shoulder and pectoral regions - national university 5 shoulder region .pdftopographical anatomy of...
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Shoulder and Pectoral regions
Dr.Elraiah Mohamed
Makie 0122858517
Msc
Anatomy department
Faculty Of Medicine2nd Year Semster4
By the end of this session the student should be able to :
Describe the muscles of the pectoral & shoulder regions , their action and innervations
study the common clinical correlations
Topographical Anatomy of the pectoral and shoulder regions
Shoulder: proximal segment of the limb that overlaps
parts of the trunk
Arm (L. brachium): first segment of the free upper
limb and the longest segment of the limb.
Forearm (L. antebrachium): second longest segment
of the limb.
Hand (L. manus): part of the upper limb distal to the
forearm that is formed around the carpus,
metacarpus, and phalanges.
An injury to the upper limb, particularly the
hand, are far out of proportion to the extent of
the injury,
A sound understanding of the structure and
function of the upper limb is of the highest
importance.
Knowledge of its structure without an
understanding of its functions is almost useless
clinically because the aim of treating an injured
limb is to preserve or restore its functions.
G-H joint A-C joint S-C joint S-T joint Subacromial space
-Trapezius.-Latissimus dorsi.
- Levator scapulæ. - Rhomboideus major.- Rhomboideus minor.
Superficial layer
Deep layer
•Muscles Connecting the Upper Limp to the Vertebral Column
The superficial axioappendicular muscles are
trapezius
latissimus dorsi
The deep posterior thoracoappendicularmuscles are
levator scapulae and rhomboids.
These muscles provide direct attachment of the appendicular skeleton to the axial skeleton.
Muscles connecting scapula to humerus◦ Teres Major◦ Rotator Cuff Supraspinatus Infraspinatus Teres Minor Subscapularis
◦ Deltoid
Subscapularis
Supraspinatus
Infraspinatus
Teres Minor
◦ Function mainly to reinforce the capsule of the shoulder
◦ Act to stabilize head of humerusin glenoid cavity and prevent dislocation
◦ Secondarily act as synergists and fixators
Supraspinatus assists deltoid in abduction
Subscapularis, infraspinatus & teres minor depress humeral head
Injury or disease may damage the musculotendinous rotator cuff, producing instability of the glenohumeral joint.
Trauma may tear or rupture one or more of the tendons of the SITS muscles; that of the supraspinatus is most commonly involved.
Degenerative tendonitis of the rotator cuff is common, especially in older people.
Origin :from occipital bone, ligamentum nuchae, spine of seventh cervical vertebra, spines of all thoracic vertebrae
Insertion: Upper fibers into lateral third of clavicle; middle and lower fibers into acromion and spine of scapula
Innervations :Spinal part of accessory nerve (motor) and C3 and 4 (sensory) XI cranial nerve (spinal part)
Action :Upper fibers elevate the scapula; middle fibers pull scapula medially; lower fibers pull medial border of scapula downward
Origin : Transverse processes of first four cervical
vertebrae
Insertion: Medial border of scapula
Innervations : C3 and 4 and dorsal scapular nerve C3, 4, 5
Action : Raises medial border of scapula
Origin :from Ligamentum nuchae and spines
of seventh cervical and first thoracic vertebrae
Insertion: Medial border of scapula
Innervations : Dorsal scapular nerve C4, 5
Action : Raises medial border of scapula
upward and medially
Origin : Second to fifth thoracic spines
Insertion: Medial border of scapula
Innervations : Dorsal scapular nerve C4, 5
Action : Raises medial border of scapula
upward and medially
Origin : Lateral third of clavicle, acromion,
spine of scapula
Insertion: Middle of lateral surface of shaft of
humerus
Innervations : Axillary nerve C5, 6
Action : Abducts arm; anterior fibers flex and
medially rotate arm; posterior fibers extend
and laterally rotate arm
Origin : Supraspinous fossa of scapula
Insertion: Greater tuberosity of humerus;
capsule of shoulder joint
Innervations : Suprascapular nerve C4, 5, 6
Action : Abducts arm and stabilizes shoulder
joint
Origin : Infraspinous fossa of scapula
Insertion: Greater tuberosity of humerus;
capsule of shoulder joint
Innervations : Suprascapular nerve (C4), 5, 6
Action : Laterally rotates arm and stabilizes
shoulder joint
Origin : Lower third of lateral border of scapula
Insertion: Medial lip of bicipital groove of
humerus
Innervations : Lower subscapular nerve C6, 7
Action : Medially rotates and adducts arm and
stabilizes shoulder joint
Origin : Upper two thirds of lateral border of
scapula
Insertion: Greater tuberosity of humerus; capsule of
shoulder joint
Innervations : Axillary nerve (C4), C5, 6
Action : Laterally rotates arm and stabilizes
shoulder joint
Origin : Subscapular fossa
Insertion: Lesser tuberosity of humerus
Innervations : Upper and lower subscapular
nerves C5, 6, 7
Action : Medially rotates arm and stabilizes
shoulder joint
Origin : Iliac crest, lumbar fascia, spines of lower six
thoracic vertebrae, lower three or four ribs, and
inferior angle of scapula
Insertion: Floor of bicipital groove of humerus
Innervations : Thoracodorsal nerve C6, 7, 8,
Action : Extends, adducts, and medially rotates the
arm
Blood supply of scapulohumeral Muscles
nerves supply of scapulohumeral Muscles
nerves supply of scapulohumeral Muscles
The deltoid atrophies when the axillary nerve (C5 and C6) is severely damaged. the axillary nerve is usually injured during:
fracture of surgical neck of the humerus dislocation of the. glenohumeral joint compression from the incorrect use of crutches. Result of deltoid atrophy : rounded contour of the shoulder disappears. This gives the shoulder a flattened appearance and
produces a slight hollow inferior to the acromion. a loss of sensation may occur over the lateral side of the
proximal part of the arm
The deltoid is a common site for the intramuscular injection of drugs.
The axillary nerve runs transversely under cover of the deltoid at the level of the surgical neck of the humerus.
Awareness of its location avoids injury to it during surgical approaches to the shoulder.
Four anterior axioappendicular (thoracoappendicular or
pectoral) muscles move the pectoral girdle:
pectoralis major
pectoralis minor
subclavius
serratus anterior.
Anterior Axioappendicular Muscles
Pectoralis major.
Pectoralis minor.
Subclavius.
Serratus anterior.
Main Action Innervation Distal
Attachment
(Insertion)
Proximal
Attachment
(Origin)
Muscle
Adducts and
medially rotates
humerus; draws
scapula anteriorly
and inferiorly
Acting alone,
clavicular head
flexes humerus
and sternocostal
head extends it
from the flexed
position
Lateral and
medial
pectoral
nerves;
clavicular
head (C5, C6),
sternocostal
head (C7, C8,
T1)
Lateral lip of
intertubercular
groove of
humerus
Clavicular head:
anterior surface of
medial half of
clavicle
Sternocostal head:
anterior surface of
sternum, superior
six costal cartilages,
aponeurosis of
external oblique
muscle
Pectoralis
major
Stabilizes scapula
by drawing it
inferiorly and
anteriorly against
thoracic wall
Medial pectoral
nerve (C8, T1)
Medial border
and superior
surface of
coracoid
process of
scapula
3rd to 5th ribs near
their costal
cartilages
Pectoralis
minor
Muscles of the Pectoral region:
Main Action Innervation Distal
Attachment
Proximal
Attachment
Muscle
Anchors and
depresses
clavicle
Nerve to sub-
clavius (C5,
C6)
Inferior
surface of
middle third
of clavicle
Junction of
1st rib and
its costal
cartilage
Subclavius
Protracts
scapula and
holds it against
thoracic wall;
rotates scapula
Long
thoracic
nerve (C5,
C6, C7)
Anterior
surface of
medial
border of
scapula
External
surfaces of
lateral parts
of 1st to 8th
ribs
Serratus
anterior
Muscles of the Pectoral region:
Subclavius Muscle
winged scapula
- winged scapula Due to injury to the longthoracic nerve which leads to Paralysis ofthe Serratus Anterior , giving the scapulathe appearance of a wing.- the medial border of the scapula moveslaterally and posteriorly away from thethoracic wall,
long thoracic nerve
Nerve supply of the Serratus Anterior
Suprclavicular & intercostal Nerves
Clavipectoral fascia
clavipectoral fascia
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