LAB 7—UPPER LIMBS

MUSCLES

Anconeus Muscle

Lateral view, left side Cat information: anconeus origin: distal end of dorsal surface of humerus insertion: lateral surface of ulna from distal margin of the semilunar notch to proximal end of the olecranon nerve: radial action: pronation of hand

Posterior view, right side Human information: anconeus origin: posterior surface of lateral epicondyle of humerus insertion: lateral aspect of olecranon process and posterior surface of proximal portion of ulna nerve: radial (C7-C8) action: extension of the forearm,

Brachialis Muscle

Lateral view, left side Cat information: brachialis origin: lateral surface of hume-rus insertion: lateral surface of ulna just distal to the semilunar notch nerve: musculocutaneous action: flexion of forearm

Anterior view, right side Human information: brachialis origin: distal half of the an-terior surface of humerus insertion: ulnar tuberosity and coronoid process of ulna nerve: musculocutaneous (C5-C6) action: flexion of forearm (elbow)

Infraspinatus Muscle

Lateral view, left side

Lateral view with spinodeltoid reflected, left side Cat information: infraspinatus origin: infraspinous fossa of scapula insertion: greater tubercle of humerus nerve: suprascapular action: abduction and lateral rotation of arm

Posterior view, left side Human information: infraspinatus (rotator cuff) origin: infraspinous fossa of scapula insertion: posterior aspect of greater tubercle of humerus, and capsule of shoulder joint nerve: suprascapular (C5, C6) action: lateral (external) rotation and, horizontal abduction of arm This is one of the four rotator cuff muscles.

Subscapularis Muscle

Dorsal view, left side Cat information: subscapularis origin: subscapular fossa of scapula insertion: dorsal border of the lesser tubercle of humerus nerve: subscapular action: adduction and extension of arm

Anterior view, right side Human information: subscapularis (rotator cuff) origin: entire anterior surface of the subscapular fossa of scapula insertion: lesser tubercle of humerus, and capsule of shoulder joint nerve: upper and lower subscapular nerves (C5, C6) action: medial (internal) rotation of arm This is one of the four rotator cuff muscles.

Supraspinatus Muscle

Dorsolateral view, left side Cat information: supraspinatus origin: supraspinous fossa of scapula insertion: greater tubercle of humerus nerve: suprascapular action: extension of arm

Posterior view, right side Human information: supraspinatus (rotator cuff) origin: medial 66.7% of supraspinous fossa of scapula insertion: greater tubercle of humerus and capsule of shoulder joint nerve: suprascapular (C5 and C6) action: abduction of arm This is one of the four rotator cuff muscles.

Teres Major Muscle

Lateral view, left side Cat information: teres major origin: dorsal one third of the caudal border of scapula insertion: by a common tendon with the latissimus dorsi on the medial surface of the shaft of humerus nerve: subscapular (middle division) action: rotates arm inward, flexion of arm in opposition to infraspinatus, teres minor and the deltoids

Posterior view, left side Human information: teres major origin: posterior surface of the inferior angle of scapula on inferior third of scapular axillary border insertion: crest of lesser tubercle of humerus, medial to latissimus dorsi tendon and fused with that tendon nerve: lower subscapular (C5 and C6) action: extension, adduction, and medial (internal) rotation of arm

Lateral view, left side Cat information: teres minor origin: caudal border of scapula insertion: by a short tendon to the tubercle immediately distal to the infraspinatus fossa on the greater tubercle of humerus nerve: axillary action: assists infraspinatus to rotate arm outward, flexion of arm

Teres Minor Muscle

Posterior view, left side

Human information: teres minor origin: posterior surface of the scapula adjacent to the scapular axillary border insertion: inferior facet on posterior surface of the greater tubercle of humerus (inferior to insertion of infraspinatus) nerve: axillary (C5 and C6) action: lateral (external) rotation and horizontal abduction of arm This is one of the four rotator cuff muscles. If the axillary nerve is damaged and this muscle is no longer active, the individual will exhibit the condition known as head waiter's syndrome with medial rotation of the arm.

Triceps Brachii (lateral head)

Triceps Brachii (Lateral Head)

Lateral view, left side Cat information: triceps brachii, lateral head origin: shaft of humerus insertion: olecranon process of ulna nerve: radial action: extension of

Triceps Brachii (Lateral Head)

Posterior view, left side Human information:

triceps brachii, lateral head origin: posterior surface of humerus

proximal to the spiral groove insertion: olecranon process of ulna

nerve: radial (C7-C8) action: extension of forearm (elbow)

Triceps Brachii (Long)

Lateral view after lateral head of tri-ceps has been transected, left side

Medial view, left side Lateral view, left side

Cat information: triceps brachii, long head origin: caudal surface of glenoid cavity of scapula insertion: olecranon process of ulna nerve: radial action: extension of forearm

Posterior view, left side Human information:

triceps brachii, long head origin: infraglenoid tubercle of scapula

insertion: olecranon process of ulna nerve: radial (C7-C8)

action: extension of forearm, extend and adduct arm

You should note the perimysium (pearlescent pantyhose) on the long head of the triceps brachii. Functionally this is

important as it strengthens the muscle cells and keeps them from tearing. It is

found on all skeletal muscles, but is par-ticularly noticeable in a few muscles such

as this one.

Lateral view, left side

Cat information: triceps brachii, medial head origin: shaft of humerus insertion: olecranon process of ulna nerve: radial action: extension of forearm

Posterior view, left side Human information: triceps brachii, medial head origin: posterior surface of humerus distal to radial (spiral) groove insertion: olecranon process of ulna nerve: radial (C7-C8) action: prime extensor of forearm

Triceps Brachii—Medial Head

Radial Nerve

Lateral view, left side

The radial nerve is fondly referred to as the "biggest hugest nervus in the arm" by Dr. J's students. It is a branch of the posterior cord containing nerves from the anterior rami of C5, C6, C7, C8, and T1. It serves the posterior compart-ment of the arm and forearm as well as the brachioradialis muscle. It controls all the extensor muscles found in the arm and forearm and two of the supinator muscles (supinator and brachioradialis). It also receives sensory in-put from the posterolateral cutaneous area of the hand. When damaged it is results in the clinical condition called wrist drop.

Dorsolateral view, left side Dorsal view, left side

The suprascapular nerve serves the supraspinatus and infraspinatus muscles and the shoulder joint. These are both rotator cuff muscles. The origin of the suprascapular nerve is from the upper trunk of the brachial plexus (including the anterior rami from spinal nerves C5 and C6). The su-prascapular nerve runs through the suprascapular notch with the suprascapular artery. That would make it a Grant, Grant, Grant thing.

Suprascapular Nerve

Lateral view, left side The caudal humeral circumflex artery is a branch of the subscapular artery. It gets its name from the fact that it passes around the caudal side of the humerus. It forms collateral circulation with the cranial humeral circumflex artery in the lateral region of the arm. In the cat it serves the lateral and long heads of the triceps, acromio-deltoid, and spinodeltoid. In humans it serves the deltoid muscle and the shoulder joint.

Caudal Humeral Circumflex Artery

Cephalic Vein

Lateral view, left side The cephalic vein is observed on the superficial, lateral side of the forearm and arm. Inferior to the clavicle it passes into the axilla where it joins the axillary vein. The axillary vein passes through the thoracic wall to become the subclavian vein. In the forearm the cephalic vein runs with the superficial branch of the radial nerve on the surface of the brachioradialis muscle.

Subscapular Artery

Lateral view, left side

The subscapular artery is the largest lateral branch of the axillary artery. It marks the end of the axillary artery and the beginning of the brachial ar-tery. It arises from the distal third of the axillary artery on the posterior surface. In the cat it has two branches, the caudal humeral circumflex and the thoracodorsal. It continues between the subscapularis and teres major and it sends branches to the subscapularis, long head of the triceps brachii and latissimus dorsi. It then continues over the surface of the infraspinatus muscle and serves the infraspinatus, supraspinatus, acromiotrapezius and spinotra-pezius. Occasionally it gives rise to the cranial humeral circumflex artery, although that vessel is more often a branch of the brachial artery. In hu-mans the subscapular artery serves the posterior wall of the axilla and the posterior scapular region and has just the two terminal branches, the thora-codorsal artery and the circumflex scapular artery.

Suprascapular Artery

Dorsolateral view, left side The suprascapular artery is a branch of the transverse scapular artery. It passes through the suprascapular notch with the suprascapular nerve and it sends branches to the supraspinatus and infraspinatus mus-cles. This makes it a Grant, Grant, Grant thing. In humans the suprascapular artery is a branch of the thyrocervical trunk or it may be a branch of the subclavian artery. It passes superior to the suprascapular notch but then runs with the suprascapular nerve. It serves the infraspinatus, supraspi-natus and many other structures as it moves toward those muscles.

Transverse Scapaular Artery

Dorsal view, left side The transverse scapular artery is a branch of the thyrocervical artery. On the deep side of the scapula it runs with the suprascapular nerve and it then gives rise to the suprascapular artery. There is no comparable artery in humans.

Transverse Scapular Artery