proximal segment of limb...region of upper limb attachment to the trunk proximal segment of limb...

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).

Clavicle & scapula [pectoral girdle-shoulder girdle]

Proximal end of humerus

BONE FRAMEWORK OF THE SHOULDER

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

4 muscles

pass between the scapula and proximal end of humerus:

Supraspinatus

Infraspinatus

Teres minor

Teres major

POSTERIOR SCAPULAR REGION

+ 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

Laterally rotates the humerus

Component of the rotator cuff.

Middle part of lateral border of scapula

Inferior facet of greater tubercle of humerus

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

2) Infraspinatus

3) Teres minor

4) Subscapularis

(SITS muscles)

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

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

Pectoralis 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)