KIN 301: Pectoral Girdle

What is the shoulder?

a complex multi-joint structure

what articulations/joints occur at the shoulder?

sternum and clavicle
clavicle and scapula
scapula and humerus
scapula and thorax (not bony articulation)

___ articulation with the __ is the ONLY bony link to axial skeleton

Clavicle, sternum

pectoral girdle is made up of two bony articulations:

sternoclavicular and acromioclavicular

Sternoclavicular is the... ? what type of joint

Articulation between manubrium of sternum and sternal end of clavicle
Saddle synovial joint

Acromioclavicular (AC) is the... ? what type of joint

Articulation between acromial end of clavicle and acromion process of scapula
Planar synovial joint

The SV joint can elevate __, retract __, protract __, and depress __

45 e
15 r
15 p
10 d

The AC joint has 20-30 total _____ and ____ motion

gliding, rotational

What is upward rotation of the ST joint?

What is the point of reference for rotation of the ST joint?

the glenoid fossa, if points up the scapula upwardly rotated, if points down the scapula downwardly rotated

What is elevation and depression of the ST joint

What are the 6 movements of the shoulder girdle?

protraction,
retraction,
elevation,
depression,
upward rotation,
downward rotation

What makes an open chain exercise?

axial skeleton is fixed, and clavicle and scapula move
-raising your hand/lateral raises

What makes a closed chain exercise?

arm is fixed in place
axial skeleton moves
- push/pull up

What is the only bony connection to the axial skeleton?

SC joint

Force couples

Because the scapula has so much rotation and translation mobility, often time multiple muscles are needed to produce a pure scapular rotation

Peripheral Nervous System (PNS) contains...

31 pairs of Spinal Nerves

What are the 4 plexuses

Cervical Plexus (head and neck)
Brachial Plexus (upper extremity)
Thoracic Nerves (no plexus, direct to axial muscles)
Lumbosacral Plexus (lower extremity)

what is a plexus

"braid"
Axons of spinal nerves inter-weave to form peripheral nerves that have contributions from multiple spinal nerves
Creates redundancy!

injury to one spinal level will ___ cause a complete motor or sensory deficit, only partial

not

Where is the brachial plexus

Ventral rami of spinal nerves C5-T1

What does the brachial plexus innervate?

pectoral girdle and upper limbs (except trapezius)

What is scapular winging?

Describes when the scapula is not held down against the thorax

What is scapular winging associated with?

Often associated with failure to activate Serratus Anterior muscle
Could be associated with damage to Long Thoracic Nerve, which innervates this muscle

Pectoral girdle muscles: (3)

1. Stabilize scapula so the shoulder joint muscles will have a stable base from which to exert force for moving the humerus
2. Contract to maintain scapula in a relatively static position during shoulder joint actions
3/ Contract to move shoulder girdle and to enhance movement of upper extremity when shoulder goes through extreme ranges of motion