SPR L4 Applied Anatomy Flashcards
An elderly lady presents to the Accident and Emergency Department of her local hospital, following a fall on any icy pavement. Medical assessment of the patient reveals the following:
Severe pain in the region of the right shoulder
Inability to abduct the right upper limb fully (deltoid muscle is responsible for this)
An absence of sensation over the upper lateral region of the right arm
Location of the surgical neck of the humerus – located where the head of the humerus, lesser and greater Ts, all these regions combine to meet the shaft of the humerus
Which nerve is closely related to the surgical neck of the humerus – axillary nerve (only)
From which cord of the brachial plexus does the axillary nerve arise? POST Cord of the Brachial plexus. Axillary nerve comes off obliquely.
Distribution of the axillary nerve (mixed nerve)
Motor = deltoid muscle and teres minor muscle
Cutaneous Distribution = upper lateral region of the arm (the badge area)
Axillary nerve, post circumflex artery both through quadrangular space
Axillary nerve, passes through the quadrangular space in the post scapular region
Upper = Teres Minor
Lateral = Shaft of humerus
Medial = Long head of the triceps
Lower= Teres Major
Axillary is the only nerve supplying deltoid – this muscle is responsible for complete abduction of the arm.
Post group = extension
Lateral fibres = abduction
Supraspinatous muscle = FIRST 15 degrees of abduction
Pt may have tingling/pins and needles = altered sensation to the badge area
A twenty-three year-old man attends Accident and Emergency following a fall whilst ice-skating. X-ray reveals a fracture to the medial epicondyle of the right humerus.
Using your knowledge of upper limb anatomy, describe the potential motor and sensory deficits following such a fracture.
Which nerve is closely related to the medial epicondyle of the humerus? Ulnar Nerve – passes immediately posterior to this bony region.
Where does the ulnar nerve come from? Arises from the medial cord of the brachial plexus.
Motor Distribution of the Ulnar Nerve – Nerve travels within the ANT compartment of the arm.
- Flexor Carpi Ulnaris m.
- Medial half of flexor digitorum profundus m
- Hypothenar mm (all of them)
- Adductor pollicis m.
- Medial two lumbrical mm.
- Palmar and dorsal interossei
Course = within ant compartment of the arm, medially. Passes POST to the medial epicondyle, then travels into the ant compartment of the forearm medially. Medial location is key when understanding that FCUlnaris and Medial half of FDP are innervated by this nerve.
Flexor Carpi Ulnaris m.
Involved with flexion of the hand at the wrist joint
Reduced flexion in this patient – because other muscles are involved in flexion (FCRadialis, FDS, FDP)
Works together with extensor carpi ulnaris, to produce adduction of the hand – both of the muscles have to be contracting. Would expect patient’s ability to adduct the hand to be reduced. ECU will be doing something so won’t have loss of adduction of the hand.
FCR and ECRL and ECRB all work together for abduction of the hand. Styloid of radius means that abduction is more limited than adduction
Medial half of Flexor Digitorum Profundus Muscle
Tendons go to distal phalanx of each of the fingers
Flexion at the wrist, at the MCP joints, and at PIP and DIP. This is the only muscle in the human body that acts at the DIP joint.
Lateral half innervated by median nerve
Patient would be unable to flex the DIP joints of his ring and little fingers
Reduced flexion in PIP joints (FDSuperficialis is still acting here)
Median nerve is still intact, so lateral fingers are fine
Reduced ability to flex the wrist
Hypothenar mm.
Deep branch of the ulnar nerve innvate the hypothenar muscles
Abductor digiti minimi m.
Flexor Digiti minimi brevis m.
Opponens digiti minimi – patient won’t be able to bring their little finger towards the thumb, but can bring thumb over to the little finger side
Adductor Pollicis m
Bringing the thumb back to the palm – patient cant perform this movement
Medial Two Lumbrical mm
Medial two limbrical muscles are innervated by a deep branch of the ulnar nerve
Allow us to flex at MP and Extend at IP.
Medial two have lost innervation. Patient can’t flex at MP and extend at IP. Will present with extension at MP, and fingers will be flexed = ULNAR CLAW. Hand has taken on the appearance of a claw
Palmar and Dorsal interossei.
The palmar interossei are innervated by a deep branch of the ulnar nerve
Axial Line = dashed green line of diagram. V. Important.
Point of reference of movement of the fingers.
When you are using these muscle you are adducting the fingers. NOTE: cannot adduct the middle finger. All others adduct towards it.
Patient has lost ability to adduct the fingers, won’t be able to grip a piece of paper between the fingers, will have lost this grip
The dorsal interossei are innervated by a deep branch of the ulnar nerve
Patient would lose ability to abduct digits.
Note: could abduct thumb – abductor pollicis brevis
Function of INterosseuous msucles
PAD – palmar adduct
DAB – dorsal abduct
Cutaneous Distribution
Note the region in blue
This is a palmar aspect
Ulnar gives branches to skin of palmar aspect of little finer and medial half of the ring finger.
Ulnar nerve supplies medial aspect of the dorsum of hand. All of little finger, and medial half of ring finger (including nail beds)
This is the normal pattern of distribution. Quite a lot of variation in terms of sensory distribution in the dorsum of the hand
Remember LOAF (all these supplied by median nerve)
