**7. Angiology and neurology**

### **7.1 Head**

From the brachiocephalic trunk branches the left and subsequently the right common carotid artery. These arteries are laterally covered by the sternocleidomastoideus muscle. The internal jugular vein and vagal nerve are closely associated and lie just lateral to the artery. The common carotid artery divides into the internal and external carotid arteries at the mandibular angle. The former artery provides blood to the eye and the brains, while the latter gives off, amongst others, the linguofacial artery to continue as the maxillary artery.

The external jugular vein travels along the lateral aspect of the sternocleidomastoideus muscle and drains the venous blood from the head. This vein is suited for venipuncture. The accessory jugular vein lies parallel to the external jugular vein with which it fuses caudal to the collar bone. The caudal auricular veins, superficial temporal vein and maxillary vein drain into the external jugular vein. The facial vein drains partly into this vein, but mainly into the internal jugular vein. Both the external and internal jugular veins drain into the subclavian vein that in turn flow into the brachiocephalic vein. The cranial cava vein receives the left and right brachiocephalic veins.

In between the common carotid artery and the internal jugular vein lies the vagal nerve. It runs separately from the sympathetic trunk that lies deep against the cervical vertebrae. At the entrance of the thorax, the laryngeus recurrens nerve leaves the vagal nerve. The left sweeps around the aortic arch whereas the right makes a curvature around the right subclavian artery. The laryngeus recurrens nerve subsequently returns to the larynx, lateral to the trachea. Some major nerves and blood vessels of the rhesus monkey head are depicted in **Figure 65**.

#### **7.2 Thoracic limb**

After crossing the 1st rib and giving off several branches to the head, neck, shoulder and thorax, the subclavian artery continues as the axillary artery that is accompanied by the axillary vein. The latter artery continues as the brachial artery after the a. subscapularis and a. circumflexa humeri cranialis have branched off. The brachial

*Anatomy of the Rhesus Monkey (*Macaca mulatta*): The Essentials for the Biomedical Researcher DOI: http://dx.doi.org/10.5772/intechopen.99067*

#### **Figure 65.**

*A: Right lateral view of the rhesus monkey head of which the right side of the mandible has been removed with 1: n. lingualis, 2: n. vagus, 3: n. accessorius, 4: n. hypoglossus, 5: ansa cervicalis, 6: a. carotis communis, 7: a. lingualis. B: Right lateral view of a vascular corrosion cast of the rhesus monkey head with 1: a. facialis, 2: a. submentalis, 3: a. labialis superior, 4: a. nasalis lateralis, 5: a. angularis oculi, 6: a. temporalis superficialis, 7: vascular network of the parotid gland, 8: a. mentalis, 9: aa. temporales profundae, 10: v. facialis, 11: v. angularis oculi.*

artery runs parallel to the n. medianus and gives off the a. profunda brachii as first branch. Subsequent branches are the collateralis ulnaris arteries that run collateral to the n. ulnaris. Just proximal to the elbow joint, the brachial artery splits into the radial and ulnar arteries. The former artery runs at the lateral side of the forearm towards the carpus where it gives origin to the dorsal and palmar arches. The ulnar artery joins the palmar arch. These arches supply the hand and fingers. **Figures 66** and **68** present the discussed arteries.

The venous circulation of the thoracic limbs consists of a deep and a superficial system. The deep system accompanies the arteries (e.g. v. subclavia, v. axillaris, v. brachialis), while the superficial veins have no arterial counterpart. In the rhesus monkey, the superficial venous system is poorly developed since the venous drainage of the hand and forearm is mainly provided by paired vv. comitantes. The cephalic vein, which is located at the cranial side of the antebrachium, is the major superficial vein of the forelimb. It forms a common stem with the accessory jugular vein that drains into the external jugular vein. It can be used for venipuncture, but is not preferred in the rhesus monkey (**Figure 67**).

The nerves of the forelimb originate from the brachial plexus (C5 – T2) at the medial side of the upper arm. The thoracodorsal nerve innervates the latissimus dorsi muscle. The axillary nerve finds its way from medial to lateral superficially in the angle between the coracobrachialis and teres major muscles and deeper between the triceps and teres minor muscles to innervate the flexor muscles of the shoulder (deltoid, coracobrachialis and both teres muscles). The radial nerve runs from medial to lateral between the lateral and medial heads of the triceps muscle and perforates the brachioradialis muscle. Its muscular branches innervate the triceps and anconeus muscles as well as the extensor musculature of the upper arm, forearm and hand. The musculocutaneus nerve innervates the flexor muscles of the elbow joint (rami musculares to the coracobrachialis, biceps brachii and brachialis muscles). The median nerve runs parallel to the brachial artery in between the biceps brachii and

#### **Figure 66.**

*Blood vessels and nerves of the thoracic limb. A: Medial view of the left upper arm with 1: a. brachialis, 2: a. collateralis ulnaris proximalis, 3: a. collateralis ulnaris distalis, 4: a. radialis, 5: n. medianus, 6: n. ulnaris. B: Medial/palmar view of the right forearm and hand with 1: n. medianus, 2: n. ulnaris, 3: ramus dorsalis (n. ulnaris), 4: nn. digitales palmares communes, 5: ramus superficialis (n. ulnaris), 6: a. ulnaris, 7: a. radialis, 8: arcus palmaris.*

*Anatomy of the Rhesus Monkey (*Macaca mulatta*): The Essentials for the Biomedical Researcher DOI: http://dx.doi.org/10.5772/intechopen.99067*

**Figure 67.** *Medial (A) and dorsal (B) views of the thoracic limb showing 1: v. brachialis, 2: n. medianus, 3: v. cephalica, 4: n. cutaneus brachii medialis, 5: n. cutaneus antebrachii medialis.*

brachialis muscle. More distally, it lies deep to the flexor muscles of the forearm, which it innervates. Its most distal branches are the digital nerves. The ulnar nerve can be found between the medial and long head of the triceps muscle. It crosses the elbow region in between the flexor carpi ulnaris and flexor digitorum profundus muscles to reach the hand. Its dorsal, superficial and deep branches innervate the flexor musculature of the fingers in addition to the median nerve. The n. cutaneus brachii et antebrachii medialis runs initially parallel to the ulnar nerve. The brachial and antebrachial branches innervate the skin at the medial sides of the upper and lower arm, respectively. The here discussed nerves are depicted in **Figures 66**–**68**.

### **7.3 Body**

In this paragraph, some essential data on the ramifications of the abdominal aorta and caudal vena cava will be shared. As regards the arterial system that is depicted in **Figure 69**, it should be noticed that the truncus celiacus is very short and soon divides into the common hepatic artery, the gastrolienalis artery and the cranial mesenteric artery. The common hepatic artery branches into the a. hepatica propria that supplies the liver and arteries for the stomach, pancreas and duodenum. The a. gastrolienalis subsequently divides into the a. lienalis and a. gastrica sinistra. The a. mesenterica cranialis ramifies into the jejunal, ileal and colic arteries. Only approximately 1 cm caudal to the celiac trunk branches the right renal artery off the abdominal aorta. The left renal artery can be found a few mm more caudal. The caudal mesenteric artery branches off a few cm caudal to the left renal artery. This artery ramifies into the a.

#### **Figure 68.**

*Medial views of the nerves and blood vessels of the right forelimb. A: Plexus brachialis at the level of the shoulder joint with 1: n. thoracodorsalis, 2: n. axillaris, 3: n. radialis, 4: rami musculares, 5: n. musculocutaneus, 6: n. medianus, 7: n. ulnaris, 8: n. cutaneus brachii et antebrachii medialis, 9: a. axillaris, 10: a. circumflexa humeri cranialis, 11: a. subscapularis, 12: a. profunda brachii, 13: a. brachialis. B: Blood vessels and nerves at the level of the elbow joint with 1: n. medianus, 2: n. ulnaris, 3: n. musculocutaneus, 4: n. cutaneus brachii et antebrachii medialis, 5: Rami musculares, 6: n. cutaneus antebrachii lateralis, 7: n. radialis, 8: a. brachialis, 9: a. radialis, 10: a. ulnaris.*

colica sinistra, a. sigmoidea and a. rectalis cranialis. Just cranial to the terminal bifurcation of the abdominal aorta into the common iliac arteries can the origin of the a. circumflexa ilium profunda be found.

Regarding the venous system, the reader should be reminded of the fact that the arterial truncus celiacus has no venous counterpart. The portal vein is described above (**Figure 51**). The veins of the caudal segment of the caudal vena cava can be studied by means of **Figure 70**.

#### **7.4 Pelvic limb**

The abdominal aorta divides into the left and right common iliac arteries within the pelvic cavity. These arteries subsequently divide into the external and internal iliac arteries (**Figure 69**). In the proximal part of the thigh, the external iliac artery continues as the femoral artery, which is suitable for palpation of the pulse, after the a. profunda femoris has branched off. This artery gives origin to the lateral circumflex artery, which branches supply the vasti muscles. The femoral artery then divides into the saphena artery and the popliteal artery. The latter artery runs deep between both heads of the gastrocnemius muscle and gives the medial and lateral a. genus distalis as branches. These branches supply the knee region together with the a. genus proximalis of the a. saphena. This artery emerges in the angle formed by the sartorius and gracilis muscles and runs superficially to the medial side of the tibia. She subsequently migrates to the cranial aspect of the tarsus to become the a. dorsalis pedis

*Anatomy of the Rhesus Monkey (*Macaca mulatta*): The Essentials for the Biomedical Researcher DOI: http://dx.doi.org/10.5772/intechopen.99067*

#### **Figure 69.**

*Corrosion cast of the abdominal arteries, ventral view. 1: aorta abdominalis, 2: a. renalis dextra, 3: a. renalis sinistra, 4: a. adrenalis, 5: truncus celiacus, 6: a. hepatica communis, 7: a. gastrolienalis, 8: a. gastrica, 9: a. lienalis, 10: a. mesenterica cranialis, 11: aa. jejunales et ileales, 12: a. mesenterica caudalis, 13: a. circumflexa ilium profunda, 14: a. iliaca communis sinistra, 15: a. iliaca comunis dextra, 16: a. iliaca externa sinistra, 17: a. iliaca interna sinistra, 18: a. iliaca interna dextra, 19: a. iliaca externa dextra.*

(superficialis et profunda). From the popliteal artery branches the a. tibialis cranialis. She becomes the a. tibialis caudalis at the level of the lower leg. At the level of the foot, the a. tibialis caudalis divides into the a. plantaris lateralis et medialis. The arterial and nerve system of the hind limb are visualized in **Figures 71** and **73**.

In analogy with the thoracic limb, the venous drainage of the pelvic limb is mainly effectuated by the vv. comitantes. The vv. marginalis medialis et lateralis pedis drain the dorsal side of the foot. The v. marginalis medialis pedis drains into the superficially located v. saphena magna that proximately flows into the femoral vein. The v. marginalis lateralis pedis drains into the v. saphena parva. It is an important vein as it drains the larger part of the hind leg and is suitable for venipuncture at the caudal aspect of the calf (**Figure 72**). In the popliteal fossa, she drains into the popliteal vein. This vein runs adjacent to the eponymous artery and flows into the femoral vein. This vein is also suitable for venipuncture. The femoral vein proximally drains into the external iliac vein that in turn flows into the common iliac vein.

#### **Figure 70.**

*Latex cast of the caudal segment of the caudal cava vein of the male rhesus monkey, ventral view. 1: v. cava caudalis, 2a: v. renalis dextra, 2b: v. renalis sinistra, 3: v. adrenalis sinistra, 4a: v. testicularis dextra, 4b: v. testicularis sinistra, 5: v. mesenterica caudalis, 6a: v. circumflexa ilium profunda dextra, 6b: v. circumflexa ilium profunda sinistra, 7a: v. iliaca communis dextra, 7b: v. iliaca communis sinistra, 8a: v. iliaca externa dextra, 8b: v. iliaca externa sinistra, 9a: v. profunda femoris dextra, 9b: v. profunda femoris sinistra, 10a: v. circumflexa femoris lateralis dextra, 10b: v. circumflexa femoris lateralis sinistra, 11a: v. femoralis dextra, 11b: v. femoralis sinistra, 12a: v. iliaca interna dextra, 12b: v. iliaca interna sinistra, 13a + 14a: v. gluteus cranialis superficialis dextra, 13b + 14b: v. gluteus cranialis superficialis sinistra, 15a + 15b: Continuation of v. iliaca interna dextra et sinistra, 16a: v. obturatoria dextra, 16b: v. obturatoria sinistra.*

The nerves of the hind limb originate from the lumbosacral plexus. The femoral nerve is associated with the eponymous blood vessels. Its muscular branches innervate the extensor muscles of the knee. In addition, cranial cutaneous branches innervate the skin at the craniomedial side of the upper leg and the medial side of the knee. The distal continuation of the femoral nerve is the n. saphenus that accompanies the a. saphena and innervates the skin at the craniomedial aspect of the lower leg. The n. gluteus caudalis, that innervates the m. gluteus superficialis, emerges together with the sciatic nerve. This nerve divides into the n. fibularis communis and n. tibialis. The former nerve deviates towards the lateral head of the gastrocnemius muscle. Halfway the upper leg, the n. cutaneus surae lateralis branches off to innervate the skin at the caudolateral side of the lower leg. Here, nerve biopsy can be performed. At the level of the knee, the n. fibularis communis divides into the n. fibularis superficialis et profundus. The latter travels deep to the fibularis longus and extensor digitorum

*Anatomy of the Rhesus Monkey (*Macaca mulatta*): The Essentials for the Biomedical Researcher DOI: http://dx.doi.org/10.5772/intechopen.99067*

#### **Figure 71.**

*Vasculature and nerves of the pelvic limb. A: Dorsomedial view of the right upper leg with 1: a. femoralis, 2: a. circumflexa femoris lateralis, 3: a. profunda femoris, 4: n. femoralis, 5: rami cutanei craniales, 6: n. saphenus. B: Medial view of the thigh and knee of the left leg with 1: a. femoralis, 2: a. genus proximalis, 3: a. saphena: 4: a. dorsalis pedis profunda: 5: a. dorsalis pedis superficialis, 6: n. saphenus. C: Caudal view of the popliteal region of the left leg with 1: a. poplitea, 2: a. tibialis cranialis, 3: a. tibialis caudalis, 4: n. tibialis.*

#### **Figure 72.**

*Superficial veins of the pelvic limb. A: Subcutaneous localization of the v. saphena parva. B: Catheterization of the v. saphena parva.*

longus muscles to innervate the flexors of the tarsal joint and the extensors of the toes. The former gives off ramifications to the fibularis muscles and branches into the skin at the dorsolateral side of the foot. The tibial nerve presents several ramifications at the level of the knee. The majority migrate between the heads of the gastrocnemius

#### **Figure 73.**

*Nerves and blood vessels of the right pelvic limb. Laterocaudal view of the right knee with 1: n. tibialis, 2: n. cutaneus surae medialis, 3: rami musculares, 4: n. fibularis communis, 5: n. cutaneus surae lateralis. B: Laterocaudal, superficial view of the lower leg with 1: n. fibularis profundus, 2: n. fibularis superficialis, 3: n. cutaneus pedis dorsalis medialis, 4: n. cutaneus pedis dorsalis intermedius. C: Laterocaudal, deep view of the lower leg with 1: n. tibialis, 2: n. cutaneus surae medialis, 3: n. suralis, 4: n. fibularis communis, 5: a. et v. poplitea, 6: v. saphena parva.*

muscle to innervate the popliteus muscle, the extensors of the tarsal joint and the flexor musculature of the toes. A specific branch, the n. cutaneus surae caudalis, innervates the skin at the caudal side of the lower leg. More distally, it runs more laterally and is then called the n. suralis. Just proximal to the medial ankle, the tibial nerve divides into the medial and lateral plantar nerves. The n. flexoris femoris runs adjacent to the proximal part of the tibial nerve and branches into the hamstrings.
