LEC 3 - Pectoral Girdle

What does the upper limb refer to? Give its fx

=The arm (brachium), forearm (antebrachium), hand and the pectoral girdle

FX=to move freely and therefore sense and grasp objects around the body

Describe the pectoral girdle/shoulder And its fx

PG=is comprises of the clavicle and scapula.

FX=links the free limb of to the axial skeleton at the SC joint. (Acts as a mobile base to help extend the range of movement of the free limb.)

Muscles associated with the PG extended onto the front and back of the thorax + also onto the pelvic rim

What is the most mobile joint in the body?

=shoulder joint

(More mobile=more unstable=needs more muscle to control and stabilise it)

What muscles insertions or origins are in the coloured sections?

BLUE=trapezium insertio

GREEN=deltoid origin

PURPLE=pec major origin

Gives the names of what is covered in 1,2,3 and 4

1=acromium

2=acromio-clavicular joint (AC)

3=deltoid tubercle

4=manubrium

What part of the clavicle is most prone to fracture?

=middle third as no ligaments or muscle attach so less stable

What is the names of the covered parts?

1=coracoclavicular ligament

2=subclavian groove (subclavius muscle inserts)

3-costoclavicular ligament

What are the four ligament of the sternoclavicular joint?

1/ant sternoclavicualr ligament

2/post sternoclavicualr ligament (these are stronger to prevent damage to nerves and blood vessels posterior to the clavicle)

3/interclavicular ligament (across jugular notch)

4/costoclavicular ligament (chief stabiliser)

What is inside the AC joint?

A wedge shaped fibrocartilagenous intra-articulate disc.

FX=alllows the clavicle and scapulae to move independently

Describe the ligaments of the AC joint

x1 Intrinsic=acromioclavicular ligament

x2 Extrinsic/external coracoclavicular ligament

What type of joints are the AC and SC joints?

Synovial joints

What is the conceptual joint?

=not a true joint.

It acts to brace the scapula up against the thorax

Describe the O, I, A and IN of SUBCLAVIUS

O=costal cartilage of first rib

I=subclavian groove (inferior clavicle surface)

A=braces clavicle to prevent it being pulled out from SC joint

IN=subclavina nerve C5

Describe the O, I, A and IN of SERRATUS ANTERIOR

O= ribs 1→8/9

I= medial border of scapula

A=protracts the scapula. Lower fibres help to superiorly rotate the scapula

IN=long thoracic nerve

CLINICAL RELEVANCE=wing scapula occurs when thoracic nerve is severed and therefore nerve supply to serratus anterior is compromised (normally holds the scapula against the thorax)

Describe the O, I, A and IN of PECTORALIS MINOR

O= ribs 3→5 (anterior-lateral side)

I= coracoid process

A=depresses scapula. (Helps with breathing)

IN=medial pectoral nerve

(Medial pec nerve must pass through pec minor to reach pec major)

Describe the O, I, A and IN of PECTORALIS MAJOR

O=sternum (sternocostal head) and clavicle (clavicular head)

I=lateral lip of intertubular groove (front of humerus)

A=adduction and internal rotation of humerus. can help protract the scapula

IN= lateral and medial pectoral nerves

Describe the O, I, A and IN of TRAPEZIUS (Posterior muscle)

O= broad origin from superior nuchal lines to T12 (cervical and thoracic spinal processes)

I=anatomical horseshoe S=clavicle Middle=accromium I=spine

A=all=retracts scapula S=elevates scapula Mid=retracts scapula Inf=depresses scapula. S and In=superior rotation of scapula

IN=accesory nerve (cranial nerve X)

Describe the O, I A, & IN of TRAPEZIUS (posterior muscle)

O= Broad origin from superior nuchal line to T12 (cervical and thoracic spinal processes)

I=Anatomical horseshoe (sup=clavicle, middle= acromion, inferior=spine of scapula)

A=All=retracts scapula. Sup=elevates scapula, Mid= retracts scapula Inf=depresses scapula. Sup and Inf=superior rotation of scapula

IN=Accesory nerve (cranial nerve X)

Describe the O, I A, & IN of LEVATOR SCAPULAE (PM)

O=transverse processes of C1-C4

I=superior angle of scapula

A=elevates scapula, lateral flexes/extends the neck

IN=dorsal scapula nerve (& C3, C4)

Describe the O, I A, & IN of RHOMBOID MINOR (PM)

O= C7-T1 spinous processes

I=medial border of scapula

A=retracts scapula, can also elevate scapula

IN=dorsal scapular nerve

Describe the O, I A, & IN of RHOMBOID MAJOR (PM)

O=T2-T5 spinous processes

I=medial border of scapula

A=retracts scapula, can also elevate scapula

IN=dorsal scapula nerve

Describe the O, I A, & IN of LATISSIMUS DORSI (PM)

O=broad origin —> spinous processes T7-S5 and iliac crest

I=Floor of inter-tubercular groove on anterior humerus

A=Adducts and internally rotates humerus, over fibres can depress scapula

IN=thoracodorsal nerve