Download deltoid muscles

Region of upper limb attachment to the trunk
Proximal segment of limb
overlaps parts of the trunk (thorax and back) and lower lateral neck.
includes
Pectoral
Scapular
Deltoid regions of the upper limb
lateral part (greater supraclavicular fossa) of lateral cervical region.
Overlies half of the pectoral girdle.
The pectoral (shoulder) girdle formed by:
Scapulae and clavicles
completed anteriorly by the manubrium of the sternum
(part of the axial skeleton).
BONE FRAMEWORK OF THE SHOULDER
Clavicle & scapula [pectoral girdle-shoulder girdle]
Proximal end of humerus
The superficial muscles of the
shoulder
trapezius & deltoid muscles
together form the smooth
muscular contour over the
lateral part of the shoulder.
Connect scapula to trunk &
clavicle to arm.
.
The 3 joints in the shoulder complex :
Sternoclavicular joint
Acromioclavicular joint
Glenohumeral joint
Muscles
The two most superficial muscles of the shoulder
trapezius and deltoid muscles.
Trapezius attaches scapula & clavicle to the trunk
Deltoid attaches scapula & clavicle to the humerus
SUPERFICIAL
POSTERIOR AXIOAPPENDICULAR MUSCLES
EXTRINSIC SHOULDER MUSCLES
Trapezius & latissimus dorsi
POSTERIOR
AXIOAPPENDICULAR
MUSCLES
EXTRINSIC SHOULDER
MUSCLES
Levator scapulae & rhomboids
SCAPULOHUMERAL
(INSTRINSIC SHOULDER) MUSCLES
6 scapulohumeral muscles
Deltoid, teres major, supraspinatus, infraspinatus,
subscapularis, and teres minor
pass from scapula to humerus
Act on the glenohumeral joint.
All the intrinsic muscles but the deltoid and the
subscapularis are muscles of the posterior scapular region.
Large and triangular in shape
Base attached to the scapula and clavicle
Apex attached to the humerus
Lateral 1/3 of clavicle
Acromion
Spine of scapula
Deltoid tuberosity of humerus
Major function:
Abduction of the arm
beyond the initial 15° accomplished by supraspinatus
Clavicular: flexes and medially rotates arm
Acromial: abduction of arm
Spinal: extends and laterally rotates arm
Innervation:
Axillary nerve
branch of the posterior cord of the brachial plexus
 Thick, triangular muscle
 Lies on the costal surface of the scapula
Subscapular fossa
Lesser tubercle of humerus
Primary medial rotator of the arm
Adducts the arm.
Joins the other rotator cuff muscles in holding the head
of the humerus in the glenoid cavity during all
movements of the glenohumeral joint!
Innervation: Superior and inferior subscapular nerves
POSTERIOR SCAPULAR REGION
4 muscles
pass between the scapula and proximal end of humerus:
Supraspinatus
Infraspinatus
Teres minor
Teres major
+ part of long head of the triceps brachii,
passes between the scapula and the proximal end of the forearm.
 Originate from 2 large fossae, 1 above and 1 below the
spine, on the posterior surface of the scapula.
 Insert on greater tubercle of the humerus.
 Supraspinatus initiates abduction of the arm.
 Infraspinatus laterally rotates the humerus.
 A cord-like muscle
Middle part of lateral border of scapula
Inferior facet of greater tubercle of humerus
 Laterally rotates the humerus
 Component of the rotator cuff.
Posterior surface of inferior angle of scapula
Medial lip of intertubercular sulcus of humerus
Medially rotates and extends the humerus.
4 intrinsic shoulder muscles
1) Supraspinatus
(SITS muscles)
2) Infraspinatus
3) Teres minor
4) Subscapularis
Form a musculotendinous
rotator cuff around the
glenohumeral joint.
Insertion exception:
Supraspinatus
Infraspinatus
Teres minor
greater tubercle
Subscapularis
lesser tubercle
Functional exception:
All except supraspinatus are rotators of the humerus
Supraspinatus, besides being part of the rotator cuff,
initiates and assists the deltoid in the first 15° of abduction
of the arm.
Suprascapular foramen
The route through which structures pass between the
base of the neck and the posterior scapular region.
Formed by
suprascapular notch
of scapula
&
superior transverse
scapular
(suprascapular)
ligament,
which converts the
notch into a foramen.
The suprascapular nerve passes through the
suprascapular foramen;
Suprascapular artery & suprascapular vein follow the same course as
the nerve, but normally pass immediately superior to the superior
transverse scapular ligament and not through the foramen.
Quadrangular space
axillary nerve & posterior circumflex humeral artery and vein
Triangular space
circumflex scapular artery and vein
Triangular interval
radial nerve ,profunda brachii artery (deep artery of arm)
The two major nerves of the posterior scapular region:
Suprascapular & Axillary nerves
originate from the brachial plexus in the axilla.
Originates where?
Base of the neck from superior trunk of brachial plexus
Reach where through which space?
Posterior scapular region through suprascapular foramen
Which muscles innervates ?
Supraspinatus muscle & infraspinatus
Originates where?
Posterior cord of brachial plexus
Reach where through which space?
From the posterior wall of axilla to posterior scapular
region through quadrangular space
Which muscles innervates ?
Deltoid & teres minor
Cutaneous branch?
Superior lateral cutaneous nerve of the arm
carries general sensation from the skin over the
inferior part of the deltoid muscle.
3 major arteries in the posterior scapular region
 Suprascapular artery
 Posterior circumflex humeral artery
 Circumflex scapular artery
These arteries
contribute to an
interconnected
vascular network
around the scapula.
Posterior circumflex humeral artery anastomoses with anterior
circumflex humeral artery and also with branches from:
profunda brachii
(brachial artery)
suprascapular
.
(subclavian
artery)
thoracoacromial
(axillary artery)
arteries
A system connecting each subclavian artery and the
corresponding axillary artery, forming an anastomosis around the
scapula.
It allows blood to flow past the joint regardless of the position of the arm.
It includes:
transverse
cervical artery
.
(subclavian artery)
transverse scapular artery
(subclavian artery)
subscapular artery
(axillary artery)
branches of thoracic aorta
This collateral circulation allows for
blood to continue circulating if the
subclavian is obstructed.
Movements of the shoulder girdle
Abduction of the shoulder is initiated by the supraspinatus; the
deltoid can then abduct to 90 degrees.
Further movement to 180 degrees (elevation) is brought about
by rotation of the scapula upwards by the trapezius and
serratus anterior.
As soon as abduction commences at the shoulder joint, so the
rotation of the scapula begins.
Principal muscles acting on the shoulder joint
Abductors
Supraspinatus
Deltoid
Adductors
Pectoralis major
Lattisimus dorsi
Extensors
Teres major
Lattisimus dorsi
Deltoid (posterior fibres)
Flexors
Pectorali major
Coracobrachialis
Deltoid (anterior fibres)
Medial rotators
Pectoralis major
Lattisimus dorsi
Teres major
Deltoid (anterior fibres)
Subscapularis
Lateral rotators
Infraspinatus
Teres minor
Deltoid (posterior fibres)