Trail Guide: Triceps
Brachii
Coracobrachialis
Synergists – Muscles Working Together
Shoulder
(glenohumeral joint)
Shoulder
(glenohumeral joint)
Shoulder
(glenohumeral joint)
Shoulder
(glenohumeral joint)
Shoulder
(glenohumeral joint)
Shoulder
(glenohumeral joint)
Scapula
(scapulothoracic joint)
Scapula
(scapulothoracic joint)
Scapula
(scapulothoracic joint)
Other Structures of the Shoulder and Arm
Axilla
Other Structures of the Shoulder and Arm
Axilla
4 walls
Lateral wall= biceps brachii + coracobrachialis
Posterior wall= subscapularis + latissimus dorsi
Anterior wall= pectoralis major
Medial wall= rib cage and serratus anterior
Other Structures of the Shoulder and Arm
Axilla
Sternoclavicular Joint
Ligaments of the Shoulder and Glenohumeral Joint
Ligaments of the Shoulder and Glenohumeral Joint
Glenohumeral Joint
Glenohumeral Joint
Coracoclavicular Ligament
•Provide stability for the AC joint
•Composed of trapezoid and conoid ligaments
•Run from coracoid process of the scapula to
the inferior surface of the clavicle
Coracoacromial Ligament
•Attaches the scapula’s coracoid process to the acromion
•Coracoacromial ligament + Acromion = Coracoacromial arch
•Protects the rotator cuff tendons and subacromial bursa
from direct trauma by the acromion
Subacromial Bursa
•Aka “Subdeltoid bursa”
•Fluid filled sac
•Abduction of the arm compresses the bursa,
therefore can indicate subacromial bursitis if
painful abduction.
Axillary Lymph Nodes
Brachial Artery
•Continuation of the axillary
artery.
•Branches at elbow into radial
and ulnar arteries
•Runs between the biceps brachii
and triceps brachii muscles on the
medial arm